linux_dsm_epyc7002/arch/arm64/include/asm/irq.h

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#ifndef __ASM_IRQ_H
#define __ASM_IRQ_H
#define IRQ_STACK_SIZE THREAD_SIZE
#define IRQ_STACK_START_SP THREAD_START_SP
#ifndef __ASSEMBLER__
#include <linux/percpu.h>
#include <asm-generic/irq.h>
#include <asm/thread_info.h>
struct pt_regs;
DECLARE_PER_CPU(unsigned long [IRQ_STACK_SIZE/sizeof(long)], irq_stack);
/*
* The highest address on the stack, and the first to be used. Used to
arm64: irq: fix walking from irq stack to task stack Running with CONFIG_DEBUG_SPINLOCK=y can trigger a BUG with the new IRQ stack code: BUG: spinlock lockup suspected on CPU#1 This is due to the IRQ_STACK_TO_TASK_STACK macro incorrectly retrieving the task stack pointer stashed at the top of the IRQ stack. Sayeth James: | Yup, this is what is happening. Its an off-by-one due to broken | thinking about how the stack works. My broken thinking was: | | > top ------------ | > | dummy_lr | <- irq_stack_ptr | > ------------ | > | x29 | | > ------------ | > | x19 | <- irq_stack_ptr - 0x10 | > ------------ | > | xzr | | > ------------ | | But the stack-pointer is decreased before use. So it actually looks | like this: | | > ------------ | > | | <- irq_stack_ptr | > top ------------ | > | dummy_lr | | > ------------ | > | x29 | <- irq_stack_ptr - 0x10 | > ------------ | > | x19 | | > ------------ | > | xzr | <- irq_stack_ptr - 0x20 | > ------------ | | The value being used as the original stack is x29, which in all the | tests is sp but without the current frames data, hence there are no | missing frames in the output. | | Jungseok Lee picked it up with a 32bit user space because aarch32 | can't use x29, so it remains 0 forever. The fix he posted is correct. This patch fixes the macro and adds some of this wisdom to a comment, so that the layout of the IRQ stack is well understood. Cc: James Morse <james.morse@arm.com> Reported-by: Jungseok Lee <jungseoklee85@gmail.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2015-12-09 20:58:42 +07:00
* find the dummy-stack frame put down by el?_irq() in entry.S, which
* is structured as follows:
*
* ------------
* | | <- irq_stack_ptr
* top ------------
* | x19 | <- irq_stack_ptr - 0x08
arm64: irq: fix walking from irq stack to task stack Running with CONFIG_DEBUG_SPINLOCK=y can trigger a BUG with the new IRQ stack code: BUG: spinlock lockup suspected on CPU#1 This is due to the IRQ_STACK_TO_TASK_STACK macro incorrectly retrieving the task stack pointer stashed at the top of the IRQ stack. Sayeth James: | Yup, this is what is happening. Its an off-by-one due to broken | thinking about how the stack works. My broken thinking was: | | > top ------------ | > | dummy_lr | <- irq_stack_ptr | > ------------ | > | x29 | | > ------------ | > | x19 | <- irq_stack_ptr - 0x10 | > ------------ | > | xzr | | > ------------ | | But the stack-pointer is decreased before use. So it actually looks | like this: | | > ------------ | > | | <- irq_stack_ptr | > top ------------ | > | dummy_lr | | > ------------ | > | x29 | <- irq_stack_ptr - 0x10 | > ------------ | > | x19 | | > ------------ | > | xzr | <- irq_stack_ptr - 0x20 | > ------------ | | The value being used as the original stack is x29, which in all the | tests is sp but without the current frames data, hence there are no | missing frames in the output. | | Jungseok Lee picked it up with a 32bit user space because aarch32 | can't use x29, so it remains 0 forever. The fix he posted is correct. This patch fixes the macro and adds some of this wisdom to a comment, so that the layout of the IRQ stack is well understood. Cc: James Morse <james.morse@arm.com> Reported-by: Jungseok Lee <jungseoklee85@gmail.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2015-12-09 20:58:42 +07:00
* ------------
* | x29 | <- irq_stack_ptr - 0x10
* ------------
*
* where x19 holds a copy of the task stack pointer where the struct pt_regs
* from kernel_entry can be found.
arm64: irq: fix walking from irq stack to task stack Running with CONFIG_DEBUG_SPINLOCK=y can trigger a BUG with the new IRQ stack code: BUG: spinlock lockup suspected on CPU#1 This is due to the IRQ_STACK_TO_TASK_STACK macro incorrectly retrieving the task stack pointer stashed at the top of the IRQ stack. Sayeth James: | Yup, this is what is happening. Its an off-by-one due to broken | thinking about how the stack works. My broken thinking was: | | > top ------------ | > | dummy_lr | <- irq_stack_ptr | > ------------ | > | x29 | | > ------------ | > | x19 | <- irq_stack_ptr - 0x10 | > ------------ | > | xzr | | > ------------ | | But the stack-pointer is decreased before use. So it actually looks | like this: | | > ------------ | > | | <- irq_stack_ptr | > top ------------ | > | dummy_lr | | > ------------ | > | x29 | <- irq_stack_ptr - 0x10 | > ------------ | > | x19 | | > ------------ | > | xzr | <- irq_stack_ptr - 0x20 | > ------------ | | The value being used as the original stack is x29, which in all the | tests is sp but without the current frames data, hence there are no | missing frames in the output. | | Jungseok Lee picked it up with a 32bit user space because aarch32 | can't use x29, so it remains 0 forever. The fix he posted is correct. This patch fixes the macro and adds some of this wisdom to a comment, so that the layout of the IRQ stack is well understood. Cc: James Morse <james.morse@arm.com> Reported-by: Jungseok Lee <jungseoklee85@gmail.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2015-12-09 20:58:42 +07:00
*
*/
#define IRQ_STACK_PTR(cpu) ((unsigned long)per_cpu(irq_stack, cpu) + IRQ_STACK_START_SP)
/*
* The offset from irq_stack_ptr where entry.S will store the original
* stack pointer. Used by unwind_frame() and dump_backtrace().
*/
#define IRQ_STACK_TO_TASK_STACK(ptr) (*((unsigned long *)((ptr) - 0x08)))
extern void set_handle_irq(void (*handle_irq)(struct pt_regs *));
static inline int nr_legacy_irqs(void)
{
return 0;
}
static inline bool on_irq_stack(unsigned long sp, int cpu)
{
/* variable names the same as kernel/stacktrace.c */
unsigned long low = (unsigned long)per_cpu(irq_stack, cpu);
unsigned long high = low + IRQ_STACK_START_SP;
return (low <= sp && sp <= high);
}
#endif /* !__ASSEMBLER__ */
#endif