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893b24181b
linux/arch/arm64
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Will Deacon 893b24181b arm64: sme: Use STR P to clear FFR context field in streaming SVE mode 
The FFR is a predicate register which can vary between 16 and 256 bits
in size depending upon the configured vector length. When saving the
SVE state in streaming SVE mode, the FFR register is inaccessible and
so commit 9f58486657 ("arm64/sve: Make access to FFR optional") simply
clears the FFR field of the in-memory context structure. Unfortunately,
it achieves this using an unconditional 8-byte store and so if the SME
vector length is anything other than 64 bytes in size we will either
fail to clear the entire field or, worse, we will corrupt memory
immediately following the structure. This has led to intermittent kfence
splats in CI [1] and can trigger kmalloc Redzone corruption messages
when running the 'fp-stress' kselftest:

 | =============================================================================
 | BUG kmalloc-1k (Not tainted): kmalloc Redzone overwritten
 | -----------------------------------------------------------------------------
 |
 | 0xffff000809bf1e22-0xffff000809bf1e27 @offset=7714. First byte 0x0 instead of 0xcc
 | Allocated in do_sme_acc+0x9c/0x220 age=2613 cpu=1 pid=531
 |  __kmalloc+0x8c/0xcc
 |  do_sme_acc+0x9c/0x220
 |  ...

Replace the 8-byte store with a store of a predicate register which has
been zero-initialised with PFALSE, ensuring that the entire field is
cleared in memory.

[1] https://lore.kernel.org/r/CA+G9fYtU7HsV0R0dp4XEH5xXHSJFw8KyDf5VQrLLfMxWfxQkag@mail.gmail.com

Cc: Mark Brown <broonie@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Naresh Kamboju <naresh.kamboju@linaro.org>
Fixes: 9f58486657 ("arm64/sve: Make access to FFR optional")
Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
Signed-off-by: Will Deacon <will@kernel.org>
Reviewed-by: Mark Brown <broonie@kernel.org>
Tested-by: Anders Roxell <anders.roxell@linaro.org>
Link: https://lore.kernel.org/r/20230628155605.22296-1-will@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2023-06-29 11:29:31 +01:00
..
boot hte: Changes for v6.4-rc1 2023-05-03 11:00:27 -07:00
configs arm64: defconfig: enable building the nvmem-reboot-mode module 2023-04-17 16:38:41 +02:00
crypto crypto: arm64/aes-neonbs - fix crash with CFI enabled 2023-03-14 17:06:44 +08:00
hyperv
include arm64: sme: Use STR P to clear FFR context field in streaming SVE mode 2023-06-29 11:29:31 +01:00
kernel Merge branch 'for-next/feat_s1pie' into for-next/core 2023-06-23 18:34:16 +01:00
kvm Merge branch 'for-next/feat_s1pie' into for-next/core 2023-06-23 18:34:16 +01:00
lib arm64: xor-neon: mark xor_arm64_neon_*() static 2023-05-25 17:44:01 +01:00
mm Merge branch 'for-next/feat_s1pie' into for-next/core 2023-06-23 18:34:16 +01:00
net bpf, arm64: Fixed a BTI error on returning to patched function 2023-04-03 17:44:03 +02:00
tools Merge branch 'for-next/feat_s1pie' into for-next/core 2023-06-23 18:34:16 +01:00
xen
Kbuild
Kconfig arm64: module: mandate MODULE_PLTS 2023-06-06 17:39:05 +01:00
Kconfig.debug
Kconfig.platforms arm64 updates for 6.3: 2023-02-21 15:27:48 -08:00
Makefile arm64 updates for 6.3: 2023-02-21 15:27:48 -08:00