Recently the kernel got the kmem_cache iterator to traverse metadata of
slab objects. This can be used to symbolize dynamic locks in a slab.
The new slab_caches hash map will have the pointer of the kmem_cache as
a key and save the name and a id. The id will be saved in the flags
part of the lock.
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
tools/perf/util/bpf_lock_contention.c | 50 +++++++++++++++++++
.../perf/util/bpf_skel/lock_contention.bpf.c | 28 +++++++++++
tools/perf/util/bpf_skel/lock_data.h | 12 +++++
tools/perf/util/bpf_skel/vmlinux/vmlinux.h | 8 +++
4 files changed, 98 insertions(+)
diff --git a/tools/perf/util/bpf_lock_contention.c b/tools/perf/util/bpf_lock_contention.c
index 41a1ad08789511c3..558590c3111390fc 100644
--- a/tools/perf/util/bpf_lock_contention.c
+++ b/tools/perf/util/bpf_lock_contention.c
@@ -12,12 +12,59 @@
#include <linux/zalloc.h>
#include <linux/string.h>
#include <bpf/bpf.h>
+#include <bpf/btf.h>
#include <inttypes.h>
#include "bpf_skel/lock_contention.skel.h"
#include "bpf_skel/lock_data.h"
static struct lock_contention_bpf *skel;
+static bool has_slab_iter;
+
+static void check_slab_cache_iter(struct lock_contention *con)
+{
+ struct btf *btf = btf__load_vmlinux_btf();
+ s32 ret;
+
+ if (btf == NULL) {
+ pr_debug("BTF loading failed: %s\n", strerror(errno));
+ return;
+ }
+
+ ret = btf__find_by_name_kind(btf, "bpf_iter__kmem_cache", BTF_KIND_STRUCT);
+ if (ret < 0) {
+ bpf_program__set_autoload(skel->progs.slab_cache_iter, false);
+ pr_debug("slab cache iterator is not available: %d\n", ret);
+ goto out;
+ }
+
+ has_slab_iter = true;
+
+ bpf_map__set_max_entries(skel->maps.slab_caches, con->map_nr_entries);
+out:
+ btf__free(btf);
+}
+
+static void run_slab_cache_iter(void)
+{
+ int fd;
+ char buf[256];
+
+ if (!has_slab_iter)
+ return;
+
+ fd = bpf_iter_create(bpf_link__fd(skel->links.slab_cache_iter));
+ if (fd < 0) {
+ pr_debug("cannot create slab cache iter: %d\n", fd);
+ return;
+ }
+
+ /* This will run the bpf program */
+ while (read(fd, buf, sizeof(buf)) > 0)
+ continue;
+
+ close(fd);
+}
int lock_contention_prepare(struct lock_contention *con)
{
@@ -109,6 +156,8 @@ int lock_contention_prepare(struct lock_contention *con)
skel->rodata->use_cgroup_v2 = 1;
}
+ check_slab_cache_iter(con);
+
if (lock_contention_bpf__load(skel) < 0) {
pr_err("Failed to load lock-contention BPF skeleton\n");
return -1;
@@ -304,6 +353,7 @@ static void account_end_timestamp(struct lock_contention *con)
int lock_contention_start(void)
{
+ run_slab_cache_iter();
skel->bss->enabled = 1;
return 0;
}
diff --git a/tools/perf/util/bpf_skel/lock_contention.bpf.c b/tools/perf/util/bpf_skel/lock_contention.bpf.c
index 1069bda5d733887f..fd24ccb00faec0ba 100644
--- a/tools/perf/util/bpf_skel/lock_contention.bpf.c
+++ b/tools/perf/util/bpf_skel/lock_contention.bpf.c
@@ -100,6 +100,13 @@ struct {
__uint(max_entries, 1);
} cgroup_filter SEC(".maps");
+struct {
+ __uint(type, BPF_MAP_TYPE_HASH);
+ __uint(key_size, sizeof(long));
+ __uint(value_size, sizeof(struct slab_cache_data));
+ __uint(max_entries, 1);
+} slab_caches SEC(".maps");
+
struct rw_semaphore___old {
struct task_struct *owner;
} __attribute__((preserve_access_index));
@@ -136,6 +143,8 @@ int perf_subsys_id = -1;
__u64 end_ts;
+__u32 slab_cache_id;
+
/* error stat */
int task_fail;
int stack_fail;
@@ -563,4 +572,23 @@ int BPF_PROG(end_timestamp)
return 0;
}
+SEC("iter/kmem_cache")
+int slab_cache_iter(struct bpf_iter__kmem_cache *ctx)
+{
+ struct kmem_cache *s = ctx->s;
+ struct slab_cache_data d;
+
+ if (s == NULL)
+ return 0;
+
+ d.id = ++slab_cache_id << LCB_F_SLAB_ID_SHIFT;
+ bpf_probe_read_kernel_str(d.name, sizeof(d.name), s->name);
+
+ if (d.id >= LCB_F_SLAB_ID_END)
+ return 0;
+
+ bpf_map_update_elem(&slab_caches, &s, &d, BPF_NOEXIST);
+ return 0;
+}
+
char LICENSE[] SEC("license") = "Dual BSD/GPL";
diff --git a/tools/perf/util/bpf_skel/lock_data.h b/tools/perf/util/bpf_skel/lock_data.h
index 4f0aae5483745dfa..c15f734d7fc4aecb 100644
--- a/tools/perf/util/bpf_skel/lock_data.h
+++ b/tools/perf/util/bpf_skel/lock_data.h
@@ -32,9 +32,16 @@ struct contention_task_data {
#define LCD_F_MMAP_LOCK (1U << 31)
#define LCD_F_SIGHAND_LOCK (1U << 30)
+#define LCB_F_SLAB_ID_SHIFT 16
+#define LCB_F_SLAB_ID_START (1U << 16)
+#define LCB_F_SLAB_ID_END (1U << 26)
+#define LCB_F_SLAB_ID_MASK 0x03FF0000U
+
#define LCB_F_TYPE_MAX (1U << 7)
#define LCB_F_TYPE_MASK 0x0000007FU
+#define SLAB_NAME_MAX 28
+
struct contention_data {
u64 total_time;
u64 min_time;
@@ -55,4 +62,9 @@ enum lock_class_sym {
LOCK_CLASS_RQLOCK,
};
+struct slab_cache_data {
+ u32 id;
+ char name[SLAB_NAME_MAX];
+};
+
#endif /* UTIL_BPF_SKEL_LOCK_DATA_H */
diff --git a/tools/perf/util/bpf_skel/vmlinux/vmlinux.h b/tools/perf/util/bpf_skel/vmlinux/vmlinux.h
index 4dcad7b682bdee9c..7b81d3173917fdb5 100644
--- a/tools/perf/util/bpf_skel/vmlinux/vmlinux.h
+++ b/tools/perf/util/bpf_skel/vmlinux/vmlinux.h
@@ -195,4 +195,12 @@ struct bpf_perf_event_data_kern {
*/
struct rq {};
+struct kmem_cache {
+ const char *name;
+} __attribute__((preserve_access_index));
+
+struct bpf_iter__kmem_cache {
+ struct kmem_cache *s;
+} __attribute__((preserve_access_index));
+
#endif // __VMLINUX_H
--
2.47.0.277.g8800431eea-googOn Thu, Nov 07, 2024 at 10:14:57PM -0800, Namhyung Kim wrote:
> Recently the kernel got the kmem_cache iterator to traverse metadata of
> slab objects. This can be used to symbolize dynamic locks in a slab.
>
> The new slab_caches hash map will have the pointer of the kmem_cache as
> a key and save the name and a id. The id will be saved in the flags
> part of the lock.
Trying to fix this
cd . && make GEN_VMLINUX_H=1 FEATURES_DUMP=/home/acme/git/perf-tools-next/tools/perf/BUILD_TEST_FEATURE_DUMP -j28 O=/tmp/tmp.DWo9tIFvWU DESTDIR=/tmp/tmp.ex3iljqLBT
BUILD: Doing 'make -j28' parallel build
Warning: Kernel ABI header differences:
diff -u tools/include/uapi/drm/drm.h include/uapi/drm/drm.h
diff -u tools/include/uapi/linux/kvm.h include/uapi/linux/kvm.h
diff -u tools/include/uapi/linux/perf_event.h include/uapi/linux/perf_event.h
diff -u tools/arch/x86/include/asm/cpufeatures.h arch/x86/include/asm/cpufeatures.h
diff -u tools/arch/x86/include/uapi/asm/kvm.h arch/x86/include/uapi/asm/kvm.h
diff -u tools/arch/arm64/include/uapi/asm/kvm.h arch/arm64/include/uapi/asm/kvm.h
diff -u tools/arch/arm64/include/uapi/asm/unistd.h arch/arm64/include/uapi/asm/unistd.h
diff -u tools/include/uapi/asm-generic/unistd.h include/uapi/asm-generic/unistd.h
diff -u tools/include/uapi/asm-generic/mman.h include/uapi/asm-generic/mman.h
diff -u tools/perf/arch/x86/entry/syscalls/syscall_32.tbl arch/x86/entry/syscalls/syscall_32.tbl
diff -u tools/perf/arch/x86/entry/syscalls/syscall_64.tbl arch/x86/entry/syscalls/syscall_64.tbl
diff -u tools/perf/arch/powerpc/entry/syscalls/syscall.tbl arch/powerpc/kernel/syscalls/syscall.tbl
diff -u tools/perf/arch/s390/entry/syscalls/syscall.tbl arch/s390/kernel/syscalls/syscall.tbl
diff -u tools/perf/arch/mips/entry/syscalls/syscall_n64.tbl arch/mips/kernel/syscalls/syscall_n64.tbl
diff -u tools/perf/trace/beauty/include/uapi/linux/fcntl.h include/uapi/linux/fcntl.h
diff -u tools/perf/trace/beauty/include/uapi/linux/mount.h include/uapi/linux/mount.h
diff -u tools/perf/trace/beauty/include/uapi/linux/prctl.h include/uapi/linux/prctl.h
Makefile.config:989: No libllvm 13+ found, slower source file resolution, please install llvm-devel/llvm-dev
Makefile.config:1171: No openjdk development package found, please install JDK package, e.g. openjdk-8-jdk, java-1.8.0-openjdk-devel
GEN /tmp/tmp.DWo9tIFvWU/common-cmds.h
CC /tmp/tmp.DWo9tIFvWU/dlfilters/dlfilter-test-api-v0.o
CC /tmp/tmp.DWo9tIFvWU/dlfilters/dlfilter-test-api-v2.o
CC /tmp/tmp.DWo9tIFvWU/dlfilters/dlfilter-show-cycles.o
GEN /tmp/tmp.DWo9tIFvWU/arch/arm64/include/generated/asm/sysreg-defs.h
LINK /tmp/tmp.DWo9tIFvWU/dlfilters/dlfilter-test-api-v2.so
LINK /tmp/tmp.DWo9tIFvWU/dlfilters/dlfilter-show-cycles.so
LINK /tmp/tmp.DWo9tIFvWU/dlfilters/dlfilter-test-api-v0.so
PERF_VERSION = 6.13.rc1.g61c6ae4ddd41
GEN perf-iostat
GEN perf-archive
INSTALL /tmp/tmp.DWo9tIFvWU/libsubcmd/include/subcmd/exec-cmd.h
INSTALL /tmp/tmp.DWo9tIFvWU/libsubcmd/include/subcmd/help.h
INSTALL /tmp/tmp.DWo9tIFvWU/libsubcmd/include/subcmd/pager.h
INSTALL /tmp/tmp.DWo9tIFvWU/libsubcmd/include/subcmd/parse-options.h
INSTALL /tmp/tmp.DWo9tIFvWU/libsubcmd/include/subcmd/run-command.h
INSTALL libsubcmd_headers
INSTALL /tmp/tmp.DWo9tIFvWU/libperf/include/perf/bpf_perf.h
INSTALL /tmp/tmp.DWo9tIFvWU/libperf/include/perf/core.h
INSTALL /tmp/tmp.DWo9tIFvWU/libperf/include/perf/cpumap.h
INSTALL /tmp/tmp.DWo9tIFvWU/libperf/include/perf/threadmap.h
INSTALL /tmp/tmp.DWo9tIFvWU/libperf/include/perf/evlist.h
INSTALL /tmp/tmp.DWo9tIFvWU/libperf/include/perf/evsel.h
INSTALL /tmp/tmp.DWo9tIFvWU/libperf/include/perf/event.h
INSTALL /tmp/tmp.DWo9tIFvWU/libperf/include/perf/mmap.h
CC /tmp/tmp.DWo9tIFvWU/libperf/core.o
INSTALL /tmp/tmp.DWo9tIFvWU/libperf/include/internal/cpumap.h
INSTALL /tmp/tmp.DWo9tIFvWU/libperf/include/internal/evlist.h
INSTALL /tmp/tmp.DWo9tIFvWU/libapi/include/api/cpu.h
CC /tmp/tmp.DWo9tIFvWU/libperf/cpumap.o
INSTALL /tmp/tmp.DWo9tIFvWU/libsymbol/include/symbol/kallsyms.h
INSTALL /tmp/tmp.DWo9tIFvWU/libperf/include/internal/evsel.h
INSTALL /tmp/tmp.DWo9tIFvWU/libapi/include/api/io.h
INSTALL /tmp/tmp.DWo9tIFvWU/libapi/include/api/debug.h
INSTALL /tmp/tmp.DWo9tIFvWU/libperf/include/internal/lib.h
