linux/tools/lib, branch v6.17

perf subcmd: avoid crash in exclude_cmds when excludes is empty

2025-09-13T00:51:35Z

When cross-compiling the perf tool for ARM64, `perf help` may crash with the following assertion failure: help.c:122: exclude_cmds: Assertion `cmds->names[ci] == NULL' failed. This happens when the perf binary is not named exactly "perf" or when multiple "perf-*" binaries exist in the same directory. In such cases, the `excludes` command list can be empty, which leads to the final assertion in exclude_cmds() being triggered. Add a simple guard at the beginning of exclude_cmds() to return early if excludes->cnt is zero, preventing the crash. Signed-off-by: hupu Reported-by: Guilherme Amadio Reviewed-by: Namhyung Kim Link: https://lore.kernel.org/r/20250909094953.106706-1-amadio@gentoo.org Signed-off-by: Namhyung Kim

libbpf: Add the ability to suppress perf event enablement

2025-08-07T16:01:41Z

Automatically enabling a perf event after attaching a BPF prog to it is not always desirable. Add a new "dont_enable" field to struct bpf_perf_event_opts. While introducing "enable" instead would be nicer in that it would avoid a double negation in the implementation, it would make DECLARE_LIBBPF_OPTS() less efficient. Acked-by: Eduard Zingerman Suggested-by: Jiri Olsa Tested-by: Thomas Richter Co-developed-by: Thomas Richter Signed-off-by: Thomas Richter Signed-off-by: Ilya Leoshkevich Link: https://lore.kernel.org/r/20250806162417.19666-2-iii@linux.ibm.com Signed-off-by: Alexei Starovoitov

Merge tag 'bpf-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf

2025-08-02T00:13:26Z

Pull bpf fixes from Alexei Starovoitov: - Fix kCFI failures in JITed BPF code on arm64 (Sami Tolvanen, Puranjay Mohan, Mark Rutland, Maxwell Bland) - Disallow tail calls between BPF programs that use different cgroup local storage maps to prevent out-of-bounds access (Daniel Borkmann) - Fix unaligned access in flow_dissector and netfilter BPF programs (Paul Chaignon) - Avoid possible use of uninitialized mod_len in libbpf (Achill Gilgenast) * tag 'bpf-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf: selftests/bpf: Test for unaligned flow_dissector ctx access bpf: Improve ctx access verifier error message bpf: Check netfilter ctx accesses are aligned bpf: Check flow_dissector ctx accesses are aligned arm64/cfi,bpf: Support kCFI + BPF on arm64 cfi: Move BPF CFI types and helpers to generic code cfi: add C CFI type macro libbpf: Avoid possible use of uninitialized mod_len bpf: Fix oob access in cgroup local storage bpf: Move cgroup iterator helpers to bpf.h bpf: Move bpf map owner out of common struct bpf: Add cookie object to bpf maps

Merge tag 'perf-tools-for-v6.17-2025-08-01' of git://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools

