kernel.git/tools/perf/util/callchain.c, branch linux-rolling-stable

perf tools: Merge deferred user callchains

2025-12-03T05:59:14Z

Save samples with deferred callchains in a separate list and deliver them after merging the user callchains. If users don't want to merge they can set tool->merge_deferred_callchains to false to prevent the behavior. With previous result, now perf script will show the merged callchains. $ perf script ... pwd 2312 121.163435: 249113 cpu/cycles/P: ffffffff845b78d8 __build_id_parse.isra.0+0x218 ([kernel.kallsyms]) ffffffff83bb5bf6 perf_event_mmap+0x2e6 ([kernel.kallsyms]) ffffffff83c31959 mprotect_fixup+0x1e9 ([kernel.kallsyms]) ffffffff83c31dc5 do_mprotect_pkey+0x2b5 ([kernel.kallsyms]) ffffffff83c3206f __x64_sys_mprotect+0x1f ([kernel.kallsyms]) ffffffff845e6692 do_syscall_64+0x62 ([kernel.kallsyms]) ffffffff8360012f entry_SYSCALL_64_after_hwframe+0x76 ([kernel.kallsyms]) 7f18fe337fa7 mprotect+0x7 (/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2) 7f18fe330e0f _dl_sysdep_start+0x7f (/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2) 7f18fe331448 _dl_start_user+0x0 (/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2) ... The old output can be get using --no-merge-callchain option. Also perf report can get the user callchain entry at the end. $ perf report --no-children --stdio -q -S __build_id_parse.isra.0 # symbol: __build_id_parse.isra.0 8.40% pwd [kernel.kallsyms] | ---__build_id_parse.isra.0 perf_event_mmap mprotect_fixup do_mprotect_pkey __x64_sys_mprotect do_syscall_64 entry_SYSCALL_64_after_hwframe mprotect _dl_sysdep_start _dl_start_user Reviewed-by: Ian Rogers Signed-off-by: Namhyung Kim

perf record: Add --call-graph fp,defer option for deferred callchains

2025-12-03T05:59:13Z

Add a new callchain record mode option for deferred callchains. For now it only works with FP (frame-pointer) mode. And add the missing feature detection logic to clear the flag on old kernels. $ perf record --call-graph fp,defer -vv true ... ------------------------------------------------------------ perf_event_attr: type 0 (PERF_TYPE_HARDWARE) size 136 config 0 (PERF_COUNT_HW_CPU_CYCLES) { sample_period, sample_freq } 4000 sample_type IP|TID|TIME|CALLCHAIN|PERIOD read_format ID|LOST disabled 1 inherit 1 mmap 1 comm 1 freq 1 enable_on_exec 1 task 1 sample_id_all 1 mmap2 1 comm_exec 1 ksymbol 1 bpf_event 1 defer_callchain 1 defer_output 1 ------------------------------------------------------------ sys_perf_event_open: pid 162755 cpu 0 group_fd -1 flags 0x8 sys_perf_event_open failed, error -22 switching off deferred callchain support Reviewed-by: Ian Rogers Signed-off-by: Namhyung Kim

perf report: Use map_symbol__copy() when copying callchains

2025-03-07T22:06:56Z

It seems there are places to miss updating refcount of maps. Let's use map_symbol__copy() helper to properly copy them with refcounts updated. Link: https://lore.kernel.org/r/20250307061250.320849-1-namhyung@kernel.org Signed-off-by: Namhyung Kim

perf callchain: Allow symbols to be optional when resolving a callchain

2024-09-10T20:32:47Z

In uses like 'perf inject' it is not necessary to gather the symbol for each call chain location, the map for the sample IP is wanted so that build IDs and the like can be injected. Make gathering the symbol in the callchain_cursor optional. For a 'perf inject -B' command this lowers the peak RSS from 54.1MB to 29.6MB by avoiding loading symbols. Signed-off-by: Ian Rogers Acked-by: Namhyung Kim Cc: Adrian Hunter Cc: Alexander Shishkin Cc: Anne Macedo Cc: Casey Chen Cc: Colin Ian King Cc: Ingo Molnar Cc: Jiri Olsa Cc: Kan Liang Cc: Mark Rutland Cc: Peter Zijlstra Cc: Sun Haiyong Link: https://lore.kernel.org/r/20240909203740.143492-5-irogers@google.com Signed-off-by: Arnaldo Carvalho de Melo

perf callchain: Add a for_each callback style API

2024-08-13T18:28:19Z

Add a for_each callback style API to callchain with sample__for_each_callchain_node(). Possibly in the future such an API can avoid the overhead of constructing the call chain list. Signed-off-by: Ian Rogers Acked-by: Namhyung Kim Cc: Adrian Hunter Cc: Alexander Shishkin Cc: Casey Chen Cc: Colin Ian King Cc: Ingo Molnar Cc: Jiri Olsa Cc: Kan Liang Cc: Mark Rutland Cc: Peter Zijlstra Cc: Tom Zanussi Link: https://lore.kernel.org/r/20240812224119.744968-1-irogers@google.com [ Split from a larger patch that introduced the API and use it ] Signed-off-by: Arnaldo Carvalho de Melo

