[v2,0/2] perf: arm64: Kernel support for Dwarf unwinding through SVE functions

Message

James Clark May 17, 2022, 10:07 a.m. UTC

Changes since v1:

  * Add Mark's review tag
  * Clarify in docs that it's the SVE register length
  * Split patchset into kernel side and Perf tool changes

When SVE registers are pushed onto the stack the VG register is required to
unwind because the stack offsets would vary by the SVE register width at the
time when the sample was taken.

These first two patches add support for sampling the VG register to the kernel
and the docs. There is another patchset to add support to userspace perf.

A small change is also required to libunwind or libdw depending on which
unwinder is used, and these will be published later. Without these changes Perf
continues to work with both libraries, although the VG register is still not
used for unwinding. 

Thanks
James

James Clark (2):
  perf: arm64: Add SVE vector granule register to user regs
  arm64/sve: Add Perf extensions documentation

 Documentation/arm64/sve.rst             | 20 +++++++++++++++++
 arch/arm64/include/uapi/asm/perf_regs.h |  7 +++++-
 arch/arm64/kernel/perf_regs.c           | 30 +++++++++++++++++++++++--
 drivers/perf/arm_pmu.c                  |  2 +-
 4 files changed, 55 insertions(+), 4 deletions(-)

Comments

Leo Yan June 4, 2022, 2:07 a.m. UTC | #1

On Tue, May 17, 2022 at 11:07:41AM +0100, James Clark wrote:
> Changes since v1:
> 
>   * Add Mark's review tag
>   * Clarify in docs that it's the SVE register length
>   * Split patchset into kernel side and Perf tool changes
> 
> When SVE registers are pushed onto the stack the VG register is required to
> unwind because the stack offsets would vary by the SVE register width at the
> time when the sample was taken.
> 
> These first two patches add support for sampling the VG register to the kernel
> and the docs. There is another patchset to add support to userspace perf.

Hi Catalin, Will,

Since James is on vacation, just want to ping if you could pick up
this two patches?  Mark.B has given review tags for this patch set.

I did this is because there has another patch set in perf tool to
enable SVE registsers [1], which is dependent on this patch set's
merging.

Thanks,
Leo

[1] https://lore.kernel.org/lkml/[e-mail]/

Leo Yan June 4, 2022, 2:14 a.m. UTC | #2

On Sat, Jun 04, 2022 at 10:07:21AM +0800, Leo Yan wrote:
> On Tue, May 17, 2022 at 11:07:41AM +0100, James Clark wrote:
> > Changes since v1:
> > 
> >   * Add Mark's review tag
> >   * Clarify in docs that it's the SVE register length
> >   * Split patchset into kernel side and Perf tool changes
> > 
> > When SVE registers are pushed onto the stack the VG register is required to
> > unwind because the stack offsets would vary by the SVE register width at the
> > time when the sample was taken.
> > 
> > These first two patches add support for sampling the VG register to the kernel
> > and the docs. There is another patchset to add support to userspace perf.
> 
> Hi Catalin, Will,
> 
> Since James is on vacation, just want to ping if you could pick up
> this two patches?  Mark.B has given review tags for this patch set.

Sorry, or the kernel patch should be via arm tree and the document patch
via Jonathan's tree?

> I did this is because there has another patch set in perf tool to
> enable SVE registsers [1], which is dependent on this patch set's
> merging.
> 
> Thanks,
> Leo
> 
> [1] https://lore.kernel.org/lkml/[e-mail]/