2025-08-01T23:55:47Z

Pull perf tools updates from Namhyung Kim: "Build-ID processing goodies: Build-IDs are content based hashes to link regions of memory to ELF files in post processing. They have been available in distros for quite a while: $ file /bin/bash /bin/bash: ELF 64-bit LSB pie executable, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, BuildID[sha1]=707a1c670cd72f8e55ffedfbe94ea98901b7ce3a, for GNU/Linux 3.2.0, stripped It is possible to ask the kernel to get it from mmap executable backing storage at time they are being put in place and send it as metadata at that moment to have in perf.data. Prefer that across the board to speed up 'record' time - it post processes the samples to find binaries touched by any samples and to save them with build-ID. It can skip reading build-ID in userspace if it comes from the kernel. perf record: * Make --buildid-mmap default. The kernel can generate MMAP2 events with a build-ID from ELF header. Use that by default instead of using inode and device ID to identify binaries. It also can be disabled with --no-buildid-mmap. * Use BPF for -u/--uid option to sample processes belong to a user. BPF can track user processes more accurately and the existing logic often fails to get the list of processes due to race with reading the /proc filesystem. * Generate PERF_RECORD_BPF_METADATA when it profiles BPF programs and they have variables starting with "bpf_metadata_". This will help to identify BPF objects used in the profile. This has been supported in bpftool for some time and allows the recording of metadata such as commit hashes, versions, etc, that now gets recorded in perf.data as well. * Collect list of DSOs touched in the sample callchains as well as in the sample itself. This would increase the processing time at the end of record, but can improve the data quality. perf stat: * Add a new 'drm' pseudo-PMU support like in 'hwmon'. It can collect DRM usage stats using fdinfo in /proc. On my Intel laptop, it shows like below: $ perf list drm ... drm: drm-active-stolen-system0 [Total memory active in one or more engines. Unit: drm_i915] drm-active-system0 [Total memory active in one or more engines. Unit: drm_i915] drm-engine-capacity-video [Engine capacity. Unit: drm_i915] drm-engine-copy [Utilization in ns. Unit: drm_i915] drm-engine-render [Utilization in ns. Unit: drm_i915] drm-engine-video [Utilization in ns. Unit: drm_i915] ... $ sudo perf stat -a -e drm-engine-render,drm-engine-video,drm-engine-capacity-video sleep 1 Performance counter stats for 'system wide': 48,137,316,988,873 ns drm-engine-render 34,452,696,746 ns drm-engine-video 20 capacity drm-engine-capacity-video 1.002086194 seconds time elapsed perf list * Add description for software events. The description is in JSON format and the event parser now can handle the software events like others (for example, it's case-insensitive and subject to wildcard matching). $ perf list software List of pre-defined events (to be used in -e or -M): software: alignment-faults [Number of kernel handled memory alignment faults. Unit: software] bpf-output [An event used by BPF programs to write to the perf ring buffer. Unit: software] cgroup-switches [Number of context switches to a task in a different cgroup. Unit: software] context-switches [Number of context switches [This event is an alias of cs]. Unit: software] cpu-clock [Per-CPU high-resolution timer based event. Unit: software] cpu-migrations [Number of times a process has migrated to a new CPU [This event is an alias of migrations]. Unit: software] cs [Number of context switches [This event is an alias of