Remove global variable addr2line_timeout_ms and add it as a member
to symbol_conf structure.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Reviewed-by: Ian Rogers <irogers@google.com>
[namhyung: move the initialization to util/symbol.c]
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
The index into the cpumap array and the number of entries within the
array can never be negative, so let's make them unsigned. This is
prompted by reports that gcc 13 with -O6 is giving a
alloc-size-larger-than errors. The change makes the cpumap changes and
then updates the declaration of index variables throughout perf and
libperf to be unsigned. The two things are hard to separate as
compiler warnings about mixing signed and unsigned types breaks the
build.
Reported-by: Chingbin Li <liqb365@163.com>
Closes: https://lore.kernel.org/lkml/20260212025127.841090-1-liqb365@163.com/
Tested-by: Chingbin Li <liqb365@163.com>
Signed-off-by: Ian Rogers <irogers@google.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Add support for parsing an optional layout parameter in the --symfs
command line option. The format is:
--symfs <directory[,layout]>
Where layout can be:
- 'hierarchy': matches full path (default)
- 'flat': only matches base name
When debugging symbol files from a copy of the filesystem (e.g., from a
container or remote machine), the debug files are often stored in a
flat directory structure with only filenames, not the full original
paths. In this case, using 'flat' layout allows perf to find debug
symbols by matching only the filename rather than the full path.
For example, given a binary path like:
/build/output/lib/foo.so
With 'perf report --symfs /debug/files,flat', perf will look for:
/debug/files/foo.so
Instead of:
/debug/files/build/output/lib/foo.so
This is particularly useful when:
- Extracting debug files from containers with different directory layouts
- Working with build systems that flatten directory structures
Signed-off-by: Changbin Du <changbin.du@huawei.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Pull perf tools updates from Namhyung Kim:
"Perf event/metric description:
Unify all event and metric descriptions in JSON format. Now event
parsing and handling is greatly simplified by that.
From users point of view, perf list will provide richer information
about hardware events like the following.
$ perf list hw
List of pre-defined events (to be used in -e or -M):
legacy hardware:
branch-instructions
[Retired branch instructions [This event is an alias of branches]. Unit: cpu]
branch-misses
[Mispredicted branch instructions. Unit: cpu]
branches
[Retired branch instructions [This event is an alias of branch-instructions]. Unit: cpu]
bus-cycles
[Bus cycles,which can be different from total cycles. Unit: cpu]
cache-misses
[Cache misses. Usually this indicates Last Level Cache misses; this is intended to be used in conjunction with the
PERF_COUNT_HW_CACHE_REFERENCES event to calculate cache miss rates. Unit: cpu]
cache-references
[Cache accesses. Usually this indicates Last Level Cache accesses but this may vary depending on your CPU. This may include
prefetches and coherency messages; again this depends on the design of your CPU. Unit: cpu]
cpu-cycles
[Total cycles. Be wary of what happens during CPU frequency scaling [This event is an alias of cycles]. Unit: cpu]
cycles
[Total cycles. Be wary of what happens during CPU frequency scaling [This event is an alias of cpu-cycles]. Unit: cpu]
instructions
[Retired instructions. Be careful,these can be affected by various issues,most notably hardware interrupt counts. Unit: cpu]
ref-cycles
[Total cycles; not affected by CPU frequency scaling. Unit: cpu]
But most notable changes would be in the perf stat. On the right side,
the default metrics are better named and aligned. :)
$ perf stat -- perf test -w noploop
Performance counter stats for 'perf test -w noploop':
11 context-switches # 10.8 cs/sec cs_per_second
0 cpu-migrations # 0.0 migrations/sec migrations_per_second
3,612 page-faults # 3532.5 faults/sec page_faults_per_second
1,022.51 msec task-clock # 1.0 CPUs CPUs_utilized
110,466 branch-misses # 0.0 % branch_miss_rate (88.66%)
6,934,452,104 branches # 6781.8 M/sec branch_frequency (88.66%)
4,657,032,590 cpu-cycles # 4.6 GHz cycles_frequency (88.65%)
27,755,874,218 instructions # 6.0 instructions insn_per_cycle (89.03%)
TopdownL1 # 0.3 % tma_backend_bound
# 9.3 % tma_bad_speculation (89.05%)
# 9.7 % tma_frontend_bound (77.86%)
# 80.7 % tma_retiring (88.81%)
1.025318171 seconds time elapsed
1.013248000 seconds user
0.012014000 seconds sys
Deferred unwinding support:
With the kernel support (commit c69993ecdd: "perf: Support deferred
user unwind"), perf can use deferred callchains for userspace stack
trace with frame pointers like below:
$ perf record --call-graph fp,defer ...
