[PATCH 4.14 07/60] arm64: errata: Remove AES hwcap for COMPAT tasks

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

From: James Morse <james.morse@arm.com>

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@kernel.org>
Signed-off-by: James Morse <james.morse@arm.com>
Link: https://lore.kernel.org/r/20220714161523.279570-3-james.morse@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
[florian: resolved conflicts in arch/arm64/tools/cpucaps and cpu_errata.c]
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 Documentation/arm64/silicon-errata.txt |    2 ++
 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, 48 insertions(+), 2 deletions(-)

--- a/Documentation/arm64/silicon-errata.txt
+++ b/Documentation/arm64/silicon-errata.txt
@@ -53,7 +53,9 @@ stable kernels.
 | ARM            | Cortex-A57      | #832075         | ARM64_ERRATUM_832075        |
 | ARM            | Cortex-A57      | #852523         | N/A                         |
 | ARM            | Cortex-A57      | #834220         | ARM64_ERRATUM_834220        |
+| ARM            | Cortex-A57      | #1742098        | ARM64_ERRATUM_1742098       |
 | ARM            | Cortex-A72      | #853709         | N/A                         |
+| ARM            | Cortex-A72      | #1655431        | ARM64_ERRATUM_1742098       |
 | ARM            | Cortex-A73      | #858921         | ARM64_ERRATUM_858921        |
 | ARM            | Cortex-A55      | #1024718        | ARM64_ERRATUM_1024718       |
 | ARM            | Cortex-A76      | #1188873        | ARM64_ERRATUM_1188873       |
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -472,6 +472,22 @@ config ARM64_ERRATUM_1188873
 
 	  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 CAVIUM_ERRATUM_22375
 	bool "Cavium erratum 22375, 24313"
 	default y
--- a/arch/arm64/include/asm/cpucaps.h
+++ b/arch/arm64/include/asm/cpucaps.h
@@ -47,7 +47,8 @@
 #define ARM64_SSBS				27
 #define ARM64_WORKAROUND_1188873		28
 #define ARM64_SPECTRE_BHB			29
+#define ARM64_WORKAROUND_1742098		30
 
-#define ARM64_NCAPS				30
+#define ARM64_NCAPS				31
 
 #endif /* __ASM_CPUCAPS_H */
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -576,6 +576,14 @@ check_branch_predictor(const struct arm6
 	return (need_wa > 0);
 }
 
+#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[] = {
 #if	defined(CONFIG_ARM64_ERRATUM_826319) || \
 	defined(CONFIG_ARM64_ERRATUM_827319) || \
@@ -741,6 +749,14 @@ const struct arm64_cpu_capabilities arm6
 		.matches = is_spectre_bhb_affected,
 		.cpu_enable = spectre_bhb_enable_mitigation,
 	},
+#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
 	{
 	}
 };
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -30,6 +30,7 @@
 #include <asm/cpu.h>
 #include <asm/cpufeature.h>
 #include <asm/cpu_ops.h>
+#include <asm/hwcap.h>
 #include <asm/mmu_context.h>
 #include <asm/processor.h>
 #include <asm/sysreg.h>
@@ -1010,6 +1011,14 @@ static void cpu_enable_ssbs(const struct
 }
 #endif /* CONFIG_ARM64_SSBD */
 
+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 */
+}
+
 static const struct arm64_cpu_capabilities arm64_features[] = {
 	{
 		.desc = "GIC system register CPU interface",
@@ -1588,8 +1597,10 @@ void __init setup_cpu_features(void)
 	mark_const_caps_ready();
 	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();
+	}
 
 	/* Advertise that we have computed the system capabilities */
 	set_sys_caps_initialised();