arch/Kconfig | 14 + arch/x86/Kconfig | 2 + arch/x86/entry/vdso/Makefile | 6 +- arch/x86/entry/vdso/vdso-layout.lds.S | 5 +- arch/x86/entry/vdso/vdso32/system_call.S | 10 +- arch/x86/entry/vdso/vgetrandom-chacha.S | 3 +- arch/x86/entry/vdso/vsgx.S | 19 +- arch/x86/include/asm/dwarf2.h | 40 ++- arch/x86/include/asm/linkage.h | 29 +- arch/x86/include/asm/mmu.h | 2 +- arch/x86/include/asm/unwind_user.h | 11 + arch/x86/include/asm/vdso.h | 1 - fs/binfmt_elf.c | 35 +- include/linux/entry-common.h | 3 + include/linux/mm_types.h | 3 + include/linux/perf_event.h | 12 +- include/linux/sched.h | 5 + include/linux/sframe.h | 41 +++ include/linux/unwind_user.h | 99 ++++++ include/uapi/linux/elf.h | 1 + include/uapi/linux/perf_event.h | 22 +- include/uapi/linux/prctl.h | 3 + kernel/Makefile | 1 + kernel/bpf/stackmap.c | 14 +- kernel/events/callchain.c | 47 +-- kernel/events/core.c | 70 +++- kernel/fork.c | 14 + kernel/sys.c | 11 + kernel/unwind/Makefile | 2 + kernel/unwind/sframe.c | 380 ++++++++++++++++++++++ kernel/unwind/sframe.h | 215 ++++++++++++ kernel/unwind/user.c | 318 ++++++++++++++++++ mm/init-mm.c | 6 + tools/include/uapi/linux/perf_event.h | 22 +- tools/lib/perf/include/perf/event.h | 7 + tools/perf/Documentation/perf-script.txt | 5 + tools/perf/builtin-script.c | 92 ++++++ tools/perf/util/callchain.c | 24 ++ tools/perf/util/callchain.h | 3 + tools/perf/util/event.c | 1 + tools/perf/util/evlist.c | 1 + tools/perf/util/evlist.h | 1 + tools/perf/util/evsel.c | 32 +- tools/perf/util/evsel.h | 1 + tools/perf/util/machine.c | 1 + tools/perf/util/perf_event_attr_fprintf.c | 1 + tools/perf/util/sample.h | 3 +- tools/perf/util/session.c | 78 +++++ tools/perf/util/tool.c | 2 + tools/perf/util/tool.h | 4 +- 50 files changed, 1634 insertions(+), 88 deletions(-) create mode 100644 arch/x86/include/asm/unwind_user.h create mode 100644 include/linux/sframe.h create mode 100644 include/linux/unwind_user.h create mode 100644 kernel/unwind/Makefile create mode 100644 kernel/unwind/sframe.c create mode 100644 kernel/unwind/sframe.h create mode 100644 kernel/unwind/user.c
This has all the changes discussed in v2, plus VDSO sframe support and
Namhyung's perf tool patches (see detailed changelog below).
I did quite a bit of testing, it seems to work well. It still needs
some binutils and glibc patches which I'll send in a reply.
Questions for perf experts:
- Is the perf_event lifetime managed correctly or do we need to do
something to ensure it exists in unwind_user_task_work()?
Or alternatively is the original perf_event even needed in
unwind_user_task_work() or can a new one be created on demand?
- Is --call-graph=sframe needed for consistency?
- Should perf use the context cookie? Note that because the callback
is usually only called once for multiple NMIs in the same entry
context, it's possible for the PERF_RECORD_CALLCHAIN_DEFERRED event
to arrive *before* some of the corresponding kernel events. The
context cookie disambiguates the corner cases.
Based on tip/master.
Also at:
git://git.kernel.org/pub/scm/linux/kernel/git/jpoimboe/linux.git sframe-v3
v3:
- move the "deferred" logic out of perf and into unwind_user with new
unwind_user_deferred() interface [Steven, Mathieu]
- add more sframe sanity checks [Steven]
- make frame pointers optional depending on arch [Jens]
- fix perf event output [Namhyung]
- include Namhyung's perf tool patches
- enable sframe generation in VDSO
- fix build errors [robot]
v2: https://lore.kernel.org/cover.1726268190.git.jpoimboe@kernel.org
- rebase on v6.11-rc7
- reorganize the patches to add sframe first
- change to sframe v2
- add new perf event type: PERF_RECORD_CALLCHAIN_DEFERRED
- add new perf attribute: defer_callchain
v1: https://lore.kernel.org/cover.1699487758.git.jpoimboe@kernel.org
Some distros have started compiling frame pointers into all their
packages to enable the kernel to do system-wide profiling of user space.
Unfortunately that creates a runtime performance penalty across the
entire system. Using DWARF (or .eh_frame) instead isn't feasible
because of complexity and slowness.
For in-kernel unwinding we solved this problem with the creation of the
ORC unwinder for x86_64. Similarly, for user space the GNU assembler
has created the SFrame ("Simple Frame") v2 format starting with binutils
2.41.
These patches add support for unwinding user space from the kernel using
SFrame with perf. It should be easy to add user unwinding support for
other components like ftrace.
There were two main challenges:
1) Finding .sframe sections in shared/dlopened libraries
The kernel has no visibility to the contents of shared libraries.
This was solved by adding a PR_ADD_SFRAME option to prctl() which
allows the runtime linker to manually provide the in-memory address
of an .sframe section to the kernel.
2) Dealing with page faults
Keeping all binaries' sframe data pinned would likely waste a lot of
memory. Instead, read it from user space on demand. That can't be
done from perf NMI context due to page faults, so defer the unwind to
the next user exit. Since the NMI handler doesn't do exit work,
self-IPI and then schedule task work to be run on exit from the IPI.