This will be transparent to users when it comes to other commands like
perf report and perf script. They will merge the deferred callchains
to the previous samples as if they were collected together.
ARM SPE updates
- Extensive enhancements to support various kinds of memory
operations including GCS, MTE allocation tags, memcpy/memset,
register access, and SIMD operations.
- Add inverted data source filter (inv_data_src_filter) support to
exclude certain data sources.
- Improve documentation.
Vendor event updates:
- Intel: Updated event files for Sierra Forest, Panther Lake, Meteor
Lake, Lunar Lake, Granite Rapids, and others.
- Arm64: Added metrics for i.MX94 DDR PMU and Cortex-A720AE
definitions.
- RISC-V: Added JSON support for T-HEAD C920V2.
Misc:
- Improve pointer tracking in data type profiling. It'd give better
output when the variable is using container_of() to convert type.
- Annotation support for perf c2c report in TUI. Press 'a' key to
enter annotation view from cacheline browser window. This will show
which instruction is causing the cacheline contention.
- Lots of fixes and test coverage improvements!"
* tag 'perf-tools-for-v6.19-2025-12-06' of git://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools: (214 commits)
libperf: Use 'extern' in LIBPERF_API visibility macro
perf stat: Improve handling of termination by signal
perf tests stat: Add test for error for an offline CPU
perf stat: When no events, don't report an error if there is none
perf tests stat: Add "--null" coverage
perf cpumap: Add "any" CPU handling to cpu_map__snprint_mask
libperf cpumap: Fix perf_cpu_map__max for an empty/NULL map
perf stat: Allow no events to open if this is a "--null" run
perf test kvm: Add some basic perf kvm test coverage
perf tests evlist: Add basic evlist test
perf tests script dlfilter: Add a dlfilter test
perf tests kallsyms: Add basic kallsyms test
perf tests timechart: Add a perf timechart test
perf tests top: Add basic perf top coverage test
perf tests buildid: Add purge and remove testing
perf tests c2c: Add a basic c2c
perf c2c: Clean up some defensive gets and make asan clean
perf jitdump: Fix missed dso__put
perf mem-events: Don't leak online CPU map
perf hist: In init, ensure mem_info is put on error paths
...
Add missing dso__put for the dso created in maps__split_kallsyms.
Signed-off-by: Ian Rogers <irogers@google.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
This is for test functions to find the kallsyms correctly. It can find
the machine from the kernel maps and use its root_dir. This is helpful
to setup fake /proc directory for testing.
Reviewed-by: Ian Rogers <irogers@google.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
In maps__split_kallsyms(), it assumes new kernel map when it finds a
symbol without module after any module and the initial kernel map has
some symbols. Because it expects modules are out of the kernel map so
modules should not have symbols in the kernel map.
For example, the following memory map shows symbols and maps. Any
symbols in the module 1 area will go to the module 1. The main kernel
map starts at 0xffffffffbc200000. But if any symbol has a module
between the symbols in that area, next symbols after 0xffffffffbd008000
will generate new kernel maps like [kernel].1.
kernel address | |
| |
0xffffffffc0000000 |---------------------|
| (symbols) |
| ... | <--- [kernel].N
0xffffffffbc400000 |---------------------|
| (symbols) |
| module 2 | <--- bad?
0xffffffffbc380000 |---------------------|
| ... |
| (symbols) |
| [kernel.kallsyms] | <--- initial map
0xffffffffbc200000 |---------------------|
| |
| |
0xffffffffabcde000 |---------------------|
| (symbols) |
| module 1 |
0xffffffffabcd0000 |---------------------|
This is very fragile when the module has a symbol that falls into the
main kernel map for some reason. My system has a livepatch module with
such symbols. And it created a lot of new kernel maps after those
symbols. But the symbol may have broken addresses and the later symbols
can still be found in the initial kernel map.
Let's check the symbol address in the initial map and use it if found.
Reviewed-by: Ian Rogers <irogers@google.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
It's counted twice as it's increased after calling maps__insert(). I
guess we want to increase it only after it's added properly.