CC /tmp/tmp.DWo9tIFvWU/libsymbol/kallsyms.o
CC /tmp/tmp.DWo9tIFvWU/libperf/threadmap.o
GEN /tmp/tmp.DWo9tIFvWU/libbpf/bpf_helper_defs.h
INSTALL /tmp/tmp.DWo9tIFvWU/libperf/include/internal/mmap.h
MKDIR /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/include/bpf
CC /tmp/tmp.DWo9tIFvWU/libperf/evsel.o
INSTALL /tmp/tmp.DWo9tIFvWU/libperf/include/internal/rc_check.h
INSTALL /tmp/tmp.DWo9tIFvWU/libapi/include/api/fd/array.h
INSTALL /tmp/tmp.DWo9tIFvWU/libperf/include/internal/threadmap.h
INSTALL /tmp/tmp.DWo9tIFvWU/libbpf/include/bpf/bpf.h
CC /tmp/tmp.DWo9tIFvWU/libperf/evlist.o
INSTALL /tmp/tmp.DWo9tIFvWU/libapi/include/api/fs/fs.h
CC /tmp/tmp.DWo9tIFvWU/libapi/cpu.o
INSTALL libsymbol_headers
INSTALL /tmp/tmp.DWo9tIFvWU/libapi/include/api/fs/tracing_path.h
MKDIR /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/
INSTALL /tmp/tmp.DWo9tIFvWU/libbpf/include/bpf/libbpf.h
CC /tmp/tmp.DWo9tIFvWU/libperf/mmap.o
MKDIR /tmp/tmp.DWo9tIFvWU/libapi/fd/
INSTALL /tmp/tmp.DWo9tIFvWU/libperf/include/internal/xyarray.h
MKDIR /tmp/tmp.DWo9tIFvWU/libapi/fs/
INSTALL /tmp/tmp.DWo9tIFvWU/libbpf/include/bpf/btf.h
CC /tmp/tmp.DWo9tIFvWU/libperf/zalloc.o
CC /tmp/tmp.DWo9tIFvWU/libapi/debug.o
CC /tmp/tmp.DWo9tIFvWU/libapi/fd/array.o
CC /tmp/tmp.DWo9tIFvWU/libapi/fs/fs.o
INSTALL /tmp/tmp.DWo9tIFvWU/libbpf/include/bpf/libbpf_common.h
INSTALL /tmp/tmp.DWo9tIFvWU/libbpf/include/bpf/libbpf_legacy.h
CC /tmp/tmp.DWo9tIFvWU/libapi/str_error_r.o
INSTALL /tmp/tmp.DWo9tIFvWU/libbpf/include/bpf/bpf_helpers.h
MKDIR /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/
INSTALL libperf_headers
INSTALL libapi_headers
INSTALL /tmp/tmp.DWo9tIFvWU/libbpf/include/bpf/bpf_tracing.h
CC /tmp/tmp.DWo9tIFvWU/libapi/fs/tracing_path.o
INSTALL /tmp/tmp.DWo9tIFvWU/libbpf/include/bpf/bpf_endian.h
CC /tmp/tmp.DWo9tIFvWU/libperf/xyarray.o
CC /tmp/tmp.DWo9tIFvWU/libapi/fs/cgroup.o
INSTALL /tmp/tmp.DWo9tIFvWU/libbpf/include/bpf/bpf_core_read.h
INSTALL /tmp/tmp.DWo9tIFvWU/libbpf/include/bpf/skel_internal.h
INSTALL /tmp/tmp.DWo9tIFvWU/libbpf/include/bpf/libbpf_version.h
CC /tmp/tmp.DWo9tIFvWU/libperf/lib.o
INSTALL /tmp/tmp.DWo9tIFvWU/libbpf/include/bpf/usdt.bpf.h
INSTALL /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/include/bpf/hashmap.h
INSTALL /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/include/bpf/relo_core.h
INSTALL /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/include/bpf/libbpf_internal.h
CC /tmp/tmp.DWo9tIFvWU/libsubcmd/help.o
CC /tmp/tmp.DWo9tIFvWU/libsubcmd/exec-cmd.o
CC /tmp/tmp.DWo9tIFvWU/libsubcmd/pager.o
CC /tmp/tmp.DWo9tIFvWU/libsubcmd/parse-options.o
CC /tmp/tmp.DWo9tIFvWU/libsubcmd/run-command.o
CC /tmp/tmp.DWo9tIFvWU/libsubcmd/sigchain.o
CC /tmp/tmp.DWo9tIFvWU/libsubcmd/subcmd-config.o
INSTALL /tmp/tmp.DWo9tIFvWU/libbpf/include/bpf/bpf_helper_defs.h
INSTALL libbpf_headers
GEN /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/bpf_helper_defs.h
INSTALL /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/include/bpf/bpf.h
INSTALL /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/include/bpf/libbpf.h
INSTALL /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/include/bpf/btf.h
INSTALL /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/include/bpf/libbpf_common.h
INSTALL /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/include/bpf/libbpf_legacy.h
INSTALL /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/include/bpf/bpf_helpers.h
INSTALL /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/include/bpf/bpf_tracing.h
INSTALL /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/include/bpf/bpf_endian.h
INSTALL /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/include/bpf/bpf_core_read.h
INSTALL /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/include/bpf/skel_internal.h
INSTALL /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/include/bpf/libbpf_version.h
INSTALL /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/include/bpf/usdt.bpf.h
LD /tmp/tmp.DWo9tIFvWU/libapi/fd/libapi-in.o
LD /tmp/tmp.DWo9tIFvWU/libsymbol/libsymbol-in.o
AR /tmp/tmp.DWo9tIFvWU/libsymbol/libsymbol.a
LD /tmp/tmp.DWo9tIFvWU/libapi/fs/libapi-in.o
INSTALL /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/include/bpf/bpf_helper_defs.h
INSTALL libbpf_headers
LD /tmp/tmp.DWo9tIFvWU/libapi/libapi-in.o
CC /tmp/tmp.DWo9tIFvWU/libbpf/staticobjs/libbpf.o
CC /tmp/tmp.DWo9tIFvWU/libbpf/staticobjs/bpf.o
CC /tmp/tmp.DWo9tIFvWU/libbpf/staticobjs/nlattr.o
CC /tmp/tmp.DWo9tIFvWU/libbpf/staticobjs/btf.o
CC /tmp/tmp.DWo9tIFvWU/libbpf/staticobjs/libbpf_errno.o
CC /tmp/tmp.DWo9tIFvWU/libbpf/staticobjs/str_error.o
LD /tmp/tmp.DWo9tIFvWU/libperf/libperf-in.o
AR /tmp/tmp.DWo9tIFvWU/libapi/libapi.a
CC /tmp/tmp.DWo9tIFvWU/libbpf/staticobjs/netlink.o
CC /tmp/tmp.DWo9tIFvWU/libbpf/staticobjs/bpf_prog_linfo.o
CC /tmp/tmp.DWo9tIFvWU/libbpf/staticobjs/libbpf_probes.o
CC /tmp/tmp.DWo9tIFvWU/libbpf/staticobjs/hashmap.o
CC /tmp/tmp.DWo9tIFvWU/libbpf/staticobjs/btf_dump.o
CC /tmp/tmp.DWo9tIFvWU/libbpf/staticobjs/ringbuf.o
CC /tmp/tmp.DWo9tIFvWU/libbpf/staticobjs/strset.o
CC /tmp/tmp.DWo9tIFvWU/libbpf/staticobjs/linker.o
CC /tmp/tmp.DWo9tIFvWU/libbpf/staticobjs/gen_loader.o
CC /tmp/tmp.DWo9tIFvWU/libbpf/staticobjs/relo_core.o
CC /tmp/tmp.DWo9tIFvWU/libbpf/staticobjs/usdt.o
AR /tmp/tmp.DWo9tIFvWU/libperf/libperf.a
CC /tmp/tmp.DWo9tIFvWU/libbpf/staticobjs/zip.o
CC /tmp/tmp.DWo9tIFvWU/libbpf/staticobjs/elf.o
CC /tmp/tmp.DWo9tIFvWU/libbpf/staticobjs/features.o
CC /tmp/tmp.DWo9tIFvWU/libbpf/staticobjs/btf_iter.o
CC /tmp/tmp.DWo9tIFvWU/libbpf/staticobjs/btf_relocate.o
CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/libbpf.o
CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/bpf.o
CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/nlattr.o
CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/btf.o
CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/libbpf_errno.o
CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/str_error.o
CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/netlink.o
CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/bpf_prog_linfo.o
CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/libbpf_probes.o
CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/hashmap.o
CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/btf_dump.o
CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/ringbuf.o
CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/strset.o
CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/linker.o
CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/gen_loader.o
CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/relo_core.o
CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/usdt.o
CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/zip.o
CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/elf.o
CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/features.o
CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/btf_iter.o
CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/btf_relocate.o
LD /tmp/tmp.DWo9tIFvWU/libsubcmd/libsubcmd-in.o
AR /tmp/tmp.DWo9tIFvWU/libsubcmd/libsubcmd.a
LD /tmp/tmp.DWo9tIFvWU/libbpf/staticobjs/libbpf-in.o
LINK /tmp/tmp.DWo9tIFvWU/libbpf/libbpf.a
LD /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/libbpf-in.o
LINK /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/libbpf.a
CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/main.o
CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/common.o
CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/json_writer.o
CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/gen.o
CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/btf.o
LINK /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/bpftool
GEN /tmp/tmp.DWo9tIFvWU/util/bpf_skel/vmlinux.h
CLANG /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bpf_prog_profiler.bpf.o
CLANG /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bperf_leader.bpf.o
CLANG /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bperf_follower.bpf.o
CLANG /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bperf_cgroup.bpf.o
CLANG /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/func_latency.bpf.o
CLANG /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/off_cpu.bpf.o
CLANG /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/lock_contention.bpf.o
CLANG /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/kwork_trace.bpf.o
CLANG /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/sample_filter.bpf.o
CLANG /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/kwork_top.bpf.o
CLANG /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bench_uprobe.bpf.o
CLANG /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/augmented_raw_syscalls.bpf.o
GENSKEL /tmp/tmp.DWo9tIFvWU/util/bpf_skel/bench_uprobe.skel.h
GENSKEL /tmp/tmp.DWo9tIFvWU/util/bpf_skel/func_latency.skel.h
util/bpf_skel/lock_contention.bpf.c:612:28: error: declaration of 'struct bpf_iter__kmem_cache' will not be visible outside of this function [-Werror,-Wvisibility]
612 | int slab_cache_iter(struct bpf_iter__kmem_cache *ctx)
| ^
util/bpf_skel/lock_contention.bpf.c:614:28: error: incomplete definition of type 'struct bpf_iter__kmem_cache'
614 | struct kmem_cache *s = ctx->s;
| ~~~^
util/bpf_skel/lock_contention.bpf.c:612:28: note: forward declaration of 'struct bpf_iter__kmem_cache'
612 | int slab_cache_iter(struct bpf_iter__kmem_cache *ctx)
| ^
2 errors generated.
