diff options
Diffstat (limited to 'arch/arm64/include/asm/stacktrace')
| -rw-r--r-- | arch/arm64/include/asm/stacktrace/common.h | 176 | ||||
| -rw-r--r-- | arch/arm64/include/asm/stacktrace/nvhe.h | 55 |
2 files changed, 231 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 000000000..508f734de --- /dev/null +++ b/arch/arm64/include/asm/stacktrace/common.h @@ -0,0 +1,176 @@ +/* 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/kprobes.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) + * + * @kr_cur: When KRETPROBES is selected, holds the kretprobe instance + * associated with the most recently encountered replacement lr + * value. + * + * @task: The task being unwound. + * + * @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; +#ifdef CONFIG_KRETPROBES + struct llist_node *kr_cur; +#endif + struct task_struct *task; + + 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, + struct task_struct *task) +{ + state->task = task; +#ifdef CONFIG_KRETPROBES + state->kr_cur = NULL; +#endif + + state->stack = stackinfo_get_unknown(); +} + +static struct stack_info *unwind_find_next_stack(const struct unwind_state *state, + unsigned long sp, + unsigned long size) +{ + for (int i = 0; i < state->nr_stacks; i++) { + struct stack_info *info = &state->stacks[i]; + + if (stackinfo_on_stack(info, sp, size)) + return info; + } + + return NULL; +} + +/** + * unwind_consume_stack() - Check if an object is on an accessible stack, + * updating stack boundaries so that future unwind steps cannot consume this + * object again. + * + * @state: the current unwind state. + * @sp: the base address of the object. + * @size: the size of the object. + * + * Return: 0 upon success, an error code otherwise. + */ +static inline int unwind_consume_stack(struct unwind_state *state, + unsigned long sp, + unsigned long size) +{ + struct stack_info *next; + + if (stackinfo_on_stack(&state->stack, sp, size)) + goto found; + + next = unwind_find_next_stack(state, sp, size); + if (!next) + return -EINVAL; + + /* + * 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. + * + * Remove the current stack from the list of stacks so that it cannot + * be found on a subsequent transition. + * + * 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. + */ + state->stack = *next; + *next = stackinfo_get_unknown(); + +found: + /* + * 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; + return 0; +} + +/** + * 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) +{ + unsigned long fp = state->fp; + int err; + + if (fp & 0x7) + return -EINVAL; + + err = unwind_consume_stack(state, fp, 16); + if (err) + return err; + + /* + * Record this frame record's values. + */ + state->fp = READ_ONCE(*(unsigned long *)(fp)); + state->pc = READ_ONCE(*(unsigned long *)(fp + 8)); + + return 0; +} + +#endif /* __ASM_STACKTRACE_COMMON_H */ diff --git a/arch/arm64/include/asm/stacktrace/nvhe.h b/arch/arm64/include/asm/stacktrace/nvhe.h new file mode 100644 index 000000000..25ab83a31 --- /dev/null +++ b/arch/arm64/include/asm/stacktrace/nvhe.h @@ -0,0 +1,55 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * KVM nVHE hypervisor stack tracing support. + * + * The unwinder implementation depends on the nVHE mode: + * + * 1) Non-protected nVHE mode - the host can directly access the + * HYP stack pages and unwind the HYP stack in EL1. This saves having + * to allocate shared buffers for the host to read the unwinded + * stacktrace. + * + * 2) pKVM (protected nVHE) mode - the host cannot directly access + * the HYP memory. The stack is unwinded in EL2 and dumped to a shared + * buffer where the host can read and print the stacktrace. + * + * Copyright (C) 2022 Google LLC + */ +#ifndef __ASM_STACKTRACE_NVHE_H +#define __ASM_STACKTRACE_NVHE_H + +#include <asm/stacktrace/common.h> + +/** + * kvm_nvhe_unwind_init() - Start an unwind from the given nVHE HYP fp and pc + * + * @state : unwind_state to initialize + * @fp : frame pointer at which to start the unwinding. + * @pc : program counter at which to start the unwinding. + */ +static inline void kvm_nvhe_unwind_init(struct unwind_state *state, + unsigned long fp, + unsigned long pc) +{ + unwind_init_common(state, NULL); + + state->fp = fp; + state->pc = pc; +} + +#ifndef __KVM_NVHE_HYPERVISOR__ +/* + * Conventional (non-protected) nVHE HYP stack unwinder + * + * In non-protected mode, the unwinding is done from kernel proper context + * (by the host in EL1). + */ + +DECLARE_KVM_NVHE_PER_CPU(unsigned long [OVERFLOW_STACK_SIZE/sizeof(long)], overflow_stack); +DECLARE_KVM_NVHE_PER_CPU(struct kvm_nvhe_stacktrace_info, kvm_stacktrace_info); +DECLARE_PER_CPU(unsigned long, kvm_arm_hyp_stack_page); + +void kvm_nvhe_dump_backtrace(unsigned long hyp_offset); + +#endif /* __KVM_NVHE_HYPERVISOR__ */ +#endif /* __ASM_STACKTRACE_NVHE_H */ |