lkml.org 
[lkml]   [2013]   [Nov]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH RFC 2/6] arm64: Kprobes with single stepping support
    On Wed, Nov 13, 2013 at 01:58:07PM +0000, Peter Zijlstra wrote:
    > On Mon, Nov 11, 2013 at 10:58:12AM +0000, Will Deacon wrote:
    > > Single-stepping on x86 is different to the step behaviour on arm64 afaik. On
    > > ARM, we have to manually remove the breakpoint, perform a single-step, then
    > > add the breakpoint again. If we re-enable debug exceptions in the kprobe
    > > handler, the step will complete early and we'll never step off the
    > > breakpoint.
    >
    > This is about hardware breakpoints right? Which are per-cpu? Otherwise
    > removing the breakpoint would open up a hole for another thread to slip
    > through while you're single stepping.

    Correct, but our hardware breakpoints don't have any resume feature, so they
    have to be disabled on the relevant CPU, then stepped on that same CPU
    before they can be reactivated.

    Will


    \
     
     \ /
      Last update: 2013-11-13 15:41    [W:3.618 / U:0.004 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site