forked from Minki/linux
d224a69e3d
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>
61 lines
1.5 KiB
C
61 lines
1.5 KiB
C
#ifndef __ASM_IRQ_H
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#define __ASM_IRQ_H
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#define IRQ_STACK_SIZE THREAD_SIZE
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#define IRQ_STACK_START_SP THREAD_START_SP
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#ifndef __ASSEMBLER__
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#include <linux/percpu.h>
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#include <asm-generic/irq.h>
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#include <asm/thread_info.h>
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struct pt_regs;
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DECLARE_PER_CPU(unsigned long [IRQ_STACK_SIZE/sizeof(long)], irq_stack);
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/*
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* The highest address on the stack, and the first to be used. Used to
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* find the dummy-stack frame put down by el?_irq() in entry.S, which
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* is structured as follows:
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*
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* ------------
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* | | <- irq_stack_ptr
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* top ------------
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* | x19 | <- irq_stack_ptr - 0x08
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* ------------
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* | x29 | <- irq_stack_ptr - 0x10
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* ------------
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*
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* where x19 holds a copy of the task stack pointer where the struct pt_regs
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* from kernel_entry can be found.
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*
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*/
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#define IRQ_STACK_PTR(cpu) ((unsigned long)per_cpu(irq_stack, cpu) + IRQ_STACK_START_SP)
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/*
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* The offset from irq_stack_ptr where entry.S will store the original
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* stack pointer. Used by unwind_frame() and dump_backtrace().
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*/
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#define IRQ_STACK_TO_TASK_STACK(ptr) (*((unsigned long *)((ptr) - 0x08)))
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extern void set_handle_irq(void (*handle_irq)(struct pt_regs *));
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static inline int nr_legacy_irqs(void)
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{
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return 0;
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}
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static inline bool on_irq_stack(unsigned long sp, int cpu)
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{
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/* variable names the same as kernel/stacktrace.c */
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unsigned long low = (unsigned long)per_cpu(irq_stack, cpu);
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unsigned long high = low + IRQ_STACK_START_SP;
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return (low <= sp && sp <= high);
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}
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#endif /* !__ASSEMBLER__ */
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#endif
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