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| author |   Thomas Gleixner <tglx@linutronix.de> | 2021-02-10 00:40:43 +0100 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2021-02-10 23:34:13 +0100 |
| commit | e7f89001797148e8dc7060c335df2c56e73a8c7a (patch) | |
| tree | 6fd44fa30593a4d513f47aa7c1c80d4f3ec588ab /arch/x86/include/asm/irq_stack.h | |
| parent | x86/entry: Fix instrumentation annotation (diff) | |
| download | linux-dev-e7f89001797148e8dc7060c335df2c56e73a8c7a.tar.xz linux-dev-e7f89001797148e8dc7060c335df2c56e73a8c7a.zip | |
x86/irq: Sanitize irq stack tracking
The recursion protection for hard interrupt stacks is an unsigned int per
CPU variable initialized to -1 named __irq_count.
The irq stack switching is only done when the variable is -1, which creates
worse code than just checking for 0. When the stack switching happens it
uses this_cpu_add/sub(1), but there is no reason to do so. It simply can
use straight writes. This is a historical leftover from the low level ASM
code which used inc and jz to make a decision.
Rename it to hardirq_stack_inuse, make it a bool and use plain stores.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210210002512.228830141@linutronix.de
Diffstat (limited to 'arch/x86/include/asm/irq_stack.h')
| -rw-r--r-- | arch/x86/include/asm/irq_stack.h | 14 |
1 files changed, 7 insertions, 7 deletions
diff --git a/arch/x86/include/asm/irq_stack.h b/arch/x86/include/asm/irq_stack.h index 775816965c6a..4487bb989cea 100644 --- a/arch/x86/include/asm/irq_stack.h +++ b/arch/x86/include/asm/irq_stack.h @@ -9,7 +9,7 @@ #ifdef CONFIG_X86_64 static __always_inline bool irqstack_active(void) { - return __this_cpu_read(irq_count) != -1; + return __this_cpu_read(hardirq_stack_inuse); } void asm_call_on_stack(void *sp, void (*func)(void), void *arg); @@ -22,9 +22,9 @@ static __always_inline void __run_on_irqstack(void (*func)(void)) { void *tos = __this_cpu_read(hardirq_stack_ptr); - __this_cpu_add(irq_count, 1); + __this_cpu_write(hardirq_stack_inuse, true); asm_call_on_stack(tos - 8, func, NULL); - __this_cpu_sub(irq_count, 1); + __this_cpu_write(hardirq_stack_inuse, false); } static __always_inline void @@ -33,9 +33,9 @@ __run_sysvec_on_irqstack(void (*func)(struct pt_regs *regs), { void *tos = __this_cpu_read(hardirq_stack_ptr); - __this_cpu_add(irq_count, 1); + __this_cpu_write(hardirq_stack_inuse, true); asm_call_sysvec_on_stack(tos - 8, func, regs); - __this_cpu_sub(irq_count, 1); + __this_cpu_write(hardirq_stack_inuse, false); } static __always_inline void @@ -44,9 +44,9 @@ __run_irq_on_irqstack(void (*func)(struct irq_desc *desc), { void *tos = __this_cpu_read(hardirq_stack_ptr); - __this_cpu_add(irq_count, 1); + __this_cpu_write(hardirq_stack_inuse, true); asm_call_irq_on_stack(tos - 8, func, desc); - __this_cpu_sub(irq_count, 1); + __this_cpu_write(hardirq_stack_inuse, false); } #else /* CONFIG_X86_64 */ |