kernel/linux.git/include/linux/trace_events.h, branch v6.12.80

tracing: Wake up poll waiters for hist files when removing an event

2026-03-04T12:21:59+00:00

[ Upstream commit 9678e53179aa7e907360f5b5b275769008a69b80 ] The event_hist_poll() function attempts to verify whether an event file is being removed, but this check may not occur or could be unnecessarily delayed. This happens because hist_poll_wakeup() is currently invoked only from event_hist_trigger() when a hist command is triggered. If the event file is being removed, no associated hist command will be triggered and a waiter will be woken up only after an unrelated hist command is triggered. Fix the issue by adding a call to hist_poll_wakeup() in remove_event_file_dir() after setting the EVENT_FILE_FL_FREED flag. This ensures that a task polling on a hist file is woken up and receives EPOLLERR. Cc: stable@vger.kernel.org Cc: Mathieu Desnoyers Cc: Tom Zanussi Acked-by: Masami Hiramatsu (Google) Link: https://patch.msgid.link/20260219162737.314231-3-petr.pavlu@suse.com Fixes: 1bd13edbbed6 ("tracing/hist: Add poll(POLLIN) support on hist file") Signed-off-by: Petr Pavlu Signed-off-by: Steven Rostedt (Google) Signed-off-by: Sasha Levin

tracing/hist: Add poll(POLLIN) support on hist file

2025-04-10T12:39:35+00:00

[ Upstream commit 1bd13edbbed6e7e396f1aab92b224a4775218e68 ] Add poll syscall support on the `hist` file. The Waiter will be waken up when the histogram is updated with POLLIN. Currently, there is no way to wait for a specific event in userspace. So user needs to peek the `trace` periodicaly, or wait on `trace_pipe`. But it is not a good idea to peek at the `trace` for an event that randomly happens. And `trace_pipe` is not coming back until a page is filled with events. This allows a user to wait for a specific event on the `hist` file. User can set a histogram trigger on the event which they want to monitor and poll() on its `hist` file. Since this poll() returns POLLIN, the next poll() will return soon unless a read() happens on that hist file. NOTE: To read the hist file again, you must set the file offset to 0, but just for monitoring the event, you may not need to read the histogram. Cc: Shuah Khan Cc: Mathieu Desnoyers Link: https://lore.kernel.org/173527247756.464571.14236296701625509931.stgit@devnote2 Signed-off-by: Masami Hiramatsu (Google) Reviewed-by: Tom Zanussi Signed-off-by: Steven Rostedt (Google) Stable-dep-of: 0b4ffbe4888a ("tracing: Correct the refcount if the hist/hist_debug file fails to open") Signed-off-by: Sasha Levin

tracing: Constify string literal data member in struct trace_event_call

2025-01-02T09:34:21+00:00

commit 452f4b31e3f70a52b97890888eeb9eaa9a87139a upstream. The name member of the struct trace_event_call is assigned with generated string literals; declare them pointer to read-only. Reported by clang: security/landlock/syscalls.c:179:1: warning: initializing 'char *' with an expression of type 'const char[34]' discards qualifiers [-Wincompatible-pointer-types-discards-qualifiers] 179 | SYSCALL_DEFINE3(landlock_create_ruleset, | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 180 | const struct landlock_ruleset_attr __user *const, attr, | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 181 | const size_t, size, const __u32, flags) | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ./include/linux/syscalls.h:226:36: note: expanded from macro 'SYSCALL_DEFINE3' 226 | #define SYSCALL_DEFINE3(name, ...) SYSCALL_DEFINEx(3, _##name, __VA_ARGS__) | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ./include/linux/syscalls.h:234:2: note: expanded from macro 'SYSCALL_DEFINEx' 234 | SYSCALL_METADATA(sname, x, __VA_ARGS__) \ | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ./include/linux/syscalls.h:184:2: note: expanded from macro 'SYSCALL_METADATA' 184 | SYSCALL_TRACE_ENTER_EVENT(sname); \ | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ./include/linux/syscalls.h:151:30: note: expanded from macro 'SYSCALL_TRACE_ENTER_EVENT' 151 | .name = "sys_enter"#sname, \ | ^~~~~~~~~~~~~~~~~ Cc: stable@vger.kernel.org Cc: Masami Hiramatsu Cc: Mathieu Desnoyers Cc: Mickaël Salaün Cc: Günther Noack Cc: Nathan Chancellor Cc: Nick Desaulniers Cc: Bill Wendling Cc: Justin Stitt Link: https://lore.kernel.org/20241125105028.42807-1-cgoettsche@seltendoof.de Fixes: b77e38aa240c3 ("tracing: add event trace infrastructure") Signed-off-by: Christian Göttsche Signed-off-by: Steven Rostedt (Google) Signed-off-by: Greg Kroah-Hartman

