kernel/git/next/linux-next.git/tools/perf/util/probe-finder.c, branch master

perf probe-finder: Fix libdw API contract violations

2026-05-06T00:50:56+00:00

Check return values of `dwarf_formsdata`, `dwarf_entrypc`, `dwarf_highpc`, `dwarf_bytesize`, `dwarf_attr`, `dwarf_decl_line`, `dwarf_getfuncs`, and `dwarf_formref_die`. Validate `dwarf_diename` and `dwarf_diecu` results to prevent potential crashes. Fix C90 mixed declarations. Additionally: - Avoid vfprintf undefined behavior with NULL strings by using the `die_name()` helper for `dwarf_diename()` in `pr_*` calls, including when warning about tail calls. - Prevent NULL pointer dereference in `convert_variable_fields()` when processing array elements for variables in registers. - Fallback to offset 0 in `line_range_search_cb()` instead of skipping functions without `DW_AT_decl_line`. - Relax `dwarf_getfuncs` error checking in `find_probe_point_by_func()` and `find_line_range_by_func()` to prevent premature CU search aborts, ensuring robustness against corrupted CUs. Fixes: 66f69b2197167cb9 ("perf probe: Support DW_AT_const_value constant value") Fixes: 3d918a12a1b3088a ("perf probe: Find fentry mcount fuzzed parameter location") Fixes: bcfc082150c6b1e9 ("perf probe: Remove redundant dwarf functions") Fixes: 221d061182b8ff55 ("perf probe: Fix to search local variables in appropriate scope") Fixes: b55a87ade3839c33 ("perf probe: Remove die() from probe-finder code") Fixes: 4c859351226c920b ("perf probe: Support glob wildcards for function name") Assisted-by: Gemini-CLI:Google Gemini 3 Signed-off-by: Ian Rogers Cc: Adrian Hunter Cc: Ingo Molnar Cc: James Clark Cc: Jiri Olsa Cc: Masami Hiramatsu Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Zecheng Li Signed-off-by: Arnaldo Carvalho de Melo

perf tools: Use calloc() where applicable

2026-04-09T02:21:05+00:00

Instead of using zalloc(nr_entries * sizeof_entry) that is what calloc() does. In some places where linux/zalloc.h isn't needed, remove it, add when needed and was getting it indirectly. Signed-off-by: Arnaldo Carvalho de Melo Signed-off-by: Namhyung Kim

perf build-id: Ensure struct build_id is empty before use

2025-07-25T17:37:55+00:00

If a build ID is read then not all code paths may ensure it is empty before use. Initialize the build_id to be zero-ed unless there is clear initialization such as a call to build_id__init. Signed-off-by: Ian Rogers Link: https://lore.kernel.org/r/20250724163302.596743-6-irogers@google.com Signed-off-by: Namhyung Kim

perf build-id: Change sprintf functions to snprintf

2025-07-25T17:37:13+00:00

Pass in a size argument rather than implying all build id strings must be SBUILD_ID_SIZE. Signed-off-by: Ian Rogers Link: https://lore.kernel.org/r/20250724163302.596743-4-irogers@google.com [ fixed some build errors ] Signed-off-by: Namhyung Kim

