Pull tracing updates from Steven Rostedt: - Cleanup with guard() and free() helpers There were several places in the code that had a lot of "goto out" in the error paths to either unlock a lock or free some memory that was allocated. But this is error prone. Convert the code over to use the guard() and free() helpers that let the compiler unlock locks or free memory when the function exits. - Update the Rust tracepoint code to use the C code too There was some duplication of the tracepoint code for Rust that did the same logic as the C code. Add a helper that makes it possible for both algorithms to use the same logic in one place. - Add poll to trace event hist files It is useful to know when an event is triggered, or even with some filtering. Since hist files of events get updated when active and the event is triggered, allow applications to poll the hist file and wake up when an event is triggered. This will let the application know that the event it is waiting for happened. - Add :mod: command to enable events for current or future modules The function tracer already has a way to enable functions to be traced in modules by writing ":mod:<module>" into set_ftrace_filter. That will enable either all the functions for the module if it is loaded, or if it is not, it will cache that command, and when the module is loaded that matches <module>, its functions will be enabled. This also allows init functions to be traced. But currently events do not have that feature. Add the command where if ':mod:<module>' is written into set_event, then either all the modules events are enabled if it is loaded, or cache it so that the module's events are enabled when it is loaded. This also works from the kernel command line, where "trace_event=:mod:<module>", when the module is loaded at boot up, its events will be enabled then. * tag 'trace-v6.14-3' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (26 commits) tracing: Fix output of set_event for some cached module events tracing: Fix allocation of printing set_event file content tracing: Rename update_cache() to update_mod_cache() tracing: Fix #if CONFIG_MODULES to #ifdef CONFIG_MODULES selftests/ftrace: Add test that tests event :mod: commands tracing: Cache ":mod:" events for modules not loaded yet tracing: Add :mod: command to enabled module events selftests/tracing: Add hist poll() support test tracing/hist: Support POLLPRI event for poll on histogram tracing/hist: Add poll(POLLIN) support on hist file tracing: Fix using ret variable in tracing_set_tracer() tracepoint: Reduce duplication of __DO_TRACE_CALL tracing/string: Create and use __free(argv_free) in trace_dynevent.c tracing: Switch trace_stat.c code over to use guard() tracing: Switch trace_stack.c code over to use guard() tracing: Switch trace_osnoise.c code over to use guard() and __free() tracing: Switch trace_events_synth.c code over to use guard() tracing: Switch trace_events_filter.c code over to use guard() tracing: Switch trace_events_trigger.c code over to use guard() tracing: Switch trace_events_hist.c code over to use guard() ...
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 <shuah@kernel.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Link: https://lore.kernel.org/173527247756.464571.14236296701625509931.stgit@devnote2 Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> Reviewed-by: Tom Zanussi <zanussi@kernel.org> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
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 <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Mickaël Salaün <mic@digikod.net>
Cc: Günther Noack <gnoack@google.com>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Bill Wendling <morbo@google.com>
Cc: Justin Stitt <justinstitt@google.com>
Link: https://lore.kernel.org/20241125105028.42807-1-cgoettsche@seltendoof.de
Fixes: b77e38aa240c3 ("tracing: add event trace infrastructure")
Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
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 <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
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) <rostedt@goodmis.org>
The scheduler added NEED_RESCHED_LAZY scheduling. Record this state as part of trace flags and expose it in the need_resched field. Record and expose NEED_RESCHED_LAZY. [bigeasy: Commit description, documentation bits.] Cc: Peter Zijlstra <peterz@infradead.org> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Link: https://lore.kernel.org/20241122202849.7DfYpJR0@linutronix.de Reviewed-by: Ankur Arora <ankur.a.arora@oracle.com> Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
It was possible to enable tracing with no IRQ tracing support. The
tracing infrastructure would then record TRACE_FLAG_IRQS_NOSUPPORT as
the only tracing flag and show an 'X' in the output.
The last user of this feature was PPC32 which managed to implement it
during PowerPC merge in 2009. Since then, it was unused and the PPC32
dependency was finally removed in commit 0ea5ee035133a ("tracing: Remove
PPC32 wart from config TRACING_SUPPORT").
Since the PowerPC merge the code behind !CONFIG_TRACE_IRQFLAGS_SUPPORT
with TRACING enabled can no longer be selected used and the 'X' is not
displayed or recorded.
Remove the CONFIG_TRACE_IRQFLAGS_SUPPORT from the tracing code. Remove
TRACE_FLAG_IRQS_NOSUPPORT.
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/20241022110112.XJI8I9T2@linutronix.de
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
After commit dcb0b5575d24 ("tracing: Remove TRACE_EVENT_FL_USE_CALL_FILTER
logic"), no one's going to set the TRACE_EVENT_FL_FILTERED or change the
call->filter, so remove related logic.
Link: https://lore.kernel.org/20240911010026.2302849-1-zhengyejian@huaweicloud.com
Signed-off-by: Zheng Yejian <zhengyejian@huaweicloud.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
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
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 <mathieu.desnoyers@efficios.com> Link: https://lore.kernel.org/20240726144208.687cce24@rorschach.local.home Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
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 <dongml2@chinatelecom.cn>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>