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perf trace: Forward error codes when trying to read syscall info
authorArnaldo Carvalho de Melo <acme@redhat.com>
Wed, 17 Jul 2019 22:53:51 +0000 (19:53 -0300)
committerArnaldo Carvalho de Melo <acme@redhat.com>
Mon, 29 Jul 2019 21:34:42 +0000 (18:34 -0300)
commit5d2bd88975117062766a48b5f36ce31d2c1a8269
treea4d45c0fd2cebaa3b153c9b5dbfe05637ee13a97
parentcfa9ac73d6f9790f569959a729cbc9d52bff4270
perf trace: Forward error codes when trying to read syscall info

We iterate thru the syscall table produced from the kernel syscall
tables reading info, propagate the error and add to the debug message.

This helps in fixing further bugs, such as failing to read the
"sendfile" syscall info when it really should try the aliasm
"sendfile64".

  Problems reading syscall 40: 2 (No such file or directory)(sendfile) information

  # grep sendfile /tmp/build/perf/arch/x86/include/generated/asm/syscalls_64.c
[40] = "sendfile",
  #

I.e. in the tracefs format file for the syscall tracepoints we have it
as sendfile64:

  # find /sys -type f -name format | grep sendfile
  /sys/kernel/debug/tracing/events/syscalls/sys_enter_sendfile64/format
  /sys/kernel/debug/tracing/events/syscalls/sys_exit_sendfile64/format
  #

But as "sendfile" in the file used to build the syscall table used in
perf:

  $ grep sendfile arch/x86/entry/syscalls/syscall_64.tbl
  40 common sendfile __x64_sys_sendfile64
  $

So we need to add, in followup patches, aliases in 'perf trace' syscall
data structures to cope with thie.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Luis Cláudio Gonçalves <lclaudio@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-w3eluap63x9je0bb8o3t79tz@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
tools/perf/builtin-trace.c