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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162// SPDX-License-Identifier: GPL-2.0/** Generic interfaces for unwinding user space*/#include <linux/kernel.h>#include <linux/sched.h>#include <linux/sched/task_stack.h>#include <linux/unwind_user.h>#include <linux/uaccess.h>
#define for_each_user_frame(state) \ for (unwind_user_start(state); !(state)->done; unwind_user_next(state))
static inline intget_user_word(unsigned long *word, unsigned long base, int off, unsigned int ws){ unsigned long __user *addr = (void __user *)base + off;#ifdef CONFIG_COMPAT if (ws == sizeof(int)) { unsigned int data; int ret = get_user(data, (unsigned int __user *)addr); *word = data; return ret; }#endif return get_user(*word, addr);}
static int unwind_user_next_common(struct unwind_user_state *state, const struct unwind_user_frame *frame){ unsigned long cfa, fp, ra;
/* Get the Canonical Frame Address (CFA) */ if (frame->use_fp) { if (state->fp < state->sp) return -EINVAL; cfa = state->fp; } else { cfa = state->sp; } cfa += frame->cfa_off;
/* Make sure that stack is not going in wrong direction */ if (cfa <= state->sp) return -EINVAL;
/* Make sure that the address is word aligned */ if (cfa & (state->ws - 1)) return -EINVAL;
/* Get the Return Address (RA) */ if (get_user_word(&ra, cfa, frame->ra_off, state->ws)) return -EINVAL;
/* Get the Frame Pointer (FP) */ if (frame->fp_off && get_user_word(&fp, cfa, frame->fp_off, state->ws)) return -EINVAL;
state->ip = ra; state->sp = cfa; if (frame->fp_off) state->fp = fp; state->topmost = false; return 0;}
static int unwind_user_next_fp(struct unwind_user_state *state){ struct pt_regs *regs = task_pt_regs(current);
if (state->topmost && unwind_user_at_function_start(regs)) { const struct unwind_user_frame fp_entry_frame = { ARCH_INIT_USER_FP_ENTRY_FRAME(state->ws) }; return unwind_user_next_common(state, &fp_entry_frame); }
const struct unwind_user_frame fp_frame = { ARCH_INIT_USER_FP_FRAME(state->ws) }; return unwind_user_next_common(state, &fp_frame);}
static int unwind_user_next(struct unwind_user_state *state){ unsigned long iter_mask = state->available_types; unsigned int bit;
if (state->done) return -EINVAL;
for_each_set_bit(bit, &iter_mask, NR_UNWIND_USER_TYPE_BITS) { enum unwind_user_type type = BIT(bit);
state->current_type = type; switch (type) { case UNWIND_USER_TYPE_FP: if (!unwind_user_next_fp(state)) return 0; continue; default: WARN_ONCE(1, "Undefined unwind bit %d", bit); break; } break; }
/* No successful unwind method. */ state->current_type = UNWIND_USER_TYPE_NONE; state->done = true; return -EINVAL;}
static int unwind_user_start(struct unwind_user_state *state){ struct pt_regs *regs = task_pt_regs(current);
memset(state, 0, sizeof(*state));
if ((current->flags & PF_KTHREAD) || !user_mode(regs)) { state->done = true; return -EINVAL; }
if (IS_ENABLED(CONFIG_HAVE_UNWIND_USER_FP)) state->available_types |= UNWIND_USER_TYPE_FP;
state->ip = instruction_pointer(regs); state->sp = user_stack_pointer(regs); state->fp = frame_pointer(regs); state->ws = unwind_user_word_size(regs); if (!state->ws) { state->done = true; return -EINVAL; } state->topmost = true;
return 0;}
int unwind_user(struct unwind_stacktrace *trace, unsigned int max_entries){ struct unwind_user_state state;
trace->nr = 0;
if (!max_entries) return -EINVAL;
if (current->flags & PF_KTHREAD) return 0;
for_each_user_frame(&state) { trace->entries[trace->nr++] = state.ip; if (trace->nr >= max_entries) break; }
return 0;}