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tracing/syscalls: Fix perf syscall tracing when syscall_nr == -1

syscall_get_nr can return -1 in the case that the task is not executing
a system call.

This patch fixes perf_syscall_{enter,exit} to check that the syscall
number is valid before using it as an index into a bitmap.

Link: http://lkml.kernel.org/r/1345137254-7377-1-git-send-email-will.deacon@arm.com

Change-Id: Ib91ef74205792e974ca3dafac2816a61ad3a8c57
Cc: Jason Baron <jbaron@redhat.com>
Cc: Wade Farnsworth <wade_farnsworth@mentor.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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wildea01 authored and andi34 committed Aug 16, 2012
1 parent ab17739 commit 4fcfda76bda903bfbb8aba3c66dd4f1b78c06ec0
Showing with 4 additions and 0 deletions.
  1. +4 −0 kernel/trace/trace_syscalls.c
@@ -518,6 +518,8 @@ static void perf_syscall_enter(void *ignore, struct pt_regs *regs, long id)
int size;
syscall_nr = syscall_get_nr(current, regs);
if (syscall_nr < 0)
return;
if (!test_bit(syscall_nr, enabled_perf_enter_syscalls))
return;
@@ -592,6 +594,8 @@ static void perf_syscall_exit(void *ignore, struct pt_regs *regs, long ret)
int size;
syscall_nr = syscall_get_nr(current, regs);
if (syscall_nr < 0)
return;
if (!test_bit(syscall_nr, enabled_perf_exit_syscalls))
return;

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