[PATCH stable 5.15] arm64: errata: Remove AES hwcap for COMPAT tasks

From: Florian Fainelli
Date: Thu Oct 20 2022 - 19:02:04 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: resolved conflicts in arch/arm64/tools/cpucaps and cpu_errata.c]
Signed-off-by: Florian Fainelli <f.fainelli@xxxxxxxxx>
---
Documentation/arm64/silicon-errata.rst | 4 ++++
arch/arm64/Kconfig | 16 ++++++++++++++++
arch/arm64/kernel/cpu_errata.c | 16 ++++++++++++++++
arch/arm64/kernel/cpufeature.c | 14 +++++++++++++-
arch/arm64/tools/cpucaps | 1 +
5 files changed, 50 insertions(+), 1 deletion(-)

diff --git a/Documentation/arm64/silicon-errata.rst b/Documentation/arm64/silicon-errata.rst
index 663001f69773..83e6f8c05d07 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 24cce3b9ff1a..b1aa3d7e9fbe 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -487,6 +487,22 @@ 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/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
index 25c495f58f67..c1e5c55664cb 100644
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -350,6 +350,14 @@ 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
{
@@ -559,6 +567,14 @@ 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 3e52a9e8b50b..13e3cb1acbdf 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -79,6 +79,7 @@
#include <asm/cpufeature.h>
#include <asm/cpu_ops.h>
#include <asm/fpsimd.h>
+#include <asm/hwcap.h>
#include <asm/insn.h>
#include <asm/kvm_host.h>
#include <asm/mmu_context.h>
@@ -1915,6 +1916,14 @@ 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 */
+}
+
#ifdef CONFIG_KVM
static bool is_kvm_protected_mode(const struct arm64_cpu_capabilities *entry, int __unused)
{
@@ -2942,8 +2951,10 @@ 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");
@@ -2995,6 +3006,7 @@ static int enable_mismatched_32bit_el0(unsigned int cpu)
cpu_active_mask);
get_cpu_device(lucky_winner)->offline_disabled = true;
setup_elf_hwcaps(compat_elf_hwcaps);
+ elf_hwcap_fixup();
pr_info("Asymmetric 32-bit EL0 support detected on CPU %u; CPU hot-unplug disabled on CPU %u\n",
cpu, lucky_winner);
return 0;
diff --git a/arch/arm64/tools/cpucaps b/arch/arm64/tools/cpucaps
index cfaffd3c8289..6b1e70aee8cf 100644
--- a/arch/arm64/tools/cpucaps
+++ b/arch/arm64/tools/cpucaps
@@ -54,6 +54,7 @@ WORKAROUND_1418040
WORKAROUND_1463225
WORKAROUND_1508412
WORKAROUND_1542419
+WORKAROUND_1742098
WORKAROUND_2457168
WORKAROUND_CAVIUM_23154
WORKAROUND_CAVIUM_27456
--
2.25.1