The patch titled
Subject: arm64: mte: add asymmetric mode support
has been removed from the -mm tree. Its filename was
arm64-mte-add-asymmetric-mode-support.patch
This patch was dropped because an alternative patch was merged
------------------------------------------------------
From: Vincenzo Frascino <vincenzo.frascino@xxxxxxx>
Subject: arm64: mte: add asymmetric mode support
MTE provides an asymmetric mode for detecting tag exceptions. In
particular, when such a mode is present, the CPU triggers a fault on a tag
mismatch during a load operation and asynchronously updates a register
when a tag mismatch is detected during a store operation.
Add support for MTE asymmetric mode.
Note: If the CPU does not support MTE asymmetric mode the kernel falls
back on synchronous mode which is the default for kasan=on.
Link: https://lkml.kernel.org/r/20211004202253.27857-5-vincenzo.frascino@xxxxxxx
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@xxxxxxx>
Reviewed-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Cc: Andrey Konovalov <andreyknvl@xxxxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Cc: Branislav Rankov <branislav.rankov@xxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Evgenii Stepanov <eugenis@xxxxxxxxxx>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
Cc: Marco Elver <elver@xxxxxxxxxx>
Cc: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/arm64/include/asm/memory.h | 1
arch/arm64/include/asm/mte-kasan.h | 5 ++++
arch/arm64/kernel/mte.c | 33 ++++++++++++++++++++++++++-
3 files changed, 38 insertions(+), 1 deletion(-)
--- a/arch/arm64/include/asm/memory.h~arm64-mte-add-asymmetric-mode-support
+++ a/arch/arm64/include/asm/memory.h
@@ -243,6 +243,7 @@ static inline const void *__tag_set(cons
#ifdef CONFIG_KASAN_HW_TAGS
#define arch_enable_tagging_sync() mte_enable_kernel_sync()
#define arch_enable_tagging_async() mte_enable_kernel_async()
+#define arch_enable_tagging_asymm() mte_enable_kernel_asymm()
#define arch_force_async_tag_fault() mte_check_tfsr_exit()
#define arch_get_random_tag() mte_get_random_tag()
#define arch_get_mem_tag(addr) mte_get_mem_tag(addr)
--- a/arch/arm64/include/asm/mte-kasan.h~arm64-mte-add-asymmetric-mode-support
+++ a/arch/arm64/include/asm/mte-kasan.h
@@ -130,6 +130,7 @@ static inline void mte_set_mem_tag_range
void mte_enable_kernel_sync(void);
void mte_enable_kernel_async(void);
+void mte_enable_kernel_asymm(void);
#else /* CONFIG_ARM64_MTE */
@@ -161,6 +162,10 @@ static inline void mte_enable_kernel_asy
{
}
+static inline void mte_enable_kernel_asymm(void)
+{
+}
+
#endif /* CONFIG_ARM64_MTE */
#endif /* __ASSEMBLY__ */
--- a/arch/arm64/kernel/mte.c~arm64-mte-add-asymmetric-mode-support
+++ a/arch/arm64/kernel/mte.c
@@ -26,7 +26,12 @@
static DEFINE_PER_CPU_READ_MOSTLY(u64, mte_tcf_preferred);
#ifdef CONFIG_KASAN_HW_TAGS
-/* Whether the MTE asynchronous mode is enabled. */
+/*
+ * The MTE asynchronous and asymmetric mode have the same
+ * behavior for the store operations.
+ *
+ * Whether the MTE asynchronous or asymmetric mode is enabled.
+ */
DEFINE_STATIC_KEY_FALSE(mte_async_mode);
EXPORT_SYMBOL_GPL(mte_async_mode);
#endif
@@ -137,6 +142,32 @@ void mte_enable_kernel_async(void)
if (!system_uses_mte_async_mode())
static_branch_enable(&mte_async_mode);
}
+
+void mte_enable_kernel_asymm(void)
+{
+ if (cpus_have_cap(ARM64_MTE_ASYMM)) {
+ __mte_enable_kernel("asymmetric", SCTLR_ELx_TCF_ASYMM);
+
+ /*
+ * MTE asymm mode behaves as async mode for store
+ * operations. The mode is set system wide by the
+ * first PE that executes this function.
+ *
+ * Note: If in future KASAN acquires a runtime switching
+ * mode in between sync and async, this strategy needs
+ * to be reviewed.
+ */
+ if (!system_uses_mte_async_mode())
+ static_branch_enable(&mte_async_mode);
+ } else {
+ /*
+ * If the CPU does not support MTE asymmetric mode the
+ * kernel falls back on synchronous mode which is the
+ * default for kasan=on.
+ */
+ mte_enable_kernel_sync();
+ }
+}
#endif
#ifdef CONFIG_KASAN_HW_TAGS
_
Patches currently in -mm which might be from vincenzo.frascino@xxxxxxx are
kasan-extend-kasan-mode-kernel-parameter.patch