Special thanks to Indu for the original concept, and to Steven and Peter
for helping a lot with the design. And to Steven for letting me do it ;-)
Josh Poimboeuf (15):
x86/vdso: Fix DWARF generation for getrandom()
x86/asm: Avoid emitting DWARF CFI for non-VDSO
x86/asm: Fix VDSO DWARF generation with kernel IBT enabled
x86/vdso: Use SYM_FUNC_{START,END} in __kernel_vsyscall()
x86/vdso: Use CFI macros in __vdso_sgx_enter_enclave()
x86/vdso: Enable sframe generation in VDSO
unwind: Add user space unwinding API
unwind/x86: Enable CONFIG_HAVE_UNWIND_USER_FP
unwind: Introduce sframe user space unwinding
unwind/x86: Enable CONFIG_HAVE_UNWIND_USER_SFRAME
unwind: Add deferred user space unwinding API
perf: Remove get_perf_callchain() 'init_nr' argument
perf: Remove get_perf_callchain() 'crosstask' argument
perf: Simplify get_perf_callchain() user logic
perf: Add deferred user callchains
Namhyung Kim (4):
perf tools: Minimal CALLCHAIN_DEFERRED support
perf record: Enable defer_callchain for user callchains
perf script: Display PERF_RECORD_CALLCHAIN_DEFERRED
perf tools: Merge deferred user callchains
arch/Kconfig | 14 +
arch/x86/Kconfig | 2 +
arch/x86/entry/vdso/Makefile | 6 +-
arch/x86/entry/vdso/vdso-layout.lds.S | 5 +-
arch/x86/entry/vdso/vdso32/system_call.S | 10 +-
arch/x86/entry/vdso/vgetrandom-chacha.S | 3 +-
arch/x86/entry/vdso/vsgx.S | 19 +-
arch/x86/include/asm/dwarf2.h | 40 ++-
arch/x86/include/asm/linkage.h | 29 +-
arch/x86/include/asm/mmu.h | 2 +-
arch/x86/include/asm/unwind_user.h | 11 +
arch/x86/include/asm/vdso.h | 1 -
fs/binfmt_elf.c | 35 +-
include/linux/entry-common.h | 3 +
include/linux/mm_types.h | 3 +
include/linux/perf_event.h | 12 +-
include/linux/sched.h | 5 +
include/linux/sframe.h | 41 +++
include/linux/unwind_user.h | 99 ++++++
include/uapi/linux/elf.h | 1 +
include/uapi/linux/perf_event.h | 22 +-
include/uapi/linux/prctl.h | 3 +
kernel/Makefile | 1 +
kernel/bpf/stackmap.c | 14 +-
kernel/events/callchain.c | 47 +--
kernel/events/core.c | 70 +++-
kernel/fork.c | 14 +
kernel/sys.c | 11 +
kernel/unwind/Makefile | 2 +
kernel/unwind/sframe.c | 380 ++++++++++++++++++++++
kernel/unwind/sframe.h | 215 ++++++++++++
kernel/unwind/user.c | 318 ++++++++++++++++++
mm/init-mm.c | 6 +
tools/include/uapi/linux/perf_event.h | 22 +-
tools/lib/perf/include/perf/event.h | 7 +
tools/perf/Documentation/perf-script.txt | 5 +
tools/perf/builtin-script.c | 92 ++++++
tools/perf/util/callchain.c | 24 ++
tools/perf/util/callchain.h | 3 +
tools/perf/util/event.c | 1 +
tools/perf/util/evlist.c | 1 +
tools/perf/util/evlist.h | 1 +
tools/perf/util/evsel.c | 32 +-
tools/perf/util/evsel.h | 1 +
tools/perf/util/machine.c | 1 +
tools/perf/util/perf_event_attr_fprintf.c | 1 +
tools/perf/util/sample.h | 3 +-
tools/perf/util/session.c | 78 +++++
tools/perf/util/tool.c | 2 +
tools/perf/util/tool.h | 4 +-
50 files changed, 1634 insertions(+), 88 deletions(-)
create mode 100644 arch/x86/include/asm/unwind_user.h
create mode 100644 include/linux/sframe.h
create mode 100644 include/linux/unwind_user.h
create mode 100644 kernel/unwind/Makefile
create mode 100644 kernel/unwind/sframe.c
create mode 100644 kernel/unwind/sframe.h
create mode 100644 kernel/unwind/user.c
--
2.47.0
On Mon, Oct 28, 2024 at 02:47:27PM -0700, Josh Poimboeuf wrote: > This has all the changes discussed in v2, plus VDSO sframe support and > Namhyung's perf tool patches (see detailed changelog below). > > I did quite a bit of testing, it seems to work well. It still needs > some binutils and glibc patches which I'll send in a reply. > > Questions for perf experts: > > - Is the perf_event lifetime managed correctly or do we need to do > something to ensure it exists in unwind_user_task_work()? > > Or alternatively is the original perf_event even needed in > unwind_user_task_work() or can a new one be created on demand? > > - Is --call-graph=sframe needed for consistency? > > - Should perf use the context cookie? Note that because the callback > is usually only called once for multiple NMIs in the same entry > context, it's possible for the PERF_RECORD_CALLCHAIN_DEFERRED event > to arrive *before* some of the corresponding kernel events. The > context cookie disambiguates the corner cases. > > Based on tip/master. > > Also at: > > git://git.kernel.org/pub/scm/linux/kernel/git/jpoimboe/linux.git sframe-v3 Argh, apparently it's a bad idea to pass "*.patch" twice on the git-send-email cmdline ;-) Sorry for sending it twice! -- Josh
On Mon, Oct 28, 2024 at 02:47:27PM -0700, Josh Poimboeuf wrote:
> It still needs some binutils and glibc patches
binutils+glibc patches attached.
--
Josh
From: Indu Bhagat <indu.bhagat@oracle.com>
Date: Fri, 25 Oct 2024 14:33:19 -0700
To: jpoimboe@kernel.org
Subject: [PATCH 1/3] ld: fix PR/32297
X-Mailer: git-send-email 2.43.0
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Content-Type: text/plain; charset=utf-8
From: Josh Poimboeuf <jpoimboe@kernel.org>
When _creating_ SFrame information for the linker created .plt.sec, the
code correctly checks for presence of .plt.sec. When _writing_ the
SFrame section for the corresponding .plt.sec, however, the conditionals
were wrongly checking for splt. This was causing an assertion at link
time.
