Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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kernel
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linux
1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Copyright (c) 2025, Oracle and/or its affiliates.
4 */
5
6#include <objtool/trace.h>
7
8bool trace;
9int trace_depth;
10
11/*
12 * Macros to trace CFI state attributes changes.
13 */
14
15#define TRACE_CFI_ATTR(attr, prev, next, fmt, ...) \
16({ \
17 if ((prev)->attr != (next)->attr) \
18 TRACE("%s=" fmt " ", #attr, __VA_ARGS__); \
19})
20
21#define TRACE_CFI_ATTR_BOOL(attr, prev, next) \
22 TRACE_CFI_ATTR(attr, prev, next, \
23 "%s", (next)->attr ? "true" : "false")
24
25#define TRACE_CFI_ATTR_NUM(attr, prev, next, fmt) \
26 TRACE_CFI_ATTR(attr, prev, next, fmt, (next)->attr)
27
28#define CFI_REG_NAME_MAXLEN 16
29
30/*
31 * Return the name of a register. Note that the same static buffer
32 * is returned if the name is dynamically generated.
33 */
34static const char *cfi_reg_name(unsigned int reg)
35{
36 static char rname_buffer[CFI_REG_NAME_MAXLEN];
37 const char *rname;
38
39 switch (reg) {
40 case CFI_UNDEFINED:
41 return "<undefined>";
42 case CFI_CFA:
43 return "cfa";
44 case CFI_SP_INDIRECT:
45 return "(sp)";
46 case CFI_BP_INDIRECT:
47 return "(bp)";
48 }
49
50 if (reg < CFI_NUM_REGS) {
51 rname = arch_reg_name[reg];
52 if (rname)
53 return rname;
54 }
55
56 if (snprintf(rname_buffer, CFI_REG_NAME_MAXLEN, "r%d", reg) == -1)
57 return "<error>";
58
59 return (const char *)rname_buffer;
60}
61
62/*
63 * Functions and macros to trace CFI registers changes.
64 */
65
66static void trace_cfi_reg(const char *prefix, int reg, const char *fmt,
67 int base_prev, int offset_prev,
68 int base_next, int offset_next)
69{
70 char *rname;
71
72 if (base_prev == base_next && offset_prev == offset_next)
73 return;
74
75 if (prefix)
76 TRACE("%s:", prefix);
77
78 if (base_next == CFI_UNDEFINED) {
79 TRACE("%1$s=<undef> ", cfi_reg_name(reg));
80 } else {
81 rname = strdup(cfi_reg_name(reg));
82 TRACE(fmt, rname, cfi_reg_name(base_next), offset_next);
83 free(rname);
84 }
85}
86
87static void trace_cfi_reg_val(const char *prefix, int reg,
88 int base_prev, int offset_prev,
89 int base_next, int offset_next)
90{
91 trace_cfi_reg(prefix, reg, "%1$s=%2$s%3$+d ",
92 base_prev, offset_prev, base_next, offset_next);
93}
94
95static void trace_cfi_reg_ref(const char *prefix, int reg,
96 int base_prev, int offset_prev,
97 int base_next, int offset_next)
98{
99 trace_cfi_reg(prefix, reg, "%1$s=(%2$s%3$+d) ",
100 base_prev, offset_prev, base_next, offset_next);
101}
102
103#define TRACE_CFI_REG_VAL(reg, prev, next) \
104 trace_cfi_reg_val(NULL, reg, prev.base, prev.offset, \
105 next.base, next.offset)
106
107#define TRACE_CFI_REG_REF(reg, prev, next) \
108 trace_cfi_reg_ref(NULL, reg, prev.base, prev.offset, \
109 next.base, next.offset)
110
111void trace_insn_state(struct instruction *insn, struct insn_state *sprev,
112 struct insn_state *snext)
113{
114 struct cfi_state *cprev, *cnext;
115 int i;
116
117 if (!memcmp(sprev, snext, sizeof(struct insn_state)))
118 return;
119
120 cprev = &sprev->cfi;
121 cnext = &snext->cfi;
122
123 disas_print_insn(stderr, objtool_disas_ctx, insn,
124 trace_depth - 1, "state: ");
125
126 /* print registers changes */
127 TRACE_CFI_REG_VAL(CFI_CFA, cprev->cfa, cnext->cfa);
128 for (i = 0; i < CFI_NUM_REGS; i++) {
129 TRACE_CFI_REG_VAL(i, cprev->vals[i], cnext->vals[i]);
130 TRACE_CFI_REG_REF(i, cprev->regs[i], cnext->regs[i]);
131 }
132
133 /* print attributes changes */
134 TRACE_CFI_ATTR_NUM(stack_size, cprev, cnext, "%d");
135 TRACE_CFI_ATTR_BOOL(drap, cprev, cnext);
136 if (cnext->drap) {
137 trace_cfi_reg_val("drap", cnext->drap_reg,
138 cprev->drap_reg, cprev->drap_offset,
139 cnext->drap_reg, cnext->drap_offset);
140 }
141 TRACE_CFI_ATTR_BOOL(bp_scratch, cprev, cnext);
142 TRACE_CFI_ATTR_NUM(instr, sprev, snext, "%d");
143 TRACE_CFI_ATTR_NUM(uaccess_stack, sprev, snext, "%u");
144
145 TRACE("\n");
146
147 insn->trace = 1;
148}
149
150void trace_alt_begin(struct instruction *orig_insn, struct alternative *alt,
151 char *alt_name)
152{
153 struct instruction *alt_insn;
154 char suffix[2];
155
156 alt_insn = alt->insn;
157
158 if (alt->type == ALT_TYPE_EX_TABLE) {
159 /*
160 * When there is an exception table then the instruction
161 * at the original location is executed but it can cause
162 * an exception. In that case, the execution will be
163 * redirected to the alternative instruction.
164 *
165 * The instruction at the original location can have
166 * instruction alternatives, so we just print the location
167 * of the instruction that can cause the exception and
168 * not the instruction itself.
169 */
170 TRACE_ALT_INFO_NOADDR(orig_insn, "/ ", "%s for instruction at 0x%lx <%s+0x%lx>",
171 alt_name,
172 orig_insn->offset, orig_insn->sym->name,
173 orig_insn->offset - orig_insn->sym->offset);
174 } else {
175 TRACE_ALT_INFO_NOADDR(orig_insn, "/ ", "%s", alt_name);
176 }
177
178 if (alt->type == ALT_TYPE_JUMP_TABLE) {
179 /*
180 * For a jump alternative, if the default instruction is
181 * a NOP then it is replaced with the jmp instruction,
182 * otherwise it is replaced with a NOP instruction.
183 */
184 trace_depth++;
185 if (orig_insn->type == INSN_NOP) {
186 suffix[0] = (orig_insn->len == 5) ? 'q' : '\0';
187 TRACE_ADDR(orig_insn, "jmp%-3s %lx <%s+0x%lx>", suffix,
188 alt_insn->offset, alt_insn->sym->name,
189 alt_insn->offset - alt_insn->sym->offset);
190 } else {
191 TRACE_ADDR(orig_insn, "nop%d", orig_insn->len);
192 trace_depth--;
193 }
194 }
195}
196
197void trace_alt_end(struct instruction *orig_insn, struct alternative *alt,
198 char *alt_name)
199{
200 if (alt->type == ALT_TYPE_JUMP_TABLE && orig_insn->type == INSN_NOP)
201 trace_depth--;
202 TRACE_ALT_INFO_NOADDR(orig_insn, "\\ ", "%s", alt_name);
203}