045aecdfcb
Systems which implement SME without also implementing SVE are
architecturally valid but were not initially supported by the kernel,
unfortunately we missed one issue in the ptrace code.
The SVE register setting code is shared between SVE and streaming mode
SVE. When we set full SVE register state we currently enable TIF_SVE
unconditionally, in the case where streaming SVE is being configured on a
system that supports vanilla SVE this is not an issue since we always
initialise enough state for both vector lengths but on a system which only
support SME it will result in us attempting to restore the SVE vector
length after having set streaming SVE registers.
Fix this by making the enabling of SVE conditional on setting SVE vector
state. If we set streaming SVE state and SVE was not already enabled this
will result in a SVE access trap on next use of normal SVE, this will cause
us to flush our register state but this is fine since the only way to
trigger a SVE access trap would be to exit streaming mode which will cause
the in register state to be flushed anyway.
Fixes: e12310a0d30f ("arm64/sme: Implement ptrace support for streaming mode SVE registers")
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20230803-arm64-fix-ptrace-ssve-no-sve-v1-1-49df214bfb3e@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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.