[PATCH 2/4] arm64: entry: Always inline helpers used by non-instrumentable paths

[Jisheng Zhang]

The noinstr entry and exit paths call MTE and SME helpers, CPU feature
checks, and the architecture-specific rescheduling check. Several of
these helpers use plain inline, which permits the compiler to emit
instrumentable out-of-line copies.

A GCC build with CONFIG_CC_OPTIMIZE_FOR_SIZE=y emitted
mte_disable_tco_entry(), sme_enter_from_user_mode() and
sme_exit_to_user_mode() in .text.

Use __always_inline for these helpers and their nested feature checks
so they inherit the instrumentation restrictions of their callers

Signed-off-by: Jisheng Zhang <jszhang@xxxxxxxxxx>
Assisted-by: LLM
---
 arch/arm64/include/asm/cpufeature.h   | 8 ++++----
 arch/arm64/include/asm/entry-common.h | 2 +-
 arch/arm64/include/asm/fpsimd.h       | 4 ++--
 arch/arm64/include/asm/mte-kasan.h    | 4 ++--
 arch/arm64/include/asm/mte.h          | 6 +++---
 5 files changed, 12 insertions(+), 12 deletions(-)

diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index e3c8a1493dc8..c62949693b92 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -774,7 +774,7 @@ static __always_inline bool system_supports_fpsimd(void)
 	return alternative_has_cap_likely(ARM64_HAS_FPSIMD);
 }
 
-static inline bool system_uses_hw_pan(void)
+static __always_inline bool system_uses_hw_pan(void)
 {
 	return alternative_has_cap_unlikely(ARM64_HAS_PAN);
 }
@@ -840,12 +840,12 @@ static __always_inline bool system_uses_irq_prio_masking(void)
 	return alternative_has_cap_unlikely(ARM64_HAS_GIC_PRIO_MASKING);
 }
 
-static inline bool system_supports_mte(void)
+static __always_inline bool system_supports_mte(void)
 {
 	return alternative_has_cap_unlikely(ARM64_MTE);
 }
 
-static inline bool system_has_prio_mask_debugging(void)
+static __always_inline bool system_has_prio_mask_debugging(void)
 {
 	return IS_ENABLED(CONFIG_ARM64_DEBUG_PRIORITY_MASKING) &&
 	       system_uses_irq_prio_masking();
@@ -950,7 +950,7 @@ static inline bool cpu_has_hw_af(void)
 						ID_AA64MMFR1_EL1_HAFDBS_SHIFT);
 }
 
-static inline bool cpu_has_pan(void)
+static __always_inline bool cpu_has_pan(void)
 {
 	u64 mmfr1 = read_cpuid(ID_AA64MMFR1_EL1);
 	return cpuid_feature_extract_unsigned_field(mmfr1,
diff --git a/arch/arm64/include/asm/entry-common.h b/arch/arm64/include/asm/entry-common.h
index 1905765159aa..4856bc453c01 100644
--- a/arch/arm64/include/asm/entry-common.h
+++ b/arch/arm64/include/asm/entry-common.h
@@ -27,7 +27,7 @@ static __always_inline void arch_exit_to_user_mode_work(struct pt_regs *regs,
 
 #define arch_exit_to_user_mode_work arch_exit_to_user_mode_work
 
-static inline bool arch_irqentry_exit_need_resched(void)
+static __always_inline bool arch_irqentry_exit_need_resched(void)
 {
 	/*
 	 * DAIF.DA are cleared at the start of IRQ/FIQ handling, and when GIC
diff --git a/arch/arm64/include/asm/fpsimd.h b/arch/arm64/include/asm/fpsimd.h
index a67d5774e672..157d0551f627 100644
--- a/arch/arm64/include/asm/fpsimd.h
+++ b/arch/arm64/include/asm/fpsimd.h
@@ -749,14 +749,14 @@ void sme_enable_dvmsync(void);
 void sme_set_active(void);
 void sme_clear_active(void);
 
-static inline void sme_enter_from_user_mode(void)
+static __always_inline void sme_enter_from_user_mode(void)
 {
 	if (alternative_has_cap_unlikely(ARM64_WORKAROUND_4193714) &&
 	    test_thread_flag(TIF_SME))
 		sme_clear_active();
 }
 
-static inline void sme_exit_to_user_mode(void)
+static __always_inline void sme_exit_to_user_mode(void)
 {
 	if (alternative_has_cap_unlikely(ARM64_WORKAROUND_4193714) &&
 	    test_thread_flag(TIF_SME))
diff --git a/arch/arm64/include/asm/mte-kasan.h b/arch/arm64/include/asm/mte-kasan.h
index de910f1c19e1..cc2151325eb0 100644
--- a/arch/arm64/include/asm/mte-kasan.h
+++ b/arch/arm64/include/asm/mte-kasan.h
@@ -18,14 +18,14 @@
 /* Whether the MTE asynchronous mode is enabled. */
 DECLARE_STATIC_KEY_FALSE(mte_async_or_asymm_mode);
 
-static inline bool system_uses_mte_async_or_asymm_mode(void)
+static __always_inline bool system_uses_mte_async_or_asymm_mode(void)
 {
 	return static_branch_unlikely(&mte_async_or_asymm_mode);
 }
 
 #else /* CONFIG_KASAN_HW_TAGS */
 
-static inline bool system_uses_mte_async_or_asymm_mode(void)
+static __always_inline bool system_uses_mte_async_or_asymm_mode(void)
 {
 	return false;
 }
diff --git a/arch/arm64/include/asm/mte.h b/arch/arm64/include/asm/mte.h
index 83f3b05fc784..b2bf2e70c9ae 100644
--- a/arch/arm64/include/asm/mte.h
+++ b/arch/arm64/include/asm/mte.h
@@ -222,7 +222,7 @@ static inline bool folio_try_hugetlb_mte_tagging(struct folio *folio)
 }
 #endif
 
-static inline void mte_disable_tco_entry(struct task_struct *task)
+static __always_inline void mte_disable_tco_entry(struct task_struct *task)
 {
 	if (!system_supports_mte())
 		return;
@@ -245,7 +245,7 @@ static inline void mte_disable_tco_entry(struct task_struct *task)
 #ifdef CONFIG_KASAN_HW_TAGS
 void mte_check_tfsr_el1(void);
 
-static inline void mte_check_tfsr_entry(void)
+static __always_inline void mte_check_tfsr_entry(void)
 {
 	if (!kasan_hw_tags_enabled())
 		return;
@@ -256,7 +256,7 @@ static inline void mte_check_tfsr_entry(void)
 	mte_check_tfsr_el1();
 }
 
-static inline void mte_check_tfsr_exit(void)
+static __always_inline void mte_check_tfsr_exit(void)
 {
 	if (!kasan_hw_tags_enabled())
 		return;
-- 
2.55.0