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Steven Rostedt a544d9a66b tracing: Have syscall trace events read user space string 
As of commit 654ced4a13 ("tracing: Introduce tracepoint_is_faultable()")
system call trace events allow faulting in user space memory. Have some of
the system call trace events take advantage of this.

Use the trace_user_fault_read() logic to read the user space buffer from
user space and instead of just saving the pointer to the buffer in the
system call event, also save the string that is passed in.

The syscall event has its nb_args shorten from an int to a short (where
even u8 is plenty big enough) and the freed two bytes are used for
"user_mask".  The new "user_mask" field is used to store the index of the
"args" field array that has the address to read from user space. This
value is set to 0 if the system call event does not need to read user
space for a field. This mask can be used to know if the event may fault or
not. Only one bit set in user_mask is supported at this time.

This allows the output to look like this:

 sys_access(filename: 0x7f8c55368470 "/etc/ld.so.preload", mode: 4)
 sys_execve(filename: 0x564ebcf5a6b8 "/usr/bin/emacs", argv: 0x7fff357c0300, envp: 0x564ebc4a4820)

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/20251028231147.261867956@kernel.org
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
 		2025-10-28 20:10:58 -04:00
..
events dma-mapping fixes for Linux 6.18: 2025-10-07 12:48:06 -07:00
misc NFSD: filecache: add STATX_DIOALIGN and STATX_DIO_READ_ALIGN support 2025-09-30 16:10:05 -04:00
stages tracing: Add __print_dynamic_array() helper 2024-10-30 17:24:32 +01:00
bpf_probe.h tracepoint: Have tracepoints created with DECLARE_TRACE() have _tp suffix 2025-05-14 11:19:32 -04:00
define_custom_trace.h
…
define_trace.h tracepoint: Have tracepoints created with DECLARE_TRACE() have _tp suffix 2025-05-14 11:19:32 -04:00
perf.h tracing/perf: Add might_fault check to syscall probes 2024-10-09 17:09:46 -04:00
syscall.h tracing: Have syscall trace events read user space string 2025-10-28 20:10:58 -04:00
trace_custom_events.h
…
trace_events.h tracing/ftrace: Add might_fault check to syscall probes 2024-10-09 17:09:36 -04:00