diff options
author | Benjamin Herrenschmidt <benh@kernel.crashing.org> | 2013-09-23 08:29:11 +0400 |
---|---|---|
committer | Benjamin Herrenschmidt <benh@kernel.crashing.org> | 2013-09-25 08:15:36 +0400 |
commit | 0366a1c70b89efed4f9d590216bb004a16effbed (patch) | |
tree | 5090ad127863968876119f1bb022a7bce32842ab /arch/powerpc/kernel/irq.c | |
parent | 4a10c2ac2f368583138b774ca41fac4207911983 (diff) | |
download | linux-0366a1c70b89efed4f9d590216bb004a16effbed.tar.xz |
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 <benh@kernel.crashing.org>
Diffstat (limited to 'arch/powerpc/kernel/irq.c')
-rw-r--r-- | arch/powerpc/kernel/irq.c | 104 |
1 files changed, 52 insertions, 52 deletions
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; } } |