This issue has been known to affect glibc build with SFrame enabled.
No testcase is added just yet. A later commit ensures correct SFrame
stack trace information is created for .plt.got. A test case (where only
.plt and .plt.got are created) is added then.
PR/32297 sframe: bfd assertion with empty main on IBT enabled system
ChangeLog:
PR/32297
* bfd/elfxx-x86.c (_bfd_x86_elf_late_size_sections): Check for
plt_second member not for splt.
---
bfd/elfxx-x86.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/bfd/elfxx-x86.c b/bfd/elfxx-x86.c
index dd951b91f50..0d83ce57d4f 100644
--- a/bfd/elfxx-x86.c
+++ b/bfd/elfxx-x86.c
@@ -2680,8 +2680,8 @@ _bfd_x86_elf_late_size_sections (bfd *output_bfd,
_bfd_x86_elf_write_sframe_plt (output_bfd, info, SFRAME_PLT);
if (htab->plt_second_sframe != NULL
- && htab->elf.splt != NULL
- && htab->elf.splt->size != 0
+ && htab->plt_second != NULL
+ && htab->plt_second->size != 0
&& htab->plt_second_sframe->contents == NULL)
_bfd_x86_elf_write_sframe_plt (output_bfd, info, SFRAME_PLT_SEC);
}
--
2.43.0
From: Indu Bhagat <indu.bhagat@oracle.com>
Date: Fri, 25 Oct 2024 14:33:20 -0700
To: jpoimboe@kernel.org
Subject: [PATCH 2/3] ld: fix wrong SFrame info for lazy IBT PLT
X-Mailer: git-send-email 2.43.0
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Content-Type: text/plain; charset=utf-8
From: Josh Poimboeuf <jpoimboe@kernel.org>
Fix PR/32296 sframe: wrong SFrame info for pltN and .plt.sec for -z ibtplt
The x86 psABI defines a 2-PLT scheme for IBT which uses .plt and
.plt.sec entries. It was observed that SFrame information for .plt.sec
section was incorrect. The erroneous assumption was that SFrame stack
trace information for .plt.sec with lazy binding is the same as SFrame
stack trace information for .plt with lazy binding. This is corrected
now by initializing a new SFrame PLT helper object
elf_x86_64_sframe_ibt_plt for lazy PLT with IBT.
Add a testcase where linking with -z ibtplt generates .plt.sec entries and
ensure correct SFrame information for it.
ChangeLog:
PR/32296
* bfd/elf64-x86-64.c (elf_x86_64_sframe_ibt_pltn_fre2): New
definition elf_x86_64_sframe_ibt_plt. Use it in
elf_x86_64_sframe_plt.
(elf_x86_64_link_setup_gnu_properties): Lazy IBT PLT entries are
different from lazy PLT.
* bfd/elfxx-x86.c (_bfd_x86_elf_create_sframe_plt): Adjust for
SFrame for IBT PLT.
* ld/testsuite/ld-x86-64/x86-64.exp: Add new test.
* ld/testsuite/ld-x86-64/sframe-ibt-plt-1.d: New test.
---
bfd/elf64-x86-64.c | 34 +++++++++++++++++++----
bfd/elfxx-x86.c | 29 ++++++++++---------
ld/testsuite/ld-x86-64/sframe-ibt-plt-1.d | 33 ++++++++++++++++++++++
ld/testsuite/ld-x86-64/x86-64.exp | 1 +
4 files changed, 79 insertions(+), 18 deletions(-)
create mode 100644 ld/testsuite/ld-x86-64/sframe-ibt-plt-1.d
diff --git a/bfd/elf64-x86-64.c b/bfd/elf64-x86-64.c
index 4330bbd1648..abbebbe92b4 100644
--- a/bfd/elf64-x86-64.c
+++ b/bfd/elf64-x86-64.c
@@ -906,6 +906,14 @@ static const sframe_frame_row_entry elf_x86_64_sframe_pltn_fre2 =
SFRAME_V1_FRE_INFO (SFRAME_BASE_REG_SP, 1, SFRAME_FRE_OFFSET_1B) /* FRE info. */
};
+/* .sframe FRE covering the .plt section entry for IBT. */
+static const sframe_frame_row_entry elf_x86_64_sframe_ibt_pltn_fre2 =
+{
+ 9, /* SFrame FRE start address. */
+ {16, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, /* 12 bytes. */
+ SFRAME_V1_FRE_INFO (SFRAME_BASE_REG_SP, 1, SFRAME_FRE_OFFSET_1B) /* FRE info. */
+};
+
/* .sframe FRE covering the second .plt section entry. */
static const sframe_frame_row_entry elf_x86_64_sframe_sec_pltn_fre1 =
{
@@ -930,7 +938,7 @@ static const struct elf_x86_sframe_plt elf_x86_64_sframe_non_lazy_plt =
{ &elf_x86_64_sframe_null_fre }
};
-/* SFrame helper object for lazy PLT. Also used for IBT enabled PLT. */
+/* SFrame helper object for lazy PLT. */
static const struct elf_x86_sframe_plt elf_x86_64_sframe_plt =
{
LAZY_PLT_ENTRY_SIZE,
@@ -942,9 +950,25 @@ static const struct elf_x86_sframe_plt elf_x86_64_sframe_plt =
/* Array of SFrame FREs for plt. */
{ &elf_x86_64_sframe_pltn_fre1, &elf_x86_64_sframe_pltn_fre2 },
NON_LAZY_PLT_ENTRY_SIZE,
- 1, /* Number of FREs for PLTn for second PLT. */
- /* FREs for second plt (stack trace info for .plt.got is
- identical). Used when IBT or non-lazy PLT is in effect. */
+ 1, /* Number of FREs for second PLT. */
+ /* Array of SFrame FREs for second PLT. */
+ { &elf_x86_64_sframe_sec_pltn_fre1 }
+};
+
+/* SFrame helper object for lazy PLT with IBT. */