Reviewed-by: Ian Rogers <irogers@google.com>
Fixes: 2e538c4a18 ("perf tools: Improve kernel/modules symbol lookup")
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
The maps__split_kallsyms() will split symbols to module DSOs if it comes
from a module. It also handled some unusual kernel symbols after modules
by creating new kernel maps like "[kernel].0".
But they are pseudo DSOs to have those unexpected symbols. They should
not be considered as unloaded kernel DSOs. Otherwise the dso__load()
for them will end up calling dso__load_kallsyms() and then
maps__split_kallsyms() again and again.
Reviewed-by: Ian Rogers <irogers@google.com>
Fixes: 2e538c4a18 ("perf tools: Improve kernel/modules symbol lookup")
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Simplify the build ID reading code by removing the non-blocking option.
Having to pass the correct option to this function was fragile and a
mistake would result in a hang, see the linked fix. Furthermore,
compressed files are always opened blocking anyway, ignoring the
non-blocking option.
We also don't expect to read build IDs from non-regular files. The only
hits to this function that are non-regular are devices that won't be elf
files with build IDs, for example "/dev/dri/renderD129".
Now instead of opening these as non-blocking and failing to read, we
skip them. Even if something like a pipe or character device did have a
build ID, I don't think it would have worked because you need to call
read() in a loop, check for -EAGAIN and handle timeouts to make
non-blocking reads work.
Link: https://lore.kernel.org/linux-perf-users/20251022-james-perf-fix-dso-block-v1-1-c4faab150546@linaro.org/
Signed-off-by: James Clark <james.clark@linaro.org>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
I started seeing this in recent Fedora 42 kernels:
root@x1:~# uname -a
Linux x1 6.17.4-200.fc42.x86_64 #1 SMP PREEMPT_DYNAMIC Sun Oct 19 18:47:49 UTC 2025 x86_64 GNU/Linux
root@x1:~#
root@x1:~# perf test 1
1: vmlinux symtab matches kallsyms : FAILED!
root@x1:~#
Related to:
root@x1:~# grep ' 1 ' /proc/kallsyms
ffffffffb098bc00 1 __pfx__RNCINvNtNtNtCsfwaGRd4cjqE_4core4iter8adapters3map12map_try_foldjNtCskFudTml27HW_12drm_panic_qr7VersionuINtNtNtBa_3ops12control_flow11ControlFlowB10_ENcB10_0NCINvNvNtNtNtB8_6traits8iterator8Iterator4find5checkB10_NCNvMB12_B10_13from_segments0E0E0B12_
ffffffffb098bc10 1 _RNCINvNtNtNtCsfwaGRd4cjqE_4core4iter8adapters3map12map_try_foldjNtCskFudTml27HW_12drm_panic_qr7VersionuINtNtNtBa_3ops12control_flow11ControlFlowB10_ENcB10_0NCINvNvNtNtNtB8_6traits8iterator8Iterator4find5checkB10_NCNvMB12_B10_13from_segments0E0E0B12_
root@x1:~#
That is found in:
root@x1:~# pahole --running_kernel_vmlinux
/usr/lib/debug/lib/modules/6.17.4-200.fc42.x86_64/vmlinux
root@x1:~#
root@x1:~# readelf -sW /usr/lib/debug/lib/modules/6.17.4-200.fc42.x86_64/vmlinux | grep __pfx__RNCINvNtNtNtCsfwaGRd4cjqE_4core4iter8adapters3map12map_try_foldjNtCskFudTml27HW_12drm_panic_qr7VersionuINtNtNtBa_3ops12control_flow11ControlFlowB10_ENcB10_0NCINvNvNtNtNtB8_6traits8iterator8Iterator4find5checkB10_NCNvMB12_B10_13from_segments0E0E0B12_
150649: ffffffff81f8bc00 16 FUNC LOCAL DEFAULT 1 __pfx__RNCINvNtNtNtCsfwaGRd4cjqE_4core4iter8adapters3map12map_try_foldjNtCskFudTml27HW_12drm_panic_qr7VersionuINtNtNtBa_3ops12control_flow11ControlFlowB10_ENcB10_0NCINvNvNtNtNtB8_6traits8iterator8Iterator4find5checkB10_NCNvMB12_B10_13from_segments0E0E0B12_
root@x1:~#
But was being filtered out when reading /proc/kallsyms, as the '1'
symbol type was not being handled, do it, there are just two of them at
this point.