perf probe: Pick the correct dwarf die while adding probe points

2025-02-26T22:25:14+00:00

Perf probe on vfs_fstatat fails as below on a powerpc system $ ./perf probe -nf --max-probes=512 -a 'vfs_fstatat $params' Segmentation fault (core dumped) This is observed while running perftool-testsuite_probe testcase. While running with verbose, its observed that segfault happens at: synthesize_probe_trace_arg () synthesize_probe_trace_command () probe_file.add_event () apply_perf_probe_events () __cmd_probe () cmd_probe () run_builtin () handle_internal_command () main () Code in synthesize_probe_trace_arg() access a null value and results in segfault. Data structure which is null: struct probe_trace_arg arg->value We are hitting a case where arg->value is null in probe point: "vfs_fstatat $params". This is happening since 'commit e896474fe485 ("getname_maybe_null() - the third variant of pathname copy-in")' Before the commit, probe point for vfs_fstatat was getting added only for one location: Writing event: p:probe/vfs_fstatat _text+6345404 dfd=%gpr3:s32 filename=%gpr4:x64 stat=%gpr5:x64 flags=%gpr6:s32 With this change, vfs_fstatat code is inlined for other locations in the code: Probe point found: __do_sys_lstat64+48 Probe point found: __do_sys_stat64+48 Probe point found: __do_sys_newlstat+48 Probe point found: __do_sys_newstat+48 Probe point found: vfs_fstatat+0 When trying to find matching dwarf information entry (DIE) from the debuginfo, the code incorrectly picks DIE which is not referring to vfs_fstatat. Snippet from dwarf entry in vmlinux debuginfo file. The main abstract die is: <1><4214883>: Abbrev Number: 147 (DW_TAG_subprogram) <4214885> DW_AT_external : 1 <4214885> DW_AT_name : (indirect string, offset: 0x17b9f3): vfs_fstatat With formal parameters: <2><4214896>: Abbrev Number: 51 (DW_TAG_formal_parameter) <4214897> DW_AT_name : dfd <2><42148a3>: Abbrev Number: 23 (DW_TAG_formal_parameter) <42148a4> DW_AT_name : (indirect string, offset: 0x8fda9): filename <2><42148b0>: Abbrev Number: 23 (DW_TAG_formal_parameter) <42148b1> DW_AT_name : (indirect string, offset: 0x16bd9c): stat <2><42148bd>: Abbrev Number: 23 (DW_TAG_formal_parameter) <42148be> DW_AT_name : (indirect string, offset: 0x39832b): flags While collecting variables/parameters for a probe point, the function copy_variables_cb() also looks at dwarf debug entries based on the instruction address. Snippet if (dwarf_haspc(die_mem, vf->pf->addr)) return DIE_FIND_CB_CONTINUE; else return DIE_FIND_CB_SIBLING; But incase of inlined function instance for vfs_fstatat, there are two entries which has the instruction address entry point as same. Instance 1: which is for vfs_fstatat and DW_AT_abstract_origin points to 0x4214883 (reference above for main abstract die) <3><42131fa>: Abbrev Number: 59 (DW_TAG_inlined_subroutine) <42131fb> DW_AT_abstract_origin: <0x4214883> <42131ff> DW_AT_entry_pc : 0xc00000000062b1e0 Instance 2: which is not for vfs_fstatat but for getname <5><4213270>: Abbrev Number: 39 (DW_TAG_inlined_subroutine) <4213271> DW_AT_abstract_origin: <0x4215b6b> <4213275> DW_AT_entry_pc : 0xc00000000062b1e0 But the copy_variables_cb() continues to add parameters from second instance also based on the dwarf_haspc() check. This results in formal parameters for getname also appended to params. But while filling in the args->value for these parameters, since these args are not part of dwarf with offset "42131fa". Hence value will be null. This incorrect args results in segfault when value field is accessed. Save the dwarf dieoffset of the actual DW_TAG_subprogram as part of "struct probe_finder". In copy_variables_cb(), include check to make sure the DW_AT_abstract_origin points to the correct entry if the dwarf_haspc() matches the instruction address. Signed-off-by: Athira Rajeev Acked-by: Masami Hiramatsu (Google) Link: https://lore.kernel.org/r/20250225123042.37263-1-atrajeev@linux.ibm.com Signed-off-by: Namhyung Kim

perf probe: Replace unacceptable characters when generating event name

2024-12-10T18:41:10+00:00

Replace unacceptable characters with '_' when generating event name from the probing function name. This is not for a C program. For the a C program, it will continue to remove suffixes. Note that this language checking depends on the debuginfo. So without the debuginfo, perf probe will always replaces unacceptable characters with '_'. For example. $ ./perf probe -x cro3 -D \"cro3::cmd::servo::run_show\" p:probe_cro3/cro3_cmd_servo_run_show /work/cro3/target/x86_64-unknown-linux-gnu/debug/cro3:0x197530 $ ./perf probe -x /work/go/example/outyet/main -D 'main.(*Server).poll' p:probe_main/main_Server_poll /work/go/example/outyet/main:0x353040 Signed-off-by: Masami Hiramatsu Cc: Alexander Lobakin Cc: Dima Kogan Cc: Ian Rogers Cc: Ingo Molnar Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Przemek Kitszel Link: https://lore.kernel.org/r/173145728160.2747044.18089011235495186810.stgit@mhiramat.roam.corp.google.com [ Removed some extra tabs in the new struct fields ] Signed-off-by: Arnaldo Carvalho de Melo