+static const struct elf_x86_sframe_plt elf_x86_64_sframe_ibt_plt =
+{
+ LAZY_PLT_ENTRY_SIZE,
+ 2, /* Number of FREs for PLT0. */
+ /* Array of SFrame FREs for plt0. */
+ { &elf_x86_64_sframe_plt0_fre1, &elf_x86_64_sframe_plt0_fre2 },
+ LAZY_PLT_ENTRY_SIZE,
+ 2, /* Number of FREs for PLTn. */
+ /* Array of SFrame FREs for plt. */
+ { &elf_x86_64_sframe_pltn_fre1, &elf_x86_64_sframe_ibt_pltn_fre2 },
+ LAZY_PLT_ENTRY_SIZE,
+ 1, /* Number of FREs for second PLT. */
+ /* Array of SFrame FREs for second plt. */
{ &elf_x86_64_sframe_sec_pltn_fre1 }
};
@@ -5678,7 +5702,7 @@ elf_x86_64_link_setup_gnu_properties (struct bfd_link_info *info)
{
init_table.sframe_lazy_plt = &elf_x86_64_sframe_plt;
init_table.sframe_non_lazy_plt = &elf_x86_64_sframe_non_lazy_plt;
- init_table.sframe_lazy_ibt_plt = &elf_x86_64_sframe_plt;
+ init_table.sframe_lazy_ibt_plt = &elf_x86_64_sframe_ibt_plt;
init_table.sframe_non_lazy_ibt_plt = &elf_x86_64_sframe_non_lazy_plt;
}
else
diff --git a/bfd/elfxx-x86.c b/bfd/elfxx-x86.c
index 0d83ce57d4f..cb90f688b6f 100644
--- a/bfd/elfxx-x86.c
+++ b/bfd/elfxx-x86.c
@@ -1831,7 +1831,6 @@ _bfd_x86_elf_create_sframe_plt (bfd *output_bfd,
struct elf_x86_link_hash_table *htab;
const struct elf_backend_data *bed;
- bool plt0_generated_p;
unsigned int plt0_entry_size;
unsigned char func_info;
uint32_t fre_type;
@@ -1845,14 +1844,11 @@ _bfd_x86_elf_create_sframe_plt (bfd *output_bfd,
unsigned plt_entry_size = 0;
unsigned int num_pltn_fres = 0;
unsigned int num_pltn_entries = 0;
+ const sframe_frame_row_entry * const *pltn_fres;
bed = get_elf_backend_data (output_bfd);
htab = elf_x86_hash_table (info, bed->target_id);
/* Whether SFrame stack trace info for plt0 is to be generated. */
- plt0_generated_p = htab->plt.has_plt0;
- plt0_entry_size
- = (plt0_generated_p) ? htab->sframe_plt->plt0_entry_size : 0;
-
switch (plt_sec_type)
{
case SFRAME_PLT:
@@ -1860,7 +1856,10 @@ _bfd_x86_elf_create_sframe_plt (bfd *output_bfd,
ectx = &htab->plt_cfe_ctx;
dpltsec = htab->elf.splt;
- plt_entry_size = htab->plt.plt_entry_size;
+ plt0_entry_size
+ = htab->plt.has_plt0 ? htab->sframe_plt->plt0_entry_size : 0;
+ plt_entry_size = htab->sframe_plt->pltn_entry_size;
+ pltn_fres = htab->sframe_plt->pltn_fres;
num_pltn_fres = htab->sframe_plt->pltn_num_fres;
num_pltn_entries
= (dpltsec->size - plt0_entry_size) / plt_entry_size;
@@ -1870,12 +1869,15 @@ _bfd_x86_elf_create_sframe_plt (bfd *output_bfd,
case SFRAME_PLT_SEC:
{
ectx = &htab->plt_second_cfe_ctx;
- /* FIXME - this or htab->plt_second_sframe ? */
- dpltsec = htab->plt_second_eh_frame;
+ dpltsec = htab->plt_second;
+
+ plt0_entry_size = 0;
plt_entry_size = htab->sframe_plt->sec_pltn_entry_size;
+ pltn_fres = htab->sframe_plt->sec_pltn_fres;
num_pltn_fres = htab->sframe_plt->sec_pltn_num_fres;
num_pltn_entries = dpltsec->size / plt_entry_size;
+
break;
}
default:
@@ -1897,7 +1899,7 @@ _bfd_x86_elf_create_sframe_plt (bfd *output_bfd,
/* Add SFrame FDE and the associated FREs for plt0 if plt0 has been
generated. */
- if (plt0_generated_p)
+ if (plt0_entry_size)
{
/* Add SFrame FDE for plt0, the function start address is updated later
at _bfd_elf_merge_section_sframe time. */
@@ -1934,16 +1936,17 @@ _bfd_x86_elf_create_sframe_plt (bfd *output_bfd,
plt0_entry_size, /* func start addr. */
dpltsec->size - plt0_entry_size,
func_info,
- 16,
+ plt_entry_size,
0 /* Num FREs. */);
sframe_frame_row_entry pltn_fre;
- /* Now add the FREs for pltn. Simply adding the two FREs suffices due
+ /* Now add the FREs for pltn. Simply adding the FREs suffices due
to the usage of SFRAME_FDE_TYPE_PCMASK above. */
for (unsigned int j = 0; j < num_pltn_fres; j++)
{
- pltn_fre = *(htab->sframe_plt->pltn_fres[j]);
- sframe_encoder_add_fre (*ectx, 1, &pltn_fre);
+ unsigned int func_idx = plt0_entry_size ? 1 : 0;
+ pltn_fre = *(pltn_fres[j]);
+ sframe_encoder_add_fre (*ectx, func_idx, &pltn_fre);
}
}
diff --git a/ld/testsuite/ld-x86-64/sframe-ibt-plt-1.d b/ld/testsuite/ld-x86-64/sframe-ibt-plt-1.d
new file mode 100644
index 00000000000..26be4dfc6a0
--- /dev/null
+++ b/ld/testsuite/ld-x86-64/sframe-ibt-plt-1.d
@@ -0,0 +1,33 @@
+#as: --gsframe
+#source: ibt-plt-3.s
+#objdump: --sframe=.sframe
+#ld: -shared -z ibtplt --no-rosegment
+#name: SFrame for IBT PLT .plt.sec
+
+.*: +file format .*
+
+Contents of the SFrame section .sframe:
+ Header :
+
+ Version: SFRAME_VERSION_2
+ Flags: SFRAME_F_FDE_SORTED
+ CFA fixed RA offset: \-8
+#...
