arm64: Modify stack trace and dump for use with irq_stack
This patch allows unwind_frame() to traverse from interrupt stack to task stack correctly. It requires data from a dummy stack frame, created during irq_stack_entry(), added by a later patch. A similar approach is taken to modify dump_backtrace(), which expects to find struct pt_regs underneath any call to functions marked __exception. When on an irq_stack, the struct pt_regs is stored on the old task stack, the location of which is stored in the dummy stack frame. Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org> [james.morse: merged two patches, reworked for per_cpu irq_stacks, and no alignment guarantees, added irq_stack definitions] Signed-off-by: James Morse <james.morse@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
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@ -1,10 +1,32 @@
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#ifndef __ASM_IRQ_H
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#ifndef __ASM_IRQ_H
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#define __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-generic/irq.h>
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#include <asm/thread_info.h>
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struct pt_regs;
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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.
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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 - 0x10));
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extern void set_handle_irq(void (*handle_irq)(struct pt_regs *));
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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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static inline int nr_legacy_irqs(void)
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@ -12,4 +34,14 @@ static inline int nr_legacy_irqs(void)
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return 0;
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return 0;
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}
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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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#endif
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@ -30,6 +30,9 @@
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unsigned long irq_err_count;
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unsigned long irq_err_count;
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/* irq stack only needs to be 16 byte aligned - not IRQ_STACK_SIZE aligned */
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DEFINE_PER_CPU(unsigned long [IRQ_STACK_SIZE/sizeof(long)], irq_stack) __aligned(16);
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int arch_show_interrupts(struct seq_file *p, int prec)
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int arch_show_interrupts(struct seq_file *p, int prec)
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{
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{
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show_ipi_list(p, prec);
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show_ipi_list(p, prec);
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@ -20,6 +20,7 @@
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#include <linux/sched.h>
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#include <linux/sched.h>
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#include <linux/stacktrace.h>
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#include <linux/stacktrace.h>
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#include <asm/irq.h>
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#include <asm/stacktrace.h>
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#include <asm/stacktrace.h>
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/*
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/*
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@ -39,17 +40,41 @@ int notrace unwind_frame(struct stackframe *frame)
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{
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{
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unsigned long high, low;
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unsigned long high, low;
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unsigned long fp = frame->fp;
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unsigned long fp = frame->fp;
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unsigned long irq_stack_ptr;
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/*
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* Use raw_smp_processor_id() to avoid false-positives from
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* CONFIG_DEBUG_PREEMPT. get_wchan() calls unwind_frame() on sleeping
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* task stacks, we can be pre-empted in this case, so
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* {raw_,}smp_processor_id() may give us the wrong value. Sleeping
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* tasks can't ever be on an interrupt stack, so regardless of cpu,
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* the checks will always fail.
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*/
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irq_stack_ptr = IRQ_STACK_PTR(raw_smp_processor_id());
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low = frame->sp;
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low = frame->sp;
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high = ALIGN(low, THREAD_SIZE);
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/* irq stacks are not THREAD_SIZE aligned */
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if (on_irq_stack(frame->sp, raw_smp_processor_id()))
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high = irq_stack_ptr;
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else
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high = ALIGN(low, THREAD_SIZE) - 0x20;
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if (fp < low || fp > high - 0x18 || fp & 0xf)
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if (fp < low || fp > high || fp & 0xf)
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return -EINVAL;
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return -EINVAL;
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frame->sp = fp + 0x10;
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frame->sp = fp + 0x10;
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frame->fp = *(unsigned long *)(fp);
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frame->fp = *(unsigned long *)(fp);
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frame->pc = *(unsigned long *)(fp + 8);
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frame->pc = *(unsigned long *)(fp + 8);
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/*
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* Check whether we are going to walk through from interrupt stack
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* to task stack.
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* If we reach the end of the stack - and its an interrupt stack,
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* read the original task stack pointer from the dummy frame.
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*/
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if (frame->sp == irq_stack_ptr)
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frame->sp = IRQ_STACK_TO_TASK_STACK(irq_stack_ptr);
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return 0;
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return 0;
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}
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}
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@ -146,6 +146,7 @@ static void dump_instr(const char *lvl, struct pt_regs *regs)
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static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
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static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
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{
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{
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struct stackframe frame;
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struct stackframe frame;
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unsigned long irq_stack_ptr = IRQ_STACK_PTR(smp_processor_id());
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pr_debug("%s(regs = %p tsk = %p)\n", __func__, regs, tsk);
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pr_debug("%s(regs = %p tsk = %p)\n", __func__, regs, tsk);
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@ -180,11 +181,22 @@ static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
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if (ret < 0)
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if (ret < 0)
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break;
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break;
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stack = frame.sp;
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stack = frame.sp;
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if (in_exception_text(where))
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if (in_exception_text(where)) {
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/*
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* If we switched to the irq_stack before calling this
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* exception handler, then the pt_regs will be on the
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* task stack. The easiest way to tell is if the large
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* pt_regs would overlap with the end of the irq_stack.
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*/
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if (stack < irq_stack_ptr &&
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(stack + sizeof(struct pt_regs)) > irq_stack_ptr)
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stack = IRQ_STACK_TO_TASK_STACK(irq_stack_ptr);
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dump_mem("", "Exception stack", stack,
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dump_mem("", "Exception stack", stack,
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stack + sizeof(struct pt_regs), false);
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stack + sizeof(struct pt_regs), false);
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}
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}
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}
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}
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}
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void show_stack(struct task_struct *tsk, unsigned long *sp)
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void show_stack(struct task_struct *tsk, unsigned long *sp)
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{
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{
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