The following commit has been merged into the irq/core branch of tip: Commit-ID: 441e90369344d229c0f04024ea5d4d51f06b137d Gitweb: https://git.kernel.org/tip/441e90369344d229c0f04024ea5d4d51f06b137d Author: Thomas Gleixner <tglx@xxxxxxxxxxxxx> AuthorDate: Fri, 24 Sep 2021 18:12:45 +02:00 Committer: Borislav Petkov <bp@xxxxxxx> CommitterDate: Mon, 27 Sep 2021 12:28:32 +02:00 x86/softirq: Disable softirq stacks on PREEMPT_RT PREEMPT_RT preempts softirqs and the current implementation avoids do_softirq_own_stack() and only uses __do_softirq(). Disable the unused softirqs stacks on PREEMPT_RT to safe some memory and ensure that do_softirq_own_stack() is not used which is not expected. [ bigeasy: commit description. ] Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> Signed-off-by: Borislav Petkov <bp@xxxxxxx> Link: https://lkml.kernel.org/r/20210924161245.2357247-1-bigeasy@xxxxxxxxxxxxx --- arch/x86/include/asm/irq_stack.h | 3 +++ arch/x86/kernel/irq_32.c | 2 ++ 2 files changed, 5 insertions(+) diff --git a/arch/x86/include/asm/irq_stack.h b/arch/x86/include/asm/irq_stack.h index 562854c..ea0c5ab 100644 --- a/arch/x86/include/asm/irq_stack.h +++ b/arch/x86/include/asm/irq_stack.h @@ -185,6 +185,7 @@ IRQ_CONSTRAINTS, regs, vector); \ } +#ifndef CONFIG_PREEMPT_RT #define ASM_CALL_SOFTIRQ \ "call %P[__func] \n" @@ -201,6 +202,8 @@ __this_cpu_write(hardirq_stack_inuse, false); \ } +#endif + #else /* CONFIG_X86_64 */ /* System vector handlers always run on the stack they interrupted. */ #define run_sysvec_on_irqstack_cond(func, regs) \ diff --git a/arch/x86/kernel/irq_32.c b/arch/x86/kernel/irq_32.c index 044902d..e5dd6da 100644 --- a/arch/x86/kernel/irq_32.c +++ b/arch/x86/kernel/irq_32.c @@ -132,6 +132,7 @@ int irq_init_percpu_irqstack(unsigned int cpu) return 0; } +#ifndef CONFIG_PREEMPT_RT void do_softirq_own_stack(void) { struct irq_stack *irqstk; @@ -148,6 +149,7 @@ void do_softirq_own_stack(void) call_on_stack(__do_softirq, isp); } +#endif void __handle_irq(struct irq_desc *desc, struct pt_regs *regs) {
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