make[4]: *** [Makefile.perf:1248: /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/lock_contention.bpf.o] Error 1
make[4]: *** Waiting for unfinished jobs....
make[3]: *** [Makefile.perf:292: sub-make] Error 2
make[2]: *** [Makefile:76: all] Error 2
make[1]: *** [tests/make:344: make_gen_vmlinux_h_O] Error 1
make: *** [Makefile:109: build-test] Error 2
make: Leaving directory '/home/acme/git/perf-tools-next/tools/perf'
real 3m43.896s
user 29m30.716s
sys 6m36.609s
⬢ [acme@toolbox perf-tools-next]$
> Signed-off-by: Namhyung Kim <namhyung@kernel.org>
> ---
> tools/perf/util/bpf_lock_contention.c | 50 +++++++++++++++++++
> .../perf/util/bpf_skel/lock_contention.bpf.c | 28 +++++++++++
> tools/perf/util/bpf_skel/lock_data.h | 12 +++++
> tools/perf/util/bpf_skel/vmlinux/vmlinux.h | 8 +++
> 4 files changed, 98 insertions(+)
>
> diff --git a/tools/perf/util/bpf_lock_contention.c b/tools/perf/util/bpf_lock_contention.c
> index 41a1ad08789511c3..558590c3111390fc 100644
> --- a/tools/perf/util/bpf_lock_contention.c
> +++ b/tools/perf/util/bpf_lock_contention.c
> @@ -12,12 +12,59 @@
> #include <linux/zalloc.h>
> #include <linux/string.h>
> #include <bpf/bpf.h>
> +#include <bpf/btf.h>
> #include <inttypes.h>
>
> #include "bpf_skel/lock_contention.skel.h"
> #include "bpf_skel/lock_data.h"
>
> static struct lock_contention_bpf *skel;
> +static bool has_slab_iter;
> +
> +static void check_slab_cache_iter(struct lock_contention *con)
> +{
> + struct btf *btf = btf__load_vmlinux_btf();
> + s32 ret;
> +
> + if (btf == NULL) {
> + pr_debug("BTF loading failed: %s\n", strerror(errno));
> + return;
> + }
> +
> + ret = btf__find_by_name_kind(btf, "bpf_iter__kmem_cache", BTF_KIND_STRUCT);
> + if (ret < 0) {
> + bpf_program__set_autoload(skel->progs.slab_cache_iter, false);
> + pr_debug("slab cache iterator is not available: %d\n", ret);
> + goto out;
> + }
> +
> + has_slab_iter = true;
> +
> + bpf_map__set_max_entries(skel->maps.slab_caches, con->map_nr_entries);
> +out:
> + btf__free(btf);
> +}
> +
> +static void run_slab_cache_iter(void)
> +{
> + int fd;
> + char buf[256];
> +
> + if (!has_slab_iter)
> + return;
> +
> + fd = bpf_iter_create(bpf_link__fd(skel->links.slab_cache_iter));
> + if (fd < 0) {
> + pr_debug("cannot create slab cache iter: %d\n", fd);
> + return;
> + }
> +
> + /* This will run the bpf program */
> + while (read(fd, buf, sizeof(buf)) > 0)
> + continue;
> +
> + close(fd);
> +}
>
> int lock_contention_prepare(struct lock_contention *con)
> {
> @@ -109,6 +156,8 @@ int lock_contention_prepare(struct lock_contention *con)
> skel->rodata->use_cgroup_v2 = 1;
> }
>
> + check_slab_cache_iter(con);
> +
> if (lock_contention_bpf__load(skel) < 0) {
> pr_err("Failed to load lock-contention BPF skeleton\n");
> return -1;
> @@ -304,6 +353,7 @@ static void account_end_timestamp(struct lock_contention *con)
>
> int lock_contention_start(void)
> {
> + run_slab_cache_iter();
> skel->bss->enabled = 1;
> return 0;
> }
> diff --git a/tools/perf/util/bpf_skel/lock_contention.bpf.c b/tools/perf/util/bpf_skel/lock_contention.bpf.c
> index 1069bda5d733887f..fd24ccb00faec0ba 100644
> --- a/tools/perf/util/bpf_skel/lock_contention.bpf.c
> +++ b/tools/perf/util/bpf_skel/lock_contention.bpf.c
> @@ -100,6 +100,13 @@ struct {
> __uint(max_entries, 1);
> } cgroup_filter SEC(".maps");
>
> +struct {
> + __uint(type, BPF_MAP_TYPE_HASH);
> + __uint(key_size, sizeof(long));
> + __uint(value_size, sizeof(struct slab_cache_data));
> + __uint(max_entries, 1);
> +} slab_caches SEC(".maps");
> +
> struct rw_semaphore___old {
> struct task_struct *owner;
> } __attribute__((preserve_access_index));
> @@ -136,6 +143,8 @@ int perf_subsys_id = -1;
>
> __u64 end_ts;
>
> +__u32 slab_cache_id;
> +
> /* error stat */
> int task_fail;
> int stack_fail;
> @@ -563,4 +572,23 @@ int BPF_PROG(end_timestamp)
> return 0;
> }
>
> +SEC("iter/kmem_cache")
> +int slab_cache_iter(struct bpf_iter__kmem_cache *ctx)
> +{
> + struct kmem_cache *s = ctx->s;
> + struct slab_cache_data d;
> +
> + if (s == NULL)
> + return 0;
> +
> + d.id = ++slab_cache_id << LCB_F_SLAB_ID_SHIFT;
> + bpf_probe_read_kernel_str(d.name, sizeof(d.name), s->name);
> +
> + if (d.id >= LCB_F_SLAB_ID_END)
> + return 0;
> +
> + bpf_map_update_elem(&slab_caches, &s, &d, BPF_NOEXIST);
> + return 0;
> +}
> +
> char LICENSE[] SEC("license") = "Dual BSD/GPL";
> diff --git a/tools/perf/util/bpf_skel/lock_data.h b/tools/perf/util/bpf_skel/lock_data.h
> index 4f0aae5483745dfa..c15f734d7fc4aecb 100644
> --- a/tools/perf/util/bpf_skel/lock_data.h
> +++ b/tools/perf/util/bpf_skel/lock_data.h
> @@ -32,9 +32,16 @@ struct contention_task_data {
> #define LCD_F_MMAP_LOCK (1U << 31)
> #define LCD_F_SIGHAND_LOCK (1U << 30)
>
> +#define LCB_F_SLAB_ID_SHIFT 16
> +#define LCB_F_SLAB_ID_START (1U << 16)
> +#define LCB_F_SLAB_ID_END (1U << 26)
> +#define LCB_F_SLAB_ID_MASK 0x03FF0000U
> +
> #define LCB_F_TYPE_MAX (1U << 7)
> #define LCB_F_TYPE_MASK 0x0000007FU
>
> +#define SLAB_NAME_MAX 28
> +
> struct contention_data {
> u64 total_time;
> u64 min_time;
> @@ -55,4 +62,9 @@ enum lock_class_sym {
> LOCK_CLASS_RQLOCK,
> };
>
> +struct slab_cache_data {
> + u32 id;
> + char name[SLAB_NAME_MAX];
> +};
> +
> #endif /* UTIL_BPF_SKEL_LOCK_DATA_H */
> diff --git a/tools/perf/util/bpf_skel/vmlinux/vmlinux.h b/tools/perf/util/bpf_skel/vmlinux/vmlinux.h
> index 4dcad7b682bdee9c..7b81d3173917fdb5 100644
> --- a/tools/perf/util/bpf_skel/vmlinux/vmlinux.h
> +++ b/tools/perf/util/bpf_skel/vmlinux/vmlinux.h
> @@ -195,4 +195,12 @@ struct bpf_perf_event_data_kern {
> */
> struct rq {};
>
> +struct kmem_cache {
> + const char *name;
> +} __attribute__((preserve_access_index));
> +
> +struct bpf_iter__kmem_cache {
> + struct kmem_cache *s;
> +} __attribute__((preserve_access_index));
> +
> #endif // __VMLINUX_H
> --
> 2.47.0.277.g8800431eea-goog
On Mon, Dec 09, 2024 at 01:36:52PM -0300, Arnaldo Carvalho de Melo wrote:
> On Thu, Nov 07, 2024 at 10:14:57PM -0800, Namhyung Kim wrote:
> > Recently the kernel got the kmem_cache iterator to traverse metadata of
> > slab objects. This can be used to symbolize dynamic locks in a slab.
> >
> > The new slab_caches hash map will have the pointer of the kmem_cache as
> > a key and save the name and a id. The id will be saved in the flags
> > part of the lock.
>
> Trying to fix this
So you have that struct in tools/perf/util/bpf_skel/vmlinux/vmlinux.h,
but then, this kernel is old and doesn't have the kmem_cache iterator,
so using the generated vmlinux.h will fail the build.
