Messages in this thread Patch in this message | | | Date | Wed, 6 Jun 2012 08:08:19 -0700 | From | tip-bot for Oleg Nesterov <> | Subject | [tip:perf/core] uprobes: Optimize is_swbp_at_addr() for current-%3Emm |
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Commit-ID: a41d60e10a611f0addf2741e2d56c95e14bd5ee0 Gitweb: http://git.kernel.org/tip/a41d60e10a611f0addf2741e2d56c95e14bd5ee0 Author: Oleg Nesterov <oleg@redhat.com> AuthorDate: Tue, 29 May 2012 21:27:44 +0200 Committer: Ingo Molnar <mingo@kernel.org> CommitDate: Wed, 6 Jun 2012 11:30:54 +0200
uprobes: Optimize is_swbp_at_addr() for current-%3Emm
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> --- 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;
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