+
+ Function Index :
+
+ func idx \[0\]: pc = 0x1000, size = 16 bytes
+ STARTPC +CFA +FP +RA +
+ 0+1000 +sp\+16 +u +f +
+ 0+1006 +sp\+24 +u +f +
+
+ func idx \[1\]: pc = 0x1010, size = 32 bytes
+ STARTPC\[m\] +CFA +FP +RA +
+ 0+0000 +sp\+8 +u +f +
+ 0+0009 +sp\+16 +u +f +
+
+ func idx \[2\]: pc = 0x1030, size = 32 bytes
+ STARTPC\[m\] +CFA +FP +RA +
+ 0+0000 +sp\+8 +u +f +
+
+#...
diff --git a/ld/testsuite/ld-x86-64/x86-64.exp b/ld/testsuite/ld-x86-64/x86-64.exp
index bd7574d6965..0632397bccc 100644
--- a/ld/testsuite/ld-x86-64/x86-64.exp
+++ b/ld/testsuite/ld-x86-64/x86-64.exp
@@ -547,6 +547,7 @@ run_dump_test "pr32191-x32"
if { ![skip_sframe_tests] } {
run_dump_test "sframe-simple-1"
run_dump_test "sframe-plt-1"
+ run_dump_test "sframe-ibt-plt-1"
}
if ![istarget "x86_64-*-linux*"] {
--
2.43.0
From: Indu Bhagat <indu.bhagat@oracle.com>
Date: Fri, 25 Oct 2024 14:33:21 -0700
To: jpoimboe@kernel.org
Cc: Indu Bhagat <indu.bhagat@oracle.com>
Subject: [PATCH 3/3] ld: generate SFrame stack trace info for .plt.got
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PR/32298 sframe: no SFrame stack trace info generated for .plt.got
Add support to generate SFrame stack trace info for .plt.got section.
Enhance the current definition of struct elf_x86_sframe_plt to include
initialized SFrame FDE/FREs applicable for .plt.got section. There are
two variants of .plt.got entries: 16 byte and 8 byte.
8 byte:
ff 25 00 00 00 00 jmpq *name@GOTPCREL(%rip)
66 90 xchg %ax,%ax
16 byte:
f3 0f 1e fa endbr64
ff 25 66 2f 00 00 jmpq *name@GOTPCREL(%rip)
66 0f 1f 44 00 00 nopw 0x0(%rax,%rax,1)
For the testcase, define some application symbols such that their PLT
entry is placed in .plt.got and ensure SFrame information is generated
with and without -z ibtplt.
ChangeLog:
PR/32298
* bfd/elf64-x86-64.c (elf_x86_64_link_setup_gnu_properties):
PLT GOT entry size is different for IBT vs non IBT PLTs.
* bfd/elfxx-x86.c (enum dynobj_sframe_plt_type): New enum for
SFRAME_PLT_GOT.
(_bfd_x86_elf_create_sframe_plt): Handle SFRAME_PLT_GOT.
(_bfd_x86_elf_write_sframe_plt): Likewise.
(_bfd_x86_elf_late_size_sections): Likewise.
(_bfd_x86_elf_finish_dynamic_sections): Likewise.
* bfd/elfxx-x86.h (struct elf_x86_sframe_plt): Add new members
to keep information about PLT GOT entries.
(struct elf_x86_link_hash_table): Add support for creating
SFrame section for .plt.got.
* ld/testsuite/ld-x86-64/x86-64.exp: Add new tests.
* ld/testsuite/ld-x86-64/sframe-pltgot-1.d: New test.
* ld/testsuite/ld-x86-64/sframe-pltgot-1.s: New test.
* ld/testsuite/ld-x86-64/sframe-pltgot-2.d: New test.
---
bfd/elf64-x86-64.c | 42 ++++++++++--
bfd/elfxx-x86.c | 86 ++++++++++++++++++++++--
bfd/elfxx-x86.h | 6 ++
ld/testsuite/ld-x86-64/sframe-pltgot-1.d | 28 ++++++++
ld/testsuite/ld-x86-64/sframe-pltgot-1.s | 15 +++++
ld/testsuite/ld-x86-64/sframe-pltgot-2.d | 28 ++++++++
ld/testsuite/ld-x86-64/x86-64.exp | 2 +
7 files changed, 198 insertions(+), 9 deletions(-)
create mode 100644 ld/testsuite/ld-x86-64/sframe-pltgot-1.d
create mode 100644 ld/testsuite/ld-x86-64/sframe-pltgot-1.s
create mode 100644 ld/testsuite/ld-x86-64/sframe-pltgot-2.d
diff --git a/bfd/elf64-x86-64.c b/bfd/elf64-x86-64.c
index abbebbe92b4..a62fa621f99 100644
--- a/bfd/elf64-x86-64.c
+++ b/bfd/elf64-x86-64.c
@@ -922,7 +922,7 @@ static const sframe_frame_row_entry elf_x86_64_sframe_sec_pltn_fre1 =
SFRAME_V1_FRE_INFO (SFRAME_BASE_REG_SP, 1, SFRAME_FRE_OFFSET_1B) /* FRE info. */
};
-/* SFrame helper object for non-lazy PLT. Also used for IBT enabled PLT. */
+/* SFrame helper object for non-lazy PLT. */
static const struct elf_x86_sframe_plt elf_x86_64_sframe_non_lazy_plt =
{
LAZY_PLT_ENTRY_SIZE,
@@ -935,7 +935,31 @@ static const struct elf_x86_sframe_plt elf_x86_64_sframe_non_lazy_plt =
{ &elf_x86_64_sframe_sec_pltn_fre1, &elf_x86_64_sframe_null_fre },
0,
0, /* There is no second PLT necessary. */
- { &elf_x86_64_sframe_null_fre }
+ { &elf_x86_64_sframe_null_fre },
+ NON_LAZY_PLT_ENTRY_SIZE,
+ 1, /* Number of FREs for PLT GOT. */
