James Clark cbb0c02caf perf: arm64: Add SVE vector granule register to user regs
Dwarf based unwinding in a function that pushes SVE registers onto
the stack requires the unwinder to know the length of the SVE register
to calculate the stack offsets correctly. This was added to the Arm
specific Dwarf spec as the VG pseudo register[1].

Add the vector length at position 46 if it's requested by userspace and
SVE is supported. If it's not supported then fail to open the event.

The vector length must be on each sample because it can be changed
at runtime via a prctl or ptrace call. Also by adding it as a register
rather than a separate attribute, minimal changes will be required in an
unwinder that already indexes into the register list.

[1]: https://github.com/ARM-software/abi-aa/blob/main/aadwarf64/aadwarf64.rst

Reviewed-by: Mark Brown <broonie@kernel.org>
Signed-off-by: James Clark <james.clark@arm.com>
Link: https://lore.kernel.org/r/20220901132658.1024635-2-james.clark@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
2022-09-22 15:06:02 +01:00
2022-08-28 15:05:29 -07:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
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