Cc: Alex Gaynor <alex.gaynor@gmail.com>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Andreas Hindborg <a.hindborg@kernel.org>
Cc: Benno Lossin <lossin@kernel.org>
Cc: Björn Roy Baron <bjorn3_gh@protonmail.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Danilo Krummrich <dakr@kernel.org>
Cc: Gary Guo <gary@garyguo.net>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Trevor Gross <tmgross@umich.edu>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
I started seeing this in recent Fedora 42 kernels:
# uname -a
Linux number 6.16.3-200.fc42.x86_64 #1 SMP PREEMPT_DYNAMIC Sat Aug 23 17:02:17 UTC 2025 x86_64 GNU/Linux
#
# perf test vmlinux
1: vmlinux symtab matches kallsyms : FAILED!
#
Rust is enabled and these were the symbols causing the above failure,
i.e. found in vmlinux but not in /proc/kallsyms:
$ grep -w N /proc/kallsyms
0000000000000000 N __pfx__RNCINvNtNtNtCsbDUBuN8AbD4_4core4iter8adapters3map12map_try_foldjNtCs6vVzKs5jPr6_12drm_panic_qr7VersionuINtNtNtBa_3ops12control_flow11ControlFlowB10_ENcB10_0NCINvNvNtNtNtB8_6traits8iterator8Iterator4find5checkB10_NCNvMB12_B10_13from_segments0E0E0B12_
0000000000000000 N _RNCINvNtNtNtCsbDUBuN8AbD4_4core4iter8adapters3map12map_try_foldjNtCs6vVzKs5jPr6_12drm_panic_qr7VersionuINtNtNtBa_3ops12control_flow11ControlFlowB10_ENcB10_0NCINvNvNtNtNtB8_6traits8iterator8Iterator4find5checkB10_NCNvMB12_B10_13from_segments0E0E0B12_
$
So accept those 'N' symbols as well.
About them, from 'man nm':
"N" The symbol is a debugging symbol.
"n" The symbol is in a non-data, non-code, non-debug read-only section.
Reviewed-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: James Clark <james.clark@linaro.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
When synthesizing build-ids, for build ID mmap2 events, they will be
added for data mmaps if -d/--data is specified. The files opened for
their build IDs may block on the open causing perf to hang during
synthesis. There is some robustness in existing calls to
filename__read_build_id by checking the file path is to a regular
file, which unfortunately fails for symlinks. Rather than adding more
is_regular_file calls, switch filename__read_build_id to take a
"block" argument and specify O_NONBLOCK when this is false. The
existing is_regular_file checking callers and the event synthesis
callers are made to pass false and thereby avoiding the hang.
Fixes: 53b00ff358 ("perf record: Make --buildid-mmap the default")
Signed-off-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20250823000024.724394-3-irogers@google.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
The kcore loading creates a set of list nodes that have reference
counted references to maps of the kcore. The list node freeing in the
success path wasn't releasing the maps, add the missing puts. It is
unclear why this leak was being missed by leak sanitizer.
Fixes: 8372020996 ("perf map: Move map list node into symbol")
Signed-off-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20250624190326.2038704-2-irogers@google.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Recently it added -fno-strict-aliasing to sync with the kernel behavior.
But it caused an error due to potential uninitialized access like below:
In file included from util/symbol.c:27:
In function ‘dso__set_symbol_names_len’,
inlined from ‘dso__sort_by_name’ at util/symbol.c:638:4:
util/dso.h:654:46: error: ‘len’ may be used uninitialized [-Werror=maybe-uninitialized]
654 | RC_CHK_ACCESS(dso)->symbol_names_len = len;
| ^
util/symbol.c: In function ‘dso__sort_by_name’:
util/symbol.c:634:24: note: ‘len’ was declared here
634 | size_t len;
| ^~~
Let's just initialize it with 0.
Fixes: 55a18d2f3f ("perf build: enable -fno-strict-aliasing")
Closes: https://lore.kernel.org/r/aF7JC8zkG5-_-nY_@google.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
I started seeing this in recent Fedora 42 kernels:
# uname -a
Linux number 6.14.3-300.fc42.x86_64 #1 SMP PREEMPT_DYNAMIC Sun Apr 20 16:08:39 UTC 2025 x86_64 GNU/Linux
#
# perf test vmlinux
1: vmlinux symtab matches kallsyms : FAILED!
