kernel/bpf/helpers.c | 34 ++++++++++++++++++++++++++++++++++ 1 file changed, 34 insertions(+)
add a kfunc 'bpf_ptrace_vprintk' printing bpf msg with trace_marker
format requirement so that these msgs can be retrieved by android
perfetto by default and well represented in perfetto UI.
[testing prog]
const volatile bool ptrace_enabled = true;
extern int bpf_ptrace_vprintk(char *fmt, u32 fmt_size, const void *args, u32 args__sz) __ksym;
({ \
if (!ptrace_enabled) { \
bpf_printk(fmt, __VA_ARGS__); \
} else { \
char __fmt[] = fmt; \
_Pragma("GCC diagnostic push") \
_Pragma("GCC diagnostic ignored \"-Wint-conversion\"") \
u64 __params[] = { __VA_ARGS__ }; \
_Pragma("GCC diagnostic pop") \
bpf_ptrace_vprintk(__fmt, sizeof(__fmt), __params, sizeof(__params)); \
} \
})
SEC("perf_event")
int do_sample(struct bpf_perf_event_data *ctx)
{
u64 ip = PT_REGS_IP(&ctx->regs);
u64 id = bpf_get_current_pid_tgid();
s32 pid = id >> 32;
s32 tid = id;
debug_printk("N|%d|BPRF-%d|BPRF:%llx", pid, tid, ip);
return 0;
}
[output]:
app-3151 [000] d.h1. 6059.904239: tracing_mark_write: N|2491|BPRF-3151|BPRF:58750d0eec
Signed-off-by: Eric Yan <eric.yan@oppo.com>
---
kernel/bpf/helpers.c | 34 ++++++++++++++++++++++++++++++++++
1 file changed, 34 insertions(+)
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 1a43d06eab28..e3d17d3b17c5 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -2521,6 +2521,39 @@ __bpf_kfunc struct task_struct *bpf_task_from_pid(s32 pid)
return p;
}
+static noinline void tracing_mark_write(char *buf)
+{
+ trace_printk(buf);
+}
+
+/**
+ * same as bpf_trace_vprintk, except for a trace_marker format requirement
+ */
+__bpf_kfunc int bpf_ptrace_vprintk(char *fmt, u32 fmt_size, const void *args, u32 args__sz)
+{
+ struct bpf_bprintf_data data = {
+ .get_bin_args = true,
+ .get_buf = true,
+ };
+ int ret, num_args;
+
+ if (args__sz & 7 || args__sz > MAX_BPRINTF_VARARGS * 8 || (args__sz && !args))
+ return -EINVAL;
+ num_args = args__sz / 8;
+
+ ret = bpf_bprintf_prepare(fmt, fmt_size, args, num_args, &data);
+ if (ret < 0)
+ return ret;
+
+ ret = bstr_printf(data.buf, MAX_BPRINTF_BUF, fmt, data.bin_args);
+
+ tracing_mark_write(data.buf);
+
+ bpf_bprintf_cleanup(&data);
+
+ return ret;
+}
+
/**
* bpf_dynptr_slice() - Obtain a read-only pointer to the dynptr data.
* @p: The dynptr whose data slice to retrieve
@@ -3090,6 +3123,7 @@ BTF_ID_FLAGS(func, bpf_iter_bits_new, KF_ITER_NEW)
BTF_ID_FLAGS(func, bpf_iter_bits_next, KF_ITER_NEXT | KF_RET_NULL)
BTF_ID_FLAGS(func, bpf_iter_bits_destroy, KF_ITER_DESTROY)
BTF_ID_FLAGS(func, bpf_copy_from_user_str, KF_SLEEPABLE)
+BTF_ID_FLAGS(func, bpf_ptrace_vprintk)
BTF_KFUNCS_END(common_btf_ids)
static const struct btf_kfunc_id_set common_kfunc_set = {
--
2.34.1Hi Eric,
kernel test robot noticed the following build warnings:
[auto build test WARNING on bpf-next/master]
[also build test WARNING on bpf/master linus/master next-20240925]
[cannot apply to v6.11]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Eric-Yan/Add-BPF-Kernel-Function-bpf_ptrace_vprintk/20240925-180530
base: https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
patch link: https://lore.kernel.org/r/20240925100254.436-1-eric.yan%40oppo.com
patch subject: [PATCH] Add BPF Kernel Function bpf_ptrace_vprintk
config: x86_64-buildonly-randconfig-003-20240926 (https://download.01.org/0day-ci/archive/20240926/202409261116.risxWG3M-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240926/202409261116.risxWG3M-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202409261116.risxWG3M-lkp@intel.com/
