529 lines
14 KiB
C
529 lines
14 KiB
C
// 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/exception.h>
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#include <asm/orc_header.h>
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#include <asm/orc_lookup.h>
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#include <asm/orc_types.h>
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#include <asm/ptrace.h>
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#include <asm/setup.h>
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#include <asm/stacktrace.h>
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#include <asm/tlb.h>
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#include <asm/unwind.h>
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ORC_HEADER;
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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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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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static bool orc_init __ro_after_init;
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static unsigned int lookup_num_blocks __ro_after_init;
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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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.sp_reg = ORC_REG_FP,
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.sp_offset = 16,
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.fp_reg = ORC_REG_PREV_SP,
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.fp_offset = -16,
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.ra_reg = ORC_REG_PREV_SP,
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.ra_offset = -8,
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.type = ORC_TYPE_CALL
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};
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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 orc_null_entry = {
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.sp_reg = ORC_REG_SP,
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.sp_offset = sizeof(long),
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.fp_reg = ORC_REG_UNDEFINED,
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.type = ORC_TYPE_CALL
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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 *mid = first, *found = first;
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int *last = ip_table + num_entries - 1;
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if (!num_entries)
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return NULL;
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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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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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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, 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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* 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 tramp_addr, offset;
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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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/* Set tramp_addr to the start of the code copied by the trampoline */
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if (ops->flags & FTRACE_OPS_FL_SAVE_REGS)
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tramp_addr = (unsigned long)ftrace_regs_caller;
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else
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tramp_addr = (unsigned long)ftrace_caller;
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/* Now place tramp_addr to the location within the trampoline ip is at */
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offset = ip - ops->trampoline;
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tramp_addr += offset;
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/* Prevent unlikely recursion */
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if (ip == tramp_addr)
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return NULL;
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return orc_find(tramp_addr);
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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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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 &orc_null_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 (is_kernel_inittext(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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int delta = _b - _a;
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int *a = _a, *b = _b, tmp;
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struct orc_entry *orc_a, *orc_b;
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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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swap(*orc_a, *orc_b);
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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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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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struct orc_entry *orc_a;
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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 first
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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->type == ORC_TYPE_UNDEFINED ? -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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int i;
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size_t orc_size = (void *)__stop_orc_unwind - (void *)__start_orc_unwind;
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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 num_entries = orc_ip_size / sizeof(int);
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struct orc_entry *orc;
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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, 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, 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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static inline bool on_stack(struct stack_info *info, unsigned long addr, size_t len)
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{
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unsigned long begin = info->begin;
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unsigned long end = info->end;
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return (info->type != STACK_TYPE_UNKNOWN &&
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addr >= begin && addr < end && addr + len > begin && addr + len <= end);
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}
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static bool stack_access_ok(struct unwind_state *state, unsigned long addr, size_t len)
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{
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struct stack_info *info = &state->stack_info;
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if (on_stack(info, addr, len))
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return true;
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return !get_stack_info(addr, state->task, info) && on_stack(info, addr, len);
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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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return __unwind_get_return_address(state);
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}
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EXPORT_SYMBOL_GPL(unwind_get_return_address);
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void unwind_start(struct unwind_state *state, struct task_struct *task,
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struct pt_regs *regs)
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{
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__unwind_start(state, task, regs);
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state->type = UNWINDER_ORC;
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if (!unwind_done(state) && !__kernel_text_address(state->pc))
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unwind_next_frame(state);
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}
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EXPORT_SYMBOL_GPL(unwind_start);
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static bool is_entry_func(unsigned long addr)
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{
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extern u32 kernel_entry;
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extern u32 kernel_entry_end;
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return addr >= (unsigned long)&kernel_entry && addr < (unsigned long)&kernel_entry_end;
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}
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static inline unsigned long bt_address(unsigned long ra)
