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708 lines
18 KiB
708 lines
18 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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#include <linux/objtool.h> |
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#include <linux/module.h> |
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#include <linux/sort.h> |
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#include <asm/ptrace.h> |
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#include <asm/stacktrace.h> |
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#include <asm/unwind.h> |
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#include <asm/orc_types.h> |
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#include <asm/orc_lookup.h> |
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|
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#define orc_warn(fmt, ...) \ |
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printk_deferred_once(KERN_WARNING "WARNING: " fmt, ##__VA_ARGS__) |
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|
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#define orc_warn_current(args...) \ |
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({ \ |
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if (state->task == current && !state->error) \ |
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orc_warn(args); \ |
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}) |
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|
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extern int __start_orc_unwind_ip[]; |
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extern int __stop_orc_unwind_ip[]; |
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extern struct orc_entry __start_orc_unwind[]; |
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extern struct orc_entry __stop_orc_unwind[]; |
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|
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static bool orc_init __ro_after_init; |
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static unsigned int lookup_num_blocks __ro_after_init; |
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|
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static inline unsigned long orc_ip(const int *ip) |
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{ |
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return (unsigned long)ip + *ip; |
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} |
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static struct orc_entry *__orc_find(int *ip_table, struct orc_entry *u_table, |
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unsigned int num_entries, unsigned long ip) |
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{ |
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int *first = ip_table; |
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int *last = ip_table + num_entries - 1; |
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int *mid = first, *found = first; |
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|
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if (!num_entries) |
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return NULL; |
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|
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/* |
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* Do a binary range search to find the rightmost duplicate of a given |
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* starting address. Some entries are section terminators which are |
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* "weak" entries for ensuring there are no gaps. They should be |
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* ignored when they conflict with a real entry. |
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*/ |
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while (first <= last) { |
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mid = first + ((last - first) / 2); |
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|
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if (orc_ip(mid) <= ip) { |
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found = mid; |
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first = mid + 1; |
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} else |
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last = mid - 1; |
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} |
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return u_table + (found - ip_table); |
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} |
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#ifdef CONFIG_MODULES |
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static struct orc_entry *orc_module_find(unsigned long ip) |
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{ |
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struct module *mod; |
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|
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mod = __module_address(ip); |
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if (!mod || !mod->arch.orc_unwind || !mod->arch.orc_unwind_ip) |
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return NULL; |
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return __orc_find(mod->arch.orc_unwind_ip, mod->arch.orc_unwind, |
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mod->arch.num_orcs, ip); |
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} |
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#else |
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static struct orc_entry *orc_module_find(unsigned long ip) |
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{ |
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return NULL; |
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} |
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#endif |
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#ifdef CONFIG_DYNAMIC_FTRACE |
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static struct orc_entry *orc_find(unsigned long ip); |
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|
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/* |
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* Ftrace dynamic trampolines do not have orc entries of their own. |
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* But they are copies of the ftrace entries that are static and |
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* defined in ftrace_*.S, which do have orc entries. |
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* |
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* If the unwinder comes across a ftrace trampoline, then find the |
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* ftrace function that was used to create it, and use that ftrace |
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* function's orc entry, as the placement of the return code in |
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* the stack will be identical. |
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*/ |
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static struct orc_entry *orc_ftrace_find(unsigned long ip) |
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{ |
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struct ftrace_ops *ops; |
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unsigned long caller; |
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ops = ftrace_ops_trampoline(ip); |
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if (!ops) |
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return NULL; |
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if (ops->flags & FTRACE_OPS_FL_SAVE_REGS) |
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caller = (unsigned long)ftrace_regs_call; |
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else |
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caller = (unsigned long)ftrace_call; |
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/* Prevent unlikely recursion */ |
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if (ip == caller) |
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return NULL; |
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return orc_find(caller); |
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} |
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#else |
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static struct orc_entry *orc_ftrace_find(unsigned long ip) |