perf dwarf-regs: Pass ELF flags to get_dwarf_regstr

2024-11-09T16:39:13+00:00

Pass a flags value as architectures like csky need the flags to determine the ABI variant. Reviewed-by: Masami Hiramatsu (Google) Signed-off-by: Ian Rogers Cc: Anup Patel Cc: Yang Jihong Cc: Palmer Dabbelt Cc: David S. Miller Cc: Albert Ou Cc: Shenlin Liang Cc: Nick Terrell Cc: Guilherme Amadio Cc: Steinar H. Gunderson Cc: Changbin Du Cc: Alexander Lobakin Cc: Przemek Kitszel Cc: Huacai Chen Cc: Guo Ren Cc: Masahiro Yamada Cc: Will Deacon Cc: James Clark Cc: Mike Leach Cc: Chen Pei Cc: Leo Yan Cc: Oliver Upton Cc: Aditya Gupta Cc: Kajol Jain Cc: Athira Rajeev Cc: linux-arm-kernel@lists.infradead.org Cc: linux-riscv@lists.infradead.org Cc: Bibo Mao Cc: John Garry Cc: Atish Patra Cc: Dima Kogan Cc: Paul Walmsley Cc: Dr. David Alan Gilbert Cc: linux-csky@vger.kernel.org Link: https://lore.kernel.org/r/20241108234606.429459-7-irogers@google.com Signed-off-by: Namhyung Kim

perf probe: Fix retrieval of source files from a debuginfod server

2024-10-29T23:36:39+00:00

When perf is linked with libdebuginfod: root@number:~# ldd ~/bin/perf | grep debuginfod libdebuginfod.so.1 => /lib64/libdebuginfod.so.1 (0x00007ff5c3930000) root@number:~# perf check feature debuginfod debuginfod: [ on ] # HAVE_DEBUGINFOD_SUPPORT root@number:~# And we don't have a debuginfo package installed for the binary we're trying to use, vmlinux in this case as we didn't specify any using 'perf probe -x', it will use the build for the running kernel: root@number:~# perf buildid-list -k 38e927fd7799d50dbc4d99ec5e3f781b6105a6a9 root@number:~# And communicate with a debuginfo server, be it configured in a ~/.perfconfig file, excerpt from the 'perf config' man page: buildid-cache.* buildid-cache.debuginfod=URLs Specify debuginfod URLs to be used when retrieving perf.data binaries, it follows the same syntax as the DEBUGINFOD_URLS variable, like: buildid-cache.debuginfod=http://192.168.122.174:8002 Or via the DEBUGINFOD_URLS env var, as distros like fedora do by default: root@number:~# echo $DEBUGINFOD_URLS https://debuginfod.fedoraproject.org/ root@number:~# To pick and cache just what is needed, instead of requiring the manual installation of the entire kernel-debuginfo package, which is really large. It will, in this example, use the following cache files, deleted before/after this patch just to test the whole process: root@number:~# rm -f /root/.cache/debuginfod_client/38e927fd7799d50dbc4d99ec5e3f781b6105a6a9/source-a1414a5d-#usr#src#debug#kernel-6.11.4#linux-6.11.4-201.fc40.x86_64#net#ipv4#icmp.c root@number:~# rm -f /root/.cache/debuginfod_client/38e927fd7799d50dbc4d99ec5e3f781b6105a6a9/debuginfo Before this patch: root@number:~# perf probe -L icmp_rcv Failed to find source file path. Error: Failed to show lines. root@number:~# This is because 'perf probe' was using just the relative file name, in this case "net/ipv4/icmp.c", that is where the 'icmp_rcv' function is located, if we add it and comply with the debuginfo_find_source() function man page, it contacts the server, finds the necessary files, cache them locally and all works: root@number:~# perf probe -L icmp_rcv | head 0 int icmp_rcv(struct sk_buff *skb) { 2 enum skb_drop_reason reason = SKB_DROP_REASON_NOT_SPECIFIED; struct rtable *rt = skb_rtable(skb); struct net *net = dev_net(rt->dst.dev); struct icmphdr *icmph; if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) { 8 struct sec_path *sp = skb_sec_path(skb); root@number:~# Acked-by: Frank Ch. Eigler Cc: Aaron Merey Cc: Francesco Nigro Cc: Masami Hiramatsu Signed-off-by: Arnaldo Carvalho de Melo Link: https://lore.kernel.org/r/ZyACsIFUETsr7-09@x1 Signed-off-by: Namhyung Kim

