kernel/tools/perf/util/disasm.c, branch linux-6.17.y

perf disasm: Avoid undefined behavior in incrementing NULL

2025-10-19T14:37:02Z

[ Upstream commit 78d853512d6f979cf0cc41566e4f6cd82995ff34 ] Incrementing NULL is undefined behavior and triggers ubsan during the perf annotate test. Split a compound statement over two lines to avoid this. Fixes: 98f69a573c668a18 ("perf annotate: Split out util/disasm.c") Reviewed-by: Collin Funk Reviewed-by: James Clark Reviewed-by: Kuan-Wei Chiu Signed-off-by: Ian Rogers Acked-by: Namhyung Kim Cc: Adrian Hunter Cc: Alexander Shishkin Cc: Athira Rajeev Cc: Blake Jones Cc: Chun-Tse Shao Cc: Howard Chu Cc: Ingo Molnar Cc: Jan Polensky Cc: Jiri Olsa Cc: Kan Liang Cc: Li Huafei Cc: Mark Rutland Cc: Nam Cao Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Steinar H. Gunderson Cc: Thomas Gleixner Link: https://lore.kernel.org/r/20250821163820.1132977-2-irogers@google.com Signed-off-by: Arnaldo Carvalho de Melo Signed-off-by: Sasha Levin

perf build-id: Change sprintf functions to snprintf

2025-07-25T17:37:13Z

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 annotate: Fix source code annotate with objdump

2025-06-26T22:15:48Z

Recently it uses llvm and capstone to speed up annotation or disassembly of instructions. But they don't support source code view yet. Until it fixed, we can force to use objdump for source code annotation. To prevent performance loss, it's disabled by default and turned it on when user requests it in TUI by pressing 's' key. Acked-by: Ian Rogers Link: https://lore.kernel.org/r/20250625230339.702610-1-namhyung@kernel.org Reported-by: Ingo Molnar Signed-off-by: Namhyung Kim

perf annotate: Return errors from disasm_line__parse_powerpc()

2025-03-07T00:52:24Z

In disasm_line__parse_powerpc() , return code from function disasm_line__parse() is ignored. This will result in bad results if the disasm_line__parse() fails to disasm the line. Use the return code to fix this. Signed-off-by: Athira Rajeev Tested-By: Venkat Rao Bagalkote Link: https://lore.kernel.org/r/20250304154114.62093-2-atrajeev@linux.ibm.com Signed-off-by: Namhyung Kim

perf annotate: Add annotation_options.disassembler_used

2025-03-07T00:51:22Z

When doing "perf annotate", perf tool provides option to use specific disassembler like llvm/objdump/capstone. The order picked is to use llvm first and if that fails fallback to objdump ie to use PERF_DISASM_LLVM, PERF_DISASM_CAPSTONE and PERF_DISASM_OBJDUMP In powerpc, when using "data type" sort keys, first preferred approach is to read the raw instruction from the DSO. In objdump is specified in "--objdump" option, it picks the symbol disassemble using objdump. Currently disasm_line__parse_powerpc() function uses length of the "line" to determine if objdump is used. But there are few cases, where if objdump doesn't recognise the instruction, the disassembled string will be empty. Example: 134cdc: c4 05 82 41 beq 1352a0 134ce0: ac 00 8e 40 bne cr3,134d8c 134ce4: 0f 00 10 04 pld r9,1028308 ====>134ce8: d4 b0 20 e5 134cec: 16 00 40 39 li r10,22 134cf0: 48 01 21 ea ld r17,328(r1) So depending on length of line will give bad results. Add a new filed to annotation options structure, "struct annotation_options" to save the disassembler used. Use this info to determine if disassembly is done while parsing the disasm line. Reported-by: Tejas Manhas Signed-off-by: Athira Rajeev Tested-By: Venkat Rao Bagalkote Link: https://lore.kernel.org/r/20250304154114.62093-1-atrajeev@linux.ibm.com Signed-off-by: Namhyung Kim

