• Naveen N. Rao's avatar
    powerpc/kprobes: Fix handling of function offsets on ABIv2 · 290e3070
    Naveen N. Rao authored
    commit 239aeba7 ("perf powerpc: Fix kprobe and kretprobe handling with
    kallsyms on ppc64le") changed how we use the offset field in struct kprobe on
    ABIv2. perf now offsets from the global entry point if an offset is specified
    and otherwise chooses the local entry point.
    
    Fix the same in kernel for kprobe API users. We do this by extending
    kprobe_lookup_name() to accept an additional parameter to indicate the offset
    specified with the kprobe registration. If offset is 0, we return the local
    function entry and return the global entry point otherwise.
    
    With:
      # cd /sys/kernel/debug/tracing/
      # echo "p _do_fork" >> kprobe_events
      # echo "p _do_fork+0x10" >> kprobe_events
    
    before this patch:
      # cat ../kprobes/list
      c0000000000d0748  k  _do_fork+0x8    [DISABLED]
      c0000000000d0758  k  _do_fork+0x18    [DISABLED]
      c0000000000412b0  k  kretprobe_trampoline+0x0    [OPTIMIZED]
    
    and after:
      # cat ../kprobes/list
      c0000000000d04c8  k  _do_fork+0x8    [DISABLED]
      c0000000000d04d0  k  _do_fork+0x10    [DISABLED]
      c0000000000412b0  k  kretprobe_trampoline+0x0    [OPTIMIZED]
    Acked-by: default avatarAnanth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>
    Signed-off-by: default avatarNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
    Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
    290e3070
kprobes.c 61.7 KB