#
Where we have Rust enabled:
# grep CONFIG_RUST /boot/config-6.14.3-300.fc42.x86_64
CONFIG_RUSTC_VERSION=108600
CONFIG_RUST_IS_AVAILABLE=y
CONFIG_RUSTC_LLVM_VERSION=200101
CONFIG_RUSTC_HAS_COERCE_POINTEE=y
CONFIG_RUST=y
CONFIG_RUSTC_VERSION_TEXT="rustc 1.86.0 (05f9846f8 2025-03-31) (Fedora 1.86.0-1.fc42)"
CONFIG_RUST_FW_LOADER_ABSTRACTIONS=y
CONFIG_RUST_PHYLIB_ABSTRACTIONS=y
# CONFIG_RUST_DEBUG_ASSERTIONS is not set
CONFIG_RUST_OVERFLOW_CHECKS=y
# CONFIG_RUST_BUILD_ASSERT_ALLOW is not set
#
Looking at the reason for the failure:
# perf test -v vmlinux |& grep ^ERR
ERR : 0xffffffff99efc7d0: __pfx__RNCINvNtNtNtCsf5tcb0XGUW4_4core4iter8adapters3map12map_try_foldjNtCsagR6JbSOIa9_12drm_panic_qr7VersionuINtNtNtBa_3ops12control_flow11ControlFlowB10_ENcB10_0NCINvNvNtNtNtB8_6traits8iterator8Iterator4find5checkB10_NCNvMB12_B10_13from_segments0E0E0B12_ not on kallsyms
ERR : 0xffffffff99efc7e0: _RNCINvNtNtNtCsf5tcb0XGUW4_4core4iter8adapters3map12map_try_foldjNtCsagR6JbSOIa9_12drm_panic_qr7VersionuINtNtNtBa_3ops12control_flow11ControlFlowB10_ENcB10_0NCINvNvNtNtNtB8_6traits8iterator8Iterator4find5checkB10_NCNvMB12_B10_13from_segments0E0E0B12_ not on kallsyms
#
But:
# grep -w u /proc/kallsyms
ffffffff99efc7d0 u __pfx__RNCINvNtNtNtCsf5tcb0XGUW4_4core4iter8adapters3map12map_try_foldjNtCsagR6JbSOIa9_12drm_panic_qr7VersionuINtNtNtBa_3ops12control_flow11ControlFlowB10_ENcB10_0NCINvNvNtNtNtB8_6traits8iterator8Iterator4find5checkB10_NCNvMB12_B10_13from_segments0E0E0B12_
ffffffff99efc7e0 u _RNCINvNtNtNtCsf5tcb0XGUW4_4core4iter8adapters3map12map_try_foldjNtCsagR6JbSOIa9_12drm_panic_qr7VersionuINtNtNtBa_3ops12control_flow11ControlFlowB10_ENcB10_0NCINvNvNtNtNtB8_6traits8iterator8Iterator4find5checkB10_NCNvMB12_B10_13from_segments0E0E0B12_
#
The test checks that "vmlinux symtab matches kallsyms", so it finds those two
symbols in vmlinux:
# pahole --running_kernel_vmlinux
/usr/lib/debug/lib/modules/6.14.3-300.fc42.x86_64/vmlinux
#
# readelf -sW /usr/lib/debug/lib/modules/6.14.3-300.fc42.x86_64/vmlinux | grep -Ew '(__pfx__RNCINvNtNtNtCsf5tcb0XGUW4_4core4iter8adapters3map12map_try_foldjNtCsagR6JbSOIa9_12drm_panic_qr7VersionuINtNtNtBa_3ops12control_flow11ControlFlowB10_ENcB10_0NCINvNvNtNtNtB8_6traits8iterator8Iterator4find5checkB10_NCNvMB12_B10_13from_segments0E0E0B12_|_RNCINvNtNtNtCsf5tcb0XGUW4_4core4iter8adapters3map12map_try_foldjNtCsagR6JbSOIa9_12drm_panic_qr7VersionuINtNtNtBa_3ops12control_flow11ControlFlowB10_ENcB10_0NCINvNvNtNtNtB8_6traits8iterator8Iterator4find5checkB10_NCNvMB12_B10_13from_segments0E0E0B12_)'
81844: ffffffff81efc7e0 524 FUNC LOCAL DEFAULT 1 _RNCINvNtNtNtCsf5tcb0XGUW4_4core4iter8adapters3map12map_try_foldjNtCsagR6JbSOIa9_12drm_panic_qr7VersionuINtNtNtBa_3ops12control_flow11ControlFlowB10_ENcB10_0NCINvNvNtNtNtB8_6traits8iterator8Iterator4find5checkB10_NCNvMB12_B10_13from_segments0E0E0B12_
144259: ffffffff81efc7d0 16 FUNC LOCAL DEFAULT 1 __pfx__RNCINvNtNtNtCsf5tcb0XGUW4_4core4iter8adapters3map12map_try_foldjNtCsagR6JbSOIa9_12drm_panic_qr7VersionuINtNtNtBa_3ops12control_flow11ControlFlowB10_ENcB10_0NCINvNvNtNtNtB8_6traits8iterator8Iterator4find5checkB10_NCNvMB12_B10_13from_segments0E0E0B12_
#
It is there.