perf annotate: Use an array for the disassembler preference

2025-01-27T23:58:01Z

Prior to this change a string was used which could cause issues with an unrecognized disassembler in symbol__disassembler. Change to initializing an array of perf_disassembler enum values. If a value already exists then adding it a second time is ignored to avoid array out of bounds problems present in the previous code, it also allows a statically sized array and removes memory allocation needs. Errors in the disassembler string are reported when the config is parsed during perf annotate or perf top start up. If the array is uninitialized after processing the config file the default llvm, capstone then objdump values are added but without a need to parse a string. Fixes: a6e8a58de629 ("perf disasm: Allow configuring what disassemblers to use") Closes: https://lore.kernel.org/lkml/CAP-5=fUdfCyxmEiTpzS2uumUp3-SyQOseX2xZo81-dQtWXj6vA@mail.gmail.com/ Signed-off-by: Ian Rogers Tested-by: Namhyung Kim Link: https://lore.kernel.org/r/20250124043856.1177264-1-irogers@google.com Signed-off-by: Namhyung Kim

perf disasm: Return a proper error when not determining the file type

2024-12-09T20:51:53Z

Before: ⬢ [acme@toolbox a]$ perf annotate --stdio2 -i acme-perf-injected.data 'java.lang.String com.fasterxml.jackson.core.sym.CharsToNameCanonicalizer.findSymbol(char[], int, int, int)' Error: Couldn't annotate java.lang.String com.fasterxml.jackson.core.sym.CharsToNameCanonicalizer.findSymbol(char[], int, int, int): Internal error: Invalid -1 error code ⬢ [acme@toolbox a]$ After: ⬢ [acme@toolbox a]$ perf annotate --stdio2 -i acme-perf-injected.data 'java.lang.String com.fasterxml.jackson.core.sym.CharsToNameCanonicalizer.findSymbol(char[], int, int, int)' Error: Couldn't annotate java.lang.String com.fasterxml.jackson.core.sym.CharsToNameCanonicalizer.findSymbol(char[], int, int, int): Couldn't determine the file /tmp/perf-3308868.map type. ⬢ [acme@toolbox a]$ Reported-by: Francesco Nigro Reported-by: Ilan Green Cc: Adrian Hunter Cc: Ian Rogers Cc: James Clark Cc: Jiri Olsa Cc: Kan Liang Cc: Namhyung Kim Cc: Stephane Eranian Cc: Yonatan Goldschmidt Link: https://lore.kernel.org/lkml/Z092D9-r_iOgwIWM@x1 Signed-off-by: Arnaldo Carvalho de Melo

