diff options
Diffstat (limited to 'arch/arm/kernel/stacktrace.c')
| -rw-r--r-- | arch/arm/kernel/stacktrace.c | 191 |
1 files changed, 191 insertions, 0 deletions
diff --git a/arch/arm/kernel/stacktrace.c b/arch/arm/kernel/stacktrace.c new file mode 100644 index 000000000..824774999 --- /dev/null +++ b/arch/arm/kernel/stacktrace.c @@ -0,0 +1,191 @@ +// SPDX-License-Identifier: GPL-2.0-only +#include <linux/export.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> + +#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. + */ +int notrace unwind_frame(struct stackframe *frame) +{ + unsigned long high, low; + unsigned long fp = frame->fp; + + /* only go to a higher address on the stack */ + low = frame->sp; + high = ALIGN(low, THREAD_SIZE); + +#ifdef CONFIG_CC_IS_CLANG + /* check current frame pointer is within bounds */ + if (fp < low + 4 || fp > high - 4) + return -EINVAL; + + frame->sp = frame->fp; + frame->fp = READ_ONCE_NOCHECK(*(unsigned long *)(fp)); + frame->pc = READ_ONCE_NOCHECK(*(unsigned long *)(fp + 4)); +#else + /* check current frame pointer is within bounds */ + if (fp < low + 12 || fp > high - 4) + return -EINVAL; + + /* restore the registers from the stack frame */ + 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 + + return 0; +} +#endif + +void notrace walk_stackframe(struct stackframe *frame, + int (*fn)(struct stackframe *, void *), void *data) +{ + while (1) { + int ret; + + if (fn(frame, data)) + break; + ret = unwind_frame(frame); + if (ret < 0) + break; + } +} +EXPORT_SYMBOL(walk_stackframe); + +#ifdef CONFIG_STACKTRACE +struct stack_trace_data { + struct stack_trace *trace; + unsigned int no_sched_functions; + unsigned int skip; +}; + +static int save_trace(struct stackframe *frame, void *d) +{ + struct stack_trace_data *data = d; + struct stack_trace *trace = data->trace; + struct pt_regs *regs; + unsigned long addr = frame->pc; + + if (data->no_sched_functions && in_sched_functions(addr)) + return 0; + if (data->skip) { + data->skip--; + return 0; + } + + trace->entries[trace->nr_entries++] = addr; + + if (trace->nr_entries >= trace->max_entries) + return 1; + + if (!in_entry_text(frame->pc)) + return 0; + + regs = (struct pt_regs *)frame->sp; + if ((unsigned long)®s[1] > ALIGN(frame->sp, THREAD_SIZE)) + return 0; + + trace->entries[trace->nr_entries++] = regs->ARM_pc; + + return trace->nr_entries >= trace->max_entries; +} + +/* This must be noinline to so that our skip calculation works correctly */ +static noinline void __save_stack_trace(struct task_struct *tsk, + struct stack_trace *trace, unsigned int nosched) +{ + struct stack_trace_data data; + struct stackframe frame; + + data.trace = trace; + data.skip = trace->skip; + data.no_sched_functions = nosched; + + if (tsk != 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 + frame.fp = thread_saved_fp(tsk); + frame.sp = thread_saved_sp(tsk); + frame.lr = 0; /* recovered from the stack */ + frame.pc = thread_saved_pc(tsk); +#endif + } else { + /* We don't want this function nor the caller */ + data.skip += 2; + frame.fp = (unsigned long)__builtin_frame_address(0); + frame.sp = current_stack_pointer; + frame.lr = (unsigned long)__builtin_return_address(0); + frame.pc = (unsigned long)__save_stack_trace; + } + + walk_stackframe(&frame, save_trace, &data); +} + +void save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace) +{ + struct stack_trace_data data; + struct stackframe frame; + + data.trace = trace; + data.skip = trace->skip; + data.no_sched_functions = 0; + + frame.fp = regs->ARM_fp; + frame.sp = regs->ARM_sp; + frame.lr = regs->ARM_lr; + frame.pc = regs->ARM_pc; + + walk_stackframe(&frame, save_trace, &data); +} + +void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace) +{ + __save_stack_trace(tsk, trace, 1); +} +EXPORT_SYMBOL(save_stack_trace_tsk); + +void save_stack_trace(struct stack_trace *trace) +{ + __save_stack_trace(current, trace, 0); +} +EXPORT_SYMBOL_GPL(save_stack_trace); +#endif |