| #include <linux/module.h> |
| #include <linux/sort.h> |
| #include <asm/ptrace.h> |
| #include <asm/stacktrace.h> |
| #include <asm/unwind.h> |
| #include <asm/orc_types.h> |
| #include <asm/orc_lookup.h> |
| #include <asm/sections.h> |
| |
| #define orc_warn(fmt, ...) \ |
| printk_deferred_once(KERN_WARNING pr_fmt("WARNING: " fmt), ##__VA_ARGS__) |
| |
| extern int __start_orc_unwind_ip[]; |
| extern int __stop_orc_unwind_ip[]; |
| extern struct orc_entry __start_orc_unwind[]; |
| extern struct orc_entry __stop_orc_unwind[]; |
| |
| static DEFINE_MUTEX(sort_mutex); |
| int *cur_orc_ip_table = __start_orc_unwind_ip; |
| struct orc_entry *cur_orc_table = __start_orc_unwind; |
| |
| unsigned int lookup_num_blocks; |
| bool orc_init; |
| |
| static inline unsigned long orc_ip(const int *ip) |
| { |
| return (unsigned long)ip + *ip; |
| } |
| |
| static struct orc_entry *__orc_find(int *ip_table, struct orc_entry *u_table, |
| unsigned int num_entries, unsigned long ip) |
| { |
| int *first = ip_table; |
| int *last = ip_table + num_entries - 1; |
| int *mid = first, *found = first; |
| |
| if (!num_entries) |
| return NULL; |
| |
| /* |
| * Do a binary range search to find the rightmost duplicate of a given |
| * starting address. Some entries are section terminators which are |
| * "weak" entries for ensuring there are no gaps. They should be |
| * ignored when they conflict with a real entry. |
| */ |
| while (first <= last) { |
| mid = first + ((last - first) / 2); |
| |
| if (orc_ip(mid) <= ip) { |
| found = mid; |
| first = mid + 1; |
| } else |
| last = mid - 1; |
| } |
| |
| return u_table + (found - ip_table); |
| } |
| |
| #ifdef CONFIG_MODULES |
| static struct orc_entry *orc_module_find(unsigned long ip) |
| { |
| struct module *mod; |
| |
| mod = __module_address(ip); |
| if (!mod || !mod->arch.orc_unwind || !mod->arch.orc_unwind_ip) |
| return NULL; |
| return __orc_find(mod->arch.orc_unwind_ip, mod->arch.orc_unwind, |
| mod->arch.num_orcs, ip); |
| } |
| #else |
| static struct orc_entry *orc_module_find(unsigned long ip) |
| { |
| return NULL; |
| } |
| #endif |
| |
| /* |
| * If we crash with IP==0, the last successfully executed instruction |
| * was probably an indirect function call with a NULL function pointer, |
| * and we don't have unwind information for NULL. |
| * This hardcoded ORC entry for IP==0 allows us to unwind from a NULL function |
| * pointer into its parent and then continue normally from there. |
| */ |
| static struct orc_entry null_orc_entry = { |
| .sp_offset = sizeof(long), |
| .sp_reg = ORC_REG_SP, |
| .bp_reg = ORC_REG_UNDEFINED, |
| .type = ORC_TYPE_CALL |
| }; |
| |
| static struct orc_entry *orc_find(unsigned long ip) |
| { |
| if (!orc_init) |
| return NULL; |
| |
| if (ip == 0) |
| return &null_orc_entry; |
| |
| /* For non-init vmlinux addresses, use the fast lookup table: */ |
| if (ip >= LOOKUP_START_IP && ip < LOOKUP_STOP_IP) { |
| unsigned int idx, start, stop; |
| |
| idx = (ip - LOOKUP_START_IP) / LOOKUP_BLOCK_SIZE; |
| |
| if (unlikely((idx >= lookup_num_blocks-1))) { |
| orc_warn("WARNING: bad lookup idx: idx=%u num=%u ip=%pB\n", |
| idx, lookup_num_blocks, (void *)ip); |
| return NULL; |
| } |
| |
| start = orc_lookup[idx]; |
| stop = orc_lookup[idx + 1] + 1; |
| |
