> On May 15, 2018, at 1:08 AM, Alexey Budankov > <alexey.budan...@linux.intel.com> wrote: > > > Hi Andy, > >> On 09.05.2018 17:54, Peter Zijlstra wrote: >>> On Tue, May 08, 2018 at 06:21:36PM +0300, Alexey Budankov wrote: >>> >>> Store user space frame-pointer value (BP register) into Perf trace >>> on a sample for a process so the value becomes available when >>> unwinding call stacks for functions gaining event samples. >>> >>> Signed-off-by: Alexey Budankov <alexey.budan...@linux.intel.com> >>> --- >>> arch/x86/kernel/perf_regs.c | 8 +++++++- >>> 1 file changed, 7 insertions(+), 1 deletion(-) >>> >>> diff --git a/arch/x86/kernel/perf_regs.c b/arch/x86/kernel/perf_regs.c >>> index e47b2dbbdef3..8d68658eff7f 100644 >>> --- a/arch/x86/kernel/perf_regs.c >>> +++ b/arch/x86/kernel/perf_regs.c >>> @@ -156,7 +156,13 @@ void perf_get_regs_user(struct perf_regs *regs_user, >> >> >>> * Most system calls don't save these registers, don't report them. >> >> ^^^ that worries me and is the reason for the '-1's below. However I >> think with all the PTI rework this might no longer be true. >> >> The Changelog needs to state that user_regs->bp is in fact valid and >> ideally point to the commits that makes it so. Also this patch should >> update that comment. >> >> Cc Andy who keeps better track of all that than me. > > Are there any thoughts so far? Feedback on the matter above is highly > appreciated.
Sorry, I missed this. Can you forward the original patch? I don’t have it. These days, system calls should save all registers, but I’m not entirely sure I want to promise that they’ll continue to do so forever.