+ /* Array of SFrame FREs for PLT GOT. */
+ { &elf_x86_64_sframe_null_fre },
+};
+
+/* SFrame helper object for non-lazy IBT enabled PLT. */
+static const struct elf_x86_sframe_plt elf_x86_64_sframe_non_lazy_ibt_plt =
+{
+ LAZY_PLT_ENTRY_SIZE,
+ 2, /* Number of FREs for PLT0. */
+ /* Array of SFrame FREs for plt0. */
+ { &elf_x86_64_sframe_plt0_fre1, &elf_x86_64_sframe_plt0_fre2 },
+ LAZY_PLT_ENTRY_SIZE,
+ 1, /* Number of FREs for PLTn. */
+ /* Array of SFrame FREs for plt. */
+ { &elf_x86_64_sframe_sec_pltn_fre1, &elf_x86_64_sframe_null_fre },
+ 0,
+ 0, /* There is no second PLT necessary. */
+ { &elf_x86_64_sframe_null_fre },
+ LAZY_PLT_ENTRY_SIZE,
+ 1, /* Number of FREs for PLT GOT. */
+ /* Array of SFrame FREs for PLT GOT. */
+ { &elf_x86_64_sframe_null_fre },
};
/* SFrame helper object for lazy PLT. */
@@ -952,7 +976,11 @@ static const struct elf_x86_sframe_plt elf_x86_64_sframe_plt =
NON_LAZY_PLT_ENTRY_SIZE,
1, /* Number of FREs for second PLT. */
/* Array of SFrame FREs for second PLT. */
- { &elf_x86_64_sframe_sec_pltn_fre1 }
+ { &elf_x86_64_sframe_sec_pltn_fre1 },
+ NON_LAZY_PLT_ENTRY_SIZE,
+ 1, /* Number of FREs for PLT GOT. */
+ /* Array of SFrame FREs for PLT GOT. */
+ { &elf_x86_64_sframe_null_fre },
};
/* SFrame helper object for lazy PLT with IBT. */
@@ -969,7 +997,11 @@ static const struct elf_x86_sframe_plt elf_x86_64_sframe_ibt_plt =
LAZY_PLT_ENTRY_SIZE,
1, /* Number of FREs for second PLT. */
/* Array of SFrame FREs for second plt. */
- { &elf_x86_64_sframe_sec_pltn_fre1 }
+ { &elf_x86_64_sframe_sec_pltn_fre1 },
+ LAZY_PLT_ENTRY_SIZE,
+ 1, /* Number of FREs for PLT GOT. */
+ /* Array of SFrame FREs for PLT GOT. */
+ { &elf_x86_64_sframe_null_fre },
};
/* These are the standard parameters. */
@@ -5703,7 +5735,7 @@ elf_x86_64_link_setup_gnu_properties (struct bfd_link_info *info)
init_table.sframe_lazy_plt = &elf_x86_64_sframe_plt;
init_table.sframe_non_lazy_plt = &elf_x86_64_sframe_non_lazy_plt;
init_table.sframe_lazy_ibt_plt = &elf_x86_64_sframe_ibt_plt;
- init_table.sframe_non_lazy_ibt_plt = &elf_x86_64_sframe_non_lazy_plt;
+ init_table.sframe_non_lazy_ibt_plt = &elf_x86_64_sframe_non_lazy_ibt_plt;
}
else
{
diff --git a/bfd/elfxx-x86.c b/bfd/elfxx-x86.c
index cb90f688b6f..0843803171b 100644
--- a/bfd/elfxx-x86.c
+++ b/bfd/elfxx-x86.c
@@ -1817,7 +1817,8 @@ elf_x86_relative_reloc_compare (const void *pa, const void *pb)
enum dynobj_sframe_plt_type
{
SFRAME_PLT = 1,
- SFRAME_PLT_SEC = 2
+ SFRAME_PLT_SEC = 2,
+ SFRAME_PLT_GOT = 3,
};
/* Create SFrame stack trace info for the plt entries in the .plt section
@@ -1880,6 +1881,21 @@ _bfd_x86_elf_create_sframe_plt (bfd *output_bfd,
break;
}
+ case SFRAME_PLT_GOT:
+ {
+ ectx = &htab->plt_got_cfe_ctx;
+ dpltsec = htab->plt_got;
+
+ plt0_entry_size = 0;
+
+ plt_entry_size = htab->sframe_plt->plt_got_entry_size;
+ pltn_fres = htab->sframe_plt->plt_got_fres;
+ num_pltn_fres = htab->sframe_plt->plt_got_num_fres;
+ num_pltn_entries = dpltsec->size / plt_entry_size;
+
+ break;
+ }
+
default:
/* No other value is possible. */
return false;
@@ -1984,6 +2000,10 @@ _bfd_x86_elf_write_sframe_plt (bfd *output_bfd,
ectx = htab->plt_second_cfe_ctx;
sec = htab->plt_second_sframe;
break;
+ case SFRAME_PLT_GOT:
+ ectx = htab->plt_got_cfe_ctx;
+ sec = htab->plt_got_sframe;
+ break;
default:
/* No other value is possible. */
return false;
@@ -2511,7 +2531,18 @@ _bfd_x86_elf_late_size_sections (bfd *output_bfd,
htab->plt_sframe->size = sizeof (sframe_header) + 1;
}
- /* FIXME - generate for .plt.got ? */
+ if (htab->plt_got_sframe != NULL
+ && htab->plt_got != NULL
+ && htab->plt_got->size != 0
+ && !bfd_is_abs_section (htab->plt_got->output_section))
+ {
+ _bfd_x86_elf_create_sframe_plt (output_bfd, info, SFRAME_PLT_GOT);
+ /* FIXME - Dirty Hack. Set the size to something non-zero for now,
+ so that the section does not get stripped out below. The precise
+ size of this section is known only when the contents are
+ serialized in _bfd_x86_elf_write_sframe_plt. */