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{ |
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return NULL; |
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} |
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#endif |
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/* |
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* If we crash with IP==0, the last successfully executed instruction |
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* was probably an indirect function call with a NULL function pointer, |
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* and we don't have unwind information for NULL. |
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* This hardcoded ORC entry for IP==0 allows us to unwind from a NULL function |
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* pointer into its parent and then continue normally from there. |
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*/ |
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static struct orc_entry null_orc_entry = { |
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.sp_offset = sizeof(long), |
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.sp_reg = ORC_REG_SP, |
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.bp_reg = ORC_REG_UNDEFINED, |
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.type = UNWIND_HINT_TYPE_CALL |
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}; |
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/* Fake frame pointer entry -- used as a fallback for generated code */ |
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static struct orc_entry orc_fp_entry = { |
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.type = UNWIND_HINT_TYPE_CALL, |
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.sp_reg = ORC_REG_BP, |
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.sp_offset = 16, |
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.bp_reg = ORC_REG_PREV_SP, |
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.bp_offset = -16, |
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.end = 0, |
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}; |
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static struct orc_entry *orc_find(unsigned long ip) |
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{ |
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static struct orc_entry *orc; |
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if (ip == 0) |
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return &null_orc_entry; |
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/* For non-init vmlinux addresses, use the fast lookup table: */ |
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if (ip >= LOOKUP_START_IP && ip < LOOKUP_STOP_IP) { |
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unsigned int idx, start, stop; |
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idx = (ip - LOOKUP_START_IP) / LOOKUP_BLOCK_SIZE; |
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if (unlikely((idx >= lookup_num_blocks-1))) { |
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orc_warn("WARNING: bad lookup idx: idx=%u num=%u ip=%pB\n", |
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idx, lookup_num_blocks, (void *)ip); |
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return NULL; |
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} |
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start = orc_lookup[idx]; |
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stop = orc_lookup[idx + 1] + 1; |
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if (unlikely((__start_orc_unwind + start >= __stop_orc_unwind) || |
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(__start_orc_unwind + stop > __stop_orc_unwind))) { |
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orc_warn("WARNING: bad lookup value: idx=%u num=%u start=%u stop=%u ip=%pB\n", |
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idx, lookup_num_blocks, start, stop, (void *)ip); |
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return NULL; |
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} |
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return __orc_find(__start_orc_unwind_ip + start, |
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__start_orc_unwind + start, stop - start, ip); |
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} |
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/* vmlinux .init slow lookup: */ |
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if (init_kernel_text(ip)) |
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return __orc_find(__start_orc_unwind_ip, __start_orc_unwind, |
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__stop_orc_unwind_ip - __start_orc_unwind_ip, ip); |
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/* Module lookup: */ |
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orc = orc_module_find(ip); |
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if (orc) |
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return orc; |
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return orc_ftrace_find(ip); |
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} |
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#ifdef CONFIG_MODULES |
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static DEFINE_MUTEX(sort_mutex); |
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static int *cur_orc_ip_table = __start_orc_unwind_ip; |
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static struct orc_entry *cur_orc_table = __start_orc_unwind; |
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static void orc_sort_swap(void *_a, void *_b, int size) |
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{ |
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struct orc_entry *orc_a, *orc_b; |
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struct orc_entry orc_tmp; |
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int *a = _a, *b = _b, tmp; |
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int delta = _b - _a; |
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|
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/* Swap the .orc_unwind_ip entries: */ |
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tmp = *a; |
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*a = *b + delta; |
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*b = tmp - delta; |
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/* Swap the corresponding .orc_unwind entries: */ |
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orc_a = cur_orc_table + (a - cur_orc_ip_table); |
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orc_b = cur_orc_table + (b - cur_orc_ip_table); |
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orc_tmp = *orc_a; |
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*orc_a = *orc_b; |
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*orc_b = orc_tmp; |
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} |
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static int orc_sort_cmp(const void *_a, const void *_b) |
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{ |
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struct orc_entry *orc_a; |
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const int *a = _a, *b = _b; |
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unsigned long a_val = orc_ip(a); |
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unsigned long b_val = orc_ip(b); |
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if (a_val > b_val) |
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return 1; |
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if (a_val < b_val) |
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return -1; |
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/* |
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* The "weak" section terminator entries need to always be on the left |
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* to ensure the lookup code skips them in favor of real entries. |
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* These terminator entries exist to handle any gaps created by |
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* whitelisted .o files which didn't get objtool generation. |
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*/ |
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orc_a = cur_orc_table + (a - cur_orc_ip_table); |
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return orc_a->sp_reg == ORC_REG_UNDEFINED && !orc_a->end ? -1 : 1; |