tracing: Check "%s" dereference via the field and not the TP_printk format

2024-12-27T13:02:16+00:00

commit afd2627f727b89496d79a6b934a025fc916d4ded upstream. The TP_printk() portion of a trace event is executed at the time a event is read from the trace. This can happen seconds, minutes, hours, days, months, years possibly later since the event was recorded. If the print format contains a dereference to a string via "%s", and that string was allocated, there's a chance that string could be freed before it is read by the trace file. To protect against such bugs, there are two functions that verify the event. The first one is test_event_printk(), which is called when the event is created. It reads the TP_printk() format as well as its arguments to make sure nothing may be dereferencing a pointer that was not copied into the ring buffer along with the event. If it is, it will trigger a WARN_ON(). For strings that use "%s", it is not so easy. The string may not reside in the ring buffer but may still be valid. Strings that are static and part of the kernel proper which will not be freed for the life of the running system, are safe to dereference. But to know if it is a pointer to a static string or to something on the heap can not be determined until the event is triggered. This brings us to the second function that tests for the bad dereferencing of strings, trace_check_vprintf(). It would walk through the printf format looking for "%s", and when it finds it, it would validate that the pointer is safe to read. If not, it would produces a WARN_ON() as well and write into the ring buffer "[UNSAFE-MEMORY]". The problem with this is how it used va_list to have vsnprintf() handle all the cases that it didn't need to check. Instead of re-implementing vsnprintf(), it would make a copy of the format up to the %s part, and call vsnprintf() with the current va_list ap variable, where the ap would then be ready to point at the string in question. For architectures that passed va_list by reference this was possible. For architectures that passed it by copy it was not. A test_can_verify() function was used to differentiate between the two, and if it wasn't possible, it would disable it. Even for architectures where this was feasible, it was a stretch to rely on such a method that is undocumented, and could cause issues later on with new optimizations of the compiler. Instead, the first function test_event_printk() was updated to look at "%s" as well. If the "%s" argument is a pointer outside the event in the ring buffer, it would find the field type of the event that is the problem and mark the structure with a new flag called "needs_test". The event itself will be marked by TRACE_EVENT_FL_TEST_STR to let it be known that this event has a field that needs to be verified before the event can be printed using the printf format. When the event fields are created from the field type structure, the fields would copy the field type's "needs_test" value. Finally, before being printed, a new function ignore_event() is called which will check if the event has the TEST_STR flag set (if not, it returns false). If the flag is set, it then iterates through the events fields looking for the ones that have the "needs_test" flag set. Then it uses the offset field from the field structure to find the pointer in the ring buffer event. It runs the tests to make sure that pointer is safe to print and if not, it triggers the WARN_ON() and also adds to the trace output that the event in question has an unsafe memory access. The ignore_event() makes the trace_check_vprintf() obsolete so it is removed. Link: https://lore.kernel.org/all/CAHk-=wh3uOnqnZPpR0PeLZZtyWbZLboZ7cHLCKRWsocvs9Y7hQ@mail.gmail.com/ Cc: stable@vger.kernel.org Cc: Masami Hiramatsu Cc: Mark Rutland Cc: Mathieu Desnoyers Cc: Andrew Morton Cc: Al Viro Cc: Linus Torvalds Link: https://lore.kernel.org/20241217024720.848621576@goodmis.org Fixes: 5013f454a352c ("tracing: Add check of trace event print fmts for dereferencing pointers") Signed-off-by: Steven Rostedt (Google) Signed-off-by: Greg Kroah-Hartman