+ htab->plt_got_sframe->size = sizeof (sframe_header) + 1;
+ }
if (htab->plt_second_sframe != NULL
&& htab->plt_second != NULL
@@ -2578,6 +2609,7 @@ _bfd_x86_elf_late_size_sections (bfd *output_bfd,
|| s == htab->plt_second_eh_frame
|| s == htab->plt_sframe
|| s == htab->plt_second_sframe
+ || s == htab->plt_got_sframe
|| s == htab->elf.sdynbss
|| s == htab->elf.sdynrelro)
{
@@ -2622,7 +2654,8 @@ _bfd_x86_elf_late_size_sections (bfd *output_bfd,
/* Skip allocating contents for .sframe section as it is written
out differently. See below. */
- if ((s == htab->plt_sframe) || (s == htab->plt_second_sframe))
+ if ((s == htab->plt_sframe) || (s == htab->plt_second_sframe)
+ || (s == htab->plt_got_sframe))
continue;
/* NB: Initially, the iplt section has minimal alignment to
@@ -2687,6 +2720,12 @@ _bfd_x86_elf_late_size_sections (bfd *output_bfd,
&& htab->plt_second->size != 0
&& htab->plt_second_sframe->contents == NULL)
_bfd_x86_elf_write_sframe_plt (output_bfd, info, SFRAME_PLT_SEC);
+
+ if (htab->plt_got_sframe != NULL
+ && htab->plt_got != NULL
+ && htab->plt_got->size != 0
+ && htab->plt_got_sframe->contents == NULL)
+ _bfd_x86_elf_write_sframe_plt (output_bfd, info, SFRAME_PLT_GOT);
}
if (resolved_plt != NULL
@@ -2997,6 +3036,34 @@ _bfd_x86_elf_finish_dynamic_sections (bfd *output_bfd,
return NULL;
}
}
+
+ if (htab->plt_got_sframe != NULL
+ && htab->plt_got_sframe->contents != NULL)
+ {
+ if (htab->plt_got != NULL
+ && htab->plt_got->size != 0
+ && (htab->plt_got->flags & SEC_EXCLUDE) == 0
+ && htab->plt_got->output_section != NULL
+ && htab->plt_got_sframe->output_section != NULL)
+ {
+ bfd_vma plt_start = htab->plt_got->output_section->vma;
+ bfd_vma sframe_start
+ = (htab->plt_got_sframe->output_section->vma
+ + htab->plt_got_sframe->output_offset
+ + PLT_SFRAME_FDE_START_OFFSET);
+ bfd_put_signed_32 (dynobj, plt_start - sframe_start,
+ htab->plt_got_sframe->contents
+ + PLT_SFRAME_FDE_START_OFFSET);
+ }
+ if (htab->plt_got_sframe->sec_info_type == SEC_INFO_TYPE_SFRAME)
+ {
+ if (! _bfd_elf_merge_section_sframe (output_bfd, info,
+ htab->plt_got_sframe,
+ htab->plt_got_sframe->contents))
+ return NULL;
+ }
+ }
+
if (htab->elf.sgot && htab->elf.sgot->size > 0)
elf_section_data (htab->elf.sgot->output_section)->this_hdr.sh_entsize
= htab->got_entry_size;
@@ -4764,7 +4831,18 @@ _bfd_x86_elf_link_setup_gnu_properties
htab->plt_second_sframe = sec;
}
- /* FIXME - add later for plt_got. */
+
+ /* .plt.got. */
+ if (htab->plt_got != NULL)
+ {
+ sec = bfd_make_section_anyway_with_flags (dynobj,
+ ".sframe",
+ flags);
+ if (sec == NULL)
+ info->callbacks->einfo (_("%F%P: failed to create PLT GOT .sframe section\n"));
+
+ htab->plt_got_sframe = sec;
+ }
}
}
diff --git a/bfd/elfxx-x86.h b/bfd/elfxx-x86.h
index b042d45c282..cd26e8fc6f2 100644
--- a/bfd/elfxx-x86.h
+++ b/bfd/elfxx-x86.h
@@ -401,6 +401,10 @@ struct elf_x86_sframe_plt
unsigned int sec_pltn_entry_size;
unsigned int sec_pltn_num_fres;
const sframe_frame_row_entry *sec_pltn_fres[SFRAME_PLTN_MAX_NUM_FRES];
+
+ unsigned int plt_got_entry_size;
+ unsigned int plt_got_num_fres;
+ const sframe_frame_row_entry *plt_got_fres[SFRAME_PLTN_MAX_NUM_FRES];
};
struct elf_x86_lazy_plt_layout
@@ -606,6 +610,8 @@ struct elf_x86_link_hash_table
asection *plt_sframe;
sframe_encoder_ctx *plt_second_cfe_ctx;
asection *plt_second_sframe;
+ sframe_encoder_ctx *plt_got_cfe_ctx;
+ asection *plt_got_sframe;
/* Parameters describing PLT generation, lazy or non-lazy. */
struct elf_x86_plt_layout plt;
diff --git a/ld/testsuite/ld-x86-64/sframe-pltgot-1.d b/ld/testsuite/ld-x86-64/sframe-pltgot-1.d
new file mode 100644
index 00000000000..e26a741b635
--- /dev/null
+++ b/ld/testsuite/ld-x86-64/sframe-pltgot-1.d
@@ -0,0 +1,28 @@
+#as: --gsframe
+#source: sframe-pltgot-1.s
+#objdump: --sframe=.sframe
+#ld: -shared -z ibtplt --no-rosegment
+#name: SFrame for .plt.got
+
+.*: +file format .*
+
+Contents of the SFrame section .sframe:
+ Header :
+
+ Version: SFRAME_VERSION_2
+ Flags: SFRAME_F_FDE_SORTED
+ CFA fixed RA offset: \-8
+#...