- Arnaldo
> cd . && make GEN_VMLINUX_H=1 FEATURES_DUMP=/home/acme/git/perf-tools-next/tools/perf/BUILD_TEST_FEATURE_DUMP -j28 O=/tmp/tmp.DWo9tIFvWU DESTDIR=/tmp/tmp.ex3iljqLBT
> BUILD: Doing 'make -j28' parallel build
> Warning: Kernel ABI header differences:
> diff -u tools/include/uapi/drm/drm.h include/uapi/drm/drm.h
> diff -u tools/include/uapi/linux/kvm.h include/uapi/linux/kvm.h
> diff -u tools/include/uapi/linux/perf_event.h include/uapi/linux/perf_event.h
> diff -u tools/arch/x86/include/asm/cpufeatures.h arch/x86/include/asm/cpufeatures.h
> diff -u tools/arch/x86/include/uapi/asm/kvm.h arch/x86/include/uapi/asm/kvm.h
> diff -u tools/arch/arm64/include/uapi/asm/kvm.h arch/arm64/include/uapi/asm/kvm.h
> diff -u tools/arch/arm64/include/uapi/asm/unistd.h arch/arm64/include/uapi/asm/unistd.h
> diff -u tools/include/uapi/asm-generic/unistd.h include/uapi/asm-generic/unistd.h
> diff -u tools/include/uapi/asm-generic/mman.h include/uapi/asm-generic/mman.h
> diff -u tools/perf/arch/x86/entry/syscalls/syscall_32.tbl arch/x86/entry/syscalls/syscall_32.tbl
> diff -u tools/perf/arch/x86/entry/syscalls/syscall_64.tbl arch/x86/entry/syscalls/syscall_64.tbl
> diff -u tools/perf/arch/powerpc/entry/syscalls/syscall.tbl arch/powerpc/kernel/syscalls/syscall.tbl
> diff -u tools/perf/arch/s390/entry/syscalls/syscall.tbl arch/s390/kernel/syscalls/syscall.tbl
> diff -u tools/perf/arch/mips/entry/syscalls/syscall_n64.tbl arch/mips/kernel/syscalls/syscall_n64.tbl
> diff -u tools/perf/trace/beauty/include/uapi/linux/fcntl.h include/uapi/linux/fcntl.h
> diff -u tools/perf/trace/beauty/include/uapi/linux/mount.h include/uapi/linux/mount.h
> diff -u tools/perf/trace/beauty/include/uapi/linux/prctl.h include/uapi/linux/prctl.h
> Makefile.config:989: No libllvm 13+ found, slower source file resolution, please install llvm-devel/llvm-dev
> Makefile.config:1171: No openjdk development package found, please install JDK package, e.g. openjdk-8-jdk, java-1.8.0-openjdk-devel
>
> GEN /tmp/tmp.DWo9tIFvWU/common-cmds.h
> CC /tmp/tmp.DWo9tIFvWU/dlfilters/dlfilter-test-api-v0.o
> CC /tmp/tmp.DWo9tIFvWU/dlfilters/dlfilter-test-api-v2.o
> CC /tmp/tmp.DWo9tIFvWU/dlfilters/dlfilter-show-cycles.o
> GEN /tmp/tmp.DWo9tIFvWU/arch/arm64/include/generated/asm/sysreg-defs.h
> LINK /tmp/tmp.DWo9tIFvWU/dlfilters/dlfilter-test-api-v2.so
> LINK /tmp/tmp.DWo9tIFvWU/dlfilters/dlfilter-show-cycles.so
> LINK /tmp/tmp.DWo9tIFvWU/dlfilters/dlfilter-test-api-v0.so
> PERF_VERSION = 6.13.rc1.g61c6ae4ddd41
> GEN perf-iostat
> GEN perf-archive
> INSTALL /tmp/tmp.DWo9tIFvWU/libsubcmd/include/subcmd/exec-cmd.h
> INSTALL /tmp/tmp.DWo9tIFvWU/libsubcmd/include/subcmd/help.h
> INSTALL /tmp/tmp.DWo9tIFvWU/libsubcmd/include/subcmd/pager.h
> INSTALL /tmp/tmp.DWo9tIFvWU/libsubcmd/include/subcmd/parse-options.h
> INSTALL /tmp/tmp.DWo9tIFvWU/libsubcmd/include/subcmd/run-command.h
> INSTALL libsubcmd_headers
> INSTALL /tmp/tmp.DWo9tIFvWU/libperf/include/perf/bpf_perf.h
> INSTALL /tmp/tmp.DWo9tIFvWU/libperf/include/perf/core.h
> INSTALL /tmp/tmp.DWo9tIFvWU/libperf/include/perf/cpumap.h
> INSTALL /tmp/tmp.DWo9tIFvWU/libperf/include/perf/threadmap.h
> INSTALL /tmp/tmp.DWo9tIFvWU/libperf/include/perf/evlist.h
> INSTALL /tmp/tmp.DWo9tIFvWU/libperf/include/perf/evsel.h
> INSTALL /tmp/tmp.DWo9tIFvWU/libperf/include/perf/event.h
> INSTALL /tmp/tmp.DWo9tIFvWU/libperf/include/perf/mmap.h
> CC /tmp/tmp.DWo9tIFvWU/libperf/core.o
> INSTALL /tmp/tmp.DWo9tIFvWU/libperf/include/internal/cpumap.h
> INSTALL /tmp/tmp.DWo9tIFvWU/libperf/include/internal/evlist.h
> INSTALL /tmp/tmp.DWo9tIFvWU/libapi/include/api/cpu.h
> CC /tmp/tmp.DWo9tIFvWU/libperf/cpumap.o
> INSTALL /tmp/tmp.DWo9tIFvWU/libsymbol/include/symbol/kallsyms.h
> INSTALL /tmp/tmp.DWo9tIFvWU/libperf/include/internal/evsel.h
> INSTALL /tmp/tmp.DWo9tIFvWU/libapi/include/api/io.h
> INSTALL /tmp/tmp.DWo9tIFvWU/libapi/include/api/debug.h
> INSTALL /tmp/tmp.DWo9tIFvWU/libperf/include/internal/lib.h
> CC /tmp/tmp.DWo9tIFvWU/libsymbol/kallsyms.o
> CC /tmp/tmp.DWo9tIFvWU/libperf/threadmap.o
> GEN /tmp/tmp.DWo9tIFvWU/libbpf/bpf_helper_defs.h
> INSTALL /tmp/tmp.DWo9tIFvWU/libperf/include/internal/mmap.h
> MKDIR /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/include/bpf
> CC /tmp/tmp.DWo9tIFvWU/libperf/evsel.o
> INSTALL /tmp/tmp.DWo9tIFvWU/libperf/include/internal/rc_check.h
> INSTALL /tmp/tmp.DWo9tIFvWU/libapi/include/api/fd/array.h
> INSTALL /tmp/tmp.DWo9tIFvWU/libperf/include/internal/threadmap.h
> INSTALL /tmp/tmp.DWo9tIFvWU/libbpf/include/bpf/bpf.h
> CC /tmp/tmp.DWo9tIFvWU/libperf/evlist.o
> INSTALL /tmp/tmp.DWo9tIFvWU/libapi/include/api/fs/fs.h
> CC /tmp/tmp.DWo9tIFvWU/libapi/cpu.o
> INSTALL libsymbol_headers
> INSTALL /tmp/tmp.DWo9tIFvWU/libapi/include/api/fs/tracing_path.h
> MKDIR /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/
> INSTALL /tmp/tmp.DWo9tIFvWU/libbpf/include/bpf/libbpf.h
> CC /tmp/tmp.DWo9tIFvWU/libperf/mmap.o
> MKDIR /tmp/tmp.DWo9tIFvWU/libapi/fd/
> INSTALL /tmp/tmp.DWo9tIFvWU/libperf/include/internal/xyarray.h
> MKDIR /tmp/tmp.DWo9tIFvWU/libapi/fs/
> INSTALL /tmp/tmp.DWo9tIFvWU/libbpf/include/bpf/btf.h
> CC /tmp/tmp.DWo9tIFvWU/libperf/zalloc.o
> CC /tmp/tmp.DWo9tIFvWU/libapi/debug.o
> CC /tmp/tmp.DWo9tIFvWU/libapi/fd/array.o
> CC /tmp/tmp.DWo9tIFvWU/libapi/fs/fs.o
> INSTALL /tmp/tmp.DWo9tIFvWU/libbpf/include/bpf/libbpf_common.h
> INSTALL /tmp/tmp.DWo9tIFvWU/libbpf/include/bpf/libbpf_legacy.h
> CC /tmp/tmp.DWo9tIFvWU/libapi/str_error_r.o
> INSTALL /tmp/tmp.DWo9tIFvWU/libbpf/include/bpf/bpf_helpers.h
> MKDIR /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/
> INSTALL libperf_headers
> INSTALL libapi_headers
> INSTALL /tmp/tmp.DWo9tIFvWU/libbpf/include/bpf/bpf_tracing.h
> CC /tmp/tmp.DWo9tIFvWU/libapi/fs/tracing_path.o
> INSTALL /tmp/tmp.DWo9tIFvWU/libbpf/include/bpf/bpf_endian.h
> CC /tmp/tmp.DWo9tIFvWU/libperf/xyarray.o
> CC /tmp/tmp.DWo9tIFvWU/libapi/fs/cgroup.o
> INSTALL /tmp/tmp.DWo9tIFvWU/libbpf/include/bpf/bpf_core_read.h
> INSTALL /tmp/tmp.DWo9tIFvWU/libbpf/include/bpf/skel_internal.h
> INSTALL /tmp/tmp.DWo9tIFvWU/libbpf/include/bpf/libbpf_version.h
> CC /tmp/tmp.DWo9tIFvWU/libperf/lib.o
> INSTALL /tmp/tmp.DWo9tIFvWU/libbpf/include/bpf/usdt.bpf.h
> INSTALL /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/include/bpf/hashmap.h
> INSTALL /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/include/bpf/relo_core.h
> INSTALL /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/include/bpf/libbpf_internal.h
> CC /tmp/tmp.DWo9tIFvWU/libsubcmd/help.o
> CC /tmp/tmp.DWo9tIFvWU/libsubcmd/exec-cmd.o
> CC /tmp/tmp.DWo9tIFvWU/libsubcmd/pager.o
> CC /tmp/tmp.DWo9tIFvWU/libsubcmd/parse-options.o
> CC /tmp/tmp.DWo9tIFvWU/libsubcmd/run-command.o
> CC /tmp/tmp.DWo9tIFvWU/libsubcmd/sigchain.o
> CC /tmp/tmp.DWo9tIFvWU/libsubcmd/subcmd-config.o
> INSTALL /tmp/tmp.DWo9tIFvWU/libbpf/include/bpf/bpf_helper_defs.h
> INSTALL libbpf_headers
> GEN /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/bpf_helper_defs.h
> INSTALL /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/include/bpf/bpf.h
> INSTALL /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/include/bpf/libbpf.h
> INSTALL /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/include/bpf/btf.h
> INSTALL /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/include/bpf/libbpf_common.h
> INSTALL /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/include/bpf/libbpf_legacy.h
> INSTALL /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/include/bpf/bpf_helpers.h
> INSTALL /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/include/bpf/bpf_tracing.h
> INSTALL /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/include/bpf/bpf_endian.h
> INSTALL /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/include/bpf/bpf_core_read.h
> INSTALL /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/include/bpf/skel_internal.h
> INSTALL /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/include/bpf/libbpf_version.h
> INSTALL /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/include/bpf/usdt.bpf.h
> LD /tmp/tmp.DWo9tIFvWU/libapi/fd/libapi-in.o
> LD /tmp/tmp.DWo9tIFvWU/libsymbol/libsymbol-in.o
> AR /tmp/tmp.DWo9tIFvWU/libsymbol/libsymbol.a
> LD /tmp/tmp.DWo9tIFvWU/libapi/fs/libapi-in.o
> INSTALL /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/include/bpf/bpf_helper_defs.h
> INSTALL libbpf_headers
> LD /tmp/tmp.DWo9tIFvWU/libapi/libapi-in.o
> CC /tmp/tmp.DWo9tIFvWU/libbpf/staticobjs/libbpf.o
> CC /tmp/tmp.DWo9tIFvWU/libbpf/staticobjs/bpf.o
> CC /tmp/tmp.DWo9tIFvWU/libbpf/staticobjs/nlattr.o
> CC /tmp/tmp.DWo9tIFvWU/libbpf/staticobjs/btf.o
> CC /tmp/tmp.DWo9tIFvWU/libbpf/staticobjs/libbpf_errno.o
> CC /tmp/tmp.DWo9tIFvWU/libbpf/staticobjs/str_error.o
> LD /tmp/tmp.DWo9tIFvWU/libperf/libperf-in.o
> AR /tmp/tmp.DWo9tIFvWU/libapi/libapi.a
> CC /tmp/tmp.DWo9tIFvWU/libbpf/staticobjs/netlink.o
> CC /tmp/tmp.DWo9tIFvWU/libbpf/staticobjs/bpf_prog_linfo.o
> CC /tmp/tmp.DWo9tIFvWU/libbpf/staticobjs/libbpf_probes.o
> CC /tmp/tmp.DWo9tIFvWU/libbpf/staticobjs/hashmap.o
> CC /tmp/tmp.DWo9tIFvWU/libbpf/staticobjs/btf_dump.o
> CC /tmp/tmp.DWo9tIFvWU/libbpf/staticobjs/ringbuf.o
> CC /tmp/tmp.DWo9tIFvWU/libbpf/staticobjs/strset.o
> CC /tmp/tmp.DWo9tIFvWU/libbpf/staticobjs/linker.o
> CC /tmp/tmp.DWo9tIFvWU/libbpf/staticobjs/gen_loader.o
> CC /tmp/tmp.DWo9tIFvWU/libbpf/staticobjs/relo_core.o
> CC /tmp/tmp.DWo9tIFvWU/libbpf/staticobjs/usdt.o
> AR /tmp/tmp.DWo9tIFvWU/libperf/libperf.a
> CC /tmp/tmp.DWo9tIFvWU/libbpf/staticobjs/zip.o
> CC /tmp/tmp.DWo9tIFvWU/libbpf/staticobjs/elf.o
> CC /tmp/tmp.DWo9tIFvWU/libbpf/staticobjs/features.o
> CC /tmp/tmp.DWo9tIFvWU/libbpf/staticobjs/btf_iter.o
> CC /tmp/tmp.DWo9tIFvWU/libbpf/staticobjs/btf_relocate.o
> CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/libbpf.o
> CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/bpf.o
> CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/nlattr.o
> CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/btf.o
> CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/libbpf_errno.o
> CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/str_error.o
> CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/netlink.o
> CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/bpf_prog_linfo.o
> CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/libbpf_probes.o
> CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/hashmap.o
> CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/btf_dump.o
> CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/ringbuf.o
> CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/strset.o
> CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/linker.o
> CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/gen_loader.o
> CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/relo_core.o
> CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/usdt.o
> CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/zip.o
> CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/elf.o
> CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/features.o
> CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/btf_iter.o
> CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/btf_relocate.o
> LD /tmp/tmp.DWo9tIFvWU/libsubcmd/libsubcmd-in.o
> AR /tmp/tmp.DWo9tIFvWU/libsubcmd/libsubcmd.a
> LD /tmp/tmp.DWo9tIFvWU/libbpf/staticobjs/libbpf-in.o
> LINK /tmp/tmp.DWo9tIFvWU/libbpf/libbpf.a
> LD /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/libbpf-in.o
> LINK /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/libbpf/libbpf.a
> CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/main.o
> CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/common.o
> CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/json_writer.o
> CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/gen.o
> CC /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/btf.o
> LINK /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bootstrap/bpftool
> GEN /tmp/tmp.DWo9tIFvWU/util/bpf_skel/vmlinux.h
> CLANG /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bpf_prog_profiler.bpf.o
> CLANG /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bperf_leader.bpf.o
> CLANG /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bperf_follower.bpf.o
> CLANG /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bperf_cgroup.bpf.o
> CLANG /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/func_latency.bpf.o
> CLANG /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/off_cpu.bpf.o
> CLANG /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/lock_contention.bpf.o
> CLANG /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/kwork_trace.bpf.o
> CLANG /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/sample_filter.bpf.o
> CLANG /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/kwork_top.bpf.o
> CLANG /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bench_uprobe.bpf.o
> CLANG /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/augmented_raw_syscalls.bpf.o
> GENSKEL /tmp/tmp.DWo9tIFvWU/util/bpf_skel/bench_uprobe.skel.h
> GENSKEL /tmp/tmp.DWo9tIFvWU/util/bpf_skel/func_latency.skel.h
> util/bpf_skel/lock_contention.bpf.c:612:28: error: declaration of 'struct bpf_iter__kmem_cache' will not be visible outside of this function [-Werror,-Wvisibility]
> 612 | int slab_cache_iter(struct bpf_iter__kmem_cache *ctx)
> | ^
> util/bpf_skel/lock_contention.bpf.c:614:28: error: incomplete definition of type 'struct bpf_iter__kmem_cache'
> 614 | struct kmem_cache *s = ctx->s;
> | ~~~^
> util/bpf_skel/lock_contention.bpf.c:612:28: note: forward declaration of 'struct bpf_iter__kmem_cache'
> 612 | int slab_cache_iter(struct bpf_iter__kmem_cache *ctx)
> | ^
> 2 errors generated.
