arm64: entry: move el1 irq/nmi logic to C

In preparation for reworking the EL1 irq/nmi entry code, move the existing logic to C. We no longer need the asm_nmi_enter() and asm_nmi_exit() wrappers, so these are removed. The new C functions are marked noinstr, which prevents compiler instrumentation and runtime probing. In subsequent patches we'll want the new C helpers to be called in all cases, so we don't bother wrapping the calls with ifdeferry. Even when the new C functions are stubs the trivial calls are unlikely to have a measurable impact on the IRQ or NMI paths anyway. Prototypes are added to <asm/exception.h> as otherwise (in some configurations) GCC will complain about the lack of a forward declaration. We already do this for existing function, e.g. enter_from_user_mode(). The new helpers are marked as noinstr (which prevents all instrumentation, tracing, and kprobes). Otherwise, there should be no functional change as a result of this patch. Signed-off-by: Mark Rutland <[email protected]> Cc: Catalin Marinas <[email protected]> Cc: James Morse <[email protected]> Cc: Will Deacon <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Will Deacon <[email protected]>
intersectRaven · Nov 30, 2020 · 105fc33 · 105fc33
1 parent 3cb5ed4
commit 105fc33
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Showing 4 changed files with 22 additions and 45 deletions.
diff --git a/arch/arm64/include/asm/exception.h b/arch/arm64/include/asm/exception.h
@@ -31,6 +31,8 @@ static inline u32 disr_to_esr(u64 disr)
 	return esr;
 }
 
+asmlinkage void noinstr enter_el1_irq_or_nmi(struct pt_regs *regs);
+asmlinkage void noinstr exit_el1_irq_or_nmi(struct pt_regs *regs);
 asmlinkage void enter_from_user_mode(void);
 void do_mem_abort(unsigned long addr, unsigned int esr, struct pt_regs *regs);
 void do_undefinstr(struct pt_regs *regs);

diff --git a/arch/arm64/kernel/entry-common.c b/arch/arm64/kernel/entry-common.c
@@ -17,6 +17,22 @@
 #include <asm/mmu.h>
 #include <asm/sysreg.h>
 
+asmlinkage void noinstr enter_el1_irq_or_nmi(struct pt_regs *regs)
+{
+	if (IS_ENABLED(CONFIG_ARM64_PSEUDO_NMI) && !interrupts_enabled(regs))
+		nmi_enter();
+
+	trace_hardirqs_off();
+}
+
+asmlinkage void noinstr exit_el1_irq_or_nmi(struct pt_regs *regs)
+{
+	if (IS_ENABLED(CONFIG_ARM64_PSEUDO_NMI) && !interrupts_enabled(regs))
+		nmi_exit();
+	else
+		trace_hardirqs_on();
+}
+
 static void noinstr el1_abort(struct pt_regs *regs, unsigned long esr)
 {
 	unsigned long far = read_sysreg(far_el1);

diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
@@ -637,16 +637,8 @@ SYM_CODE_START_LOCAL_NOALIGN(el1_irq)
 	gic_prio_irq_setup pmr=x20, tmp=x1
 	enable_da_f
 
-#ifdef CONFIG_ARM64_PSEUDO_NMI
-	test_irqs_unmasked	res=x0, pmr=x20
-	cbz	x0, 1f
-	bl	asm_nmi_enter
-1:
-#endif
-
-#ifdef CONFIG_TRACE_IRQFLAGS
-	bl	trace_hardirqs_off
-#endif
+	mov	x0, sp
+	bl	enter_el1_irq_or_nmi
 
 	irq_handler
 
@@ -665,26 +657,8 @@ alternative_else_nop_endif
 1:
 #endif
 
-#ifdef CONFIG_ARM64_PSEUDO_NMI
-	/*
-	 * When using IRQ priority masking, we can get spurious interrupts while
-	 * PMR is set to GIC_PRIO_IRQOFF. An NMI might also have occurred in a
-	 * section with interrupts disabled. Skip tracing in those cases.
-	 */
-	test_irqs_unmasked	res=x0, pmr=x20
-	cbz	x0, 1f
-	bl	asm_nmi_exit
-1:
-#endif
-
-#ifdef CONFIG_TRACE_IRQFLAGS
-#ifdef CONFIG_ARM64_PSEUDO_NMI
-	test_irqs_unmasked	res=x0, pmr=x20
-	cbnz	x0, 1f
-#endif
-	bl	trace_hardirqs_on
-1:
-#endif
+	mov	x0, sp
+	bl	exit_el1_irq_or_nmi
 
 	kernel_exit 1
 SYM_CODE_END(el1_irq)

diff --git a/arch/arm64/kernel/irq.c b/arch/arm64/kernel/irq.c
@@ -67,18 +67,3 @@ void __init init_IRQ(void)
 		local_daif_restore(DAIF_PROCCTX_NOIRQ);
 	}
 }
-
-/*
- * Stubs to make nmi_enter/exit() code callable from ASM
- */
-asmlinkage void notrace asm_nmi_enter(void)
-{
-	nmi_enter();
-}
-NOKPROBE_SYMBOL(asm_nmi_enter);
-
-asmlinkage void notrace asm_nmi_exit(void)
-{
-	nmi_exit();
-}
-NOKPROBE_SYMBOL(asm_nmi_exit);