perf libdw: Remove unnecessary defines

2024-10-18T17:17:40+00:00

As HAVE_DWARF_GETLOCATIONS_SUPPORT and HAVE_DWARF_CFI_SUPPORT always match HAVE_DWARF_SUPPORT remove the macros and use HAVE_DWARF_SUPPORT. If building the file is guarded by CONFIG_DWARF then remove all ifs. Signed-off-by: Ian Rogers Acked-by: Namhyung Kim Cc: Anup Patel Cc: Yang Jihong Cc: Palmer Dabbelt Cc: David S. Miller Cc: Albert Ou Cc: Shenlin Liang Cc: Nick Terrell Cc: Guilherme Amadio Cc: Steinar H. Gunderson Cc: Changbin Du Cc: Alexander Lobakin Cc: Przemek Kitszel Cc: Huacai Chen Cc: Guo Ren Cc: Masahiro Yamada Cc: Masami Hiramatsu (Google) Cc: Will Deacon Cc: James Clark Cc: Mike Leach Cc: Chen Pei Cc: Leo Yan Cc: Oliver Upton Cc: Aditya Gupta Cc: Kajol Jain Cc: Athira Rajeev Cc: linux-arm-kernel@lists.infradead.org Cc: linux-riscv@lists.infradead.org Cc: Bibo Mao Cc: John Garry Cc: Atish Patra Cc: Dima Kogan Cc: Paul Walmsley Cc: Dr. David Alan Gilbert Cc: linux-csky@vger.kernel.org Link: https://lore.kernel.org/r/20241017001354.56973-10-irogers@google.com Signed-off-by: Namhyung Kim

perf probe: Move elfutils support check to libdw check

2024-10-18T17:17:40+00:00

The test _ELFUTILS_PREREQ(0, 142) is false for elfutils before 2009-06-13, but that is 15 years ago and very unlikely. Add a test to test-libdw.c and assume the libdw version is at least 0.142 to simplify the build logic. Signed-off-by: Ian Rogers Acked-by: Namhyung Kim Cc: Anup Patel Cc: Yang Jihong Cc: Palmer Dabbelt Cc: David S. Miller Cc: Albert Ou Cc: Shenlin Liang Cc: Nick Terrell Cc: Guilherme Amadio Cc: Steinar H. Gunderson Cc: Changbin Du Cc: Alexander Lobakin Cc: Przemek Kitszel Cc: Huacai Chen Cc: Guo Ren Cc: Masahiro Yamada Cc: Masami Hiramatsu (Google) Cc: Will Deacon Cc: James Clark Cc: Mike Leach Cc: Chen Pei Cc: Leo Yan Cc: Oliver Upton Cc: Aditya Gupta Cc: Kajol Jain Cc: Athira Rajeev Cc: linux-arm-kernel@lists.infradead.org Cc: linux-riscv@lists.infradead.org Cc: Bibo Mao Cc: John Garry Cc: Atish Patra Cc: Dima Kogan Cc: Paul Walmsley Cc: Dr. David Alan Gilbert Cc: linux-csky@vger.kernel.org Link: https://lore.kernel.org/r/20241017001354.56973-9-irogers@google.com Signed-off-by: Namhyung Kim