Merge tag 'probes-fixes-v6.11-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

2024-08-09T16:43:46+00:00

Pull kprobe fixes from Masami Hiramatsu: - Fix misusing str_has_prefix() parameter order to check symbol prefix correctly - bpf: remove unused declaring of bpf_kprobe_override * tag 'probes-fixes-v6.11-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: kprobes: Fix to check symbol prefixes correctly bpf: kprobe: remove unused declaring of bpf_kprobe_override

tracing: Use refcount for trace_event_file reference counter

2024-08-07T22:12:46+00:00

Instead of using an atomic counter for the trace_event_file reference counter, use the refcount interface. It has various checks to make sure the reference counting is correct, and will warn if it detects an error (like refcount_inc() on '0'). Cc: Mathieu Desnoyers Link: https://lore.kernel.org/20240726144208.687cce24@rorschach.local.home Acked-by: Masami Hiramatsu (Google) Signed-off-by: Steven Rostedt (Google)

bpf: kprobe: remove unused declaring of bpf_kprobe_override

2024-08-05T05:01:21+00:00

After the commit 66665ad2f102 ("tracing/kprobe: bpf: Compare instruction pointer with original one"), "bpf_kprobe_override" is not used anywhere anymore, and we can remove it now. Link: https://lore.kernel.org/all/20240710085939.11520-1-dongml2@chinatelecom.cn/ Fixes: 66665ad2f102 ("tracing/kprobe: bpf: Compare instruction pointer with original one") Signed-off-by: Menglong Dong Acked-by: Jiri Olsa Signed-off-by: Masami Hiramatsu (Google)