> make[4]: *** [Makefile.perf:1248: /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/lock_contention.bpf.o] Error 1
> make[4]: *** Waiting for unfinished jobs....
> make[3]: *** [Makefile.perf:292: sub-make] Error 2
> make[2]: *** [Makefile:76: all] Error 2
> make[1]: *** [tests/make:344: make_gen_vmlinux_h_O] Error 1
> make: *** [Makefile:109: build-test] Error 2
> make: Leaving directory '/home/acme/git/perf-tools-next/tools/perf'
>
> real 3m43.896s
> user 29m30.716s
> sys 6m36.609s
> ⬢ [acme@toolbox perf-tools-next]$
>
>
>
> > Signed-off-by: Namhyung Kim <namhyung@kernel.org>
> > ---
> > tools/perf/util/bpf_lock_contention.c | 50 +++++++++++++++++++
> > .../perf/util/bpf_skel/lock_contention.bpf.c | 28 +++++++++++
> > tools/perf/util/bpf_skel/lock_data.h | 12 +++++
> > tools/perf/util/bpf_skel/vmlinux/vmlinux.h | 8 +++
> > 4 files changed, 98 insertions(+)
> >
> > diff --git a/tools/perf/util/bpf_lock_contention.c b/tools/perf/util/bpf_lock_contention.c
> > index 41a1ad08789511c3..558590c3111390fc 100644
> > --- a/tools/perf/util/bpf_lock_contention.c
> > +++ b/tools/perf/util/bpf_lock_contention.c
> > @@ -12,12 +12,59 @@
> > #include <linux/zalloc.h>
> > #include <linux/string.h>
> > #include <bpf/bpf.h>
> > +#include <bpf/btf.h>
> > #include <inttypes.h>
> >
> > #include "bpf_skel/lock_contention.skel.h"
> > #include "bpf_skel/lock_data.h"
> >
> > static struct lock_contention_bpf *skel;
> > +static bool has_slab_iter;
> > +
> > +static void check_slab_cache_iter(struct lock_contention *con)
> > +{
> > + struct btf *btf = btf__load_vmlinux_btf();
> > + s32 ret;
> > +
> > + if (btf == NULL) {
> > + pr_debug("BTF loading failed: %s\n", strerror(errno));
> > + return;
> > + }
> > +
> > + ret = btf__find_by_name_kind(btf, "bpf_iter__kmem_cache", BTF_KIND_STRUCT);
> > + if (ret < 0) {
> > + bpf_program__set_autoload(skel->progs.slab_cache_iter, false);
> > + pr_debug("slab cache iterator is not available: %d\n", ret);
> > + goto out;
> > + }
> > +
> > + has_slab_iter = true;
> > +
> > + bpf_map__set_max_entries(skel->maps.slab_caches, con->map_nr_entries);
> > +out:
> > + btf__free(btf);
> > +}
> > +
> > +static void run_slab_cache_iter(void)
> > +{
> > + int fd;
> > + char buf[256];
> > +
> > + if (!has_slab_iter)
> > + return;
> > +
> > + fd = bpf_iter_create(bpf_link__fd(skel->links.slab_cache_iter));
> > + if (fd < 0) {
> > + pr_debug("cannot create slab cache iter: %d\n", fd);
> > + return;
> > + }
> > +
> > + /* This will run the bpf program */
> > + while (read(fd, buf, sizeof(buf)) > 0)
> > + continue;
> > +
> > + close(fd);
> > +}
> >
> > int lock_contention_prepare(struct lock_contention *con)
> > {
> > @@ -109,6 +156,8 @@ int lock_contention_prepare(struct lock_contention *con)
> > skel->rodata->use_cgroup_v2 = 1;
> > }
> >
> > + check_slab_cache_iter(con);
> > +
> > if (lock_contention_bpf__load(skel) < 0) {
> > pr_err("Failed to load lock-contention BPF skeleton\n");
> > return -1;
> > @@ -304,6 +353,7 @@ static void account_end_timestamp(struct lock_contention *con)
> >
> > int lock_contention_start(void)
> > {
> > + run_slab_cache_iter();
> > skel->bss->enabled = 1;
> > return 0;
> > }
> > diff --git a/tools/perf/util/bpf_skel/lock_contention.bpf.c b/tools/perf/util/bpf_skel/lock_contention.bpf.c
> > index 1069bda5d733887f..fd24ccb00faec0ba 100644
> > --- a/tools/perf/util/bpf_skel/lock_contention.bpf.c
> > +++ b/tools/perf/util/bpf_skel/lock_contention.bpf.c
> > @@ -100,6 +100,13 @@ struct {
> > __uint(max_entries, 1);
> > } cgroup_filter SEC(".maps");
> >
> > +struct {
> > + __uint(type, BPF_MAP_TYPE_HASH);
> > + __uint(key_size, sizeof(long));
> > + __uint(value_size, sizeof(struct slab_cache_data));
> > + __uint(max_entries, 1);
> > +} slab_caches SEC(".maps");
> > +
> > struct rw_semaphore___old {
> > struct task_struct *owner;
> > } __attribute__((preserve_access_index));
> > @@ -136,6 +143,8 @@ int perf_subsys_id = -1;
> >
> > __u64 end_ts;
> >
> > +__u32 slab_cache_id;
> > +
> > /* error stat */
> > int task_fail;
> > int stack_fail;
> > @@ -563,4 +572,23 @@ int BPF_PROG(end_timestamp)
> > return 0;
> > }
> >
> > +SEC("iter/kmem_cache")
> > +int slab_cache_iter(struct bpf_iter__kmem_cache *ctx)
> > +{
> > + struct kmem_cache *s = ctx->s;
> > + struct slab_cache_data d;
> > +
> > + if (s == NULL)
> > + return 0;
> > +
> > + d.id = ++slab_cache_id << LCB_F_SLAB_ID_SHIFT;
> > + bpf_probe_read_kernel_str(d.name, sizeof(d.name), s->name);
> > +
> > + if (d.id >= LCB_F_SLAB_ID_END)
> > + return 0;
> > +
> > + bpf_map_update_elem(&slab_caches, &s, &d, BPF_NOEXIST);
> > + return 0;
> > +}
> > +
> > char LICENSE[] SEC("license") = "Dual BSD/GPL";
> > diff --git a/tools/perf/util/bpf_skel/lock_data.h b/tools/perf/util/bpf_skel/lock_data.h
> > index 4f0aae5483745dfa..c15f734d7fc4aecb 100644
> > --- a/tools/perf/util/bpf_skel/lock_data.h
> > +++ b/tools/perf/util/bpf_skel/lock_data.h
> > @@ -32,9 +32,16 @@ struct contention_task_data {
> > #define LCD_F_MMAP_LOCK (1U << 31)
> > #define LCD_F_SIGHAND_LOCK (1U << 30)
> >
> > +#define LCB_F_SLAB_ID_SHIFT 16
> > +#define LCB_F_SLAB_ID_START (1U << 16)
> > +#define LCB_F_SLAB_ID_END (1U << 26)
> > +#define LCB_F_SLAB_ID_MASK 0x03FF0000U
> > +
> > #define LCB_F_TYPE_MAX (1U << 7)
> > #define LCB_F_TYPE_MASK 0x0000007FU
> >
> > +#define SLAB_NAME_MAX 28
> > +
> > struct contention_data {
> > u64 total_time;
> > u64 min_time;
> > @@ -55,4 +62,9 @@ enum lock_class_sym {
> > LOCK_CLASS_RQLOCK,
> > };
> >
> > +struct slab_cache_data {
> > + u32 id;
> > + char name[SLAB_NAME_MAX];
> > +};
> > +
> > #endif /* UTIL_BPF_SKEL_LOCK_DATA_H */
> > diff --git a/tools/perf/util/bpf_skel/vmlinux/vmlinux.h b/tools/perf/util/bpf_skel/vmlinux/vmlinux.h
> > index 4dcad7b682bdee9c..7b81d3173917fdb5 100644
> > --- a/tools/perf/util/bpf_skel/vmlinux/vmlinux.h
> > +++ b/tools/perf/util/bpf_skel/vmlinux/vmlinux.h
> > @@ -195,4 +195,12 @@ struct bpf_perf_event_data_kern {
> > */
> > struct rq {};
> >
> > +struct kmem_cache {
> > + const char *name;
> > +} __attribute__((preserve_access_index));
> > +
> > +struct bpf_iter__kmem_cache {
> > + struct kmem_cache *s;
> > +} __attribute__((preserve_access_index));
> > +
> > #endif // __VMLINUX_H
> > --
> > 2.47.0.277.g8800431eea-goog
On Mon, Dec 09, 2024 at 01:38:39PM -0300, Arnaldo Carvalho de Melo wrote:
> On Mon, Dec 09, 2024 at 01:36:52PM -0300, Arnaldo Carvalho de Melo wrote:
> > On Thu, Nov 07, 2024 at 10:14:57PM -0800, Namhyung Kim wrote:
> > > Recently the kernel got the kmem_cache iterator to traverse metadata of
> > > slab objects. This can be used to symbolize dynamic locks in a slab.
> > >
> > > The new slab_caches hash map will have the pointer of the kmem_cache as
> > > a key and save the name and a id. The id will be saved in the flags
> > > part of the lock.
> >
> > Trying to fix this
>
> So you have that struct in tools/perf/util/bpf_skel/vmlinux/vmlinux.h,
> but then, this kernel is old and doesn't have the kmem_cache iterator,
> so using the generated vmlinux.h will fail the build.
Thanks for checking this. I think we handle compatibility issues by
checking BTF at runtime but this is a build-time issue. :(
I wonder if it's really needed to generate vmlinux.h for perf. Can we
simply use the minimal vmlinux.h always?
Thanks,
Namhyung
>
> > cd . && make GEN_VMLINUX_H=1 FEATURES_DUMP=/home/acme/git/perf-tools-next/tools/perf/BUILD_TEST_FEATURE_DUMP -j28 O=/tmp/tmp.DWo9tIFvWU DESTDIR=/tmp/tmp.ex3iljqLBT
> > BUILD: Doing 'make -j28' parallel build
[...]