From the nm documentation we can see that:
"U" The symbol is undefined.
"u" The symbol is a unique global symbol. This is a GNU extension to the
standard set of ELF symbol bindings. For such a symbol the dynamic
linker will make sure that in the entire process there is just one
symbol with this name and type in use.
So lets consider 'u' symbols in /proc/kallsyms when loading it to cover this case.
Fedora:40 shows this as a 'l' symbol, so consider that as well.
With this patch 'perf test 1' is happy again:
# perf test vmlinux
1: vmlinux symtab matches kallsyms : Ok
#
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: James Clark <james.clark@linaro.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/aBE_n0PGl3g6h-cS@x1
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Fedora introduced a "MiniDebuginfo" feature, in which an LZMA-compressed
ELF file is placed inside a section named ".gnu_debugdata". This file
contains nothing but a symbol table, which can be used to supplement the
.dynsym section which only contains required symbols for runtime.
It is supported by GDB for stack traces, but it should be useful for
tracing as well. Implement support for loading symbols from
.gnu_debugdata.
Signed-off-by: Stephen Brennan <stephen.s.brennan@oracle.com>
Reviewed-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Link: https://lore.kernel.org/r/20250307232206.2102440-4-stephen.s.brennan@oracle.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
When there are more than one symbols at the same address, it needs to
choose which one is better. In choose_best_symbol() it didn't check the
type of symbols. It's possible to have labels in other symbols and in
that case, it would be better to pick the actual symbol over the labels.
To minimize the possible impact on other symbols, I only check NOTYPE
symbols specifically.
$ readelf -sW vmlinux | grep -e __do_softirq -e __softirqentry_text_start
105089: ffffffff82000000 814 FUNC GLOBAL DEFAULT 1 __do_softirq
111954: ffffffff82000000 0 NOTYPE GLOBAL DEFAULT 1 __softirqentry_text_start
The commit 77b004f4c5 tried to do the same by not giving the size
to the label symbols but it seems there's some label-only symbols in asm
code. Let's restore the original code and choose the right symbol using
type of the symbols.
Fixes: 77b004f4c5 ("perf symbol: Do not fixup end address of labels")
Reported-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Ian Rogers <irogers@google.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Link: http://lore.kernel.org/lkml/Z3b-DqBMnNb4ucEm@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
When it loads symbols from an ELF file, it loads label symbols which is
0 size. Sometimes it has the same address with other symbols and might
shadow the original symbols because it fixes up the size of the symbol.
For example, in my system __do_softirq is shadowed and only accepts the
__softirqentry_text_start instead. But it should accept __do_softirq.
$ readelf -sW vmlinux | grep -e __do_softirq -e __softirqentry_text_start
105089: ffffffff82000000 814 FUNC GLOBAL DEFAULT 1 __do_softirq
111954: ffffffff82000000 0 NOTYPE GLOBAL DEFAULT 1 __softirqentry_text_start
$ perf annotate --stdio __do_softirq
Error:
The perf.data data has no samples!
$ perf annotate --stdio __softirqentry_text_start | head
Percent | Source code & Disassembly of vmlinux for cycles (26 samples, percent: local period)
---------------------------------------------------------------------------------------------------
: 0 0xffffffff82000000 <__softirqentry_text_start>:
0.00 : ffffffff82000000: nopl (%rax,%rax)
30.77 : ffffffff82000005: pushq %rbp
3.85 : ffffffff82000006: movq %rsp, %rbp
0.00 : ffffffff82000009: pushq %r15
3.85 : ffffffff8200000b: pushq %r14
3.85 : ffffffff8200000d: pushq %r13
0.00 : ffffffff8200000f: pushq %r12
We can ignore NOTYPE symbols in the symbols__fixup_end() so that it can
pick the __do_softirq() in choose_best_symbol(). This should be fine
since most symbols have either STT_FUNC or STT_OBJECT.
