diff options
Diffstat (limited to 'arch/arm/kernel/stacktrace.c')
| -rw-r--r-- | arch/arm/kernel/stacktrace.c | 197 |
1 files changed, 197 insertions, 0 deletions
diff --git a/arch/arm/kernel/stacktrace.c b/arch/arm/kernel/stacktrace.c new file mode 100644 index 0000000000..620aa82e3b --- /dev/null +++ b/arch/arm/kernel/stacktrace.c @@ -0,0 +1,197 @@ +// SPDX-License-Identifier: GPL-2.0-only +#include <linux/export.h> +#include <linux/kprobes.h> +#include <linux/sched.h> +#include <linux/sched/debug.h> +#include <linux/stacktrace.h> + +#include <asm/sections.h> +#include <asm/stacktrace.h> +#include <asm/traps.h> + +#include "reboot.h" + +#if defined(CONFIG_FRAME_POINTER) && !defined(CONFIG_ARM_UNWIND) +/* + * Unwind the current stack frame and store the new register values in the + * structure passed as argument. Unwinding is equivalent to a function return, + * hence the new PC value rather than LR should be used for backtrace. + * + * With framepointer enabled, a simple function prologue looks like this: + * mov ip, sp + * stmdb sp!, {fp, ip, lr, pc} + * sub fp, ip, #4 + * + * A simple function epilogue looks like this: + * ldm sp, {fp, sp, pc} + * + * When compiled with clang, pc and sp are not pushed. A simple function + * prologue looks like this when built with clang: + * + * stmdb {..., fp, lr} + * add fp, sp, #x + * sub sp, sp, #y + * + * A simple function epilogue looks like this when built with clang: + * + * sub sp, fp, #x + * ldm {..., fp, pc} + * + * + * Note that with framepointer enabled, even the leaf functions have the same + * prologue and epilogue, therefore we can ignore the LR value in this case. + */ + +extern unsigned long call_with_stack_end; + +static int frame_pointer_check(struct stackframe *frame) +{ + unsigned long high, low; + unsigned long fp = frame->fp; + unsigned long pc = frame->pc; + + /* + * call_with_stack() is the only place we allow SP to jump from one + * stack to another, with FP and SP pointing to different stacks, + * skipping the FP boundary check at this point. + */ + if (pc >= (unsigned long)&call_with_stack && + pc < (unsigned long)&call_with_stack_end) + return 0; + + /* only go to a higher address on the stack */ + low = frame->sp; + high = ALIGN(low, THREAD_SIZE); + + /* check current frame pointer is within bounds */ +#ifdef CONFIG_CC_IS_CLANG + if (fp < low + 4 || fp > high - 4) + return -EINVAL; +#else + if (fp < low + 12 || fp > high - 4) + return -EINVAL; +#endif + + return 0; +} + +int notrace unwind_frame(struct stackframe *frame) +{ + unsigned long fp = frame->fp; + + if (frame_pointer_check(frame)) + return -EINVAL; + + /* + * When we unwind through an exception stack, include the saved PC + * value into the stack trace. + */ + if (frame->ex_frame) { + struct pt_regs *regs = (struct pt_regs *)frame->sp; + + /* + * We check that 'regs + sizeof(struct pt_regs)' (that is, + * ®s[1]) does not exceed the bottom of the stack to avoid + * accessing data outside the task's stack. This may happen + * when frame->ex_frame is a false positive. + */ + if ((unsigned long)®s[1] > ALIGN(frame->sp, THREAD_SIZE)) + return -EINVAL; + + frame->pc = regs->ARM_pc; + frame->ex_frame = false; + return 0; + } + + /* restore the registers from the stack frame */ +#ifdef CONFIG_CC_IS_CLANG + frame->sp = frame->fp; + frame->fp = READ_ONCE_NOCHECK(*(unsigned long *)(fp)); + frame->pc = READ_ONCE_NOCHECK(*(unsigned long *)(fp + 4)); +#else + frame->fp = READ_ONCE_NOCHECK(*(unsigned long *)(fp - 12)); + frame->sp = READ_ONCE_NOCHECK(*(unsigned long *)(fp - 8)); + frame->pc = READ_ONCE_NOCHECK(*(unsigned long *)(fp - 4)); +#endif +#ifdef CONFIG_KRETPROBES + if (is_kretprobe_trampoline(frame->pc)) + frame->pc = kretprobe_find_ret_addr(frame->tsk, + (void *)frame->fp, &frame->kr_cur); +#endif + + if (in_entry_text(frame->pc)) + frame->ex_frame = true; + + return 0; +} +#endif + +void notrace walk_stackframe(struct stackframe *frame, + bool (*fn)(void *, unsigned long), void *data) +{ + while (1) { + int ret; + + if (!fn(data, frame->pc)) + break; + ret = unwind_frame(frame); + if (ret < 0) + break; + } +} +EXPORT_SYMBOL(walk_stackframe); + +#ifdef CONFIG_STACKTRACE +static void start_stack_trace(struct stackframe *frame, struct task_struct *task, + unsigned long fp, unsigned long sp, + unsigned long lr, unsigned long pc) +{ + frame->fp = fp; + frame->sp = sp; + frame->lr = lr; + frame->pc = pc; +#ifdef CONFIG_KRETPROBES + frame->kr_cur = NULL; + frame->tsk = task; +#endif +#ifdef CONFIG_UNWINDER_FRAME_POINTER + frame->ex_frame = in_entry_text(frame->pc); +#endif +} + +void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie, + struct task_struct *task, struct pt_regs *regs) +{ + struct stackframe frame; + + if (regs) { + start_stack_trace(&frame, NULL, regs->ARM_fp, regs->ARM_sp, + regs->ARM_lr, regs->ARM_pc); + } else if (task != current) { +#ifdef CONFIG_SMP + /* + * What guarantees do we have here that 'tsk' is not + * running on another CPU? For now, ignore it as we + * can't guarantee we won't explode. + */ + return; +#else + start_stack_trace(&frame, task, thread_saved_fp(task), + thread_saved_sp(task), 0, + thread_saved_pc(task)); +#endif + } else { +here: + start_stack_trace(&frame, task, + (unsigned long)__builtin_frame_address(0), + current_stack_pointer, + (unsigned long)__builtin_return_address(0), + (unsigned long)&&here); + /* skip this function */ + if (unwind_frame(&frame)) + return; + } + + walk_stackframe(&frame, consume_entry, cookie); +} +#endif |