context-switches]. Unit: software] dummy [A placeholder event that doesn't count anything. Unit: software] emulation-faults [Number of kernel handled unimplemented instruction faults handled through emulation. Unit: software] faults [Number of page faults [This event is an alias of page-faults]. Unit: software] major-faults [Number of major page faults. Major faults require I/O to handle. Unit: software] migrations [Number of times a process has migrated to a new CPU [This event is an alias of cpu-migrations]. Unit: software] minor-faults [Number of minor page faults. Minor faults don't require I/O to handle. Unit: software] page-faults [Number of page faults [This event is an alias of faults]. Unit: software] task-clock [Per-task high-resolution timer based event. Unit: software] perf ftrace: * Add -e/--events option to perf ftrace latency to measure latency between the two events instead of a function. $ sudo perf ftrace latency -ab -e i915_request_wait_begin,i915_request_wait_end --hide-empty -- sleep 1 # DURATION | COUNT | GRAPH | 256 - 512 us | 4 | ###### | 2 - 4 ms | 2 | ### | 4 - 8 ms | 12 | ################### | 8 - 16 ms | 10 | ################ | # statistics (in usec) total time: 194915 avg time: 6961 max time: 12855 min time: 373 count: 28 * Add new function graph tracer options (--graph-opts) to display more info like arguments and return value. They will be passed to the kernel ftrace directly. $ sudo perf ftrace -G vfs_write --graph-opts retval,retaddr # tracer: function_graph # # CPU DURATION FUNCTION CALLS # | | | | | | | ... 5) | mutex_unlock() { /* <-rb_simple_write+0xda/0x150 */ 5) 0.188 us | local_clock(); /* <-lock_release+0x2ad/0x440 ret=0x3bf2a3cf90e */ 5) | rt_mutex_slowunlock() { /* <-rb_simple_write+0xda/0x150 */ 5) | _raw_spin_lock_irqsave() { /* <-rt_mutex_slowunlock+0x4f/0x200 */ 5) 0.123 us | preempt_count_add(); /* <-_raw_spin_lock_irqsave+0x23/0x90 ret=0x0 */ 5) 0.128 us | local_clock(); /* <-__lock_acquire.isra.0+0x17a/0x740 ret=0x3bf2a3cfc8b */ 5) 0.086 us | do_raw_spin_trylock(); /* <-_raw_spin_lock_irqsave+0x4a/0x90 ret=0x1 */ 5) 0.845 us | } /* _raw_spin_lock_irqsave ret=0x292 */ ... Misc: * Add perf archive --exclude-buildids option to skip some binaries. The format of the FILE should be same as an output of perf buildid-list. * Get rid of dependency of libcrypto. It was just to get SHA-1 hash so implement it directly like in the kernel. A side effect is that it needs -fno-strict-aliasing compiler option (again, like in the kernel). * Convert all shell script tests to use bash" * tag 'perf-tools-for-v6.17-2025-08-01' of git://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools: (179 commits) perf record: Cache build-ID of hit DSOs only perf test: Ensure lock contention using pipe mode perf python: Stop using deprecated PyUnicode_AsString() perf list: Skip ABI PMUs when printing pmu values perf list: Remove tracepoint printing code perf tp_pmu: Add event APIs perf tp_pmu: Factor existing tracepoint logic to new file perf parse-events: Remove non-json software events perf jevents: Add common software event json perf tools: Remove libtraceevent in .gitignore perf test: Fix comment ordering perf sort: Use perf_env to set arch sort keys and header perf test: Move PERF_SAMPLE_WEIGHT_STRUCT parsing to common test perf sample: Remove arch notion of sample parsing perf env: Remove global perf_env perf trace: Avoid global perf_env with evsel__env perf auxtrace: Pass perf_env from session through to mmap read perf machine: Explicitly pass in host perf_env perf bench synthesize: Avoid use of global perf_env perf top: Make perf_env locally scoped ...

