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authorOleg Nesterov <oleg@redhat.com>2012-05-29 21:27:44 +0200
committerIngo Molnar <mingo@kernel.org>2012-06-06 17:13:59 +0200
commitc00b275043adc14d668f36266b890f0c53d46640 (patch)
treecdb6db30f3f0d18049079d7a014f6561e056eb06 /kernel/events
parent436d03faf6961b30e13b2d0967aea9d772d6cf44 (diff)
downloadlinux-c00b275043adc14d668f36266b890f0c53d46640.tar.bz2
uprobes: Optimize is_swbp_at_addr() for current->mm
Change is_swbp_at_addr() to try to avoid the costly read_opcode() if mm == current->mm, __copy_from_user_inatomic() should succeed in the likely case. Currently this optimization is not important, but we are going to add more is_swbp_at_addr(current->mm) callers. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Anton Arapov <anton@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/20120529192744.GA8057@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/events')
-rw-r--r--kernel/events/uprobes.c12
1 files changed, 11 insertions, 1 deletions
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 985be4d80fe8..d0f5ec0dcdea 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -333,10 +333,20 @@ static int is_swbp_at_addr(struct mm_struct *mm, unsigned long vaddr)
uprobe_opcode_t opcode;
int result;
+ if (current->mm == mm) {
+ pagefault_disable();
+ result = __copy_from_user_inatomic(&opcode, (void __user*)vaddr,
+ sizeof(opcode));
+ pagefault_enable();
+
+ if (likely(result == 0))
+ goto out;
+ }
+
result = read_opcode(mm, vaddr, &opcode);
if (result)
return result;
-
+out:
if (is_swbp_insn(&opcode))
return 1;