perf tool: fix dereferencing NULL al->maps

2024-07-26T18:12:16Z

With 0dd5041c9a0e ("perf addr_location: Add init/exit/copy functions"), when cpumode is 3 (macro PERF_RECORD_MISC_HYPERVISOR), thread__find_map() could return with al->maps being NULL. The path below could add a callchain_cursor_node with NULL ms.maps. add_callchain_ip() thread__find_symbol(.., &al) thread__find_map(.., &al) // al->maps becomes NULL ms.maps = maps__get(al.maps) callchain_cursor_append(..., &ms, ...) node->ms.maps = maps__get(ms->maps) Then the path below would dereference NULL maps and get segfault. fill_callchain_info() maps__machine(node->ms.maps); Fix it by checking if maps is NULL in fill_callchain_info(). Fixes: 0dd5041c9a0e ("perf addr_location: Add init/exit/copy functions") Signed-off-by: Casey Chen Reviewed-by: Ian Rogers Reviewed-by: Arnaldo Carvalho de Melo Acked-by: Namhyung Kim Cc: yzhong@purestorage.com Link: https://lore.kernel.org/r/20240722211548.61455-1-cachen@purestorage.com Signed-off-by: Namhyung Kim

perf callchain: Use zfree() to avoid possibly accessing dangling pointers

2024-05-07T15:44:02Z

When freeing a->b it is good practice to set a->b to NULL using zfree(&a->b) so that when we have a bug where a reference to a freed 'a' pointer is kept somewhere, we can more quickly cause a segfault if some code tries to use a->b. Convert one such case in the callchain code. Cc: Adrian Hunter Cc: Ian Rogers Cc: Jiri Olsa Cc: Kan Liang Cc: Namhyung Kim Link: https://lore.kernel.org/lkml/ZjmcGobQ8E52EyjJ@x1 Signed-off-by: Arnaldo Carvalho de Melo

perf dso: Add reference count checking and accessor functions

2024-05-06T18:28:49Z

Add reference count checking to struct dso, this can help with implementing correct reference counting discipline. To avoid RC_CHK_ACCESS everywhere, add accessor functions for the variables in struct dso. The majority of the change is mechanical in nature and not easy to split up. Committer testing: 'perf test' up to this patch shows no regressions. But: util/symbol.c: In function ‘dso__load_bfd_symbols’: util/symbol.c:1683:9: error: too few arguments to function ‘dso__set_adjust_symbols’ 1683 | dso__set_adjust_symbols(dso); | ^~~~~~~~~~~~~~~~~~~~~~~ In file included from util/symbol.c:21: util/dso.h:268:20: note: declared here 268 | static inline void dso__set_adjust_symbols(struct dso *dso, bool val) | ^~~~~~~~~~~~~~~~~~~~~~~ make[6]: *** [/home/acme/git/perf-tools-next/tools/build/Makefile.build:106: /tmp/tmp.ZWHbQftdN6/util/symbol.o] Error 1 MKDIR /tmp/tmp.ZWHbQftdN6/tests/workloads/ make[6]: *** Waiting for unfinished jobs.... This was updated: - symbols__fixup_end(&dso->symbols, false); - symbols__fixup_duplicate(&dso->symbols); - dso->adjust_symbols = 1; + symbols__fixup_end(dso__symbols(dso), false); + symbols__fixup_duplicate(dso__symbols(dso)); + dso__set_adjust_symbols(dso); But not build tested with BUILD_NONDISTRO and libbfd devel files installed (binutils-devel on fedora). Add the missing argument: symbols__fixup_end(dso__symbols(dso), false); symbols__fixup_duplicate(dso__symbols(dso)); - dso__set_adjust_symbols(dso); + dso__set_adjust_symbols(dso, true); Signed-off-by: Ian Rogers Tested-by: Arnaldo Carvalho de Melo Cc: Adrian Hunter Cc: Ahelenia Ziemiańska Cc: Alexander Shishkin Cc: Andi Kleen Cc: Athira Rajeev Cc: Ben Gainey Cc: Changbin Du Cc: Chengen Du Cc: Colin Ian King Cc: Dima Kogan Cc: Ilkka Koskinen Cc: Ingo Molnar Cc: James Clark Cc: Jiri Olsa Cc: K Prateek Nayak Cc: Kan Liang Cc: Leo Yan Cc: Li Dong Cc: Mark Rutland Cc: Masami Hiramatsu Cc: Namhyung Kim Cc: Paran Lee Cc: Peter Zijlstra Cc: Song Liu Cc: Sun Haiyong Cc: Thomas Richter Cc: Tiezhu Yang Cc: Yanteng Si Cc: zhaimingbing Link: https://lore.kernel.org/r/20240504213803.218974-6-irogers@google.com Signed-off-by: Arnaldo Carvalho de Melo

perf maps: Hide maps internals

2024-02-12T20:35:41Z

Move the struct into the C file. Add maps__equal to work around exposing the struct for reference count checking. Add accessors for the unwind_libunwind_ops. Move maps_list_node to its only use in symbol.c. Signed-off-by: Ian Rogers Acked-by: Namhyung Kim Cc: K Prateek Nayak Cc: James Clark Cc: Vincent Whitchurch Cc: Alexey Dobriyan Cc: Colin Ian King Cc: Changbin Du Cc: Masami Hiramatsu Cc: Song Liu Cc: Leo Yan Cc: Athira Rajeev Cc: Liam Howlett Cc: Artem Savkov Cc: bpf@vger.kernel.org Signed-off-by: Namhyung Kim Link: https://lore.kernel.org/r/20240210031746.4057262-6-irogers@google.com

perf callchain: Fix spelling mistake "statisitcs" -> "statistics"

2023-10-28T02:26:13Z

There are a couple of spelling mistakes in perror messages. Fix them. Signed-off-by: Colin Ian King Cc: kernel-janitors@vger.kernel.org Link: https://lore.kernel.org/r/20231027084633.1167530-1-colin.i.king@gmail.com Signed-off-by: Namhyung Kim