libbpf: Avoid possible use of uninitialized mod_len

2025-07-31T18:39:46Z

Though mod_len is only read when mod_name != NULL and both are initialized together, gcc15 produces a warning with -Werror=maybe-uninitialized: libbpf.c: In function 'find_kernel_btf_id.constprop': libbpf.c:10100:33: error: 'mod_len' may be used uninitialized [-Werror=maybe-uninitialized] 10100 | if (mod_name && strncmp(mod->name, mod_name, mod_len) != 0) | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ libbpf.c:10070:21: note: 'mod_len' was declared here 10070 | int ret, i, mod_len; | ^~~~~~~ Silence the false positive. Signed-off-by: Achill Gilgenast Acked-by: Yonghong Song Acked-by: Eduard Zingerman Link: https://lore.kernel.org/r/20250729094611.2065713-1-fossdd@pwned.life Signed-off-by: Alexei Starovoitov

perf parse-events: Support user CPUs mixed with threads/processes

2025-07-24T20:41:35Z

Counting events system-wide with a specified CPU prior to this change worked: ``` $ perf stat -e 'msr/tsc/,msr/tsc,cpu=cpu_core/,msr/tsc,cpu=cpu_atom/' -a sleep 1 Performance counter stats for 'system wide': 59,393,419,099 msr/tsc/ 33,927,965,927 msr/tsc,cpu=cpu_core/ 25,465,608,044 msr/tsc,cpu=cpu_atom/ ``` However, when counting with process the counts became system wide: ``` $ perf stat -e 'msr/tsc/,msr/tsc,cpu=cpu_core/,msr/tsc,cpu=cpu_atom/' perf test -F 10 10.1: Basic parsing test : Ok 10.2: Parsing without PMU name : Ok 10.3: Parsing with PMU name : Ok Performance counter stats for 'perf test -F 10': 59,233,549 msr/tsc/ 59,227,556 msr/tsc,cpu=cpu_core/ 59,224,053 msr/tsc,cpu=cpu_atom/ ``` Make the handling of CPU maps with event parsing clearer. When an event is parsed creating an evsel the cpus should be either the PMU's cpumask or user specified CPUs. Update perf_evlist__propagate_maps so that it doesn't clobber the user specified CPUs. Try to make the behavior clearer, firstly fix up missing cpumasks. Next, perform sanity checks and adjustments from the global evlist CPU requests and for the PMU including simplifying to the "any CPU"(-1) value. Finally remove the event if the cpumask is empty. So that events are opened with a CPU and a thread change stat's create_perf_stat_counter to give both. With the change things are fixed: ``` $ perf stat --no-scale -e 'msr/tsc/,msr/tsc,cpu=cpu_core/,msr/tsc,cpu=cpu_atom/' perf test -F 10 10.1: Basic parsing test : Ok 10.2: Parsing without PMU name : Ok 10.3: Parsing with PMU name : Ok Performance counter stats for 'perf test -F 10': 63,704,975 msr/tsc/ 47,060,704 msr/tsc,cpu=cpu_core/ (4.62%) 16,640,591 msr/tsc,cpu=cpu_atom/ (2.18%) ``` However, note the "--no-scale" option is used. This is necessary as the running time for the event on the counter isn't the same as the enabled time because the thread doesn't necessarily run on the CPUs specified for the counter. All counter values are scaled with: scaled_value = value * time_enabled / time_running and so without --no-scale the scaled_value becomes very large. This problem already exists on hybrid systems for the same reason. Here are 2 runs of the same code with an instructions event that counts the same on both types of core, there is no real multiplexing happening on the event: ``` $ perf stat -e instructions perf test -F 10 ... Performance counter stats for 'perf test -F 10': 87,896,447 cpu_atom/instructions/ (14.37%) 98,171,964 cpu_core/instructions/ (85.63%) ... $ perf stat --no-scale -e instructions perf test -F 10 ... Performance counter stats for 'perf test -F 10': 13,069,890 cpu_atom/instructions/ (19.32%) 83,460,274 cpu_core/instructions/ (80.68%) ... ``` The scaling has inflated per-PMU instruction counts and the overall count by 2x. To fix this the kernel needs changing when a task+CPU event (or just task event on hybrid) is scheduled out. A fix could be that the state isn't inactive but off for such events, so that time_enabled counts don't accumulate on them. Reviewed-by: Thomas Falcon Signed-off-by: Ian Rogers Link: https://lore.kernel.org/r/20250719030517.1990983-13-irogers@google.com Signed-off-by: Namhyung Kim

libperf evsel: Factor perf_evsel__exit out of perf_evsel__delete

2025-07-24T20:41:35Z

This allows the perf_evsel__exit to be called when the struct perf_evsel is embedded inside another struct, such as struct evsel in perf. Reviewed-by: Thomas Falcon Signed-off-by: Ian Rogers Tested-by: James Clark Link: https://lore.kernel.org/r/20250719030517.1990983-8-irogers@google.com Signed-off-by: Namhyung Kim

libperf evsel: Rename own_cpus to pmu_cpus

2025-07-24T20:41:35Z

own_cpus is generally the cpumask from the PMU. Rename to pmu_cpus to try to make this clearer. Variable rename with no other changes. Reviewed-by: Thomas Falcon Signed-off-by: Ian Rogers Tested-by: James Clark Link: https://lore.kernel.org/r/20250719030517.1990983-7-irogers@google.com Signed-off-by: Namhyung Kim

tools subcmd: Tighten the filename size in check_if_command_finished

2025-07-23T01:17:53Z

FILENAME_MAX is often PATH_MAX (4kb), far more than needed for the /proc path. Make the buffer size sufficient for the maximum integer plus "/proc/" and "/status" with a '\0' terminator. Fixes: 5ce42b5de461 ("tools subcmd: Add non-waitpid check_if_command_finished()") Signed-off-by: Ian Rogers Link: https://lore.kernel.org/r/20250717150855.1032526-1-irogers@google.com Signed-off-by: Namhyung Kim

libbpf: Verify that arena map exists when adding arena relocations

2025-07-19T00:12:50Z

Fuzzer reported a memory access error in bpf_program__record_reloc() that happens when: - ".addr_space.1" section exists - there is a relocation referencing this section - there are no arena maps defined in BTF. Sanity checks for maps existence are already present in bpf_program__record_reloc(), hence this commit adds another one. [1] https://github.com/libbpf/libbpf/actions/runs/16375110681/job/46272998064 Signed-off-by: Eduard Zingerman Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20250718222059.281526-1-eddyz87@gmail.com