[PATCH v3] arm64: errata: Fix exec handling in erratum 1418040 workaround
From: D Scott Phillips <hidden>
Date: 2021-12-16 20:50:09
Subsystem:
arm64 port (aarch64 architecture), the rest · Maintainers:
Catalin Marinas, Will Deacon, Linus Torvalds
The erratum 1418040 workaround changes vct access trapping when switching
between compat and non-compat threads. The workaround logic assumes that
the hardware vct trapping state matches the previous task's compat-ness.
However, when a non-compat task execs a compat binary or vice versa, the
cntkctl state and task compat-ness get out of sync. Keep the hardware
trapping state in sync with the task personality.
Fixes: d49f7d7376d0 ("arm64: Move handling of erratum 1418040 into C code")
Signed-off-by: D Scott Phillips <redacted>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Cc: <redacted> # 5.4.x
---
v3: - Un-nest conditionals (Marc)
v2: - Use sysreg_clear_set instead of open coding (Marc)
- guard this_cpu_has_cap() check under IS_ENABLED() to avoid tons of
WARN_ON(preemptible()) when built with !CONFIG_ARM64_ERRATUM_1418040
arch/arm64/include/asm/elf.h | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)
diff --git a/arch/arm64/include/asm/elf.h b/arch/arm64/include/asm/elf.h
index 97932fbf973d..77b2e85b3e8d 100644
--- a/arch/arm64/include/asm/elf.h
+++ b/arch/arm64/include/asm/elf.h@@ -160,8 +160,19 @@ typedef struct user_fpsimd_state elf_fpregset_t; #define SET_PERSONALITY(ex) \ ({ \ + if (IS_ENABLED(CONFIG_ARM64_ERRATUM_1418040)) \ + preempt_disable(); \ + \ clear_thread_flag(TIF_32BIT); \ current->personality &= ~READ_IMPLIES_EXEC; \ + \ + if (IS_ENABLED(CONFIG_ARM64_ERRATUM_1418040) && \ + this_cpu_has_cap(ARM64_WORKAROUND_1418040)) \ + sysreg_clear_set(cntkctl_el1, 0, \ + ARCH_TIMER_USR_VCT_ACCESS_EN); \ + \ + if (IS_ENABLED(CONFIG_ARM64_ERRATUM_1418040)) \ + preempt_enable(); \ }) /* update AT_VECTOR_SIZE_ARCH if the number of NEW_AUX_ENT entries changes */
@@ -223,7 +234,18 @@ int compat_elf_check_arch(const struct elf32_hdr *); */ #define COMPAT_SET_PERSONALITY(ex) \ ({ \ + if (IS_ENABLED(CONFIG_ARM64_ERRATUM_1418040)) \ + preempt_disable(); \ + \ set_thread_flag(TIF_32BIT); \ + \ + if (IS_ENABLED(CONFIG_ARM64_ERRATUM_1418040) && \ + this_cpu_has_cap(ARM64_WORKAROUND_1418040)) \ + sysreg_clear_set(cntkctl_el1, \ + ARCH_TIMER_USR_VCT_ACCESS_EN, 0); \ + \ + if (IS_ENABLED(CONFIG_ARM64_ERRATUM_1418040)) \ + preempt_enable(); \ }) #ifdef CONFIG_COMPAT_VDSO #define COMPAT_ARCH_DLINFO \
--
2.31.1
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