| if (unlikely((__start_orc_unwind + start >= __stop_orc_unwind) || |
| (__start_orc_unwind + stop > __stop_orc_unwind))) { |
| orc_warn("WARNING: bad lookup value: idx=%u num=%u start=%u stop=%u ip=%pB\n", |
| idx, lookup_num_blocks, start, stop, (void *)ip); |
| return NULL; |
| } |
| |
| return __orc_find(__start_orc_unwind_ip + start, |
| __start_orc_unwind + start, stop - start, ip); |
| } |
| |
| /* vmlinux .init slow lookup: */ |
| if (ip >= (unsigned long)_sinittext && ip < (unsigned long)_einittext) |
| return __orc_find(__start_orc_unwind_ip, __start_orc_unwind, |
| __stop_orc_unwind_ip - __start_orc_unwind_ip, ip); |
| |
| /* Module lookup: */ |
| return orc_module_find(ip); |
| } |
| |
| static void orc_sort_swap(void *_a, void *_b, int size) |
| { |
| struct orc_entry *orc_a, *orc_b; |
| struct orc_entry orc_tmp; |
| int *a = _a, *b = _b, tmp; |
| int delta = _b - _a; |
| |
| /* Swap the .orc_unwind_ip entries: */ |
| tmp = *a; |
| *a = *b + delta; |
| *b = tmp - delta; |
| |
| /* Swap the corresponding .orc_unwind entries: */ |
| orc_a = cur_orc_table + (a - cur_orc_ip_table); |
| orc_b = cur_orc_table + (b - cur_orc_ip_table); |
| orc_tmp = *orc_a; |
| *orc_a = *orc_b; |
| *orc_b = orc_tmp; |
| } |
| |
| static int orc_sort_cmp(const void *_a, const void *_b) |
| { |
| struct orc_entry *orc_a; |
| const int *a = _a, *b = _b; |
| unsigned long a_val = orc_ip(a); |
| unsigned long b_val = orc_ip(b); |
| |
| if (a_val > b_val) |
| return 1; |
| if (a_val < b_val) |
| return -1; |
| |
| /* |
| * The "weak" section terminator entries need to always be on the left |
| * to ensure the lookup code skips them in favor of real entries. |
| * These terminator entries exist to handle any gaps created by |
| * whitelisted .o files which didn't get objtool generation. |
| */ |
| orc_a = cur_orc_table + (a - cur_orc_ip_table); |
| return orc_a->sp_reg == ORC_REG_UNDEFINED ? -1 : 1; |
| } |
| |
| #ifdef CONFIG_MODULES |
| void unwind_module_init(struct module *mod, void *_orc_ip, size_t orc_ip_size, |
| void *_orc, size_t orc_size) |
| { |
| int *orc_ip = _orc_ip; |
| struct orc_entry *orc = _orc; |
| unsigned int num_entries = orc_ip_size / sizeof(int); |
| |
| WARN_ON_ONCE(orc_ip_size % sizeof(int) != 0 || |
| orc_size % sizeof(*orc) != 0 || |
| num_entries != orc_size / sizeof(*orc)); |
| |
| /* |
| * The 'cur_orc_*' globals allow the orc_sort_swap() callback to |
| * associate an .orc_unwind_ip table entry with its corresponding |
| * .orc_unwind entry so they can both be swapped. |
| */ |
| mutex_lock(&sort_mutex); |
| cur_orc_ip_table = orc_ip; |
| cur_orc_table = orc; |
| sort(orc_ip, num_entries, sizeof(int), orc_sort_cmp, orc_sort_swap); |
| mutex_unlock(&sort_mutex); |
| |
| mod->arch.orc_unwind_ip = orc_ip; |
| mod->arch.orc_unwind = orc; |
| mod->arch.num_orcs = num_entries; |
| } |
| #endif |
| |
| void __init unwind_init(void) |
| { |
| size_t orc_ip_size = (void *)__stop_orc_unwind_ip - (void *)__start_orc_unwind_ip; |
| size_t orc_size = (void *)__stop_orc_unwind - (void *)__start_orc_unwind; |
| size_t num_entries = orc_ip_size / sizeof(int); |
| struct orc_entry *orc; |
| int i; |
| |
| if (!num_entries || orc_ip_size % sizeof(int) != 0 || |
| orc_size % sizeof(struct orc_entry) != 0 || |
| num_entries != orc_size / sizeof(struct orc_entry)) { |
