diff options
| author | James Morse <james.morse@arm.com> | 2015-12-15 11:21:25 +0000 |
|---|---|---|
| committer | Will Deacon <will.deacon@arm.com> | 2015-12-15 17:09:08 +0000 |
| commit | 971c67ce37cfeeaf560e792a2c3bc21d8b67163a (patch) | |
| tree | dabce8d15638e66a8c351454e78e3f5bac6f6c2f /arch/arm64/include | |
| parent | 129b985cc3f331d0e6908958f50757a3a1b37793 (diff) | |
arm64: reduce stack use in irq_handler
The code for switching to irq_stack stores three pieces of information on
the stack, fp+lr, as a fake stack frame (that lets us walk back onto the
interrupted tasks stack frame), and the address of the struct pt_regs that
contains the register values from kernel entry. (which dump_backtrace()
will print in any stack trace).
To reduce this, we store fp, and the pointer to the struct pt_regs.
unwind_frame() can recognise this as the irq_stack dummy frame, (as it only
appears at the top of the irq_stack), and use the struct pt_regs values
to find the missing interrupted link-register.
Suggested-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'arch/arm64/include')
| -rw-r--r-- | arch/arm64/include/asm/irq.h | 11 |
1 files changed, 4 insertions, 7 deletions
diff --git a/arch/arm64/include/asm/irq.h b/arch/arm64/include/asm/irq.h index 877c7e358384..3bece4379bd9 100644 --- a/arch/arm64/include/asm/irq.h +++ b/arch/arm64/include/asm/irq.h @@ -25,16 +25,13 @@ DECLARE_PER_CPU(unsigned long [IRQ_STACK_SIZE/sizeof(long)], irq_stack); * ------------ * | | <- irq_stack_ptr * top ------------ - * | elr_el1 | + * | x19 | <- irq_stack_ptr - 0x08 * ------------ * | x29 | <- irq_stack_ptr - 0x10 * ------------ - * | xzr | - * ------------ - * | x19 | <- irq_stack_ptr - 0x20 - * ------------ * - * where x19 holds a copy of the task stack pointer. + * where x19 holds a copy of the task stack pointer where the struct pt_regs + * from kernel_entry can be found. * */ #define IRQ_STACK_PTR(cpu) ((unsigned long)per_cpu(irq_stack, cpu) + IRQ_STACK_START_SP) @@ -43,7 +40,7 @@ DECLARE_PER_CPU(unsigned long [IRQ_STACK_SIZE/sizeof(long)], irq_stack); * 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 - 0x20)); +#define IRQ_STACK_TO_TASK_STACK(ptr) (*((unsigned long *)((ptr) - 0x08))) extern void set_handle_irq(void (*handle_irq)(struct pt_regs *)); |