perf disasm: Allow configuring what disassemblers to use

2024-11-13T19:27:35Z

The perf tools annotation code used for a long time parsing the output of binutils's objdump (or its reimplementations, like llvm's) to then parse and augment it with samples, allow navigation, etc. More recently disassemblers from the capstone and llvm (libraries, not parsing the output of tools using those libraries to mimic binutils's objdump output) were introduced. So when all those methods are available, there is a static preference for a series of attempts of disassembling a binary, with the 'llvm, capstone, objdump' sequence being hard coded. This patch allows users to change that sequence, specifying via a 'perf config' 'annotate.disassemblers' entry which and in what order disassemblers should be attempted. As alluded to in the comments in the source code of this series, this flexibility is useful for users and developers alike, elliminating the requirement to rebuild the tool with some specific set of libraries to see how the output of disassembling would be for one of these methods. root@x1:~# rm -f ~/.perfconfig root@x1:~# perf annotate -v --stdio2 update_load_avg symbol__disassemble: filename=/usr/lib/debug/lib/modules/6.11.4-201.fc40.x86_64/vmlinux, sym=update_load_avg, start=0xffffffffb6148fe0, en> annotating [0x6ff7170] /usr/lib/debug/lib/modules/6.11.4-201.fc40.x86_64/vmlinux : [0x7407ca0] update_load_avg Disassembled with llvm annotate.disassemblers=llvm,capstone,objdump Samples: 66 of event 'cpu_atom/cycles/P', 10000 Hz, Event count (approx.): 5185444, [percent: local period] update_load_avg() /usr/lib/debug/lib/modules/6.11.4-201.fc40.x86_64/vmlinux Percent 0xffffffff81148fe0 : 1.61 pushq %r15 pushq %r14 1.00 pushq %r13 movl %edx,%r13d 1.90 pushq %r12 pushq %rbp movq %rsi,%rbp pushq %rbx movq %rdi,%rbx subq $0x18,%rsp 15.14 movl 0x1a4(%rdi),%eax root@x1:~# perf config annotate.disassemblers=capstone root@x1:~# cat ~/.perfconfig # this file is auto-generated. [annotate] disassemblers = capstone root@x1:~# root@x1:~# perf annotate -v --stdio2 update_load_avg Disassembled with capstone annotate.disassemblers=capstone Samples: 66 of event 'cpu_atom/cycles/P', 10000 Hz, Event count (approx.): 5185444, [percent: local period] update_load_avg() /usr/lib/debug/lib/modules/6.11.4-201.fc40.x86_64/vmlinux Percent 0xffffffff81148fe0 : 1.61 pushq %r15 pushq %r14 1.00 pushq %r13 movl %edx,%r13d 1.90 pushq %r12 pushq %rbp movq %rsi,%rbp pushq %rbx movq %rdi,%rbx subq $0x18,%rsp 15.14 movl 0x1a4(%rdi),%eax root@x1:~# perf config annotate.disassemblers=objdump,capstone root@x1:~# perf config annotate.disassemblers annotate.disassemblers=objdump,capstone root@x1:~# cat ~/.perfconfig # this file is auto-generated. [annotate] disassemblers = objdump,capstone root@x1:~# perf annotate -v --stdio2 update_load_avg Executing: objdump --start-address=0xffffffff81148fe0 \ --stop-address=0xffffffff811497aa \ -d --no-show-raw-insn -S -C "$1" Disassembled with objdump annotate.disassemblers=objdump,capstone Samples: 66 of event 'cpu_atom/cycles/P', 10000 Hz, Event count (approx.): 5185444, [percent: local period] update_load_avg() /usr/lib/debug/lib/modules/6.11.4-201.fc40.x86_64/vmlinux Percent Disassembly of section .text: ffffffff81148fe0 : #define DO_ATTACH 0x4 ffffffff81148fe0 : #define DO_ATTACH 0x4 #define DO_DETACH 0x8 /* Update task and its cfs_rq load average */ static inline void update_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags) { 1.61 push %r15 push %r14 1.00 push %r13 mov %edx,%r13d 1.90 push %r12 push %rbp mov %rsi,%rbp push %rbx mov %rdi,%rbx sub $0x18,%rsp } /* rq->task_clock normalized against any time this cfs_rq has spent throttled */ static inline u64 cfs_rq_clock_pelt(struct cfs_rq *cfs_rq) { if (unlikely(cfs_rq->throttle_count)) 15.14 mov 0x1a4(%rdi),%eax root@x1:~# After adding a way to select the disassembler from the command line a 'perf test' comparing the output of the various diassemblers should be introduced, to test these codebases. Acked-by: Ian Rogers Cc: Adrian Hunter Cc: Athira Rajeev Cc: Jiri Olsa Cc: Kan Liang Cc: Namhyung Kim Cc: Steinar H. Gunderson Link: https://lore.kernel.org/r/20241111151734.1018476-4-acme@kernel.org Signed-off-by: Arnaldo Carvalho de Melo

perf disasm: Define stubs for the LLVM and capstone disassemblers

2024-11-13T19:20:32Z

This reduces the number of ifdefs in the main symbol__disassemble() method and paves the way for allowing the user to configure the disassemblers of preference. Acked-by: Ian Rogers Cc: Adrian Hunter Cc: Aditya Bodkhe Cc: Athira Rajeev Cc: Jiri Olsa Cc: Kan Liang Cc: Masami Hiramatsu (Google) Cc: Namhyung Kim Cc: Steinar H. Gunderson Link: https://lore.kernel.org/r/20241111151734.1018476-3-acme@kernel.org [ Applied fixes from Masami Hiramatsu and Aditya Bodkhe for when capstone devel files are not available ] Link: https://lore.kernel.org/r/B78FB6DF-24E9-4A3C-91C9-535765EC0E2A@ibm.com Link: https://lore.kernel.org/r/173145729034.2747044.453926054000880254.stgit@mhiramat.roam.corp.google.com Signed-off-by: Arnaldo Carvalho de Melo

perf disasm: Introduce symbol__disassemble_objdump()

2024-11-11T17:26:37Z

With the first disassemble method in perf, the parsing of objdump output, just like we have for llvm and capstone. This paves the way to allow the user to specify what disassemblers are preferred and to also to at some point allow building without the objdump method. Acked-by: Ian Rogers Cc: Adrian Hunter Cc: Athira Rajeev Cc: Jiri Olsa Cc: Kan Liang Cc: Namhyung Kim Cc: Steinar H. Gunderson Link: https://lore.kernel.org/r/20241111151734.1018476-2-acme@kernel.org Signed-off-by: Arnaldo Carvalho de Melo