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{
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extern unsigned long eentry;
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if (__kernel_text_address(ra))
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return ra;
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if (__module_text_address(ra))
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return ra;
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if (ra >= eentry && ra < eentry + EXCCODE_INT_END * VECSIZE) {
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unsigned long func;
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unsigned long type = (ra - eentry) / VECSIZE;
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unsigned long offset = (ra - eentry) % VECSIZE;
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switch (type) {
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case 0 ... EXCCODE_INT_START - 1:
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func = (unsigned long)exception_table[type];
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break;
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case EXCCODE_INT_START ... EXCCODE_INT_END:
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func = (unsigned long)handle_vint;
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break;
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default:
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func = (unsigned long)handle_reserved;
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break;
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}
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return func + offset;
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}
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return ra;
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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 *p, pc;
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struct pt_regs *regs;
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struct orc_entry *orc;
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struct stack_info *info = &state->stack_info;
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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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if (is_entry_func(state->pc))
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goto end;
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orc = orc_find(state->pc);
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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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} else {
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if (orc->type == ORC_TYPE_UNDEFINED)
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goto err;
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if (orc->type == ORC_TYPE_END_OF_STACK)
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goto end;
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}
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switch (orc->sp_reg) {
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case ORC_REG_SP:
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if (info->type == STACK_TYPE_IRQ && state->sp == info->end)
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orc->type = ORC_TYPE_REGS;
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else
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state->sp = state->sp + orc->sp_offset;
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break;
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case ORC_REG_FP:
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state->sp = state->fp;
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break;
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default:
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orc_warn("unknown SP base reg %d at %pB\n", orc->sp_reg, (void *)state->pc);
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goto err;
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}
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switch (orc->fp_reg) {
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case ORC_REG_PREV_SP:
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p = (unsigned long *)(state->sp + orc->fp_offset);
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if (!stack_access_ok(state, (unsigned long)p, sizeof(unsigned long)))
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goto err;
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state->fp = *p;
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break;
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case ORC_REG_UNDEFINED:
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/* Nothing. */
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break;
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default:
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orc_warn("unknown FP base reg %d at %pB\n", orc->fp_reg, (void *)state->pc);
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goto err;
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}
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switch (orc->type) {
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case ORC_TYPE_CALL:
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if (orc->ra_reg == ORC_REG_PREV_SP) {
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p = (unsigned long *)(state->sp + orc->ra_offset);
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if (!stack_access_ok(state, (unsigned long)p, sizeof(unsigned long)))
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goto err;
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pc = unwind_graph_addr(state, *p, state->sp);
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pc -= LOONGARCH_INSN_SIZE;
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} else if (orc->ra_reg == ORC_REG_UNDEFINED) {
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if (!state->ra || state->ra == state->pc)
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goto err;
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pc = unwind_graph_addr(state, state->ra, state->sp);
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pc -= LOONGARCH_INSN_SIZE;
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state->ra = 0;
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} else {
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orc_warn("unknown ra base reg %d at %pB\n", orc->ra_reg, (void *)state->pc);
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goto err;
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}
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break;
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case ORC_TYPE_REGS:
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if (info->type == STACK_TYPE_IRQ && state->sp == info->end)
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regs = (struct pt_regs *)info->next_sp;
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else
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regs = (struct pt_regs *)state->sp;
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if (!stack_access_ok(state, (unsigned long)regs, sizeof(*regs)))
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goto err;
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if ((info->end == (unsigned long)regs + sizeof(*regs)) &&
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!regs->regs[3] && !regs->regs[1])
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goto end;
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if (user_mode(regs))
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goto end;
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pc = regs->csr_era;
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if (!__kernel_text_address(pc))
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goto err;
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state->sp = regs->regs[3];
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state->ra = regs->regs[1];
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state->fp = regs->regs[22];
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get_stack_info(state->sp, state->task, info);
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break;
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default:
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orc_warn("unknown .orc_unwind entry type %d at %pB\n", orc->type, (void *)state->pc);
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goto err;
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}
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|
|
state->pc = bt_address(pc);
|
|
if (!state->pc) {
|
|
pr_err("cannot find unwind pc at %pK\n", (void *)pc);
|
|
goto err;
|
|
}
|
|
|
|
if (!__kernel_text_address(state->pc))
|
|
goto err;
|
|
|
|
preempt_enable();
|
|
return true;
|
|
|
|
err:
|
|
state->error = true;
|
|
|
|
end:
|
|
preempt_enable();
|
|
state->stack_info.type = STACK_TYPE_UNKNOWN;
|
|
return false;
|
|
}
|
|
EXPORT_SYMBOL_GPL(unwind_next_frame);
|