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} |
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void unwind_module_init(struct module *mod, void *_orc_ip, size_t orc_ip_size, |
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void *_orc, size_t orc_size) |
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{ |
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int *orc_ip = _orc_ip; |
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struct orc_entry *orc = _orc; |
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unsigned int num_entries = orc_ip_size / sizeof(int); |
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WARN_ON_ONCE(orc_ip_size % sizeof(int) != 0 || |
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orc_size % sizeof(*orc) != 0 || |
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num_entries != orc_size / sizeof(*orc)); |
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/* |
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* The 'cur_orc_*' globals allow the orc_sort_swap() callback to |
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* associate an .orc_unwind_ip table entry with its corresponding |
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* .orc_unwind entry so they can both be swapped. |
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*/ |
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mutex_lock(&sort_mutex); |
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cur_orc_ip_table = orc_ip; |
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cur_orc_table = orc; |
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sort(orc_ip, num_entries, sizeof(int), orc_sort_cmp, orc_sort_swap); |
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mutex_unlock(&sort_mutex); |
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mod->arch.orc_unwind_ip = orc_ip; |
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mod->arch.orc_unwind = orc; |
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mod->arch.num_orcs = num_entries; |
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} |
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#endif |
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void __init unwind_init(void) |
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{ |
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size_t orc_ip_size = (void *)__stop_orc_unwind_ip - (void *)__start_orc_unwind_ip; |
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size_t orc_size = (void *)__stop_orc_unwind - (void *)__start_orc_unwind; |
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size_t num_entries = orc_ip_size / sizeof(int); |
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struct orc_entry *orc; |
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int i; |
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if (!num_entries || orc_ip_size % sizeof(int) != 0 || |
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orc_size % sizeof(struct orc_entry) != 0 || |
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num_entries != orc_size / sizeof(struct orc_entry)) { |
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orc_warn("WARNING: Bad or missing .orc_unwind table. Disabling unwinder.\n"); |
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return; |
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} |
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/* |
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* Note, the orc_unwind and orc_unwind_ip tables were already |
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* sorted at build time via the 'sorttable' tool. |
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* It's ready for binary search straight away, no need to sort it. |
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*/ |
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/* Initialize the fast lookup table: */ |
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lookup_num_blocks = orc_lookup_end - orc_lookup; |
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for (i = 0; i < lookup_num_blocks-1; i++) { |
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orc = __orc_find(__start_orc_unwind_ip, __start_orc_unwind, |
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num_entries, |
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LOOKUP_START_IP + (LOOKUP_BLOCK_SIZE * i)); |
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if (!orc) { |
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orc_warn("WARNING: Corrupt .orc_unwind table. Disabling unwinder.\n"); |
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return; |
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} |
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orc_lookup[i] = orc - __start_orc_unwind; |
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} |
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/* Initialize the ending block: */ |
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orc = __orc_find(__start_orc_unwind_ip, __start_orc_unwind, num_entries, |
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LOOKUP_STOP_IP); |
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if (!orc) { |
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orc_warn("WARNING: Corrupt .orc_unwind table. Disabling unwinder.\n"); |
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return; |
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} |
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orc_lookup[lookup_num_blocks-1] = orc - __start_orc_unwind; |
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orc_init = true; |
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} |
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unsigned long unwind_get_return_address(struct unwind_state *state) |
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{ |
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if (unwind_done(state)) |
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return 0; |
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return __kernel_text_address(state->ip) ? state->ip : 0; |
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} |
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EXPORT_SYMBOL_GPL(unwind_get_return_address); |
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unsigned long *unwind_get_return_address_ptr(struct unwind_state *state) |
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{ |
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if (unwind_done(state)) |
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return NULL; |
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if (state->regs) |
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return &state->regs->ip; |
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if (state->sp) |
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return (unsigned long *)state->sp - 1; |
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return NULL; |
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} |
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static bool stack_access_ok(struct unwind_state *state, unsigned long _addr, |
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size_t len) |
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{ |
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struct stack_info *info = &state->stack_info; |
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void *addr = (void *)_addr; |
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if (!on_stack(info, addr, len) && |
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(get_stack_info(addr, state->task, info, &state->stack_mask))) |
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return false; |
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return true; |
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} |
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static bool deref_stack_reg(struct unwind_state *state, unsigned long addr, |
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unsigned long *val) |
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{ |
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if (!stack_access_ok(state, addr, sizeof(long))) |
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return false; |
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*val = READ_ONCE_NOCHECK(*(unsigned long *)addr); |
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return true; |
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} |
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static bool deref_stack_regs(struct unwind_state *state, unsigned long addr, |
