[PATCH v2] arm64: entry: Clean out some indirection

[PATCH v2] arm64: entry: Clean out some indirection

[Linus Walleij]

The conversion to generic IRQ entry left some functions
in the EL1 (kernel) IRQ entry path very shallow, so drop
the __inner_functions() where appropriate, saving some
time and stack.

This is not a fix but an optimization.

Drop stale comments about irqentry_enter/exit() while we
are at it.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
---
Changes in v2:
- Drop stale comments pointed out by Will as well.
- Link to v1: https://lore.kernel.org/r/20251014-arm64-skip-indirection-v1-1-f8ccfd9dbcb7@linaro.org
---
 arch/arm64/kernel/entry-common.c | 28 +++-------------------------
 1 file changed, 3 insertions(+), 25 deletions(-)

diff --git a/arch/arm64/kernel/entry-common.c b/arch/arm64/kernel/entry-common.c
index f546a914f04174e37bf3578490545edebb66afd1..6e8e1e620221fdb3da7a398c4c4293cce1e2b553 100644
--- a/arch/arm64/kernel/entry-common.c
+++ b/arch/arm64/kernel/entry-common.c
@@ -34,20 +34,12 @@
  * Handle IRQ/context state management when entering from kernel mode.
  * Before this function is called it is not safe to call regular kernel code,
  * instrumentable code, or any code which may trigger an exception.
- *
- * This is intended to match the logic in irqentry_enter(), handling the kernel
- * mode transitions only.
  */
-static __always_inline irqentry_state_t __enter_from_kernel_mode(struct pt_regs *regs)
-{
-	return irqentry_enter(regs);
-}
-
 static noinstr irqentry_state_t enter_from_kernel_mode(struct pt_regs *regs)
 {
 	irqentry_state_t state;
 
-	state = __enter_from_kernel_mode(regs);
+	state = irqentry_enter(regs);
 	mte_check_tfsr_entry();
 	mte_disable_tco_entry(current);
 
@@ -58,21 +50,12 @@ static noinstr irqentry_state_t enter_from_kernel_mode(struct pt_regs *regs)
  * Handle IRQ/context state management when exiting to kernel mode.
  * After this function returns it is not safe to call regular kernel code,
  * instrumentable code, or any code which may trigger an exception.
- *
- * This is intended to match the logic in irqentry_exit(), handling the kernel
- * mode transitions only, and with preemption handled elsewhere.
  */
-static __always_inline void __exit_to_kernel_mode(struct pt_regs *regs,
-						  irqentry_state_t state)
-{
-	irqentry_exit(regs, state);
-}
-
 static void noinstr exit_to_kernel_mode(struct pt_regs *regs,
 					irqentry_state_t state)
 {
 	mte_check_tfsr_exit();
-	__exit_to_kernel_mode(regs, state);
+	irqentry_exit(regs, state);
 }
 
 /*
@@ -80,17 +63,12 @@ static void noinstr exit_to_kernel_mode(struct pt_regs *regs,
  * Before this function is called it is not safe to call regular kernel code,
  * instrumentable code, or any code which may trigger an exception.
  */
-static __always_inline void __enter_from_user_mode(struct pt_regs *regs)
+static __always_inline void arm64_enter_from_user_mode(struct pt_regs *regs)
 {
 	enter_from_user_mode(regs);
 	mte_disable_tco_entry(current);
 }
 
-static __always_inline void arm64_enter_from_user_mode(struct pt_regs *regs)
-{
-	__enter_from_user_mode(regs);
-}
-
 /*
  * Handle IRQ/context state management when exiting to user mode.
  * After this function returns it is not safe to call regular kernel code,

---
base-commit: 3a8660878839faadb4f1a6dd72c3179c1df56787
change-id: 20251014-arm64-skip-indirection-4ff88c27ad02

Best regards,
-- 
Linus Walleij <linus.walleij@linaro.org>

Re: [PATCH v2] arm64: entry: Clean out some indirection

[Catalin Marinas]

On Wed, 05 Nov 2025 15:27:01 +0100, Linus Walleij wrote:
> The conversion to generic IRQ entry left some functions
> in the EL1 (kernel) IRQ entry path very shallow, so drop
> the __inner_functions() where appropriate, saving some
> time and stack.
> 
> This is not a fix but an optimization.
> 
> [...]

Applied to arm64 (for-next/misc), thanks!

[1/1] arm64: entry: Clean out some indirection
      https://git.kernel.org/arm64/c/555827a06456

-- 
Catalin