Link: https://lore.kernel.org/r/20240912224208.3360116-1-namhyung@kernel.org
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Perf test for perf probe of function from different CU fails
as below:
./perf test -vv "test perf probe of function from different CU"
116: test perf probe of function from different CU:
--- start ---
test child forked, pid 2679
Failed to find symbol foo in /tmp/perf-uprobe-different-cu-sh.Msa7iy89bx/testfile
Error: Failed to add events.
--- Cleaning up ---
"foo" does not hit any event.
Error: Failed to delete events.
---- end(-1) ----
116: test perf probe of function from different CU : FAILED!
The test does below to probe function "foo" :
# gcc -g -Og -flto -c /tmp/perf-uprobe-different-cu-sh.XniNxNEVT7/testfile-foo.c
-o /tmp/perf-uprobe-different-cu-sh.XniNxNEVT7/testfile-foo.o
# gcc -g -Og -c /tmp/perf-uprobe-different-cu-sh.XniNxNEVT7/testfile-main.c
-o /tmp/perf-uprobe-different-cu-sh.XniNxNEVT7/testfile-main.o
# gcc -g -Og -o /tmp/perf-uprobe-different-cu-sh.XniNxNEVT7/testfile
/tmp/perf-uprobe-different-cu-sh.XniNxNEVT7/testfile-foo.o
/tmp/perf-uprobe-different-cu-sh.XniNxNEVT7/testfile-main.o
# ./perf probe -x /tmp/perf-uprobe-different-cu-sh.XniNxNEVT7/testfile foo
Failed to find symbol foo in /tmp/perf-uprobe-different-cu-sh.XniNxNEVT7/testfile
Error: Failed to add events.
Perf probe fails to find symbol foo in the executable placed in
/tmp/perf-uprobe-different-cu-sh.XniNxNEVT7
Simple reproduce:
# mktemp -d /tmp/perf-checkXXXXXXXXXX
/tmp/perf-checkcWpuLRQI8j
# gcc -g -o test test.c
# cp test /tmp/perf-checkcWpuLRQI8j/
# nm /tmp/perf-checkcWpuLRQI8j/test | grep foo
00000000100006bc T foo
# ./perf probe -x /tmp/perf-checkcWpuLRQI8j/test foo
Failed to find symbol foo in /tmp/perf-checkcWpuLRQI8j/test
Error: Failed to add events.
But it works with any files like /tmp/perf/test. Only for
patterns with "/tmp/perf-", this fails.
Further debugging, commit 80d496be89 ("perf report: Add support
for profiling JIT generated code") added support for profiling JIT
generated code. This patch handles dso's of form
"/tmp/perf-$PID.map" .
The check used "if (strncmp(self->name, "/tmp/perf-", 10) == 0)"
to match "/tmp/perf-$PID.map". With this commit, any dso in
/tmp/perf- folder will be considered separately for processing
(not only JIT created map files ). Fix this by changing the
string pattern to check for "/tmp/perf-%d.map". Add a helper
function is_perf_pid_map_name to do this check. In "struct dso",
dso->long_name holds the long name of the dso file. Since the
/tmp/perf-$PID.map check uses the complete name, use dso___long_name for
the string name.
With the fix,
# ./perf test "test perf probe of function from different CU"
117: test perf probe of function from different CU : Ok
Fixes: 56cbeacf14 ("perf probe: Add test for regression introduced by switch to die_get_decl_file()")
Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Reviewed-by: Chaitanya S Prakash <chaitanyas.prakash@arm.com>
Reviewed-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: akanksha@linux.ibm.com
Cc: kjain@linux.ibm.com
Cc: maddy@linux.ibm.com
Cc: disgoel@linux.vnet.ibm.com
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/20240623064850.83720-1-atrajeev@linux.vnet.ibm.com
The linked commit updated dso__load_vmlinux() to call
dso__set_long_name() before loading the symbols. Loading the symbols may
not succeed but dso__set_long_name() takes ownership of the string. The
two callers of this function free the string themselves on failure
cases, resulting in the following error:
$ perf record -- ls
$ perf report
free(): double free detected in tcache 2
Fix it by always taking ownership of the string, even on failure. This
means the string is either freed at the very first early exit condition,
or later when the dso is deleted or the long name is replaced. Now no
special return value is needed to signify that the caller needs to
free the string.
