From 0366a1c70b89efed4f9d590216bb004a16effbed Mon Sep 17 00:00:00 2001 From: Benjamin Herrenschmidt Date: Mon, 23 Sep 2013 14:29:11 +1000 Subject: [PATCH] powerpc/irq: Run softirqs off the top of the irq stack Nowadays, irq_exit() calls __do_softirq() pretty much directly instead of calling do_softirq() which switches to the decicated softirq stack. This has lead to observed stack overflows on powerpc since we call irq_enter() and irq_exit() outside of the scope that switches to the irq stack. This fixes it by moving the stack switching up a level, making irq_enter() and irq_exit() run off the irq stack. Signed-off-by: Benjamin Herrenschmidt --- arch/powerpc/include/asm/irq.h | 4 +- arch/powerpc/kernel/irq.c | 104 ++++++++++++++++----------------- arch/powerpc/kernel/misc_32.S | 9 ++- arch/powerpc/kernel/misc_64.S | 10 ++-- 4 files changed, 62 insertions(+), 65 deletions(-) diff --git a/arch/powerpc/include/asm/irq.h b/arch/powerpc/include/asm/irq.h index 0e40843a1c6e..41f13cec8a8f 100644 --- a/arch/powerpc/include/asm/irq.h +++ b/arch/powerpc/include/asm/irq.h @@ -69,9 +69,9 @@ extern struct thread_info *softirq_ctx[NR_CPUS]; extern void irq_ctx_init(void); extern void call_do_softirq(struct thread_info *tp); -extern int call_handle_irq(int irq, void *p1, - struct thread_info *tp, void *func); +extern void call_do_irq(struct pt_regs *regs, struct thread_info *tp); extern void do_IRQ(struct pt_regs *regs); +extern void __do_irq(struct pt_regs *regs); int irq_choose_cpu(const struct cpumask *mask); diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c index c69440cef7af..2234a1276a77 100644 --- a/arch/powerpc/kernel/irq.c +++ b/arch/powerpc/kernel/irq.c @@ -441,50 +441,6 @@ void migrate_irqs(void) } #endif -static inline void handle_one_irq(unsigned int irq) -{ - struct thread_info *curtp, *irqtp; - unsigned long saved_sp_limit; - struct irq_desc *desc; - - desc = irq_to_desc(irq); - if (!desc) - return; - - /* Switch to the irq stack to handle this */ - curtp = current_thread_info(); - irqtp = hardirq_ctx[smp_processor_id()]; - - if (curtp == irqtp) { - /* We're already on the irq stack, just handle it */ - desc->handle_irq(irq, desc); - return; - } - - saved_sp_limit = current->thread.ksp_limit; - - irqtp->task = curtp->task; - irqtp->flags = 0; - - /* Copy the softirq bits in preempt_count so that the - * softirq checks work in the hardirq context. */ - irqtp->preempt_count = (irqtp->preempt_count & ~SOFTIRQ_MASK) | - (curtp->preempt_count & SOFTIRQ_MASK); - - current->thread.ksp_limit = (unsigned long)irqtp + - _ALIGN_UP(sizeof(struct thread_info), 16); - - call_handle_irq(irq, desc, irqtp, desc->handle_irq); - current->thread.ksp_limit = saved_sp_limit; - irqtp->task = NULL; - - /* Set any flag that may have been set on the - * alternate stack - */ - if (irqtp->flags) - set_bits(irqtp->flags, &curtp->flags); -} - static inline void check_stack_overflow(void) { #ifdef CONFIG_DEBUG_STACKOVERFLOW @@ -501,9 +457,9 @@ static inline void check_stack_overflow(void) #endif } -void do_IRQ(struct