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Diffstat (limited to 'arch/arm64/kernel/stacktrace.c')
| -rw-r--r-- | arch/arm64/kernel/stacktrace.c | 242 |
1 files changed, 242 insertions, 0 deletions
diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c new file mode 100644 index 000000000..17f66a74c --- /dev/null +++ b/arch/arm64/kernel/stacktrace.c @@ -0,0 +1,242 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Stack tracing support + * + * Copyright (C) 2012 ARM Ltd. + */ +#include <linux/kernel.h> +#include <linux/efi.h> +#include <linux/export.h> +#include <linux/ftrace.h> +#include <linux/sched.h> +#include <linux/sched/debug.h> +#include <linux/sched/task_stack.h> +#include <linux/stacktrace.h> + +#include <asm/efi.h> +#include <asm/irq.h> +#include <asm/stack_pointer.h> +#include <asm/stacktrace.h> + +/* + * Start an unwind from a pt_regs. + * + * The unwind will begin at the PC within the regs. + * + * The regs must be on a stack currently owned by the calling task. + */ +static __always_inline void +unwind_init_from_regs(struct unwind_state *state, + struct pt_regs *regs) +{ + unwind_init_common(state, current); + + state->fp = regs->regs[29]; + state->pc = regs->pc; +} + +/* + * Start an unwind from a caller. + * + * The unwind will begin at the caller of whichever function this is inlined + * into. + * + * The function which invokes this must be noinline. + */ +static __always_inline void +unwind_init_from_caller(struct unwind_state *state) +{ + unwind_init_common(state, current); + + state->fp = (unsigned long)__builtin_frame_address(1); + state->pc = (unsigned long)__builtin_return_address(0); +} + +/* + * Start an unwind from a blocked task. + * + * The unwind will begin at the blocked tasks saved PC (i.e. the caller of + * cpu_switch_to()). + * + * The caller should ensure the task is blocked in cpu_switch_to() for the + * duration of the unwind, or the unwind will be bogus. It is never valid to + * call this for the current task. + */ +static __always_inline void +unwind_init_from_task(struct unwind_state *state, + struct task_struct *task) +{ + unwind_init_common(state, task); + + state->fp = thread_saved_fp(task); + state->pc = thread_saved_pc(task); +} + +static __always_inline int +unwind_recover_return_address(struct unwind_state *state) +{ +#ifdef CONFIG_FUNCTION_GRAPH_TRACER + if (state->task->ret_stack && + (state->pc == (unsigned long)return_to_handler)) { + unsigned long orig_pc; + orig_pc = ftrace_graph_ret_addr(state->task, NULL, state->pc, + (void *)state->fp); + if (WARN_ON_ONCE(state->pc == orig_pc)) + return -EINVAL; + state->pc = orig_pc; + } +#endif /* CONFIG_FUNCTION_GRAPH_TRACER */ + +#ifdef CONFIG_KRETPROBES + if (is_kretprobe_trampoline(state->pc)) { + state->pc = kretprobe_find_ret_addr(state->task, + (void *)state->fp, + &state->kr_cur); + } +#endif /* CONFIG_KRETPROBES */ + + return 0; +} + +/* + * Unwind from one frame record (A) to the next frame record (B). + * + * We terminate early if the location of B indicates a malformed chain of frame + * records (e.g. a cycle), determined based on the location and fp value of A + * and the location (but not the fp value) of B. + */ +static __always_inline int +unwind_next(struct unwind_state *state) +{ + struct task_struct *tsk = state->task; + unsigned long fp = state->fp; + int err; + + /* Final frame; nothing to unwind */ + if (fp == (unsigned long)task_pt_regs(tsk)->stackframe) + return -ENOENT; + + err = unwind_next_frame_record(state); + if (err) + return err; + + state->pc = ptrauth_strip_kernel_insn_pac(state->pc); + + return unwind_recover_return_address(state); +} + +static __always_inline void +unwind(struct unwind_state *state, stack_trace_consume_fn consume_entry, + void *cookie) +{ + if (unwind_recover_return_address(state)) + return; + + while (1) { + int ret; + + if (!consume_entry(cookie, state->pc)) + break; + ret = unwind_next(state); + if (ret < 0) + break; + } +} + +/* + * Per-cpu stacks are only accessible when unwinding the current task in a + * non-preemptible context. + */ +#define STACKINFO_CPU(name) \ + ({ \ + ((task == current) && !preemptible()) \ + ? stackinfo_get_##name() \ + : stackinfo_get_unknown(); \ + }) + +/* + * SDEI stacks are only accessible when unwinding the current task in an NMI + * context. + */ +#define STACKINFO_SDEI(name) \ + ({ \ + ((task == current) && in_nmi()) \ + ? stackinfo_get_sdei_##name() \ + : stackinfo_get_unknown(); \ + }) + +#define STACKINFO_EFI \ + ({ \ + ((task == current) && current_in_efi()) \ + ? stackinfo_get_efi() \ + : stackinfo_get_unknown(); \ + }) + +noinline noinstr void arch_stack_walk(stack_trace_consume_fn consume_entry, + void *cookie, struct task_struct *task, + struct pt_regs *regs) +{ + struct stack_info stacks[] = { + stackinfo_get_task(task), + STACKINFO_CPU(irq), +#if defined(CONFIG_VMAP_STACK) + STACKINFO_CPU(overflow), +#endif +#if defined(CONFIG_VMAP_STACK) && defined(CONFIG_ARM_SDE_INTERFACE) + STACKINFO_SDEI(normal), + STACKINFO_SDEI(critical), +#endif +#ifdef CONFIG_EFI + STACKINFO_EFI, +#endif + }; + struct unwind_state state = { + .stacks = stacks, + .nr_stacks = ARRAY_SIZE(stacks), + }; + + if (regs) { + if (task != current) + return; + unwind_init_from_regs(&state, regs); + } else if (task == current) { + unwind_init_from_caller(&state); + } else { + unwind_init_from_task(&state, task); + } + + unwind(&state, consume_entry, cookie); +} + +static bool dump_backtrace_entry(void *arg, unsigned long where) +{ + char *loglvl = arg; + printk("%s %pSb\n", loglvl, (void *)where); + return true; +} + +void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk, + const char *loglvl) +{ + pr_debug("%s(regs = %p tsk = %p)\n", __func__, regs, tsk); + + if (regs && user_mode(regs)) + return; + + if (!tsk) + tsk = current; + + if (!try_get_task_stack(tsk)) + return; + + printk("%sCall trace:\n", loglvl); + arch_stack_walk(dump_backtrace_entry, (void *)loglvl, tsk, regs); + + put_task_stack(tsk); +} + +void show_stack(struct task_struct *tsk, unsigned long *sp, const char *loglvl) +{ + dump_backtrace(NULL, tsk, loglvl); + barrier(); +} |