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author | James Morse <james.morse@arm.com> | 2015-12-18 16:01:47 +0000 |
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committer | Will Deacon <will.deacon@arm.com> | 2015-12-21 17:26:01 +0000 |
commit | d224a69e3d80fe08f285d1f41d21b590bae4fa9f (patch) | |
tree | 714dfa475b1e358c18285af1d809e08fc7e6f790 /arch/arm64/kernel/irq.c | |
parent | 66b3923a1a0f77a563b43f43f6ad091354abbfe9 (diff) | |
download | op-kernel-dev-d224a69e3d80fe08f285d1f41d21b590bae4fa9f.zip op-kernel-dev-d224a69e3d80fe08f285d1f41d21b590bae4fa9f.tar.gz |
arm64: remove irq_count and do_softirq_own_stack()
sysrq_handle_reboot() re-enables interrupts while on the irq stack. The
irq_stack implementation wrongly assumed this would only ever happen
via the softirq path, allowing it to update irq_count late, in
do_softirq_own_stack().
This means if an irq occurs in sysrq_handle_reboot(), during
emergency_restart() the stack will be corrupted, as irq_count wasn't
updated.
Lose the optimisation, and instead of moving the adding/subtracting of
irq_count into irq_stack_entry/irq_stack_exit, remove it, and compare
sp_el0 (struct thread_info) with sp & ~(THREAD_SIZE - 1). This tells us
if we are on a task stack, if so, we can safely switch to the irq stack.
Finally, remove do_softirq_own_stack(), we don't need it anymore.
Reported-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
[will: use get_thread_info macro]
Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'arch/arm64/kernel/irq.c')
-rw-r--r-- | arch/arm64/kernel/irq.c | 38 |
1 files changed, 1 insertions, 37 deletions
diff --git a/arch/arm64/kernel/irq.c b/arch/arm64/kernel/irq.c index ff7ebb7..2386b26 100644 --- a/arch/arm64/kernel/irq.c +++ b/arch/arm64/kernel/irq.c @@ -25,24 +25,14 @@ #include <linux/irq.h> #include <linux/smp.h> #include <linux/init.h> -#include <linux/interrupt.h> #include <linux/irqchip.h> #include <linux/seq_file.h> unsigned long irq_err_count; -/* - * irq stack only needs to be 16 byte aligned - not IRQ_STACK_SIZE aligned. - * irq_stack[0] is used as irq_count, a non-zero value indicates the stack - * is in use, and el?_irq() shouldn't switch to it. This is used to detect - * recursive use of the irq_stack, it is lazily updated by - * do_softirq_own_stack(), which is called on the irq_stack, before - * re-enabling interrupts to process softirqs. - */ +/* irq stack only needs to be 16 byte aligned - not IRQ_STACK_SIZE aligned. */ DEFINE_PER_CPU(unsigned long [IRQ_STACK_SIZE/sizeof(long)], irq_stack) __aligned(16); -#define IRQ_COUNT() (*per_cpu(irq_stack, smp_processor_id())) - int arch_show_interrupts(struct seq_file *p, int prec) { show_ipi_list(p, prec); @@ -66,29 +56,3 @@ void __init init_IRQ(void) if (!handle_arch_irq) panic("No interrupt controller found."); } - -/* - * do_softirq_own_stack() is called from irq_exit() before __do_softirq() - * re-enables interrupts, at which point we may re-enter el?_irq(). We - * increase irq_count here so that el1_irq() knows that it is already on the - * irq stack. - * - * Called with interrupts disabled, so we don't worry about moving cpu, or - * being interrupted while modifying irq_count. - * - * This function doesn't actually switch stack. - */ -void do_softirq_own_stack(void) -{ - int cpu = smp_processor_id(); - - WARN_ON_ONCE(!irqs_disabled()); - - if (on_irq_stack(current_stack_pointer, cpu)) { - IRQ_COUNT()++; - __do_softirq(); - IRQ_COUNT()--; - } else { - __do_softirq(); - } -} |