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authorMarc Zyngier <marc.zyngier@arm.com>2018-05-29 13:11:13 +0100
committerCatalin Marinas <catalin.marinas@arm.com>2018-05-31 17:35:32 +0100
commit9dd9614f5476687abbff8d4b12cd08ae70d7c2ad (patch)
tree0d4b34722a54c5dd0ea6f4c65346466d212cda56 /arch/arm64/kernel
parent647d0519b53f440a55df163de21c52a8205431cc (diff)
downloadblackbird-op-linux-9dd9614f5476687abbff8d4b12cd08ae70d7c2ad.tar.gz
blackbird-op-linux-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/kernel')
-rw-r--r--arch/arm64/kernel/entry.S2
1 files changed, 2 insertions, 0 deletions
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
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