Re: [bug report][stable] perf probe: failed to add events

[Joseph Qi]

Hi Adrian,

On 19/2/27 20:39, Adrian Hunter wrote:
> Seems to be fixed by this:
> 
> From: Adrian Hunter <adrian.hunter@xxxxxxxxx>
> Date: Wed, 27 Feb 2019 05:35:25 +0200
> Subject: [PATCH] perf probe: Fix getting the kernel map
> 
> Since commit 4d99e4136580 ("perf machine: Workaround missing maps for x86
> PTI entry trampolines"), perf tools has been creating more than one kernel
> map, however 'perf probe' assumed there could be only one.
> 
> Fix by using machine__kernel_map() to get the main kernel map.
> 
> Signed-off-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
> Fixes: 4d99e4136580 ("perf machine: Workaround missing maps for x86 PTI entry trampolines")

Below is my investigation result before, FYI.
the first bad commit (v4.18 ~ v4.19):
d83212d5dd67 kallsyms, x86: Export addresses of PTI entry trampolines
revert this commit on 4.19.0, it works.
the first good commit again (v4.19 ~ v4.20):
bf904d2762ee x86/pti/64: Remove the SYSCALL64 entry trampoline
backported this commit as well as the related commit 98f05b5138f0 on
v4.19.24, it works.

And I've tested your fix on v4.19.24, it also works.
Tested-by: Joseph Qi <joseph.qi@xxxxxxxxxxxxxxxxx>