perf trace: Preallocate the syscall table
authorArnaldo Carvalho de Melo <acme@redhat.com>
Thu, 18 Jul 2019 23:19:30 +0000 (20:19 -0300)
committerArnaldo Carvalho de Melo <acme@redhat.com>
Mon, 29 Jul 2019 21:34:42 +0000 (18:34 -0300)
commit30a910d7d3e04dd920e4ca3e8dcabf10c67fb03e
treeff1f7977fd926a335a426703e892077d79d850ed
parentb8b1033fcaa091d82289698d7179e84e28cbd92a
perf trace: Preallocate the syscall table

We'll continue reading its details from tracefs as we need it, but
preallocate the whole thing otherwise we may realloc and end up with
pointers to the previous buffer.

I.e. in an upcoming algorithm we'll look for syscalls that have function
signatures that are similar to a given syscall to see if we can reuse
its BPF augmenter, so we may be at syscall 42, having a 'struct syscall'
pointing to that slot in trace->syscalls.table[] and try to read the
slot for an yet unread syscall, which would realloc that table to read
the info for syscall 43, say, which would trigger a realoc of
trace->syscalls.table[], and then the pointer we had for syscall 42
would be pointing to the previous block of memory. b00m.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Brendan Gregg <brendan.d.gregg@gmail.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-m3cjzzifibs13imafhkk77a0@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
tools/perf/builtin-trace.c
tools/perf/util/syscalltbl.c
tools/perf/util/syscalltbl.h