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From: Marc Zyngier <marc.zyngier@arm.com>
To: stable@vger.kernel.org
Cc: Will Deacon <will.deacon@arm.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Christoffer Dall <christoffer.dall@arm.com>
Subject: [PATCH 03/14] arm64: Add per-cpu infrastructure to call ARCH_WORKAROUND_2
Date: Fri, 20 Jul 2018 10:47:11 +0100	[thread overview]
Message-ID: <20180720094722.702-4-marc.zyngier@arm.com> (raw)
In-Reply-To: <20180720094722.702-1-marc.zyngier@arm.com>

commit 5cf9ce6e5ea50f805c6188c04ed0daaec7b6887d upstream.

In a heterogeneous system, we can end up with both affected and
unaffected CPUs. Let's check their status before calling into the
firmware.

Reviewed-by: Julien Grall <julien.grall@arm.com>
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>
---
 arch/arm64/kernel/cpu_errata.c |  2 ++
 arch/arm64/kernel/entry.S      | 11 +++++++----
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
index d98d8ce29533..d1a7a68dc142 100644
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -233,6 +233,8 @@ enable_smccc_arch_workaround_1(const struct arm64_cpu_capabilities *entry)
 #endif	/* CONFIG_HARDEN_BRANCH_PREDICTOR */
 
 #ifdef CONFIG_ARM64_SSBD
+DEFINE_PER_CPU_READ_MOSTLY(u64, arm64_ssbd_callback_required);
+
 void __init arm64_update_smccc_conduit(struct alt_instr *alt,
 				       __le32 *origptr, __le32 *updptr,
 				       int nr_inst)
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index f33e6aed3037..29ad672a6abd 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -140,8 +140,10 @@ alternative_else_nop_endif
 
 	// This macro corrupts x0-x3. It is the caller's duty
 	// to save/restore them if required.
-	.macro	apply_ssbd, state
+	.macro	apply_ssbd, state, targ, tmp1, tmp2
 #ifdef CONFIG_ARM64_SSBD
+	ldr_this_cpu	\tmp2, arm64_ssbd_callback_required, \tmp1
+	cbz	\tmp2, \targ
 	mov	w0, #ARM_SMCCC_ARCH_WORKAROUND_2
 	mov	w1, #\state
 alternative_cb	arm64_update_smccc_conduit
@@ -176,12 +178,13 @@ alternative_cb_end
 	ldr	x19, [tsk, #TSK_TI_FLAGS]	// since we can unmask debug
 	disable_step_tsk x19, x20		// exceptions when scheduling.
 
-	apply_ssbd 1
+	apply_ssbd 1, 1f, x22, x23
 
 #ifdef CONFIG_ARM64_SSBD
 	ldp	x0, x1, [sp, #16 * 0]
 	ldp	x2, x3, [sp, #16 * 1]
 #endif
+1:
 
 	mov	x29, xzr			// fp pointed to user-space
 	.else
@@ -323,8 +326,8 @@ alternative_if ARM64_WORKAROUND_845719
 alternative_else_nop_endif
 #endif
 3:
-	apply_ssbd 0
-
+	apply_ssbd 0, 5f, x0, x1
+5:
 	.endif
 
 	msr	elr_el1, x21			// set up the return data
-- 
2.18.0

  parent reply	other threads:[~2018-07-20 10:35 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-20  9:47 [PATCH 00/14] arm64: 4.17 backport of the SSBD mitigation patches Marc Zyngier
2018-07-20  9:47 ` [PATCH 01/14] arm/arm64: smccc: Add SMCCC-specific return codes Marc Zyngier
2018-07-20  9:47 ` [PATCH 02/14] arm64: Call ARCH_WORKAROUND_2 on transitions between EL0 and EL1 Marc Zyngier
2018-07-20  9:47 ` Marc Zyngier [this message]
2018-07-20  9:47 ` [PATCH 04/14] arm64: Add ARCH_WORKAROUND_2 probing Marc Zyngier
2018-07-20  9:47 ` [PATCH 05/14] arm64: Add 'ssbd' command-line option Marc Zyngier
2018-07-20  9:47 ` [PATCH 06/14] arm64: ssbd: Add global mitigation state accessor Marc Zyngier
2018-07-20  9:47 ` [PATCH 07/14] arm64: ssbd: Skip apply_ssbd if not using dynamic mitigation Marc Zyngier
2018-07-20  9:47 ` [PATCH 08/14] arm64: ssbd: Restore mitigation status on CPU resume Marc Zyngier
2018-07-20  9:47 ` [PATCH 09/14] arm64: ssbd: Introduce thread flag to control userspace mitigation Marc Zyngier
2018-07-20  9:47 ` [PATCH 10/14] arm64: ssbd: Add prctl interface for per-thread mitigation Marc Zyngier
2018-07-20  9:47 ` [PATCH 11/14] arm64: KVM: Add HYP per-cpu accessors Marc Zyngier
2018-07-20  9:47 ` [PATCH 12/14] arm64: KVM: Add ARCH_WORKAROUND_2 support for guests Marc Zyngier
2018-07-20  9:47 ` [PATCH 13/14] arm64: KVM: Handle guest's ARCH_WORKAROUND_2 requests Marc Zyngier
2018-07-20  9:47 ` [PATCH 14/14] arm64: KVM: Add ARCH_WORKAROUND_2 discovery through ARCH_FEATURES_FUNC_ID Marc Zyngier
2018-07-20 10:04 ` [PATCH 00/14] arm64: 4.17 backport of the SSBD mitigation patches Greg KH
  -- strict thread matches above, loose matches on Subject: below --
2018-05-22 15:06 [PATCH 00/14] arm64 SSBD (aka Spectre-v4) mitigation Marc Zyngier
2018-05-22 15:06 ` [PATCH 03/14] arm64: Add per-cpu infrastructure to call ARCH_WORKAROUND_2 Marc Zyngier
2018-05-22 15:06   ` Marc Zyngier
2018-05-23 10:03   ` Julien Grall
2018-05-23 10:03     ` Julien Grall
2018-05-24 11:14   ` Mark Rutland
2018-05-24 11:14     ` Mark Rutland

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