Merge tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next

2024-03-27T14:52:34+00:00

Daniel Borkmann says: ==================== pull-request: bpf-next 2024-03-25 We've added 38 non-merge commits during the last 13 day(s) which contain a total of 50 files changed, 867 insertions(+), 274 deletions(-). The main changes are: 1) Add the ability to specify and retrieve BPF cookie also for raw tracepoint programs in order to ease migration from classic to raw tracepoints, from Andrii Nakryiko. 2) Allow the use of bpf_get_{ns_,}current_pid_tgid() helper for all program types and add additional BPF selftests, from Yonghong Song. 3) Several improvements to bpftool and its build, for example, enabling libbpf logs when loading pid_iter in debug mode, from Quentin Monnet. 4) Check the return code of all BPF-related set_memory_*() functions during load and bail out in case they fail, from Christophe Leroy. 5) Avoid a goto in regs_refine_cond_op() such that the verifier can be better integrated into Agni tool which doesn't support backedges yet, from Harishankar Vishwanathan. 6) Add a small BPF trie perf improvement by always inlining longest_prefix_match, from Jesper Dangaard Brouer. 7) Small BPF selftest refactor in bpf_tcp_ca.c to utilize start_server() helper instead of open-coding it, from Geliang Tang. 8) Improve test_tc_tunnel.sh BPF selftest to prevent client connect before the server bind, from Alessandro Carminati. 9) Fix BPF selftest benchmark for older glibc and use syscall(SYS_gettid) instead of gettid(), from Alan Maguire. 10) Implement a backward-compatible method for struct_ops types with additional fields which are not present in older kernels, from Kui-Feng Lee. 11) Add a small helper to check if an instruction is addr_space_cast from as(0) to as(1) and utilize it in x86-64 JIT, from Puranjay Mohan. 12) Small cleanup to remove unnecessary error check in bpf_struct_ops_map_update_elem, from Martin KaFai Lau. 13) Improvements to libbpf fd validity checks for BPF map/programs, from Mykyta Yatsenko. * tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (38 commits) selftests/bpf: Fix flaky test btf_map_in_map/lookup_update bpf: implement insn_is_cast_user() helper for JITs bpf: Avoid get_kernel_nofault() to fetch kprobe entry IP selftests/bpf: Use start_server in bpf_tcp_ca bpf: Sync uapi bpf.h to tools directory libbpf: Add new sec_def "sk_skb/verdict" selftests/bpf: Mark uprobe trigger functions with nocf_check attribute selftests/bpf: Use syscall(SYS_gettid) instead of gettid() wrapper in bench bpf-next: Avoid goto in regs_refine_cond_op() bpftool: Clean up HOST_CFLAGS, HOST_LDFLAGS for bootstrap bpftool selftests/bpf: scale benchmark counting by using per-CPU counters bpftool: Remove unnecessary source files from bootstrap version bpftool: Enable libbpf logs when loading pid_iter in debug mode selftests/bpf: add raw_tp/tp_btf BPF cookie subtests libbpf: add support for BPF cookie for raw_tp/tp_btf programs bpf: support BPF cookie in raw tracepoint (raw_tp, tp_btf) programs bpf: pass whole link instead of prog when triggering raw tracepoint bpf: flatten bpf_probe_register call chain selftests/bpf: Prevent client connect before server bind in test_tc_tunnel.sh selftests/bpf: Add a sk_msg prog bpf_get_ns_current_pid_tgid() test ... ==================== Link: https://lore.kernel.org/r/20240325233940.7154-1-daniel@iogearbox.net Signed-off-by: Jakub Kicinski

bpf: pass whole link instead of prog when triggering raw tracepoint

2024-03-20T06:05:33+00:00

Instead of passing prog as an argument to bpf_trace_runX() helpers, that are called from tracepoint triggering calls, store BPF link itself (struct bpf_raw_tp_link for raw tracepoints). This will allow to pass extra information like BPF cookie into raw tracepoint registration. Instead of replacing `struct bpf_prog *prog = __data;` with corresponding `struct bpf_raw_tp_link *link = __data;` assignment in `__bpf_trace_##call` I just passed `__data` through into underlying bpf_trace_runX() call. This works well because we implicitly cast `void *`, and it also avoids naming clashes with arguments coming from tracepoint's "proto" list. We could have run into the same problem with "prog", we just happened to not have a tracepoint that has "prog" input argument. We are less lucky with "link", as there are tracepoints using "link" argument name already. So instead of trying to avoid naming conflicts, let's just remove intermediate local variable. It doesn't hurt readibility, it's either way a bit of a maze of calls and macros, that requires careful reading. Acked-by: Stanislav Fomichev Signed-off-by: Andrii Nakryiko Message-ID: <20240319233852.1977493-3-andrii@kernel.org> Signed-off-by: Alexei Starovoitov

tracing: Use EVENT_NULL_STR macro instead of open coding "(null)"

2024-03-18T14:33:04+00:00

The TRACE_EVENT macros has some dependency if a __string() field is NULL, where it will save "(null)" as the string. This string is also used by __assign_str(). It's better to create a single macro instead of having something that will not be caught by the compiler if there is an unfortunate typo. Link: https://lore.kernel.org/linux-trace-kernel/20240222211443.106216915@goodmis.org Cc: Masami Hiramatsu Cc: Mark Rutland Cc: Andrew Morton Cc: Ville Syrjälä Cc: Rodrigo Vivi Cc: Chuck Lever Suggested-by: Mathieu Desnoyers Signed-off-by: Steven Rostedt (Google)