Commit-ID: c00b275043adc14d668f36266b890f0c53d46640 Gitweb: http://git.kernel.org/tip/c00b275043adc14d668f36266b890f0c53d46640 Author: Oleg Nesterov <oleg@xxxxxxxxxx> AuthorDate: Tue, 29 May 2012 21:27:44 +0200 Committer: Ingo Molnar <mingo@xxxxxxxxxx> CommitDate: Wed, 6 Jun 2012 17:13:59 +0200 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@xxxxxxxxxx> Acked-by: Srikar Dronamraju <srikar@xxxxxxxxxxxxxxxxxx> Cc: Ananth N Mavinakayanahalli <ananth@xxxxxxxxxx> Cc: Anton Arapov <anton@xxxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Link: http://lkml.kernel.org/r/20120529192744.GA8057@xxxxxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> --- kernel/events/uprobes.c | 12 +++++++++++- 1 files changed, 11 insertions(+), 1 deletions(-) diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index 985be4d..d0f5ec0 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; -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html