> > GEN /tmp/tmp.DWo9tIFvWU/util/bpf_skel/vmlinux.h
> > CLANG /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bpf_prog_profiler.bpf.o
> > CLANG /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bperf_leader.bpf.o
> > CLANG /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bperf_follower.bpf.o
> > CLANG /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bperf_cgroup.bpf.o
> > CLANG /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/func_latency.bpf.o
> > CLANG /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/off_cpu.bpf.o
> > CLANG /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/lock_contention.bpf.o
> > CLANG /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/kwork_trace.bpf.o
> > CLANG /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/sample_filter.bpf.o
> > CLANG /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/kwork_top.bpf.o
> > CLANG /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bench_uprobe.bpf.o
> > CLANG /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/augmented_raw_syscalls.bpf.o
> > GENSKEL /tmp/tmp.DWo9tIFvWU/util/bpf_skel/bench_uprobe.skel.h
> > GENSKEL /tmp/tmp.DWo9tIFvWU/util/bpf_skel/func_latency.skel.h
> > util/bpf_skel/lock_contention.bpf.c:612:28: error: declaration of 'struct bpf_iter__kmem_cache' will not be visible outside of this function [-Werror,-Wvisibility]
> > 612 | int slab_cache_iter(struct bpf_iter__kmem_cache *ctx)
> > | ^
> > util/bpf_skel/lock_contention.bpf.c:614:28: error: incomplete definition of type 'struct bpf_iter__kmem_cache'
> > 614 | struct kmem_cache *s = ctx->s;
> > | ~~~^
> > util/bpf_skel/lock_contention.bpf.c:612:28: note: forward declaration of 'struct bpf_iter__kmem_cache'
> > 612 | int slab_cache_iter(struct bpf_iter__kmem_cache *ctx)
> > | ^
> > 2 errors generated.
> > make[4]: *** [Makefile.perf:1248: /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/lock_contention.bpf.o] Error 1
> > make[4]: *** Waiting for unfinished jobs....
> > make[3]: *** [Makefile.perf:292: sub-make] Error 2
> > make[2]: *** [Makefile:76: all] Error 2
> > make[1]: *** [tests/make:344: make_gen_vmlinux_h_O] Error 1
> > make: *** [Makefile:109: build-test] Error 2
> > make: Leaving directory '/home/acme/git/perf-tools-next/tools/perf'
> >
> > real 3m43.896s
> > user 29m30.716s
> > sys 6m36.609s
> > ⬢ [acme@toolbox perf-tools-next]$
> >
> >
> >
> > > Signed-off-by: Namhyung Kim <namhyung@kernel.org>
> > > ---
> > > tools/perf/util/bpf_lock_contention.c | 50 +++++++++++++++++++
> > > .../perf/util/bpf_skel/lock_contention.bpf.c | 28 +++++++++++
> > > tools/perf/util/bpf_skel/lock_data.h | 12 +++++
> > > tools/perf/util/bpf_skel/vmlinux/vmlinux.h | 8 +++
> > > 4 files changed, 98 insertions(+)
> > >
> > > diff --git a/tools/perf/util/bpf_lock_contention.c b/tools/perf/util/bpf_lock_contention.c
> > > index 41a1ad08789511c3..558590c3111390fc 100644
> > > --- a/tools/perf/util/bpf_lock_contention.c
> > > +++ b/tools/perf/util/bpf_lock_contention.c
> > > @@ -12,12 +12,59 @@
> > > #include <linux/zalloc.h>
> > > #include <linux/string.h>
> > > #include <bpf/bpf.h>
> > > +#include <bpf/btf.h>
> > > #include <inttypes.h>
> > >
> > > #include "bpf_skel/lock_contention.skel.h"
> > > #include "bpf_skel/lock_data.h"
> > >
> > > static struct lock_contention_bpf *skel;
> > > +static bool has_slab_iter;
> > > +
> > > +static void check_slab_cache_iter(struct lock_contention *con)
> > > +{
> > > + struct btf *btf = btf__load_vmlinux_btf();
> > > + s32 ret;
> > > +
> > > + if (btf == NULL) {
> > > + pr_debug("BTF loading failed: %s\n", strerror(errno));
> > > + return;
> > > + }
> > > +
> > > + ret = btf__find_by_name_kind(btf, "bpf_iter__kmem_cache", BTF_KIND_STRUCT);
> > > + if (ret < 0) {
> > > + bpf_program__set_autoload(skel->progs.slab_cache_iter, false);
> > > + pr_debug("slab cache iterator is not available: %d\n", ret);
> > > + goto out;
> > > + }
> > > +
> > > + has_slab_iter = true;
> > > +
> > > + bpf_map__set_max_entries(skel->maps.slab_caches, con->map_nr_entries);
> > > +out:
> > > + btf__free(btf);
> > > +}
> > > +
> > > +static void run_slab_cache_iter(void)
> > > +{
> > > + int fd;
> > > + char buf[256];
> > > +
> > > + if (!has_slab_iter)
> > > + return;
> > > +
> > > + fd = bpf_iter_create(bpf_link__fd(skel->links.slab_cache_iter));
> > > + if (fd < 0) {
> > > + pr_debug("cannot create slab cache iter: %d\n", fd);
> > > + return;
> > > + }
> > > +
> > > + /* This will run the bpf program */
> > > + while (read(fd, buf, sizeof(buf)) > 0)
> > > + continue;
> > > +
> > > + close(fd);
> > > +}
> > >
> > > int lock_contention_prepare(struct lock_contention *con)
> > > {
> > > @@ -109,6 +156,8 @@ int lock_contention_prepare(struct lock_contention *con)
> > > skel->rodata->use_cgroup_v2 = 1;
> > > }
> > >
> > > + check_slab_cache_iter(con);
> > > +
> > > if (lock_contention_bpf__load(skel) < 0) {
> > > pr_err("Failed to load lock-contention BPF skeleton\n");
> > > return -1;
> > > @@ -304,6 +353,7 @@ static void account_end_timestamp(struct lock_contention *con)
> > >
> > > int lock_contention_start(void)
> > > {
> > > + run_slab_cache_iter();
> > > skel->bss->enabled = 1;
> > > return 0;
> > > }
> > > diff --git a/tools/perf/util/bpf_skel/lock_contention.bpf.c b/tools/perf/util/bpf_skel/lock_contention.bpf.c
> > > index 1069bda5d733887f..fd24ccb00faec0ba 100644
> > > --- a/tools/perf/util/bpf_skel/lock_contention.bpf.c
> > > +++ b/tools/perf/util/bpf_skel/lock_contention.bpf.c
> > > @@ -100,6 +100,13 @@ struct {
> > > __uint(max_entries, 1);
> > > } cgroup_filter SEC(".maps");
> > >
> > > +struct {
> > > + __uint(type, BPF_MAP_TYPE_HASH);
> > > + __uint(key_size, sizeof(long));
> > > + __uint(value_size, sizeof(struct slab_cache_data));
> > > + __uint(max_entries, 1);
> > > +} slab_caches SEC(".maps");
> > > +
> > > struct rw_semaphore___old {
> > > struct task_struct *owner;
> > > } __attribute__((preserve_access_index));
> > > @@ -136,6 +143,8 @@ int perf_subsys_id = -1;
> > >
> > > __u64 end_ts;
> > >
> > > +__u32 slab_cache_id;
> > > +
> > > /* error stat */
> > > int task_fail;
> > > int stack_fail;
> > > @@ -563,4 +572,23 @@ int BPF_PROG(end_timestamp)
> > > return 0;
> > > }
> > >
> > > +SEC("iter/kmem_cache")
> > > +int slab_cache_iter(struct bpf_iter__kmem_cache *ctx)
> > > +{
> > > + struct kmem_cache *s = ctx->s;
> > > + struct slab_cache_data d;
> > > +
> > > + if (s == NULL)
> > > + return 0;
> > > +
> > > + d.id = ++slab_cache_id << LCB_F_SLAB_ID_SHIFT;
> > > + bpf_probe_read_kernel_str(d.name, sizeof(d.name), s->name);
> > > +
> > > + if (d.id >= LCB_F_SLAB_ID_END)
> > > + return 0;
> > > +
> > > + bpf_map_update_elem(&slab_caches, &s, &d, BPF_NOEXIST);
> > > + return 0;
> > > +}
> > > +
> > > char LICENSE[] SEC("license") = "Dual BSD/GPL";
> > > diff --git a/tools/perf/util/bpf_skel/lock_data.h b/tools/perf/util/bpf_skel/lock_data.h
> > > index 4f0aae5483745dfa..c15f734d7fc4aecb 100644
> > > --- a/tools/perf/util/bpf_skel/lock_data.h
> > > +++ b/tools/perf/util/bpf_skel/lock_data.h
> > > @@ -32,9 +32,16 @@ struct contention_task_data {
> > > #define LCD_F_MMAP_LOCK (1U << 31)
> > > #define LCD_F_SIGHAND_LOCK (1U << 30)
> > >
> > > +#define LCB_F_SLAB_ID_SHIFT 16
> > > +#define LCB_F_SLAB_ID_START (1U << 16)
> > > +#define LCB_F_SLAB_ID_END (1U << 26)
> > > +#define LCB_F_SLAB_ID_MASK 0x03FF0000U
> > > +
> > > #define LCB_F_TYPE_MAX (1U << 7)
> > > #define LCB_F_TYPE_MASK 0x0000007FU
> > >
> > > +#define SLAB_NAME_MAX 28
> > > +
> > > struct contention_data {
> > > u64 total_time;
> > > u64 min_time;
> > > @@ -55,4 +62,9 @@ enum lock_class_sym {
> > > LOCK_CLASS_RQLOCK,
> > > };
> > >
> > > +struct slab_cache_data {
> > > + u32 id;
> > > + char name[SLAB_NAME_MAX];
> > > +};
> > > +
> > > #endif /* UTIL_BPF_SKEL_LOCK_DATA_H */
> > > diff --git a/tools/perf/util/bpf_skel/vmlinux/vmlinux.h b/tools/perf/util/bpf_skel/vmlinux/vmlinux.h
> > > index 4dcad7b682bdee9c..7b81d3173917fdb5 100644
> > > --- a/tools/perf/util/bpf_skel/vmlinux/vmlinux.h
> > > +++ b/tools/perf/util/bpf_skel/vmlinux/vmlinux.h
> > > @@ -195,4 +195,12 @@ struct bpf_perf_event_data_kern {
> > > */
> > > struct rq {};
> > >
> > > +struct kmem_cache {
> > > + const char *name;
> > > +} __attribute__((preserve_access_index));
> > > +
> > > +struct bpf_iter__kmem_cache {
> > > + struct kmem_cache *s;
> > > +} __attribute__((preserve_access_index));
> > > +
> > > #endif // __VMLINUX_H
> > > --
> > > 2.47.0.277.g8800431eea-goog
On Mon, Dec 9, 2024 at 2:16 PM Namhyung Kim <namhyung@kernel.org> wrote:
>
> On Mon, Dec 09, 2024 at 01:38:39PM -0300, Arnaldo Carvalho de Melo wrote:
> > On Mon, Dec 09, 2024 at 01:36:52PM -0300, Arnaldo Carvalho de Melo wrote:
> > > On Thu, Nov 07, 2024 at 10:14:57PM -0800, Namhyung Kim wrote:
> > > > Recently the kernel got the kmem_cache iterator to traverse metadata of
> > > > slab objects. This can be used to symbolize dynamic locks in a slab.
> > > >
> > > > The new slab_caches hash map will have the pointer of the kmem_cache as
> > > > a key and save the name and a id. The id will be saved in the flags
> > > > part of the lock.
> > >
> > > Trying to fix this
> >
> > So you have that struct in tools/perf/util/bpf_skel/vmlinux/vmlinux.h,
> > but then, this kernel is old and doesn't have the kmem_cache iterator,
> > so using the generated vmlinux.h will fail the build.
>
> Thanks for checking this. I think we handle compatibility issues by
> checking BTF at runtime but this is a build-time issue. :(
>
> I wonder if it's really needed to generate vmlinux.h for perf. Can we
> simply use the minimal vmlinux.h always?
Agreed, it shouldn't be necessary. There are certain compilation
errors that will happen with a generated one that can't happen with
the minimal. They could be indicative of bugs, like a renamed struct.