+
+ Function Index :
+
+ func idx \[0\]: pc = 0x1000, size = 16 bytes
+ STARTPC +CFA +FP +RA +
+ 0+1000 +sp\+16 +u +f +
+ 0+1006 +sp\+24 +u +f +
+
+ func idx \[1\]: pc = 0x1010, size = 64 bytes
+ STARTPC\[m\] +CFA +FP +RA +
+ 0+0000 +sp\+16 +u +f +
+
+#...
diff --git a/ld/testsuite/ld-x86-64/sframe-pltgot-1.s b/ld/testsuite/ld-x86-64/sframe-pltgot-1.s
new file mode 100644
index 00000000000..e596e846439
--- /dev/null
+++ b/ld/testsuite/ld-x86-64/sframe-pltgot-1.s
@@ -0,0 +1,15 @@
+ .text
+ .globl foo
+ .type foo, @function
+foo:
+ .cfi_startproc
+ call func1@plt
+ movq func1@GOTPCREL(%rip), %rax
+ call func2@plt
+ movq func2@GOTPCREL(%rip), %rax
+ call func3@plt
+ movq func3@GOTPCREL(%rip), %rax
+ call func4@plt
+ movq func4@GOTPCREL(%rip), %rax
+ .cfi_endproc
+ .section .note.GNU-stack,"",@progbits
diff --git a/ld/testsuite/ld-x86-64/sframe-pltgot-2.d b/ld/testsuite/ld-x86-64/sframe-pltgot-2.d
new file mode 100644
index 00000000000..7a99d12faa8
--- /dev/null
+++ b/ld/testsuite/ld-x86-64/sframe-pltgot-2.d
@@ -0,0 +1,28 @@
+#as: --gsframe
+#source: sframe-pltgot-1.s
+#objdump: --sframe=.sframe
+#ld: -shared --no-rosegment
+#name: SFrame for .plt.got
+
+.*: +file format .*
+
+Contents of the SFrame section .sframe:
+ Header :
+
+ Version: SFRAME_VERSION_2
+ Flags: SFRAME_F_FDE_SORTED
+ CFA fixed RA offset: \-8
+#...
+
+ Function Index :
+
+ func idx \[0\]: pc = 0x1000, size = 16 bytes
+ STARTPC +CFA +FP +RA +
+ 0+1000 +sp\+16 +u +f +
+ 0+1006 +sp\+24 +u +f +
+
+ func idx \[1\]: pc = 0x1010, size = 32 bytes
+ STARTPC\[m\] +CFA +FP +RA +
+ 0+0000 +sp\+16 +u +f +
+
+#...
diff --git a/ld/testsuite/ld-x86-64/x86-64.exp b/ld/testsuite/ld-x86-64/x86-64.exp
index 0632397bccc..a66d28eb0d1 100644
--- a/ld/testsuite/ld-x86-64/x86-64.exp
+++ b/ld/testsuite/ld-x86-64/x86-64.exp
@@ -548,6 +548,8 @@ if { ![skip_sframe_tests] } {
run_dump_test "sframe-simple-1"
run_dump_test "sframe-plt-1"
run_dump_test "sframe-ibt-plt-1"
+ run_dump_test "sframe-pltgot-1"
+ run_dump_test "sframe-pltgot-2"
}
if ![istarget "x86_64-*-linux*"] {
--
2.43.0
diff --git a/elf/dl-load.c b/elf/dl-load.c
index 2923b1141d..ffaf722f5f 100644
--- a/elf/dl-load.c
+++ b/elf/dl-load.c
@@ -29,6 +29,7 @@
#include <bits/wordsize.h>
#include <sys/mman.h>
#include <sys/param.h>
+#include <sys/prctl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <gnu/lib-names.h>
@@ -88,6 +89,10 @@ struct filebuf
#define STRING(x) __STRING (x)
+#ifndef PT_GNU_SFRAME
+#define PT_GNU_SFRAME 0x6474e554
+#endif
+
int __stack_prot attribute_hidden attribute_relro
#if _STACK_GROWS_DOWN && defined PROT_GROWSDOWN
@@ -1213,6 +1218,10 @@ _dl_map_object_from_fd (const char *name, const char *origname, int fd,
l->l_relro_addr = ph->p_vaddr;
l->l_relro_size = ph->p_memsz;
break;
+
+ case PT_GNU_SFRAME:
+ l->l_sframe_addr = ph->p_vaddr;
+ break;
}
if (__glibc_unlikely (nloadcmds == 0))
@@ -1376,6 +1385,13 @@ cannot enable executable stack as shared object requires");
break;
}
+#define PR_ADD_SFRAME 74
+ if (l->l_sframe_addr != 0)
+ {
+ l->l_sframe_addr += l->l_addr;
+ __prctl(PR_ADD_SFRAME, l->l_sframe_addr, NULL, NULL, NULL);
+ }
+
/* We are done mapping in the file. We no longer need the descriptor. */
if (__glibc_unlikely (__close_nocancel (fd) != 0))
{
diff --git a/elf/dl-unmap-segments.h b/elf/dl-unmap-segments.h
index 1ec507e887..c4a7e9e0ed 100644
--- a/elf/dl-unmap-segments.h
+++ b/elf/dl-unmap-segments.h
@@ -21,14 +21,20 @@
#include <link.h>
#include <sys/mman.h>
+#include <sys/prctl.h>
/* _dl_map_segments ensures that any whole pages in gaps between segments
are filled in with PROT_NONE mappings. So we can just unmap the whole
range in one fell swoop. */
+#define PR_REMOVE_SFRAME 75
+
static __always_inline void
_dl_unmap_segments (struct link_map *l)
{
+ if (l->l_sframe_addr != 0)
+ __prctl(PR_REMOVE_SFRAME, l->l_sframe_addr, NULL, NULL, NULL);
+
__munmap ((void *) l->l_map_start, l->l_map_end - l->l_map_start);
}
diff --git a/include/link.h b/include/link.h
index c6af095d87..36ac75680f 100644
--- a/include/link.h
+++ b/include/link.h
@@ -348,6 +348,8 @@ struct link_map
ElfW(Addr) l_relro_addr;
size_t l_relro_size;
+ ElfW(Addr) l_sframe_addr;
+
unsigned long long int l_serial;
};
On Mon, Oct 28, 2024 at 02:47:27PM -0700, Josh Poimboeuf wrote: > - Is the perf_event lifetime managed correctly or do we need to do > something to ensure it exists in unwind_user_task_work()? You probably want a sync/cancel somewhere near the start of _free_event().
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