Re: [PATCH -tip ] [BUGFIX/URGENT] perf-probe: Do not add offset to uprobe address

[Namhyung Kim <namhyung@kernel.org>]

Hi Masami,

On Wed, 05 Feb 2014 05:18:58 +0000, Masami Hiramatsu wrote:
> Fix perf-probe not to add offset value to uprobe probe
> address when post processing.
> tevs[i].point.address is the address of symbol+offset,
> but current perf-probe adjusts the point.address by
> adding the offset. As a result, the probe address becomes
> symbol+offset+offset. This may cause unexpected
> code corruption. Urgent fix is needed.
>
> Without this fix
>   ---
>   # ./perf probe -x ./perf dso__load_vmlinux+4
>   # ./perf probe -l
>     probe_perf:dso__load_vmlinux (on 0x000000000006d2b8)
>   # nm ./perf.orig | grep dso__load_vmlinux\$
>   000000000046d0a0 T dso__load_vmlinux

Shouldn't the original symbol address be

    000000000046d2b0

?

>   ---
> You can see the given offset is 3 but the actual probed

s/3/4/ ?

Thanks,
Namhyung


> address is dso__load_vmlinux+8.
>
> With this fix
>   ---
>   # ./perf probe -x ./perf dso__load_vmlinux+4
>   # ./perf probe -l
>     probe_perf:dso__load_vmlinux (on 0x000000000006d2b4)
>   ---
> Now the problem is fixed.