This is a note to let you know that I've just added the patch titled
arm64: errata: Unify speculative SSBS errata logic
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
arm64-errata-unify-speculative-ssbs-errata-logic.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit ff3189206408d7c69183627bb3059f67c658e17c
Author: Mark Rutland <mark.rutland@xxxxxxx>
Date: Fri Aug 9 11:09:30 2024 +0100
arm64: errata: Unify speculative SSBS errata logic
[ Upstream commit ec768766608092087dfb5c1fc45a16a6f524dee2 ]
Cortex-X4 erratum 3194386 and Neoverse-V3 erratum 3312417 are identical,
with duplicate Kconfig text and some unsightly ifdeffery. While we try
to share code behind CONFIG_ARM64_WORKAROUND_SPECULATIVE_SSBS, having
separate options results in a fair amount of boilerplate code, and this
will only get worse as we expand the set of affected CPUs.
To reduce this boilerplate, unify the two behind a common Kconfig
option. This removes the duplicate text and Kconfig logic, and removes
the need for the intermediate ARM64_WORKAROUND_SPECULATIVE_SSBS option.
The set of affected CPUs is described as a list so that this can easily
be extended.
I've used ARM64_ERRATUM_3194386 (matching the Neoverse-V3 erratum ID) as
the common option, matching the way we use ARM64_ERRATUM_1319367 to
cover Cortex-A57 erratum 1319537 and Cortex-A72 erratum 1319367.
Signed-off-by: Mark Rutland <mark.rutland@xxxxxxx>
Cc: James Morse <james.morse@xxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20240603111812.1514101-5-mark.rutland@xxxxxxx
Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>
[ Mark: fix conflicts & renames, drop unneeded cpucaps.h ]
Signed-off-by: Mark Rutland <mark.rutland@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/Documentation/arm64/silicon-errata.rst b/Documentation/arm64/silicon-errata.rst
index 33595bc79dea6..13d77af92edf7 100644
--- a/Documentation/arm64/silicon-errata.rst
+++ b/Documentation/arm64/silicon-errata.rst
@@ -122,7 +122,7 @@ stable kernels.
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Neoverse-N2 | #2253138 | ARM64_ERRATUM_2253138 |
+----------------+-----------------+-----------------+-----------------------------+
-| ARM | Neoverse-V3 | #3312417 | ARM64_ERRATUM_3312417 |
+| ARM | Neoverse-V3 | #3312417 | ARM64_ERRATUM_3194386 |
+----------------+-----------------+-----------------+-----------------------------+
| ARM | MMU-500 | #841119,826419 | N/A |
+----------------+-----------------+-----------------+-----------------------------+
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index bc89287d38ed1..623b30c21c00d 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -848,34 +848,14 @@ config ARM64_ERRATUM_2224489
If unsure, say Y.
-config ARM64_WORKAROUND_SPECULATIVE_SSBS
- bool
-
config ARM64_ERRATUM_3194386
- bool "Cortex-X4: 3194386: workaround for MSR SSBS not self-synchronizing"
- select ARM64_WORKAROUND_SPECULATIVE_SSBS
+ bool "Cortex-X4/Neoverse-V3: workaround for MSR SSBS not self-synchronizing"
default y
help
- This option adds the workaround for ARM Cortex-X4 erratum 3194386.
-
- On affected cores "MSR SSBS, #0" instructions may not affect
- subsequent speculative instructions, which may permit unexepected
- speculative store bypassing.
-
- Work around this problem by placing a speculation barrier after
- kernel changes to SSBS. The presence of the SSBS special-purpose
- register is hidden from hwcaps and EL0 reads of ID_AA64PFR1_EL1, such
- that userspace will use the PR_SPEC_STORE_BYPASS prctl to change
- SSBS.
+ This option adds the workaround for the following errata:
- If unsure, say Y.
-
-config ARM64_ERRATUM_3312417
- bool "Neoverse-V3: 3312417: workaround for MSR SSBS not self-synchronizing"
- select ARM64_WORKAROUND_SPECULATIVE_SSBS
- default y
- help
- This option adds the workaround for ARM Neoverse-V3 erratum 3312417.
+ * ARM Cortex-X4 erratum 3194386
+ * ARM Neoverse-V3 erratum 3312417
On affected cores "MSR SSBS, #0" instructions may not affect
subsequent speculative instructions, which may permit unexepected
diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
index 0cf60010a0825..0fe2d65e646fe 100644
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -402,14 +402,10 @@ static struct midr_range trbe_write_out_of_range_cpus[] = {
};
#endif /* CONFIG_ARM64_WORKAROUND_TRBE_WRITE_OUT_OF_RANGE */
-#ifdef CONFIG_ARM64_WORKAROUND_SPECULATIVE_SSBS
-static const struct midr_range erratum_spec_ssbs_list[] = {
#ifdef CONFIG_ARM64_ERRATUM_3194386
+static const struct midr_range erratum_spec_ssbs_list[] = {
MIDR_ALL_VERSIONS(MIDR_CORTEX_X4),
-#endif
-#ifdef CONFIG_ARM64_ERRATUM_3312417
MIDR_ALL_VERSIONS(MIDR_NEOVERSE_V3),
-#endif
{}
};
#endif
@@ -661,7 +657,7 @@ const struct arm64_cpu_capabilities arm64_errata[] = {
CAP_MIDR_RANGE_LIST(trbe_write_out_of_range_cpus),
},
#endif
-#ifdef CONFIG_ARM64_WORKAROUND_SPECULATIVE_SSBS
+#ifdef CONFIG_ARM64_ERRATUM_3194386
{
.desc = "ARM errata 3194386, 3312417",
.capability = ARM64_WORKAROUND_SPECULATIVE_SSBS,
diff --git a/arch/arm64/kernel/proton-pack.c b/arch/arm64/kernel/proton-pack.c
index c0149af8c9e97..ebce46c4e942c 100644
--- a/arch/arm64/kernel/proton-pack.c
+++ b/arch/arm64/kernel/proton-pack.c
@@ -567,7 +567,7 @@ static enum mitigation_state spectre_v4_enable_hw_mitigation(void)
* Mitigate this with an unconditional speculation barrier, as CPUs
* could mis-speculate branches and bypass a conditional barrier.
*/
- if (IS_ENABLED(CONFIG_ARM64_WORKAROUND_SPECULATIVE_SSBS))
+ if (IS_ENABLED(CONFIG_ARM64_ERRATUM_3194386))
spec_bar();
return SPECTRE_MITIGATED;