All warnings (new ones prefixed by >>):
>> kernel/bpf/helpers.c:2530: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst
* same as bpf_trace_vprintk, except for a trace_marker format requirement
vim +2530 kernel/bpf/helpers.c
2528
2529 /**
> 2530 * same as bpf_trace_vprintk, except for a trace_marker format requirement
2531 */
2532 __bpf_kfunc int bpf_ptrace_vprintk(char *fmt, u32 fmt_size, const void *args, u32 args__sz)
2533 {
2534 struct bpf_bprintf_data data = {
2535 .get_bin_args = true,
2536 .get_buf = true,
2537 };
2538 int ret, num_args;
2539
2540 if (args__sz & 7 || args__sz > MAX_BPRINTF_VARARGS * 8 || (args__sz && !args))
2541 return -EINVAL;
2542 num_args = args__sz / 8;
2543
2544 ret = bpf_bprintf_prepare(fmt, fmt_size, args, num_args, &data);
2545 if (ret < 0)
2546 return ret;
2547
2548 ret = bstr_printf(data.buf, MAX_BPRINTF_BUF, fmt, data.bin_args);
2549
2550 tracing_mark_write(data.buf);
2551
2552 bpf_bprintf_cleanup(&data);
2553
2554 return ret;
2555 }
2556
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
add a kfunc 'bpf_ptrace_vprintk' printing bpf msg with trace_marker
format requirement so that these msgs can be retrieved by android
perfetto by default and well represented in perfetto UI.
[testing prog]
const volatile bool ptrace_enabled = true;
extern int bpf_ptrace_vprintk(char *fmt, u32 fmt_size, const void *args, u32 args__sz) __ksym;
({ \
if (!ptrace_enabled) { \
bpf_printk(fmt, __VA_ARGS__); \
} else { \
char __fmt[] = fmt; \
_Pragma("GCC diagnostic push") \
_Pragma("GCC diagnostic ignored \"-Wint-conversion\"") \
u64 __params[] = { __VA_ARGS__ }; \
_Pragma("GCC diagnostic pop") \
bpf_ptrace_vprintk(__fmt, sizeof(__fmt), __params, sizeof(__params)); \
} \
})
SEC("perf_event")
int do_sample(struct bpf_perf_event_data *ctx)
{
u64 ip = PT_REGS_IP(&ctx->regs);
u64 id = bpf_get_current_pid_tgid();
s32 pid = id >> 32;
s32 tid = id;
debug_printk("N|%d|BPRF-%d|BPRF:%llx", pid, tid, ip);
return 0;
}
[output]:
app-3151 [000] d.h1. 6059.904239: tracing_mark_write: N|2491|BPRF-3151|BPRF:58750d0eec
Signed-off-by: Eric Yan <eric.yan@oppo.com>
---
kernel/bpf/helpers.c | 34 ++++++++++++++++++++++++++++++++++
1 file changed, 34 insertions(+)
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 1a43d06eab28..1e37dae74ca6 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -2521,6 +2521,39 @@ __bpf_kfunc struct task_struct *bpf_task_from_pid(s32 pid)
return p;
}
+static noinline void tracing_mark_write(char *buf)
+{
+ trace_printk(buf);
+}
+
+/* same as bpf_trace_vprintk, only with a trace_marker format requirement
+ * @fmt: Format string, e.g. <B|E|C|N>|<%d:pid>|<%s:TAG>...
+ */
+__bpf_kfunc int bpf_ptrace_vprintk(char *fmt, u32 fmt_size, const void *args, u32 args__sz)
+{
+ struct bpf_bprintf_data data = {
+ .get_bin_args = true,
+ .get_buf = true,
+ };
+ int ret, num_args;
+
+ if (args__sz & 7 || args__sz > MAX_BPRINTF_VARARGS * 8 || (args__sz && !args))
+ return -EINVAL;
+ num_args = args__sz / 8;
+
+ ret = bpf_bprintf_prepare(fmt, fmt_size, args, num_args, &data);
+ if (ret < 0)
+ return ret;
+
+ ret = bstr_printf(data.buf, MAX_BPRINTF_BUF, fmt, data.bin_args);
+
+ tracing_mark_write(data.buf);
+
+ bpf_bprintf_cleanup(&data);
+
+ return ret;
+}
+
/**
* bpf_dynptr_slice() - Obtain a read-only pointer to the dynptr data.
