[PATCH 13/24] arm64: Introduce set_pstate_tco() helper macro
From: Pierre-Clément Tosi
Date: Sat Nov 07 2026 - 10:58:29 EST
Like other PSTATE bits, TCO deserves its own accessor.
Note that only HW KASAN common code now calls mte_{enable,disable}_tco()
so that their KASAN_HW_TAGS and ALTERNATIVE(ARM64_MTE) are superfluous.
Move the comment, as it now applies to them.
Signed-off-by: Pierre-Clément Tosi <ptosi@xxxxxxxxxx>
---
arch/arm64/include/asm/mte-kasan.h | 24 +++++++++++-------------
arch/arm64/include/asm/mte.h | 2 +-
arch/arm64/include/asm/sysreg.h | 1 +
arch/arm64/include/asm/uaccess.h | 16 ++++++++--------
arch/arm64/include/asm/word-at-a-time.h | 4 ++--
5 files changed, 23 insertions(+), 24 deletions(-)
diff --git a/arch/arm64/include/asm/mte-kasan.h b/arch/arm64/include/asm/mte-kasan.h
index 17e4155781fc..9d00e9460b0f 100644
--- a/arch/arm64/include/asm/mte-kasan.h
+++ b/arch/arm64/include/asm/mte-kasan.h
@@ -13,6 +13,8 @@
#include <linux/types.h>
+#include <asm/sysreg.h>
+
#ifdef CONFIG_KASAN_HW_TAGS
/* Whether the MTE asynchronous mode is enabled. */
@@ -34,27 +36,23 @@ static inline bool system_uses_mte_async_or_asymm_mode(void)
#ifdef CONFIG_ARM64_MTE
+/*
+ * These functions are meant to be only used from KASAN runtime through
+ * the arch_*() interface defined in asm/memory.h.
+ * These functions don't include system_supports_mte() checks,
+ * as KASAN only calls them when MTE is supported and enabled.
+ */
+
static inline void mte_disable_tco(void)
{
- if (!IS_ENABLED(CONFIG_KASAN_HW_TAGS))
- return;
- asm volatile(ALTERNATIVE("nop", SET_PSTATE_TCO(0), ARM64_MTE));
+ set_pstate_tco(0);
}
static inline void mte_enable_tco(void)
{
- if (!IS_ENABLED(CONFIG_KASAN_HW_TAGS))
- return;
- asm volatile(ALTERNATIVE("nop", SET_PSTATE_TCO(1), ARM64_MTE));
+ set_pstate_tco(1);
}
-/*
- * These functions are meant to be only used from KASAN runtime through
- * the arch_*() interface defined in asm/memory.h.
- * These functions don't include system_supports_mte() checks,
- * as KASAN only calls them when MTE is supported and enabled.
- */
-
static inline u8 mte_get_ptr_tag(void *ptr)
{
/* Note: The format of KASAN tags is 0xF<x> */
diff --git a/arch/arm64/include/asm/mte.h b/arch/arm64/include/asm/mte.h
index 614fff7dc35f..815843079eb9 100644
--- a/arch/arm64/include/asm/mte.h
+++ b/arch/arm64/include/asm/mte.h
@@ -271,7 +271,7 @@ static inline void mte_disable_tco_entry(struct task_struct *task)
*/
if (kasan_hw_tags_enabled() ||
(task->thread.sctlr_user & (1UL << SCTLR_EL1_TCF0_SHIFT)))
- asm volatile(SET_PSTATE_TCO(0));
+ set_pstate_tco(0);
}
#ifdef CONFIG_KASAN_HW_TAGS
diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
index e3b60ee03023..51c6a54d7146 100644
--- a/arch/arm64/include/asm/sysreg.h
+++ b/arch/arm64/include/asm/sysreg.h
@@ -105,6 +105,7 @@
#define set_pstate_uao(x) asm volatile(SET_PSTATE_UAO(x))
#define set_pstate_ssbs(x) asm volatile(SET_PSTATE_SSBS(x))
#define set_pstate_dit(x) asm volatile(SET_PSTATE_DIT(x))
+#define set_pstate_tco(x) asm volatile(SET_PSTATE_TCO(x))
/* Register-based PAN access, for save/restore purposes */
#define SYS_PSTATE_PAN sys_reg(3, 0, 4, 2, 3)
diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
index 9e3957ee3642..aac7676da531 100644
--- a/arch/arm64/include/asm/uaccess.h
+++ b/arch/arm64/include/asm/uaccess.h
@@ -140,13 +140,13 @@ static inline void __uaccess_disable_mte(void)
* such that a bad user address tag could trigger a kernel MTE fault.
*/
if (kasan_hw_tags_enabled())
- asm volatile(SET_PSTATE_TCO(1));
+ set_pstate_tco(1);
}
static inline void __uaccess_enable_mte(void)
{
if (kasan_hw_tags_enabled())
- asm volatile(SET_PSTATE_TCO(0));
+ set_pstate_tco(0);
}
static inline void uaccess_disable_privileged(void)
@@ -249,12 +249,12 @@ do { \
do { \
__label__ __rgm_err; \
\
- asm volatile(SET_PSTATE_TCO(1)); \
+ set_pstate_tco(1); \
__raw_get_mem(ldr, x, ptr, __rgm_err, type); \
- asm volatile(SET_PSTATE_TCO(0)); \
+ set_pstate_tco(0); \
break; \
__rgm_err: \
- asm volatile(SET_PSTATE_TCO(0)); \
+ set_pstate_tco(0); \
goto label; \
} while (0)
@@ -355,12 +355,12 @@ do { \
do { \
__label__ __rpm_err; \
\
- asm volatile(SET_PSTATE_TCO(1)); \
+ set_pstate_tco(1); \
__raw_put_mem(str, x, ptr, __rpm_err, type); \
- asm volatile(SET_PSTATE_TCO(0)); \
+ set_pstate_tco(0); \
break; \
__rpm_err: \
- asm volatile(SET_PSTATE_TCO(0)); \
+ set_pstate_tco(0); \
goto label; \
} while (0)
diff --git a/arch/arm64/include/asm/word-at-a-time.h b/arch/arm64/include/asm/word-at-a-time.h
index ec72126210d1..430d5ab8f042 100644
--- a/arch/arm64/include/asm/word-at-a-time.h
+++ b/arch/arm64/include/asm/word-at-a-time.h
@@ -67,9 +67,9 @@ static inline unsigned long load_unaligned_zeropad(const void *addr)
if (!system_uses_mte_async_or_asymm_mode())
return __load_unaligned_zeropad(addr);
- asm volatile(SET_PSTATE_TCO(1));
+ set_pstate_tco(1);
ret = __load_unaligned_zeropad(addr);
- asm volatile(SET_PSTATE_TCO(0));
+ set_pstate_tco(0);
return ret;
}
--
2.56.0.455.g6c5a503b38-goog