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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2024-06-09 20:11:04 +0300 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2024-06-19 22:33:38 +0300 |
| commit | 86a6a68febfcf57b5c2a7ba33e6d6f1f78ca5197 (patch) | |
| tree | 35355f828c8104b5542f8b851ba7015a1e9971f9 /arch/arm64/Kconfig | |
| parent | 6ba59ff4227927d3a8530fc2973b80e94b54d58f (diff) | |
| download | linux-86a6a68febfcf57b5c2a7ba33e6d6f1f78ca5197.tar.xz | |
arm64: start using 'asm goto' for get_user() when available
This generates noticeably better code with compilers that support it,
since we don't need to test the error register etc, the exception just
jumps to the error handling directly.
Note that this also marks SW_TTBR0_PAN incompatible with KCSAN support,
since KCSAN wants to save and restore the user access state.
KCSAN and SW_TTBR0_PAN were probably always incompatible, but it became
obvious only when implementing the unsafe user access functions. At
that point the default empty user_access_save/restore() functions
weren't provided by the default fallback functions.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/arm64/Kconfig')
| -rw-r--r-- | arch/arm64/Kconfig | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 5d91259ee7b5..b6e8920364de 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -1649,6 +1649,7 @@ config RODATA_FULL_DEFAULT_ENABLED config ARM64_SW_TTBR0_PAN bool "Emulate Privileged Access Never using TTBR0_EL1 switching" + depends on !KCSAN help Enabling this option prevents the kernel from accessing user-space memory directly by pointing TTBR0_EL1 to a reserved |