| orc_warn("WARNING: Bad or missing .orc_unwind table. Disabling unwinder.\n"); |
| return; |
| } |
| |
| /* Sort the .orc_unwind and .orc_unwind_ip tables: */ |
| sort(__start_orc_unwind_ip, num_entries, sizeof(int), orc_sort_cmp, |
| orc_sort_swap); |
| |
| /* Initialize the fast lookup table: */ |
| lookup_num_blocks = orc_lookup_end - orc_lookup; |
| for (i = 0; i < lookup_num_blocks-1; i++) { |
| orc = __orc_find(__start_orc_unwind_ip, __start_orc_unwind, |
| num_entries, |
| LOOKUP_START_IP + (LOOKUP_BLOCK_SIZE * i)); |
| if (!orc) { |
| orc_warn("WARNING: Corrupt .orc_unwind table. Disabling unwinder.\n"); |
| return; |
| } |
| |
| orc_lookup[i] = orc - __start_orc_unwind; |
| } |
| |
| /* Initialize the ending block: */ |
| orc = __orc_find(__start_orc_unwind_ip, __start_orc_unwind, num_entries, |
| LOOKUP_STOP_IP); |
| if (!orc) { |
| orc_warn("WARNING: Corrupt .orc_unwind table. Disabling unwinder.\n"); |
| return; |
| } |
| orc_lookup[lookup_num_blocks-1] = orc - __start_orc_unwind; |
| |
| orc_init = true; |
| } |
| |
| unsigned long unwind_get_return_address(struct unwind_state *state) |
| { |
| if (unwind_done(state)) |
| return 0; |
| |
| return __kernel_text_address(state->ip) ? state->ip : 0; |
| } |
| EXPORT_SYMBOL_GPL(unwind_get_return_address); |
| |
| unsigned long *unwind_get_return_address_ptr(struct unwind_state *state) |
| { |
| if (unwind_done(state)) |
| return NULL; |
| |
| if (state->regs) |
| return &state->regs->ip; |
| |
| if (state->sp) |
| return (unsigned long *)state->sp - 1; |
| |
| return NULL; |
| } |
| |
| static bool stack_access_ok(struct unwind_state *state, unsigned long _addr, |
| size_t len) |
| { |
| struct stack_info *info = &state->stack_info; |
| void *addr = (void *)_addr; |
| |
| if (!on_stack(info, addr, len) && |
| (get_stack_info(addr, state->task, info, &state->stack_mask))) |
| return false; |
| |
| return true; |
| } |
| |
| static bool deref_stack_reg(struct unwind_state *state, unsigned long addr, |
| unsigned long *val) |
| { |
| if (!stack_access_ok(state, addr, sizeof(long))) |
| return false; |
| |
| *val = READ_ONCE_NOCHECK(*(unsigned long *)addr); |
| return true; |
| } |
| |
| static bool deref_stack_regs(struct unwind_state *state, unsigned long addr, |
| unsigned long *ip, unsigned long *sp) |
| { |
| struct pt_regs *regs = (struct pt_regs *)addr; |
| |
| /* x86-32 support will be more complicated due to the ®s->sp hack */ |
| BUILD_BUG_ON(IS_ENABLED(CONFIG_X86_32)); |
| |
| if (!stack_access_ok(state, addr, sizeof(struct pt_regs))) |
| return false; |
| |
| *ip = regs->ip; |
| *sp = regs->sp; |
| return true; |
| } |
| |
| static bool deref_stack_iret_regs(struct unwind_state *state, unsigned long addr, |
| unsigned long *ip, unsigned long *sp) |
| { |
| struct pt_regs *regs = (void *)addr - IRET_FRAME_OFFSET; |
| |
| if (!stack_access_ok(state, addr, IRET_FRAME_SIZE)) |
| return false; |
| |
| *ip = regs->ip; |
| *sp = regs->sp; |
| return true; |
| } |
| |
| bool unwind_next_frame(struct unwind_state *state) |
| { |
| unsigned long ip_p, sp, orig_ip, prev_sp = state->sp; |
| enum stack_type prev_type = state->stack_info.type; |
| struct orc_entry *orc; |
| bool indirect = false; |
| |
| if (unwind_done(state)) |
| return false; |
| |
