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| author |   Marc Zyngier <marc.zyngier@arm.com> | 2018-05-29 13:11:13 +0100 |
|---|---|---|
| committer |   Catalin Marinas <catalin.marinas@arm.com> | 2018-05-31 17:35:32 +0100 |
| commit | 9dd9614f5476687abbff8d4b12cd08ae70d7c2ad (patch) | |
| tree | 0d4b34722a54c5dd0ea6f4c65346466d212cda56 /arch/arm64 | |
| parent | arm64: ssbd: Restore mitigation status on CPU resume (diff) | |
| download | linux-dev-9dd9614f5476687abbff8d4b12cd08ae70d7c2ad.tar.xz linux-dev-9dd9614f5476687abbff8d4b12cd08ae70d7c2ad.zip | |
arm64: ssbd: Introduce thread flag to control userspace mitigation
In order to allow userspace to be mitigated on demand, let's
introduce a new thread flag that prevents the mitigation from
being turned off when exiting to userspace, and doesn't turn
it on on entry into the kernel (with the assumption that the
mitigation is always enabled in the kernel itself).
This will be used by a prctl interface introduced in a later
patch.
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64')
| -rw-r--r-- | arch/arm64/include/asm/thread_info.h | 1 | ||||
| -rw-r--r-- | arch/arm64/kernel/entry.S | 2 |
2 files changed, 3 insertions, 0 deletions
diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h index 740aa03c5f0d..cbcf11b5e637 100644 --- a/arch/arm64/include/asm/thread_info.h +++ b/arch/arm64/include/asm/thread_info.h @@ -94,6 +94,7 @@ void arch_release_task_struct(struct task_struct *tsk); #define TIF_32BIT 22 /* 32bit process */ #define TIF_SVE 23 /* Scalable Vector Extension in use */ #define TIF_SVE_VL_INHERIT 24 /* Inherit sve_vl_onexec across exec */ +#define TIF_SSBD 25 /* Wants SSB mitigation */ #define _TIF_SIGPENDING (1 << TIF_SIGPENDING) #define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED) diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index e6f6e2339b22..28ad8799406f 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -147,6 +147,8 @@ alternative_cb arm64_enable_wa2_handling alternative_cb_end ldr_this_cpu \tmp2, arm64_ssbd_callback_required, \tmp1 cbz \tmp2, \targ + ldr \tmp2, [tsk, #TSK_TI_FLAGS] + tbnz \tmp2, #TIF_SSBD, \targ mov w0, #ARM_SMCCC_ARCH_WORKAROUND_2 mov w1, #\state alternative_cb arm64_update_smccc_conduit |