pt_regs *regs) +void __do_irq(struct pt_regs *regs) { - struct pt_regs *old_regs = set_irq_regs(regs); + struct irq_desc *desc; unsigned int irq; irq_enter(); @@ -519,18 +475,64 @@ void do_IRQ(struct pt_regs *regs) */ irq = ppc_md.get_irq(); - /* We can hard enable interrupts now */ + /* We can hard enable interrupts now to allow perf interrupts */ may_hard_irq_enable(); /* And finally process it */ - if (irq != NO_IRQ) - handle_one_irq(irq); - else + if (unlikely(irq == NO_IRQ)) __get_cpu_var(irq_stat).spurious_irqs++; + else { + desc = irq_to_desc(irq); + if (likely(desc)) + desc->handle_irq(irq, desc); + } trace_irq_exit(regs); irq_exit(); +} + +void do_IRQ(struct pt_regs *regs) +{ + struct pt_regs *old_regs = set_irq_regs(regs); + struct thread_info *curtp, *irqtp; + unsigned long saved_sp_limit; + + /* Switch to the irq stack to handle this */ + curtp = current_thread_info(); + irqtp = hardirq_ctx[raw_smp_processor_id()]; + + /* Already there ? */ + if (unlikely(curtp == irqtp)) { + __do_irq(regs); + set_irq_regs(old_regs); + return; + } + + /* Adjust the stack limit */ + saved_sp_limit = current->thread.ksp_limit; + current->thread.ksp_limit = (unsigned long)irqtp + + _ALIGN_UP(sizeof(struct thread_info), 16); + + + /* Prepare the thread_info in the irq stack */ + irqtp->task = curtp->task; + irqtp->flags = 0; + + /* Copy the preempt_count so that the [soft]irq checks work. */ + irqtp->preempt_count = curtp->preempt_count; + + /* Switch stack and call */ + call_do_irq(regs, irqtp); + + /* Restore stack limit */ + current->thread.ksp_limit = saved_sp_limit; + irqtp->task = NULL; + + /* Copy back updates to the thread_info */ + if (irqtp->flags) + set_bits(irqtp->flags, &curtp->flags); + set_irq_regs(old_regs); } @@ -592,12 +594,10 @@ void irq_ctx_init(void) memset((void *)softirq_ctx[i], 0, THREAD_SIZE); tp = softirq_ctx[i]; tp->cpu = i; - tp->preempt_count = 0; memset((void *)hardirq_ctx[i], 0, THREAD_SIZE); tp = hardirq_ctx[i]; tp->cpu = i; - tp->preempt_count = HARDIRQ_OFFSET; } } diff --git a/arch/powerpc/kernel/misc_32.S b/arch/powerpc/kernel/misc_32.S index 777d999f563b..7da3882a3622 100644 --- a/arch/powerpc/kernel/misc_32.S +++ b/arch/powerpc/kernel/misc_32.S @@ -47,13 +47,12 @@ _GLOBAL(call_do_softirq) mtlr r0 blr -_GLOBAL(call_handle_irq) +_GLOBAL(call_do_irq) mflr r0 stw r0,4(r1) - mtctr r6 - stwu r1,THREAD_SIZE-STACK_FRAME_OVERHEAD(r5) - mr r1,r5 - bctrl + stwu r1,THREAD_SIZE-STACK_FRAME_OVERHEAD(r4) + mr r1,r4 + bl __do_irq lwz r1,0(r1) lwz r0,4(r1) mtlr r0 diff --git a/arch/powerpc/kernel/misc_64.S b/arch/powerpc/kernel/misc_64.S index 971d7e78aff2..e59caf874d05 100644 --- a/arch/powerpc/kernel/misc_64.S +++ b/arch/powerpc/kernel/misc_64.S @@ -40,14 +40,12 @@ _GLOBAL(call_do_softirq) mtlr r0 blr -_GLOBAL(call_handle_irq) - ld r8,0(r6) +_GLOBAL(call_do_irq) mflr r0 std r0,16(r1) - mtctr r8 - stdu r1,THREAD_SIZE-STACK_FRAME_OVERHEAD(r5) - mr r1,r5 - bctrl + stdu r1,THREAD_SIZE-STACK_FRAME_OVERHEAD(r4) + mr r1,r4 + bl .__do_irq ld r1,0(r1) ld r0,16(r1) mtlr r0 -- GitLab