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unsigned long *ip, unsigned long *sp) |
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{ |
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struct pt_regs *regs = (struct pt_regs *)addr; |
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|
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/* x86-32 support will be more complicated due to the ®s->sp hack */ |
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BUILD_BUG_ON(IS_ENABLED(CONFIG_X86_32)); |
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if (!stack_access_ok(state, addr, sizeof(struct pt_regs))) |
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return false; |
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*ip = READ_ONCE_NOCHECK(regs->ip); |
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*sp = READ_ONCE_NOCHECK(regs->sp); |
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return true; |
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} |
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static bool deref_stack_iret_regs(struct unwind_state *state, unsigned long addr, |
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unsigned long *ip, unsigned long *sp) |
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{ |
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struct pt_regs *regs = (void *)addr - IRET_FRAME_OFFSET; |
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if (!stack_access_ok(state, addr, IRET_FRAME_SIZE)) |
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return false; |
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*ip = READ_ONCE_NOCHECK(regs->ip); |
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*sp = READ_ONCE_NOCHECK(regs->sp); |
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return true; |
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} |
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|
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/* |
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* If state->regs is non-NULL, and points to a full pt_regs, just get the reg |
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* value from state->regs. |
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* |
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* Otherwise, if state->regs just points to IRET regs, and the previous frame |
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* had full regs, it's safe to get the value from the previous regs. This can |
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* happen when early/late IRQ entry code gets interrupted by an NMI. |
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*/ |
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static bool get_reg(struct unwind_state *state, unsigned int reg_off, |
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unsigned long *val) |
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{ |
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unsigned int reg = reg_off/8; |
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if (!state->regs) |
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return false; |
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if (state->full_regs) { |
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*val = READ_ONCE_NOCHECK(((unsigned long *)state->regs)[reg]); |
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return true; |
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} |
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if (state->prev_regs) { |
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*val = READ_ONCE_NOCHECK(((unsigned long *)state->prev_regs)[reg]); |
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return true; |
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} |
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return false; |
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} |
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bool unwind_next_frame(struct unwind_state *state) |
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{ |
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unsigned long ip_p, sp, tmp, orig_ip = state->ip, prev_sp = state->sp; |
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enum stack_type prev_type = state->stack_info.type; |
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struct orc_entry *orc; |
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bool indirect = false; |
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if (unwind_done(state)) |
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return false; |
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/* Don't let modules unload while we're reading their ORC data. */ |
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preempt_disable(); |
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/* End-of-stack check for user tasks: */ |
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if (state->regs && user_mode(state->regs)) |
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goto the_end; |
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/* |
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* Find the orc_entry associated with the text address. |
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* |
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* For a call frame (as opposed to a signal frame), state->ip points to |
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* the instruction after the call. That instruction's stack layout |
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* could be different from the call instruction's layout, for example |
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* if the call was to a noreturn function. So get the ORC data for the |
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* call instruction itself. |
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*/ |
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orc = orc_find(state->signal ? state->ip : state->ip - 1); |
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if (!orc) { |
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/* |
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* As a fallback, try to assume this code uses a frame pointer. |
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* This is useful for generated code, like BPF, which ORC |
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* doesn't know about. This is just a guess, so the rest of |
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* the unwind is no longer considered reliable. |
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*/ |
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orc = &orc_fp_entry; |
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state->error = true; |
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} |
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/* End-of-stack check for kernel threads: */ |
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if (orc->sp_reg == ORC_REG_UNDEFINED) { |
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if (!orc->end) |
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goto err; |
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goto the_end; |
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} |
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/* Find the previous frame's stack: */ |
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switch (orc->sp_reg) { |
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case ORC_REG_SP: |
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sp = state->sp + orc->sp_offset; |
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break; |
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|
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case ORC_REG_BP: |
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sp = state->bp + orc->sp_offset; |
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break; |
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case ORC_REG_SP_INDIRECT: |
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sp = state->sp; |
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indirect = true; |
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break; |
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|
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case ORC_REG_BP_INDIRECT: |
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sp = state->bp + orc->sp_offset; |
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indirect = true; |
