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Diffstat (limited to 'arch/arm64/include/asm/stacktrace/common.h')
| -rw-r--r-- | arch/arm64/include/asm/stacktrace/common.h | 171 |
1 files changed, 171 insertions, 0 deletions
diff --git a/arch/arm64/include/asm/stacktrace/common.h b/arch/arm64/include/asm/stacktrace/common.h new file mode 100644 index 000000000000..821a8fdd31af --- /dev/null +++ b/arch/arm64/include/asm/stacktrace/common.h @@ -0,0 +1,171 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Common arm64 stack unwinder code. + * + * See: arch/arm64/kernel/stacktrace.c for the reference implementation. + * + * Copyright (C) 2012 ARM Ltd. + */ +#ifndef __ASM_STACKTRACE_COMMON_H +#define __ASM_STACKTRACE_COMMON_H + +#include <linux/types.h> + +struct stack_info { + unsigned long low; + unsigned long high; +}; + +/** + * struct unwind_state - state used for robust unwinding. + * + * @fp: The fp value in the frame record (or the real fp) + * @pc: The lr value in the frame record (or the real lr) + * + * @stack: The stack currently being unwound. + * @stacks: An array of stacks which can be unwound. + * @nr_stacks: The number of stacks in @stacks. + */ +struct unwind_state { + unsigned long fp; + unsigned long pc; + + struct stack_info stack; + struct stack_info *stacks; + int nr_stacks; +}; + +static inline struct stack_info stackinfo_get_unknown(void) +{ + return (struct stack_info) { + .low = 0, + .high = 0, + }; +} + +static inline bool stackinfo_on_stack(const struct stack_info *info, + unsigned long sp, unsigned long size) +{ + if (!info->low) + return false; + + if (sp < info->low || sp + size < sp || sp + size > info->high) + return false; + + return true; +} + +static inline void unwind_init_common(struct unwind_state *state) +{ + state->stack = stackinfo_get_unknown(); +} + +/** + * unwind_find_stack() - Find the accessible stack which entirely contains an + * object. + * + * @state: the current unwind state. + * @sp: the base address of the object. + * @size: the size of the object. + * + * Return: a pointer to the relevant stack_info if found; NULL otherwise. + */ +static struct stack_info *unwind_find_stack(struct unwind_state *state, + unsigned long sp, + unsigned long size) +{ + struct stack_info *info = &state->stack; + + if (stackinfo_on_stack(info, sp, size)) + return info; + + for (int i = 0; i < state->nr_stacks; i++) { + info = &state->stacks[i]; + if (stackinfo_on_stack(info, sp, size)) + return info; + } + + return NULL; +} + +/** + * unwind_consume_stack() - Update stack boundaries so that future unwind steps + * cannot consume this object again. + * + * @state: the current unwind state. + * @info: the stack_info of the stack containing the object. + * @sp: the base address of the object. + * @size: the size of the object. + * + * Return: 0 upon success, an error code otherwise. + */ +static inline void unwind_consume_stack(struct unwind_state *state, + struct stack_info *info, + unsigned long sp, + unsigned long size) +{ + struct stack_info tmp; + + /* + * Stack transitions are strictly one-way, and once we've + * transitioned from one stack to another, it's never valid to + * unwind back to the old stack. + * + * Destroy the old stack info so that it cannot be found upon a + * subsequent transition. If the stack has not changed, we'll + * immediately restore the current stack info. + * + * Note that stacks can nest in several valid orders, e.g. + * + * TASK -> IRQ -> OVERFLOW -> SDEI_NORMAL + * TASK -> SDEI_NORMAL -> SDEI_CRITICAL -> OVERFLOW + * HYP -> OVERFLOW + * + * ... so we do not check the specific order of stack + * transitions. + */ + tmp = *info; + *info = stackinfo_get_unknown(); + state->stack = tmp; + + /* + * Future unwind steps can only consume stack above this frame record. + * Update the current stack to start immediately above it. + */ + state->stack.low = sp + size; +} + +/** + * unwind_next_frame_record() - Unwind to the next frame record. + * + * @state: the current unwind state. + * + * Return: 0 upon success, an error code otherwise. + */ +static inline int +unwind_next_frame_record(struct unwind_state *state) +{ + struct stack_info *info; + struct frame_record *record; + unsigned long fp = state->fp; + + if (fp & 0x7) + return -EINVAL; + + info = unwind_find_stack(state, fp, sizeof(*record)); + if (!info) + return -EINVAL; + + unwind_consume_stack(state, info, fp, sizeof(*record)); + + /* + * Record this frame record's values. + */ + record = (struct frame_record *)fp; + state->fp = READ_ONCE(record->fp); + state->pc = READ_ONCE(record->lr); + + return 0; +} + +#endif /* __ASM_STACKTRACE_COMMON_H */ |