Messages in this thread | | | Subject | Re: [PATCH v2]: perf/x86: store user space frame-pointer value on a sample | From | Alexey Budankov <> | Date | Thu, 24 May 2018 17:37:05 +0300 |
| |
Hi,
On 23.05.2018 16:09, Peter Zijlstra wrote: > On Wed, May 23, 2018 at 01:06:58PM +0300, Alexey Budankov wrote: > >> Is the patch ready to be up streamed now? > > Please post a new one where you modify the comment about the syscalls > not saving registers and ideally find the commit that made it so.
Sent v3 with adjusted comment. As far comments become outdated quickly tried to be terse.
> > Also; I think Andy would appreciate a comment near the syscall code that > refers back to this code and states what registers we rely upon being > there (+BP for this patch).
Not sure if I can find all proper places to put comments there. However there is PUSH_AND_CLEAR_REGS macro that is employed at system call implementation so it is possible to put something like this there:
.macro PUSH_AND_CLEAR_REGS rdx=%rdx rax=%rax save_ret=0 /* ... * perf/core subsystem relies on bp register value stored * at pt_regs->bp; see arch/x86/kernel/perf_regs.c: perf_get_regs_user() * for more details; ... */
Thanks, Alexey > >
| |