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break; |
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|
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case ORC_REG_R10: |
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if (!get_reg(state, offsetof(struct pt_regs, r10), &sp)) { |
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orc_warn_current("missing R10 value at %pB\n", |
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(void *)state->ip); |
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goto err; |
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} |
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break; |
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|
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case ORC_REG_R13: |
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if (!get_reg(state, offsetof(struct pt_regs, r13), &sp)) { |
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orc_warn_current("missing R13 value at %pB\n", |
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(void *)state->ip); |
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goto err; |
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} |
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break; |
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|
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case ORC_REG_DI: |
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if (!get_reg(state, offsetof(struct pt_regs, di), &sp)) { |
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orc_warn_current("missing RDI value at %pB\n", |
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(void *)state->ip); |
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goto err; |
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} |
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break; |
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|
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case ORC_REG_DX: |
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if (!get_reg(state, offsetof(struct pt_regs, dx), &sp)) { |
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orc_warn_current("missing DX value at %pB\n", |
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(void *)state->ip); |
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goto err; |
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} |
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break; |
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|
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default: |
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orc_warn("unknown SP base reg %d at %pB\n", |
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orc->sp_reg, (void *)state->ip); |
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goto err; |
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} |
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|
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if (indirect) { |
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if (!deref_stack_reg(state, sp, &sp)) |
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goto err; |
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if (orc->sp_reg == ORC_REG_SP_INDIRECT) |
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sp += orc->sp_offset; |
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} |
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|
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/* Find IP, SP and possibly regs: */ |
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switch (orc->type) { |
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case UNWIND_HINT_TYPE_CALL: |
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ip_p = sp - sizeof(long); |
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|
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if (!deref_stack_reg(state, ip_p, &state->ip)) |
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goto err; |
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|
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state->ip = ftrace_graph_ret_addr(state->task, &state->graph_idx, |
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state->ip, (void *)ip_p); |
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|
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state->sp = sp; |
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state->regs = NULL; |
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state->prev_regs = NULL; |
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state->signal = false; |
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break; |
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|
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case UNWIND_HINT_TYPE_REGS: |
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if (!deref_stack_regs(state, sp, &state->ip, &state->sp)) { |
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orc_warn_current("can't access registers at %pB\n", |
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(void *)orig_ip); |
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goto err; |
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} |
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|
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state->regs = (struct pt_regs *)sp; |
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state->prev_regs = NULL; |
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state->full_regs = true; |
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state->signal = true; |
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break; |
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|
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case UNWIND_HINT_TYPE_REGS_PARTIAL: |
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if (!deref_stack_iret_regs(state, sp, &state->ip, &state->sp)) { |
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orc_warn_current("can't access iret registers at %pB\n", |
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(void *)orig_ip); |
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goto err; |
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} |
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|
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if (state->full_regs) |
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state->prev_regs = state->regs; |
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state->regs = (void *)sp - IRET_FRAME_OFFSET; |
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state->full_regs = false; |
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state->signal = true; |
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break; |
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|
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default: |
|
orc_warn("unknown .orc_unwind entry type %d at %pB\n", |
|
orc->type, (void *)orig_ip); |
|
goto err; |
|
} |
|
|
|
/* Find BP: */ |
|
switch (orc->bp_reg) { |
|
case ORC_REG_UNDEFINED: |
|
if (get_reg(state, offsetof(struct pt_regs, bp), &tmp)) |
|
state->bp = tmp; |
|
break; |
|
|
|
case ORC_REG_PREV_SP: |
|
if (!deref_stack_reg(state, sp + orc->bp_offset, &state->bp)) |
|
goto err; |
|
break; |
|
|
|
case ORC_REG_BP: |
|
if (!deref_stack_reg(state, state->bp + orc->bp_offset, &state->bp)) |
|
goto err; |
|
break; |
|
|
|
default: |
|
orc_warn("unknown BP base reg %d for ip %pB\n", |
|
orc->bp_reg, (void *)orig_ip); |
|
goto err; |
|
} |
|
|
|
/* 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_current("stack going in the wrong direction? at %pB\n", |
|
(void *)orig_ip); |
|
goto err; |
|
} |
|
|
|
preempt_enable(); |
|
return true; |
|
|
|
err: |
|
state->error = true; |
|
|
|
the_end: |
|
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; |
|
|
|
if (!orc_init) |
|
goto err; |
|
|
|
/* |
|
* 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 err; |
|
|
|
if (regs) { |
|
if (user_mode(regs)) |
|
goto the_end; |
|
|
|
state->ip = regs->ip; |
|
state->sp = regs->sp; |
|
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 + sizeof(*frame); |
|
state->bp = READ_ONCE_NOCHECK(frame->bp); |
|
state->ip = READ_ONCE_NOCHECK(frame->ret_addr); |
|
state->signal = (void *)state->ip == ret_from_fork; |
|
} |
|
|
|
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); |
|
state->error = true; |
|
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; |
|
|
|
err: |
|
state->error = true; |
|
the_end: |
|
state->stack_info.type = STACK_TYPE_UNKNOWN; |
|
} |
|
EXPORT_SYMBOL_GPL(__unwind_start);
|
|
|