| /* Don't let modules unload while we're reading their ORC data. */ |
| preempt_disable(); |
| |
| /* Have we reached the end? */ |
| if (state->regs && user_mode(state->regs)) |
| goto done; |
| |
| /* |
| * Find the orc_entry associated with the text address. |
| * |
| * Decrement call return addresses by one so they work for sibling |
| * calls and calls to noreturn functions. |
| */ |
| orc = orc_find(state->signal ? state->ip : state->ip - 1); |
| if (!orc || orc->sp_reg == ORC_REG_UNDEFINED) |
| goto done; |
| orig_ip = state->ip; |
| |
| /* Find the previous frame's stack: */ |
| switch (orc->sp_reg) { |
| case ORC_REG_SP: |
| sp = state->sp + orc->sp_offset; |
| break; |
| |
| case ORC_REG_BP: |
| sp = state->bp + orc->sp_offset; |
| break; |
| |
| case ORC_REG_SP_INDIRECT: |
| sp = state->sp + orc->sp_offset; |
| indirect = true; |
| break; |
| |
| case ORC_REG_BP_INDIRECT: |
| sp = state->bp + orc->sp_offset; |
| indirect = true; |
| break; |
| |
| case ORC_REG_R10: |
| if (!state->regs || !state->full_regs) { |
| orc_warn("missing regs for base reg R10 at ip %pB\n", |
| (void *)state->ip); |
| goto done; |
| } |
| sp = state->regs->r10; |
| break; |
| |
| case ORC_REG_R13: |
| if (!state->regs || !state->full_regs) { |
| orc_warn("missing regs for base reg R13 at ip %pB\n", |
| (void *)state->ip); |
| goto done; |
| } |
| sp = state->regs->r13; |
| break; |
| |
| case ORC_REG_DI: |
| if (!state->regs || !state->full_regs) { |
| orc_warn("missing regs for base reg DI at ip %pB\n", |
| (void *)state->ip); |
| goto done; |
| } |
| sp = state->regs->di; |
| break; |
| |
| case ORC_REG_DX: |
| if (!state->regs || !state->full_regs) { |
| orc_warn("missing regs for base reg DX at ip %pB\n", |
| (void *)state->ip); |
| goto done; |
| } |
| sp = state->regs->dx; |
| break; |
| |
| default: |
| orc_warn("unknown SP base reg %d for ip %pB\n", |
| orc->sp_reg, (void *)state->ip); |
| goto done; |
| } |
| |
| if (indirect) { |
| if (!deref_stack_reg(state, sp, &sp)) |
| goto done; |
| } |
| |
| /* Find IP, SP and possibly regs: */ |
| switch (orc->type) { |
| case ORC_TYPE_CALL: |
| ip_p = sp - sizeof(long); |
| |
| if (!deref_stack_reg(state, ip_p, &state->ip)) |
| goto done; |
| |
| state->ip = ftrace_graph_ret_addr(state->task, &state->graph_idx, |
| state->ip, (void *)ip_p); |
| |
| state->sp = sp; |
| state->regs = NULL; |
| state->signal = false; |
| break; |
| |
| case ORC_TYPE_REGS: |
| if (!deref_stack_regs(state, sp, &state->ip, &state->sp)) { |
| orc_warn("can't dereference registers at %p for ip %pB\n", |
| (void *)sp, (void *)orig_ip); |
| goto done; |
| } |
| |
| state->regs = (struct pt_regs *)sp; |
| state->full_regs = true; |
| state->signal = true; |
| break; |
| |
| case ORC_TYPE_REGS_IRET: |
| if (!deref_stack_iret_regs(state, sp, &state->ip, &state->sp)) { |
| orc_warn("can't dereference iret registers at %p for ip %pB\n", |
| (void *)sp, (void *)orig_ip); |
| goto done; |
| } |
| |
| state->regs = (void *)sp - IRET_FRAME_OFFSET; |
| state->full_regs = false; |
| state->signal = true; |
| break; |
| |
| default: |
| orc_warn("unknown .orc_unwind entry type %d for ip %pB\n", |
| orc->type, (void *)orig_ip); |
| break; |
| } |
| |
| /* Find BP: */ |
| switch (orc->bp_reg) { |
| case ORC_REG_UNDEFINED: |
| if (state->regs && state->full_regs) |