Fixes: e59fea47f8 ("perf symbols: Fix DSO kernel load and symbol process to correctly map DSO to its long_name, type and adjust_symbols")
Reviewed-by: Ian Rogers <irogers@google.com>
Signed-off-by: James Clark <james.clark@arm.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20240507141210.195939-5-james.clark@arm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
I got a strange error on ARM to fail on processing FINISHED_ROUND
record. It turned out that it was failing in symbol__alloc_hist()
because the symbol size is too big.
When a sample is captured on a specific BPF program, it failed. I've
added a debug code and found the end address of the symbol is from
the next module which is placed far way.
ffff800008795778-ffff80000879d6d8: bpf_prog_1bac53b8aac4bc58_netcg_sock [bpf]
ffff80000879d6d8-ffff80000ad656b4: bpf_prog_76867454b5944e15_netcg_getsockopt [bpf]
ffff80000ad656b4-ffffd69b7af74048: bpf_prog_1d50286d2eb1be85_hn_egress [bpf] <---------- here
ffffd69b7af74048-ffffd69b7af74048: $x.5 [sha3_generic]
ffffd69b7af74048-ffffd69b7af740b8: crypto_sha3_init [sha3_generic]
ffffd69b7af740b8-ffffd69b7af741e0: crypto_sha3_update [sha3_generic]
The logic in symbols__fixup_end() just uses curr->start to update the
prev->end. But in this case, it won't work as it's too different.
I think ARM has a different kernel memory layout for modules and BPF
than on x86. Actually there's a logic to handle kernel and module
boundary. Let's do the same for symbols between different modules.
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Reviewed-by: Leo Yan <leo.yan@linux.dev>
Cc: Will Deacon <will@kernel.org>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: John Garry <john.g.garry@oracle.com>
Link: https://lore.kernel.org/r/20240212233322.1855161-1-namhyung@kernel.org
This is a longstanding to do list entry: we need a way to see that a
sample took place while in idle state, as the current way to do it is
to infer that by the name of the functions that in such state have
more samples, IOW: a hack.
Maybe we can do flip a bit in samples that take place inside the
enter/exit idle section in do_idle()?
But till then, add one more :-\
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/ZR66Qgbcltt+zG7F@kernel.org
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Update "struct dso" to include new member "text_end".
This new field will represent the offset for end of text
section for a dso. For elf, this value is derived as:
sh_size (Size of section in byes) + sh_offset (Section file
offst) of the elf header for text.
For bfd, this value is derived as:
1. For PE file,
section->size + ( section->vma - dso->text_offset)
2. Other cases:
section->filepos (file position) + section->size (size of
section)
To resolve the address from a sample, perf looks at the
DSO maps. In case of address from a kernel module, there
were some address found to be not resolved. This was
observed while running perf test for "Object code reading".
Though the ip falls beteen the start address of the loaded
module (perf map->start ) and end address ( perf map->end),
it was unresolved.
Example:
Reading object code for memory address: 0xc008000007f0142c
File is: /lib/modules/6.5.0-rc3+/kernel/fs/xfs/xfs.ko
On file address is: 0x1114cc
Objdump command is: objdump -z -d --start-address=0x11142c --stop-address=0x1114ac /lib/modules/6.5.0-rc3+/kernel/fs/xfs/xfs.ko
objdump read too few bytes: 128
test child finished with -1
Here, module is loaded at:
# cat /proc/modules | grep xfs
xfs 2228224 3 - Live 0xc008000007d00000
From objdump for xfs module, text section is:
text 0010f7bc 0000000000000000 0000000000000000 000000a0 2**4
Here the offset for 0xc008000007f0142c ie 0x112074 falls out
.text section which is up to 0x10f7bc.
In this case for module, the address 0xc008000007e11fd4 is pointing
to stub instructions. This address range represents the module stubs
which is allocated on module load and hence is not part of DSO offset.
To identify such address, which falls out of text
section and within module end, added the new field "text_end" to
"struct dso".
Reported-by: Disha Goel <disgoel@linux.ibm.com>
Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Reviewed-by: Adrian Hunter <adrian.hunter@intel.com>
Reviewed-by: Kajol Jain <kjain@linux.ibm.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: maddy@linux.ibm.com
Cc: disgoel@linux.vnet.ibm.com
Cc: linuxppc-dev@lists.ozlabs.org
Link: https://lore.kernel.org/r/20230928075213.84392-1-atrajeev@linux.vnet.ibm.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