Thanks,
Ian
> >
> > > cd . && make GEN_VMLINUX_H=1 FEATURES_DUMP=/home/acme/git/perf-tools-next/tools/perf/BUILD_TEST_FEATURE_DUMP -j28 O=/tmp/tmp.DWo9tIFvWU DESTDIR=/tmp/tmp.ex3iljqLBT
> > > BUILD: Doing 'make -j28' parallel build
> [...]
> > > GEN /tmp/tmp.DWo9tIFvWU/util/bpf_skel/vmlinux.h
> > > CLANG /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bpf_prog_profiler.bpf.o
> > > CLANG /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bperf_leader.bpf.o
> > > CLANG /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bperf_follower.bpf.o
> > > CLANG /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bperf_cgroup.bpf.o
> > > CLANG /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/func_latency.bpf.o
> > > CLANG /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/off_cpu.bpf.o
> > > CLANG /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/lock_contention.bpf.o
> > > CLANG /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/kwork_trace.bpf.o
> > > CLANG /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/sample_filter.bpf.o
> > > CLANG /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/kwork_top.bpf.o
> > > CLANG /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/bench_uprobe.bpf.o
> > > CLANG /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/augmented_raw_syscalls.bpf.o
> > > GENSKEL /tmp/tmp.DWo9tIFvWU/util/bpf_skel/bench_uprobe.skel.h
> > > GENSKEL /tmp/tmp.DWo9tIFvWU/util/bpf_skel/func_latency.skel.h
> > > util/bpf_skel/lock_contention.bpf.c:612:28: error: declaration of 'struct bpf_iter__kmem_cache' will not be visible outside of this function [-Werror,-Wvisibility]
> > > 612 | int slab_cache_iter(struct bpf_iter__kmem_cache *ctx)
> > > | ^
> > > util/bpf_skel/lock_contention.bpf.c:614:28: error: incomplete definition of type 'struct bpf_iter__kmem_cache'
> > > 614 | struct kmem_cache *s = ctx->s;
> > > | ~~~^
> > > util/bpf_skel/lock_contention.bpf.c:612:28: note: forward declaration of 'struct bpf_iter__kmem_cache'
> > > 612 | int slab_cache_iter(struct bpf_iter__kmem_cache *ctx)
> > > | ^
> > > 2 errors generated.
> > > make[4]: *** [Makefile.perf:1248: /tmp/tmp.DWo9tIFvWU/util/bpf_skel/.tmp/lock_contention.bpf.o] Error 1
> > > make[4]: *** Waiting for unfinished jobs....
> > > make[3]: *** [Makefile.perf:292: sub-make] Error 2
> > > make[2]: *** [Makefile:76: all] Error 2
> > > make[1]: *** [tests/make:344: make_gen_vmlinux_h_O] Error 1
> > > make: *** [Makefile:109: build-test] Error 2
> > > make: Leaving directory '/home/acme/git/perf-tools-next/tools/perf'
> > >
> > > real 3m43.896s
> > > user 29m30.716s
> > > sys 6m36.609s
> > > ⬢ [acme@toolbox perf-tools-next]$
> > >
> > >
> > >
> > > > Signed-off-by: Namhyung Kim <namhyung@kernel.org>
> > > > ---
> > > > tools/perf/util/bpf_lock_contention.c | 50 +++++++++++++++++++
> > > > .../perf/util/bpf_skel/lock_contention.bpf.c | 28 +++++++++++
> > > > tools/perf/util/bpf_skel/lock_data.h | 12 +++++
> > > > tools/perf/util/bpf_skel/vmlinux/vmlinux.h | 8 +++
> > > > 4 files changed, 98 insertions(+)
> > > >
> > > > diff --git a/tools/perf/util/bpf_lock_contention.c b/tools/perf/util/bpf_lock_contention.c
> > > > index 41a1ad08789511c3..558590c3111390fc 100644
> > > > --- a/tools/perf/util/bpf_lock_contention.c
> > > > +++ b/tools/perf/util/bpf_lock_contention.c
> > > > @@ -12,12 +12,59 @@
> > > > #include <linux/zalloc.h>
> > > > #include <linux/string.h>
> > > > #include <bpf/bpf.h>
> > > > +#include <bpf/btf.h>
> > > > #include <inttypes.h>
> > > >
> > > > #include "bpf_skel/lock_contention.skel.h"
> > > > #include "bpf_skel/lock_data.h"
> > > >
> > > > static struct lock_contention_bpf *skel;
> > > > +static bool has_slab_iter;
> > > > +
> > > > +static void check_slab_cache_iter(struct lock_contention *con)
> > > > +{
> > > > + struct btf *btf = btf__load_vmlinux_btf();
> > > > + s32 ret;
> > > > +
> > > > + if (btf == NULL) {
> > > > + pr_debug("BTF loading failed: %s\n", strerror(errno));
> > > > + return;
> > > > + }
> > > > +
> > > > + ret = btf__find_by_name_kind(btf, "bpf_iter__kmem_cache", BTF_KIND_STRUCT);
> > > > + if (ret < 0) {
> > > > + bpf_program__set_autoload(skel->progs.slab_cache_iter, false);
> > > > + pr_debug("slab cache iterator is not available: %d\n", ret);
> > > > + goto out;
> > > > + }
> > > > +
> > > > + has_slab_iter = true;
> > > > +
> > > > + bpf_map__set_max_entries(skel->maps.slab_caches, con->map_nr_entries);
> > > > +out:
> > > > + btf__free(btf);
> > > > +}
> > > > +
> > > > +static void run_slab_cache_iter(void)
> > > > +{
> > > > + int fd;
> > > > + char buf[256];
> > > > +
> > > > + if (!has_slab_iter)
> > > > + return;
> > > > +
> > > > + fd = bpf_iter_create(bpf_link__fd(skel->links.slab_cache_iter));
> > > > + if (fd < 0) {
> > > > + pr_debug("cannot create slab cache iter: %d\n", fd);
> > > > + return;
> > > > + }
> > > > +
> > > > + /* This will run the bpf program */
> > > > + while (read(fd, buf, sizeof(buf)) > 0)
> > > > + continue;
> > > > +
> > > > + close(fd);
> > > > +}
> > > >
> > > > int lock_contention_prepare(struct lock_contention *con)
> > > > {
> > > > @@ -109,6 +156,8 @@ int lock_contention_prepare(struct lock_contention *con)
> > > > skel->rodata->use_cgroup_v2 = 1;
> > > > }
> > > >
> > > > + check_slab_cache_iter(con);
> > > > +
> > > > if (lock_contention_bpf__load(skel) < 0) {
> > > > pr_err("Failed to load lock-contention BPF skeleton\n");
> > > > return -1;
> > > > @@ -304,6 +353,7 @@ static void account_end_timestamp(struct lock_contention *con)
> > > >
> > > > int lock_contention_start(void)
> > > > {
> > > > + run_slab_cache_iter();
> > > > skel->bss->enabled = 1;
> > > > return 0;
> > > > }
> > > > diff --git a/tools/perf/util/bpf_skel/lock_contention.bpf.c b/tools/perf/util/bpf_skel/lock_contention.bpf.c
> > > > index 1069bda5d733887f..fd24ccb00faec0ba 100644
> > > > --- a/tools/perf/util/bpf_skel/lock_contention.bpf.c
> > > > +++ b/tools/perf/util/bpf_skel/lock_contention.bpf.c
> > > > @@ -100,6 +100,13 @@ struct {
> > > > __uint(max_entries, 1);
> > > > } cgroup_filter SEC(".maps");
> > > >
> > > > +struct {
> > > > + __uint(type, BPF_MAP_TYPE_HASH);
> > > > + __uint(key_size, sizeof(long));
> > > > + __uint(value_size, sizeof(struct slab_cache_data));
> > > > + __uint(max_entries, 1);
> > > > +} slab_caches SEC(".maps");
> > > > +
> > > > struct rw_semaphore___old {
> > > > struct task_struct *owner;
> > > > } __attribute__((preserve_access_index));
> > > > @@ -136,6 +143,8 @@ int perf_subsys_id = -1;
> > > >
> > > > __u64 end_ts;
> > > >
> > > > +__u32 slab_cache_id;
> > > > +
> > > > /* error stat */
> > > > int task_fail;
> > > > int stack_fail;
> > > > @@ -563,4 +572,23 @@ int BPF_PROG(end_timestamp)
> > > > return 0;
> > > > }
> > > >
> > > > +SEC("iter/kmem_cache")
> > > > +int slab_cache_iter(struct bpf_iter__kmem_cache *ctx)
> > > > +{
> > > > + struct kmem_cache *s = ctx->s;
> > > > + struct slab_cache_data d;
> > > > +
> > > > + if (s == NULL)
> > > > + return 0;
> > > > +
> > > > + d.id = ++slab_cache_id << LCB_F_SLAB_ID_SHIFT;
> > > > + bpf_probe_read_kernel_str(d.name, sizeof(d.name), s->name);
> > > > +
> > > > + if (d.id >= LCB_F_SLAB_ID_END)
> > > > + return 0;
> > > > +
> > > > + bpf_map_update_elem(&slab_caches, &s, &d, BPF_NOEXIST);
> > > > + return 0;
> > > > +}
> > > > +
> > > > char LICENSE[] SEC("license") = "Dual BSD/GPL";
> > > > diff --git a/tools/perf/util/bpf_skel/lock_data.h b/tools/perf/util/bpf_skel/lock_data.h
> > > > index 4f0aae5483745dfa..c15f734d7fc4aecb 100644
> > > > --- a/tools/perf/util/bpf_skel/lock_data.h
> > > > +++ b/tools/perf/util/bpf_skel/lock_data.h
> > > > @@ -32,9 +32,16 @@ struct contention_task_data {
> > > > #define LCD_F_MMAP_LOCK (1U << 31)
> > > > #define LCD_F_SIGHAND_LOCK (1U << 30)
> > > >
> > > > +#define LCB_F_SLAB_ID_SHIFT 16
> > > > +#define LCB_F_SLAB_ID_START (1U << 16)
> > > > +#define LCB_F_SLAB_ID_END (1U << 26)
> > > > +#define LCB_F_SLAB_ID_MASK 0x03FF0000U
> > > > +
> > > > #define LCB_F_TYPE_MAX (1U << 7)
> > > > #define LCB_F_TYPE_MASK 0x0000007FU
> > > >
> > > > +#define SLAB_NAME_MAX 28
> > > > +
> > > > struct contention_data {
> > > > u64 total_time;
> > > > u64 min_time;
> > > > @@ -55,4 +62,9 @@ enum lock_class_sym {
> > > > LOCK_CLASS_RQLOCK,
> > > > };
> > > >
> > > > +struct slab_cache_data {
> > > > + u32 id;
> > > > + char name[SLAB_NAME_MAX];
> > > > +};
> > > > +
> > > > #endif /* UTIL_BPF_SKEL_LOCK_DATA_H */
> > > > diff --git a/tools/perf/util/bpf_skel/vmlinux/vmlinux.h b/tools/perf/util/bpf_skel/vmlinux/vmlinux.h
> > > > index 4dcad7b682bdee9c..7b81d3173917fdb5 100644
> > > > --- a/tools/perf/util/bpf_skel/vmlinux/vmlinux.h
> > > > +++ b/tools/perf/util/bpf_skel/vmlinux/vmlinux.h
> > > > @@ -195,4 +195,12 @@ struct bpf_perf_event_data_kern {
> > > > */
> > > > struct rq {};
> > > >
> > > > +struct kmem_cache {
> > > > + const char *name;
> > > > +} __attribute__((preserve_access_index));
> > > > +
> > > > +struct bpf_iter__kmem_cache {
> > > > + struct kmem_cache *s;
> > > > +} __attribute__((preserve_access_index));
> > > > +
> > > > #endif // __VMLINUX_H
> > > > --
> > > > 2.47.0.277.g8800431eea-goog
On Mon, Dec 09, 2024 at 01:38:39PM -0300, Arnaldo Carvalho de Melo wrote:
> On Mon, Dec 09, 2024 at 01:36:52PM -0300, Arnaldo Carvalho de Melo wrote:
> > On Thu, Nov 07, 2024 at 10:14:57PM -0800, Namhyung Kim wrote:
> > > Recently the kernel got the kmem_cache iterator to traverse metadata of
> > > slab objects. This can be used to symbolize dynamic locks in a slab.
