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| author | James Morse <james.morse@arm.com> | 2015-12-18 17:01:47 +0100 |
|---|---|---|
| committer | Will Deacon <will.deacon@arm.com> | 2015-12-21 18:26:01 +0100 |
| commit | d224a69e3d80fe08f285d1f41d21b590bae4fa9f (patch) | |
| tree | 714dfa475b1e358c18285af1d809e08fc7e6f790 /arch/arm64/kernel/entry.S | |
| parent | arm64: hugetlb: add support for PTE contiguous bit (diff) | |
| download | linux-d224a69e3d80fe08f285d1f41d21b590bae4fa9f.tar.xz linux-d224a69e3d80fe08f285d1f41d21b590bae4fa9f.zip | |
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/entry.S')
| -rw-r--r-- | arch/arm64/kernel/entry.S | 19 |
1 files changed, 10 insertions, 9 deletions
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 0667fb7d8bb1..c0db321db7e1 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -181,19 +181,20 @@ alternative_endif .macro irq_stack_entry mov x19, sp // preserve the original sp - this_cpu_ptr irq_stack, x25, x26 - /* - * Check the lowest address on irq_stack for the irq_count value, - * incremented by do_softirq_own_stack if we have re-enabled irqs - * while on the irq_stack. + * Compare sp with the current thread_info, if the top + * ~(THREAD_SIZE - 1) bits match, we are on a task stack, and + * should switch to the irq stack. */ - ldr x26, [x25] - cbnz x26, 9998f // recursive use? + and x25, x19, #~(THREAD_SIZE - 1) + cmp x25, tsk + b.ne 9998f - /* switch to the irq stack */ + this_cpu_ptr irq_stack, x25, x26 mov x26, #IRQ_STACK_START_SP add x26, x25, x26 + + /* switch to the irq stack */ mov sp, x26 /* @@ -405,10 +406,10 @@ el1_irq: bl trace_hardirqs_off #endif + get_thread_info tsk irq_handler #ifdef CONFIG_PREEMPT - get_thread_info tsk ldr w24, [tsk, #TI_PREEMPT] // get preempt count cbnz w24, 1f // preempt count != 0 ldr x0, [tsk, #TI_FLAGS] // get flags |