[PATCH stable 5.10] arm64: errata: Remove AES hwcap for COMPAT tasks

From: Florian Fainelli
Date: Thu Oct 20 2022 - 19:01:56 EST

From: James Morse <james.morse@xxxxxxx>

commit 44b3834b2eed595af07021b1c64e6f9bc396398b upstream

Cortex-A57 and Cortex-A72 have an erratum where an interrupt that
occurs between a pair of AES instructions in aarch32 mode may corrupt
the ELR. The task will subsequently produce the wrong AES result.

The AES instructions are part of the cryptographic extensions, which are
optional. User-space software will detect the support for these
instructions from the hwcaps. If the platform doesn't support these
instructions a software implementation should be used.

Remove the hwcap bits on affected parts to indicate user-space should
not use the AES instructions.

Acked-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
Signed-off-by: James Morse <james.morse@xxxxxxx>
Link: https://lore.kernel.org/r/20220714161523.279570-3-james.morse@xxxxxxx
Signed-off-by: Will Deacon <will@xxxxxxxxxx>
[florian: removed arch/arm64/tools/cpucaps and fixup cpufeature.c]
Signed-off-by: Florian Fainelli <f.fainelli@xxxxxxxxx>
---
Documentation/arm64/silicon-errata.rst | 4 ++++
arch/arm64/Kconfig | 16 ++++++++++++++++
arch/arm64/include/asm/cpucaps.h | 3 ++-
arch/arm64/kernel/cpu_errata.c | 16 ++++++++++++++++
arch/arm64/kernel/cpufeature.c | 13 ++++++++++++-
5 files changed, 50 insertions(+), 2 deletions(-)

diff --git a/Documentation/arm64/silicon-errata.rst b/Documentation/arm64/silicon-errata.rst
index 22a07c208fee..4f3206495217 100644
--- a/Documentation/arm64/silicon-errata.rst
+++ b/Documentation/arm64/silicon-errata.rst
@@ -76,10 +76,14 @@ stable kernels.
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Cortex-A57 | #1319537 | ARM64_ERRATUM_1319367 |
+----------------+-----------------+-----------------+-----------------------------+
+| ARM | Cortex-A57 | #1742098 | ARM64_ERRATUM_1742098 |
++----------------+-----------------+-----------------+-----------------------------+
| ARM | Cortex-A72 | #853709 | N/A |
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Cortex-A72 | #1319367 | ARM64_ERRATUM_1319367 |
+----------------+-----------------+-----------------+-----------------------------+
+| ARM | Cortex-A72 | #1655431 | ARM64_ERRATUM_1742098 |
++----------------+-----------------+-----------------+-----------------------------+
| ARM | Cortex-A73 | #858921 | ARM64_ERRATUM_858921 |
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Cortex-A76 | #1188873,1418040| ARM64_ERRATUM_1418040 |
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index af65ab83e63d..34bd4cba81e6 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -481,6 +481,22 @@ config ARM64_ERRATUM_834220

If unsure, say Y.

+config ARM64_ERRATUM_1742098
+ bool "Cortex-A57/A72: 1742098: ELR recorded incorrectly on interrupt taken between cryptographic instructions in a sequence"
+ depends on COMPAT
+ default y
+ help
+ This option removes the AES hwcap for aarch32 user-space to
+ workaround erratum 1742098 on Cortex-A57 and Cortex-A72.
+
+ Affected parts may corrupt the AES state if an interrupt is
+ taken between a pair of AES instructions. These instructions
+ are only present if the cryptography extensions are present.
+ All software should have a fallback implementation for CPUs
+ that don't implement the cryptography extensions.
+
+ If unsure, say Y.
+
config ARM64_ERRATUM_845719
bool "Cortex-A53: 845719: a load might read incorrect data"
depends on COMPAT
diff --git a/arch/arm64/include/asm/cpucaps.h b/arch/arm64/include/asm/cpucaps.h
index 53030d3c03a2..d2080a41f6e6 100644
--- a/arch/arm64/include/asm/cpucaps.h
+++ b/arch/arm64/include/asm/cpucaps.h
@@ -68,7 +68,8 @@
#define ARM64_WORKAROUND_1508412 58
#define ARM64_SPECTRE_BHB 59
#define ARM64_WORKAROUND_2457168 60
+#define ARM64_WORKAROUND_1742098 61

-#define ARM64_NCAPS 61
+#define ARM64_NCAPS 62

#endif /* __ASM_CPUCAPS_H */
diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
index aaacca6fd52f..5d6f19bc628c 100644
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -356,6 +356,14 @@ static const struct midr_range erratum_1463225[] = {
};
#endif

+#ifdef CONFIG_ARM64_ERRATUM_1742098
+static struct midr_range broken_aarch32_aes[] = {
+ MIDR_RANGE(MIDR_CORTEX_A57, 0, 1, 0xf, 0xf),
+ MIDR_ALL_VERSIONS(MIDR_CORTEX_A72),
+ {},
+};
+#endif
+
const struct arm64_cpu_capabilities arm64_errata[] = {
#ifdef CONFIG_ARM64_WORKAROUND_CLEAN_CACHE
{
@@ -554,6 +562,14 @@ const struct arm64_cpu_capabilities arm64_errata[] = {
/* Cortex-A510 r0p0-r1p1 */
CAP_MIDR_RANGE(MIDR_CORTEX_A510, 0, 0, 1, 1)
},
+#endif
+#ifdef CONFIG_ARM64_ERRATUM_1742098
+ {
+ .desc = "ARM erratum 1742098",
+ .capability = ARM64_WORKAROUND_1742098,
+ CAP_MIDR_RANGE_LIST(broken_aarch32_aes),
+ .type = ARM64_CPUCAP_LOCAL_CPU_ERRATUM,
+ },
#endif
{
}
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index e72c90b82656..f3767c144593 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -76,6 +76,7 @@
#include <asm/cpufeature.h>
#include <asm/cpu_ops.h>
#include <asm/fpsimd.h>
+#include <asm/hwcap.h>
#include <asm/mmu_context.h>
#include <asm/mte.h>
#include <asm/processor.h>
@@ -1730,6 +1731,14 @@ static void cpu_enable_mte(struct arm64_cpu_capabilities const *cap)
}
#endif /* CONFIG_ARM64_MTE */

+static void elf_hwcap_fixup(void)
+{
+#ifdef CONFIG_ARM64_ERRATUM_1742098
+ if (cpus_have_const_cap(ARM64_WORKAROUND_1742098))
+ compat_elf_hwcap2 &= ~COMPAT_HWCAP2_AES;
+#endif /* ARM64_ERRATUM_1742098 */
+}
+
/* Internal helper functions to match cpu capability type */
static bool
cpucap_late_cpu_optional(const struct arm64_cpu_capabilities *cap)
@@ -2735,8 +2744,10 @@ void __init setup_cpu_features(void)
setup_system_capabilities();
setup_elf_hwcaps(arm64_elf_hwcaps);

- if (system_supports_32bit_el0())
+ if (system_supports_32bit_el0()) {
setup_elf_hwcaps(compat_elf_hwcaps);
+ elf_hwcap_fixup();
+ }

if (system_uses_ttbr0_pan())
pr_info("emulated: Privileged Access Never (PAN) using TTBR0_EL1 switching\n");
--
2.25.1