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tracing: Have persistent ring buffer print syscalls normally

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The persistent ring buffer from a previous boot has to be careful printing
events as the print formats of random events can have pointers to strings
and such that are not available.

Ftrace static events (like the function tracer event) are stable and are
printed normally.

System call event formats are also stable. Allow them to be printed
normally as well:

Instead of:

  <...>-1       [005] ...1.    57.240405: sys_enter_waitid: __syscall_nr=0xf7 (247) which=0x1 (1) upid=0x499 (1177) infop=0x7ffd5294d690 (140725988939408) options=0x5 (5) ru=0x0 (0)
  <...>-1       [005] ...1.    57.240433: sys_exit_waitid: __syscall_nr=0xf7 (247) ret=0x0 (0)
  <...>-1       [005] ...1.    57.240437: sys_enter_rt_sigprocmask: __syscall_nr=0xe (14) how=0x2 (2) nset=0x7ffd5294d7c0 (140725988939712) oset=0x0 (0) sigsetsize=0x8 (8)
  <...>-1       [005] ...1.    57.240438: sys_exit_rt_sigprocmask: __syscall_nr=0xe (14) ret=0x0 (0)
  <...>-1       [005] ...1.    57.240442: sys_enter_close: __syscall_nr=0x3 (3) fd=0x4 (4)
  <...>-1       [005] ...1.    57.240463: sys_exit_close: __syscall_nr=0x3 (3) ret=0x0 (0)
  <...>-1       [005] ...1.    57.240485: sys_enter_openat: __syscall_nr=0x101 (257) dfd=0xffffffffffdfff9c (-2097252) filename=(0xffff8b81639ca01c) flags=0x80000 (524288) mode=0x0 (0) __filename_val=/run/systemd/reboot-param
  <...>-1       [005] ...1.    57.240555: sys_exit_openat: __syscall_nr=0x101 (257) ret=0xffffffffffdffffe (-2097154)
  <...>-1       [005] ...1.    57.240571: sys_enter_openat: __syscall_nr=0x101 (257) dfd=0xffffffffffdfff9c (-2097252) filename=(0xffff8b81639ca01c) flags=0x80000 (524288) mode=0x0 (0) __filename_val=/run/systemd/reboot-param
  <...>-1       [005] ...1.    57.240620: sys_exit_openat: __syscall_nr=0x101 (257) ret=0xffffffffffdffffe (-2097154)
  <...>-1       [005] ...1.    57.240629: sys_enter_writev: __syscall_nr=0x14 (20) fd=0x3 (3) vec=0x7ffd5294ce50 (140725988937296) vlen=0x7 (7)
  <...>-1       [005] ...1.    57.242281: sys_exit_writev: __syscall_nr=0x14 (20) ret=0x24 (36)
  <...>-1       [005] ...1.    57.242286: sys_enter_reboot: __syscall_nr=0xa9 (169) magic1=0xfee1dead (4276215469) magic2=0x28121969 (672274793) cmd=0x1234567 (19088743) arg=0x0 (0)

Have:

  <...>-1       [000] ...1.    91.446011: sys_waitid(which: 1, upid: 0x4d2, infop: 0x7ffdccdadfd0, options: 5, ru: 0)
  <...>-1       [000] ...1.    91.446042: sys_waitid -> 0x0
  <...>-1       [000] ...1.    91.446045: sys_rt_sigprocmask(how: 2, nset: 0x7ffdccdae100, oset: 0, sigsetsize: 8)
  <...>-1       [000] ...1.    91.446047: sys_rt_sigprocmask -> 0x0
  <...>-1       [000] ...1.    91.446051: sys_close(fd: 4)
  <...>-1       [000] ...1.    91.446073: sys_close -> 0x0
  <...>-1       [000] ...1.    91.446095: sys_openat(dfd: 18446744073709551516, filename: 139732544945794 "/run/systemd/reboot-param", flags: O_RDONLY|O_CLOEXEC)
  <...>-1       [000] ...1.    91.446165: sys_openat -> 0xfffffffffffffffe
  <...>-1       [000] ...1.    91.446182: sys_openat(dfd: 18446744073709551516, filename: 139732544945794 "/run/systemd/reboot-param", flags: O_RDONLY|O_CLOEXEC)
  <...>-1       [000] ...1.    91.446233: sys_openat -> 0xfffffffffffffffe
  <...>-1       [000] ...1.    91.446242: sys_writev(fd: 3, vec: 0x7ffdccdad790, vlen: 7)
  <...>-1       [000] ...1.    91.447877: sys_writev -> 0x24
  <...>-1       [000] ...1.    91.447883: sys_reboot(magic1: 0xfee1dead, magic2: 0x28121969, cmd: 0x1234567, arg: 0)

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: Peter Zijlstra <peterz@infradead.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Takaya Saeki <takayas@google.com>
Cc: Tom Zanussi <zanussi@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ian Rogers <irogers@google.com>
Cc: Douglas Raillard <douglas.raillard@arm.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Link: https://lore.kernel.org/20251028231149.097404581@kernel.org
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt 2025-10-28 19:11:27 -04:00 committed by Steven Rostedt (Google)
parent b6e5d971fc
commit 25bd47a592
1 changed files with 23 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

27
kernel/trace/trace.c
View File

@ -20,6 +20,7 @@
#include <linux/security.h>
#include <linux/seq_file.h>
#include <linux/irqflags.h>
#include <linux/syscalls.h>
#include <linux/debugfs.h>
#include <linux/tracefs.h>
#include <linux/pagemap.h>
@ -4219,6 +4220,22 @@ static void test_cpu_buff_start(struct trace_iterator *iter)
iter->cpu);
}
#ifdef CONFIG_FTRACE_SYSCALLS
static bool is_syscall_event(struct trace_event *event)
{
return (event->funcs == &enter_syscall_print_funcs) ||
(event->funcs == &exit_syscall_print_funcs);
}
#define syscall_buf_size CONFIG_TRACE_SYSCALL_BUF_SIZE_DEFAULT
#else
static inline bool is_syscall_event(struct trace_event *event)
{
return false;
}
#define syscall_buf_size 0
#endif /* CONFIG_FTRACE_SYSCALLS */
static enum print_line_t print_trace_fmt(struct trace_iterator *iter)
{
struct trace_array *tr = iter->tr;
@ -4251,10 +4268,12 @@ static enum print_line_t print_trace_fmt(struct trace_iterator *iter)
* safe to use if the array has delta offsets
* Force printing via the fields.
*/
if ((tr->text_delta) &&
event->type > __TRACE_LAST_TYPE)
if ((tr->text_delta)) {
/* ftrace and system call events are still OK */
if ((event->type > __TRACE_LAST_TYPE) &&
!is_syscall_event(event))
return print_event_fields(iter, event);
}
return event->funcs->trace(iter, sym_flags, event);
}
@ -11436,7 +11455,7 @@ __init static int tracer_alloc_buffers(void)
global_trace.flags = TRACE_ARRAY_FL_GLOBAL;
global_trace.syscall_buf_sz = CONFIG_TRACE_SYSCALL_BUF_SIZE_DEFAULT;
global_trace.syscall_buf_sz = syscall_buf_size;
INIT_LIST_HEAD(&global_trace.systems);
INIT_LIST_HEAD(&global_trace.events);