| state->bp = state->regs->bp; |
| break; |
| |
| case ORC_REG_PREV_SP: |
| if (!deref_stack_reg(state, sp + orc->bp_offset, &state->bp)) |
| goto done; |
| break; |
| |
| case ORC_REG_BP: |
| if (!deref_stack_reg(state, state->bp + orc->bp_offset, &state->bp)) |
| goto done; |
| break; |
| |
| default: |
| orc_warn("unknown BP base reg %d for ip %pB\n", |
| orc->bp_reg, (void *)orig_ip); |
| goto done; |
| } |
| |
| /* Prevent a recursive loop due to bad ORC data: */ |
| if (state->stack_info.type == prev_type && |
| on_stack(&state->stack_info, (void *)state->sp, sizeof(long)) && |
| state->sp <= prev_sp) { |
| orc_warn("stack going in the wrong direction? ip=%pB\n", |
| (void *)orig_ip); |
| goto done; |
| } |
| |
| preempt_enable(); |
| return true; |
| |
| done: |
| preempt_enable(); |
| state->stack_info.type = STACK_TYPE_UNKNOWN; |
| return false; |
| } |
| EXPORT_SYMBOL_GPL(unwind_next_frame); |
| |
| void __unwind_start(struct unwind_state *state, struct task_struct *task, |
| struct pt_regs *regs, unsigned long *first_frame) |
| { |
| memset(state, 0, sizeof(*state)); |
| state->task = task; |
| |
| /* |
| * Refuse to unwind the stack of a task while it's executing on another |
| * CPU. This check is racy, but that's ok: the unwinder has other |
| * checks to prevent it from going off the rails. |
| */ |
| if (task_on_another_cpu(task)) |
| goto done; |
| |
| if (regs) { |
| if (user_mode(regs)) |
| goto done; |
| |
| state->ip = regs->ip; |
| state->sp = kernel_stack_pointer(regs); |
| state->bp = regs->bp; |
| state->regs = regs; |
| state->full_regs = true; |
| state->signal = true; |
| |
| } else if (task == current) { |
| asm volatile("lea (%%rip), %0\n\t" |
| "mov %%rsp, %1\n\t" |
| "mov %%rbp, %2\n\t" |
| : "=r" (state->ip), "=r" (state->sp), |
| "=r" (state->bp)); |
| |
| } else { |
| struct inactive_task_frame *frame = (void *)task->thread.sp; |
| |
| state->sp = task->thread.sp; |
| state->bp = READ_ONCE_NOCHECK(frame->bp); |
| state->ip = READ_ONCE_NOCHECK(frame->ret_addr); |
| } |
| |
| if (get_stack_info((unsigned long *)state->sp, state->task, |
| &state->stack_info, &state->stack_mask)) { |
| /* |
| * We weren't on a valid stack. It's possible that |
| * we overflowed a valid stack into a guard page. |
| * See if the next page up is valid so that we can |
| * generate some kind of backtrace if this happens. |
| */ |
| void *next_page = (void *)PAGE_ALIGN((unsigned long)state->sp); |
| if (get_stack_info(next_page, state->task, &state->stack_info, |
| &state->stack_mask)) |
| return; |
| } |
| |
| /* |
| * The caller can provide the address of the first frame directly |
| * (first_frame) or indirectly (regs->sp) to indicate which stack frame |
| * to start unwinding at. Skip ahead until we reach it. |
| */ |
| |
| /* When starting from regs, skip the regs frame: */ |
| if (regs) { |
| unwind_next_frame(state); |
| return; |
| } |
| |
| /* Otherwise, skip ahead to the user-specified starting frame: */ |
| while (!unwind_done(state) && |
| (!on_stack(&state->stack_info, first_frame, sizeof(long)) || |
| state->sp <= (unsigned long)first_frame)) |
| unwind_next_frame(state); |
| |
| return; |
| |
| done: |
| state->stack_info.type = STACK_TYPE_UNKNOWN; |
| return; |
| } |
| EXPORT_SYMBOL_GPL(__unwind_start); |