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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/kernel/process_64.c | |
| parent | 15f720aabe71a5662c4198b22532d95bbeec80ef (diff) | |
| download | linux-e7f89001797148e8dc7060c335df2c56e73a8c7a.tar.gz linux-e7f89001797148e8dc7060c335df2c56e73a8c7a.tar.bz2 linux-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/kernel/process_64.c')
| -rw-r--r-- | arch/x86/kernel/process_64.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index ad582f9ac5a6..d08307df69ad 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -539,7 +539,7 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p) int cpu = smp_processor_id(); WARN_ON_ONCE(IS_ENABLED(CONFIG_DEBUG_ENTRY) && - this_cpu_read(irq_count) != -1); + this_cpu_read(hardirq_stack_inuse)); if (!test_thread_flag(TIF_NEED_FPU_LOAD)) switch_fpu_prepare(prev_fpu, cpu); |