From: D Scott Phillips <scott@os.amperecomputing.com>
To: linux-arm-kernel@lists.infradead.org
Cc: Marc Zyngier <maz@kernel.org>, Will Deacon <will@kernel.org>,
Darren Hart <darren@os.amperecomputing.com>,
patches@amperecomputing.com
Subject: [PATCH] arm64: errata: Fix exec handling in erratum 1418040 workaround
Date: Wed, 15 Dec 2021 15:02:40 -0800 [thread overview]
Message-ID: <20211215230240.604489-1-scott@os.amperecomputing.com> (raw)
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 <scott@os.amperecomputing.com>
Cc: <stable@vger.kernel.org> # 5.4.x
---
arch/arm64/include/asm/elf.h | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)
diff --git a/arch/arm64/include/asm/elf.h b/arch/arm64/include/asm/elf.h
index 97932fbf973d..463ff8f00aa7 100644
--- a/arch/arm64/include/asm/elf.h
+++ b/arch/arm64/include/asm/elf.h
@@ -160,8 +160,18 @@ 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 (this_cpu_has_cap(ARM64_WORKAROUND_1418040)) { \
+ u64 val; \
+ val = read_sysreg(cntkctl_el1); \
+ val |= ARCH_TIMER_USR_VCT_ACCESS_EN; \
+ write_sysreg(val, cntkctl_el1); \
+ } \
+ 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 +233,17 @@ 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 (this_cpu_has_cap(ARM64_WORKAROUND_1418040)) { \
+ u64 val; \
+ val = read_sysreg(cntkctl_el1); \
+ val &= ~ARCH_TIMER_USR_VCT_ACCESS_EN; \
+ write_sysreg(val, cntkctl_el1); \
+ } \
+ if (IS_ENABLED(CONFIG_ARM64_ERRATUM_1418040)) \
+ preempt_enable(); \
})
#ifdef CONFIG_COMPAT_VDSO
#define COMPAT_ARCH_DLINFO \
--
2.31.1
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next reply other threads:[~2021-12-15 23:04 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-15 23:02 D Scott Phillips [this message]
2021-12-16 9:30 ` [PATCH] arm64: errata: Fix exec handling in erratum 1418040 workaround Marc Zyngier
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