> > > The new slab_caches hash map will have the pointer of the kmem_cache as
> > > a key and save the name and a id. The id will be saved in the flags
> > > part of the lock.
> > Trying to fix this
>
> So you have that struct in tools/perf/util/bpf_skel/vmlinux/vmlinux.h,
> but then, this kernel is old and doesn't have the kmem_cache iterator,
> so using the generated vmlinux.h will fail the build.
I tried passing the right offset to the iterator so as not to try to use
a type that isn't in vmlinux.h generated from the old kernel BTF:
+++ b/tools/perf/util/bpf_lock_contention.c
@@ -52,7 +52,7 @@ static void check_slab_cache_iter(struct lock_contention *con)
pr_debug("slab cache iterator is not available: %d\n", ret);
goto out;
} else {
- const struct btf_member *s = __btf_type__find_member_by_name(btf, ret, "s");
+ const struct btf_member *s = __btf_type__find_unnamed_union_with_member_by_name(btf, ret, "s");
if (s == NULL) {
skel->rodata->slab_cache_iter_member_offset = -1;
@@ -60,7 +60,9 @@ static void check_slab_cache_iter(struct lock_contention *con)
goto out;
}
skel->rodata->slab_cache_iter_member_offset = s->offset / 8; // bits -> bytes
+ pr_debug("slab cache iterator kmem_cache pointer offset: %d\n",
+ skel->rodata->slab_cache_iter_member_offset);
}
but the verifier doesn't like that:
; struct kmem_cache *s = slab_cache_iter_member_offset < 0 ? NULL : @ lock_contention.bpf.c:615
12: (7b) *(u64 *)(r10 -8) = r2 ; R2_w=ctx(off=8) R10=fp0 fp-8_w=ctx(off=8)
; if (s == NULL) @ lock_contention.bpf.c:619
13: (15) if r1 == 0x0 goto pc+22 ; R1=ctx()
; d.id = ++slab_cache_id << LCB_F_SLAB_ID_SHIFT; @ lock_contention.bpf.c:622
14: (18) r1 = 0xffffc14bcde3a014 ; R1_w=map_value(map=lock_con.bss,ks=4,vs=40,off=20)
16: (61) r3 = *(u32 *)(r1 +0) ; R1_w=map_value(map=lock_con.bss,ks=4,vs=40,off=20) R3_w=scalar(smin=0,smax=umax=0xffffffff,var_off=(0x0; 0xffffffff))
17: (07) r3 += 1 ; R3_w=scalar(smin=umin=1,smax=umax=0x100000000,var_off=(0x0; 0x1ffffffff))
18: (63) *(u32 *)(r1 +0) = r3 ; R1_w=map_value(map=lock_con.bss,ks=4,vs=40,off=20) R3_w=scalar(smin=umin=1,smax=umax=0x100000000,var_off=(0x0; 0x1ffffffff))
19: (67) r3 <<= 16 ; R3_w=scalar(smin=umin=0x10000,smax=umax=0x1000000000000,smax32=0x7fff0000,umax32=0xffff0000,var_off=(0x0; 0x1ffffffff0000))
20: (63) *(u32 *)(r10 -40) = r3 ; R3_w=scalar(smin=umin=0x10000,smax=umax=0x1000000000000,smax32=0x7fff0000,umax32=0xffff0000,var_off=(0x0; 0x1ffffffff0000)) R10=fp0 fp-40=????scalar(smin=umin=0x10000,smax=umax=0x1000000000000,smax32=0x7fff0000,umax32=0xffff0000,var_off=(0x0; 0x1ffffffff0000))
; bpf_probe_read_kernel_str(d.name, sizeof(d.name), s->name); @ lock_contention.bpf.c:623
21: (79) r3 = *(u64 *)(r2 +96)
dereference of modified ctx ptr R2 off=8 disallowed
processed 19 insns (limit 1000000) max_states_per_insn 0 total_states 0 peak_states 0 mark_read 0
-- END PROG LOAD LOG --
libbpf: prog 'slab_cache_iter': failed to load: -EACCES
libbpf: failed to load object 'lock_contention_bpf'
libbpf: failed to load BPF skeleton 'lock_contention_bpf': -EACCES
Failed to load lock-contention BPF skeleton
lock contention BPF setup failed
root@number:~#
and additionally the type is not like the one you added to the barebones
vmlinux.h:
⬢ [acme@toolbox perf-tools-next]$ git show d82e2e170d1c756b | grep 'struct bpf_iter__kmem_cache {' -A3
+struct bpf_iter__kmem_cache {
+ struct kmem_cache *s;
+} __attribute__((preserve_access_index));
+
⬢ [acme@toolbox perf-tools-next]$
But:
⬢ [acme@toolbox perf-tools-next]$ uname -a
Linux toolbox 6.13.0-rc2 #1 SMP PREEMPT_DYNAMIC Mon Dec 9 12:33:35 -03 2024 x86_64 GNU/Linux
⬢ [acme@toolbox perf-tools-next]$ pahole bpf_iter__kmem_cache
struct bpf_iter__kmem_cache {
union {
struct bpf_iter_meta * meta; /* 0 8 */
}; /* 0 8 */
union {
struct kmem_cache * s; /* 8 8 */
}; /* 8 8 */
/* size: 16, cachelines: 1, members: 2 */
/* last cacheline: 16 bytes */
};
⬢ [acme@toolbox perf-tools-next]$
Do CO-RE handle this?
- Arnaldo
On Mon, Dec 9, 2024 at 12:23 PM Arnaldo Carvalho de Melo
<acme@kernel.org> wrote:
>
> On Mon, Dec 09, 2024 at 01:38:39PM -0300, Arnaldo Carvalho de Melo wrote:
> > On Mon, Dec 09, 2024 at 01:36:52PM -0300, Arnaldo Carvalho de Melo wrote:
> > > On Thu, Nov 07, 2024 at 10:14:57PM -0800, Namhyung Kim wrote:
> > > > Recently the kernel got the kmem_cache iterator to traverse metadata of
> > > > slab objects. This can be used to symbolize dynamic locks in a slab.
>
> > > > The new slab_caches hash map will have the pointer of the kmem_cache as
> > > > a key and save the name and a id. The id will be saved in the flags
> > > > part of the lock.
>
> > > Trying to fix this
> >
> > So you have that struct in tools/perf/util/bpf_skel/vmlinux/vmlinux.h,
> > but then, this kernel is old and doesn't have the kmem_cache iterator,
> > so using the generated vmlinux.h will fail the build.
>
> I tried passing the right offset to the iterator so as not to try to use
> a type that isn't in vmlinux.h generated from the old kernel BTF:
>
> +++ b/tools/perf/util/bpf_lock_contention.c
> @@ -52,7 +52,7 @@ static void check_slab_cache_iter(struct lock_contention *con)
> pr_debug("slab cache iterator is not available: %d\n", ret);
> goto out;
> } else {
> - const struct btf_member *s = __btf_type__find_member_by_name(btf, ret, "s");
> + const struct btf_member *s = __btf_type__find_unnamed_union_with_member_by_name(btf, ret, "s");
>
> if (s == NULL) {
> skel->rodata->slab_cache_iter_member_offset = -1;
> @@ -60,7 +60,9 @@ static void check_slab_cache_iter(struct lock_contention *con)
> goto out;
> }
>
> skel->rodata->slab_cache_iter_member_offset = s->offset / 8; // bits -> bytes
> + pr_debug("slab cache iterator kmem_cache pointer offset: %d\n",
> + skel->rodata->slab_cache_iter_member_offset);
> }
>
>
> but the verifier doesn't like that:
>
> ; struct kmem_cache *s = slab_cache_iter_member_offset < 0 ? NULL : @ lock_contention.bpf.c:615
> 12: (7b) *(u64 *)(r10 -8) = r2 ; R2_w=ctx(off=8) R10=fp0 fp-8_w=ctx(off=8)
> ; if (s == NULL) @ lock_contention.bpf.c:619
> 13: (15) if r1 == 0x0 goto pc+22 ; R1=ctx()
> ; d.id = ++slab_cache_id << LCB_F_SLAB_ID_SHIFT; @ lock_contention.bpf.c:622
> 14: (18) r1 = 0xffffc14bcde3a014 ; R1_w=map_value(map=lock_con.bss,ks=4,vs=40,off=20)
> 16: (61) r3 = *(u32 *)(r1 +0) ; R1_w=map_value(map=lock_con.bss,ks=4,vs=40,off=20) R3_w=scalar(smin=0,smax=umax=0xffffffff,var_off=(0x0; 0xffffffff))
> 17: (07) r3 += 1 ; R3_w=scalar(smin=umin=1,smax=umax=0x100000000,var_off=(0x0; 0x1ffffffff))
> 18: (63) *(u32 *)(r1 +0) = r3 ; R1_w=map_value(map=lock_con.bss,ks=4,vs=40,off=20) R3_w=scalar(smin=umin=1,smax=umax=0x100000000,var_off=(0x0; 0x1ffffffff))
> 19: (67) r3 <<= 16 ; R3_w=scalar(smin=umin=0x10000,smax=umax=0x1000000000000,smax32=0x7fff0000,umax32=0xffff0000,var_off=(0x0; 0x1ffffffff0000))
> 20: (63) *(u32 *)(r10 -40) = r3 ; R3_w=scalar(smin=umin=0x10000,smax=umax=0x1000000000000,smax32=0x7fff0000,umax32=0xffff0000,var_off=(0x0; 0x1ffffffff0000)) R10=fp0 fp-40=????scalar(smin=umin=0x10000,smax=umax=0x1000000000000,smax32=0x7fff0000,umax32=0xffff0000,var_off=(0x0; 0x1ffffffff0000))
> ; bpf_probe_read_kernel_str(d.name, sizeof(d.name), s->name); @ lock_contention.bpf.c:623
> 21: (79) r3 = *(u64 *)(r2 +96)
> dereference of modified ctx ptr R2 off=8 disallowed
> processed 19 insns (limit 1000000) max_states_per_insn 0 total_states 0 peak_states 0 mark_read 0
> -- END PROG LOAD LOG --
> libbpf: prog 'slab_cache_iter': failed to load: -EACCES
> libbpf: failed to load object 'lock_contention_bpf'
> libbpf: failed to load BPF skeleton 'lock_contention_bpf': -EACCES
> Failed to load lock-contention BPF skeleton
> lock contention BPF setup failed
> root@number:~#
>
> and additionally the type is not like the one you added to the barebones
> vmlinux.h:
>
> ⬢ [acme@toolbox perf-tools-next]$ git show d82e2e170d1c756b | grep 'struct bpf_iter__kmem_cache {' -A3
> +struct bpf_iter__kmem_cache {
> + struct kmem_cache *s;
> +} __attribute__((preserve_access_index));
> +
> ⬢ [acme@toolbox perf-tools-next]$
>
> But:
>
> ⬢ [acme@toolbox perf-tools-next]$ uname -a
> Linux toolbox 6.13.0-rc2 #1 SMP PREEMPT_DYNAMIC Mon Dec 9 12:33:35 -03 2024 x86_64 GNU/Linux
> ⬢ [acme@toolbox perf-tools-next]$ pahole bpf_iter__kmem_cache
> struct bpf_iter__kmem_cache {
> union {
> struct bpf_iter_meta * meta; /* 0 8 */
> }; /* 0 8 */
> union {
> struct kmem_cache * s; /* 8 8 */
> }; /* 8 8 */
>
> /* size: 16, cachelines: 1, members: 2 */
> /* last cacheline: 16 bytes */
> };
>
> ⬢ [acme@toolbox perf-tools-next]$
>
> Do CO-RE handle this?
>
I don't know exactly what the problem you are running into is, but
yes, BPF CO-RE allows handling missing fields, incompatible field type
changes, field renames, etc. All without having to break a
compilation. See [0] (and one subsection after that) for
"documentation" and examples.
[0] https://nakryiko.com/posts/bpf-core-reference-guide/#defining-own-co-re-relocatable-type-definitions
> - Arnaldo
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