* @p: The dynptr whose data slice to retrieve
@@ -3090,6 +3123,7 @@ BTF_ID_FLAGS(func, bpf_iter_bits_new, KF_ITER_NEW)
BTF_ID_FLAGS(func, bpf_iter_bits_next, KF_ITER_NEXT | KF_RET_NULL)
BTF_ID_FLAGS(func, bpf_iter_bits_destroy, KF_ITER_DESTROY)
BTF_ID_FLAGS(func, bpf_copy_from_user_str, KF_SLEEPABLE)
+BTF_ID_FLAGS(func, bpf_ptrace_vprintk)
BTF_KFUNCS_END(common_btf_ids)
static const struct btf_kfunc_id_set common_kfunc_set = {
--
2.34.1On Thu, Sep 26, 2024 at 12:28 AM Eric Yan <eric.yan@oppo.com> wrote:
>
> add a kfunc 'bpf_ptrace_vprintk' printing bpf msg with trace_marker
> format requirement so that these msgs can be retrieved by android
> perfetto by default and well represented in perfetto UI.
>
> [testing prog]
> const volatile bool ptrace_enabled = true;
> extern int bpf_ptrace_vprintk(char *fmt, u32 fmt_size, const void *args, u32 args__sz) __ksym;
>
> ({ \
> if (!ptrace_enabled) { \
> bpf_printk(fmt, __VA_ARGS__); \
> } else { \
> char __fmt[] = fmt; \
> _Pragma("GCC diagnostic push") \
> _Pragma("GCC diagnostic ignored \"-Wint-conversion\"") \
> u64 __params[] = { __VA_ARGS__ }; \
> _Pragma("GCC diagnostic pop") \
> bpf_ptrace_vprintk(__fmt, sizeof(__fmt), __params, sizeof(__params)); \
> } \
> })
>
> SEC("perf_event")
> int do_sample(struct bpf_perf_event_data *ctx)
> {
> u64 ip = PT_REGS_IP(&ctx->regs);
> u64 id = bpf_get_current_pid_tgid();
> s32 pid = id >> 32;
> s32 tid = id;
> debug_printk("N|%d|BPRF-%d|BPRF:%llx", pid, tid, ip);
> return 0;
> }
>
> [output]:
> app-3151 [000] d.h1. 6059.904239: tracing_mark_write: N|2491|BPRF-3151|BPRF:58750d0eec
>
> Signed-off-by: Eric Yan <eric.yan@oppo.com>
> ---
> kernel/bpf/helpers.c | 34 ++++++++++++++++++++++++++++++++++
> 1 file changed, 34 insertions(+)
>
> diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
> index 1a43d06eab28..1e37dae74ca6 100644
> --- a/kernel/bpf/helpers.c
> +++ b/kernel/bpf/helpers.c
> @@ -2521,6 +2521,39 @@ __bpf_kfunc struct task_struct *bpf_task_from_pid(s32 pid)
> return p;
> }
>
> +static noinline void tracing_mark_write(char *buf)
> +{
> + trace_printk(buf);
> +}
> +
> +/* same as bpf_trace_vprintk, only with a trace_marker format requirement
> + * @fmt: Format string, e.g. <B|E|C|N>|<%d:pid>|<%s:TAG>...
> + */
> +__bpf_kfunc int bpf_ptrace_vprintk(char *fmt, u32 fmt_size, const void *args, u32 args__sz)
> +{
> + struct bpf_bprintf_data data = {
> + .get_bin_args = true,
> + .get_buf = true,
> + };
> + int ret, num_args;
> +
> + if (args__sz & 7 || args__sz > MAX_BPRINTF_VARARGS * 8 || (args__sz && !args))
> + return -EINVAL;
> + num_args = args__sz / 8;
> +
> + ret = bpf_bprintf_prepare(fmt, fmt_size, args, num_args, &data);
> + if (ret < 0)
> + return ret;
> +
> + ret = bstr_printf(data.buf, MAX_BPRINTF_BUF, fmt, data.bin_args);
> +
> + tracing_mark_write(data.buf);
> +
> + bpf_bprintf_cleanup(&data);
> +
> + return ret;
> +}
> +
> /**
> * bpf_dynptr_slice() - Obtain a read-only pointer to the dynptr data.
> * @p: The dynptr whose data slice to retrieve
> @@ -3090,6 +3123,7 @@ BTF_ID_FLAGS(func, bpf_iter_bits_new, KF_ITER_NEW)
> BTF_ID_FLAGS(func, bpf_iter_bits_next, KF_ITER_NEXT | KF_RET_NULL)
> BTF_ID_FLAGS(func, bpf_iter_bits_destroy, KF_ITER_DESTROY)
> BTF_ID_FLAGS(func, bpf_copy_from_user_str, KF_SLEEPABLE)
> +BTF_ID_FLAGS(func, bpf_ptrace_vprintk)
> BTF_KFUNCS_END(common_btf_ids)
Why new kfunc?
Use bpf_snprintf() and follow with bpf_trace_printk() ?
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