1 /* SPDX-License-Identifier: LGPL-2.1 OR MIT */
2 /*
3 * Select the instruction "csrw mhartid, x0" as the RSEQ_SIG. Unlike
4 * other architectures, the ebreak instruction has no immediate field for
5 * distinguishing purposes. Hence, ebreak is not suitable as RSEQ_SIG.
6 * "csrw mhartid, x0" can also satisfy the RSEQ requirement because it
7 * is an uncommon instruction and will raise an illegal instruction
8 * exception when executed in all modes.
9 */
10 #include <endian.h>
11
12 #if defined(__BYTE_ORDER) ? (__BYTE_ORDER == __LITTLE_ENDIAN) : defined(__LITTLE_ENDIAN)
13 #define RSEQ_SIG 0xf1401073 /* csrr mhartid, x0 */
14 #else
15 #error "Currently, RSEQ only supports Little-Endian version"
16 #endif
17
18 #if __riscv_xlen == 64
19 #define __REG_SEL(a, b) a
20 #elif __riscv_xlen == 32
21 #define __REG_SEL(a, b) b
22 #endif
23
24 #define REG_L __REG_SEL("ld ", "lw ")
25 #define REG_S __REG_SEL("sd ", "sw ")
26
27 #define RISCV_FENCE(p, s) \
28 __asm__ __volatile__ ("fence " #p "," #s : : : "memory")
29 #define rseq_smp_mb() RISCV_FENCE(rw, rw)
30 #define rseq_smp_rmb() RISCV_FENCE(r, r)
31 #define rseq_smp_wmb() RISCV_FENCE(w, w)
32 #define RSEQ_ASM_TMP_REG_1 "t6"
33 #define RSEQ_ASM_TMP_REG_2 "t5"
34 #define RSEQ_ASM_TMP_REG_3 "t4"
35 #define RSEQ_ASM_TMP_REG_4 "t3"
36
37 #define rseq_smp_load_acquire(p) \
38 __extension__ ({ \
39 rseq_unqual_scalar_typeof(*(p)) ____p1 = RSEQ_READ_ONCE(*(p)); \
40 RISCV_FENCE(r, rw); \
41 ____p1; \
42 })
43
44 #define rseq_smp_acquire__after_ctrl_dep() rseq_smp_rmb()
45
46 #define rseq_smp_store_release(p, v) \
47 do { \
48 RISCV_FENCE(rw, w); \
49 RSEQ_WRITE_ONCE(*(p), v); \
50 } while (0)
51
52 #define __RSEQ_ASM_DEFINE_TABLE(label, version, flags, start_ip, \
53 post_commit_offset, abort_ip) \
54 ".pushsection __rseq_cs, \"aw\"\n" \
55 ".balign 32\n" \
56 __rseq_str(label) ":\n" \
57 ".long " __rseq_str(version) ", " __rseq_str(flags) "\n" \
58 ".quad " __rseq_str(start_ip) ", " \
59 __rseq_str(post_commit_offset) ", " \
60 __rseq_str(abort_ip) "\n" \
61 ".popsection\n\t" \
62 ".pushsection __rseq_cs_ptr_array, \"aw\"\n" \
63 ".quad " __rseq_str(label) "b\n" \
64 ".popsection\n"
65
66 #define RSEQ_ASM_DEFINE_TABLE(label, start_ip, post_commit_ip, abort_ip) \
67 __RSEQ_ASM_DEFINE_TABLE(label, 0x0, 0x0, start_ip, \
68 ((post_commit_ip) - (start_ip)), abort_ip)
69
70 /*
71 * Exit points of a rseq critical section consist of all instructions outside
72 * of the critical section where a critical section can either branch to or
73 * reach through the normal course of its execution. The abort IP and the
74 * post-commit IP are already part of the __rseq_cs section and should not be
75 * explicitly defined as additional exit points. Knowing all exit points is
76 * useful to assist debuggers stepping over the critical section.
77 */
78 #define RSEQ_ASM_DEFINE_EXIT_POINT(start_ip, exit_ip) \
79 ".pushsection __rseq_exit_point_array, \"aw\"\n" \
80 ".quad " __rseq_str(start_ip) ", " __rseq_str(exit_ip) "\n" \
81 ".popsection\n"
82
83 #define RSEQ_ASM_STORE_RSEQ_CS(label, cs_label, rseq_cs) \
84 RSEQ_INJECT_ASM(1) \
85 "la " RSEQ_ASM_TMP_REG_1 ", " __rseq_str(cs_label) "\n" \
86 REG_S RSEQ_ASM_TMP_REG_1 ", %[" __rseq_str(rseq_cs) "]\n" \
87 __rseq_str(label) ":\n"
88
89 #define RSEQ_ASM_DEFINE_ABORT(label, abort_label) \
90 "j 222f\n" \
91 ".balign 4\n" \
92 ".long " __rseq_str(RSEQ_SIG) "\n" \
93 __rseq_str(label) ":\n" \
94 "j %l[" __rseq_str(abort_label) "]\n" \
95 "222:\n"
96
97 #define RSEQ_ASM_OP_STORE(value, var) \
98 REG_S "%[" __rseq_str(value) "], %[" __rseq_str(var) "]\n"
99
100 #define RSEQ_ASM_OP_CMPEQ(var, expect, label) \
101 REG_L RSEQ_ASM_TMP_REG_1 ", %[" __rseq_str(var) "]\n" \
102 "bne " RSEQ_ASM_TMP_REG_1 ", %[" __rseq_str(expect) "] ," \
103 __rseq_str(label) "\n"
104
105 #define RSEQ_ASM_OP_CMPEQ32(var, expect, label) \
106 "lw " RSEQ_ASM_TMP_REG_1 ", %[" __rseq_str(var) "]\n" \
107 "bne " RSEQ_ASM_TMP_REG_1 ", %[" __rseq_str(expect) "] ," \
108 __rseq_str(label) "\n"
109
110 #define RSEQ_ASM_OP_CMPNE(var, expect, label) \
111 REG_L RSEQ_ASM_TMP_REG_1 ", %[" __rseq_str(var) "]\n" \
112 "beq " RSEQ_ASM_TMP_REG_1 ", %[" __rseq_str(expect) "] ," \
113 __rseq_str(label) "\n"
114
115 #define RSEQ_ASM_CMP_CPU_ID(cpu_id, current_cpu_id, label) \
116 RSEQ_INJECT_ASM(2) \
117 RSEQ_ASM_OP_CMPEQ32(current_cpu_id, cpu_id, label)
118
119 #define RSEQ_ASM_OP_R_LOAD(var) \
120 REG_L RSEQ_ASM_TMP_REG_1 ", %[" __rseq_str(var) "]\n"
121
122 #define RSEQ_ASM_OP_R_STORE(var) \
123 REG_S RSEQ_ASM_TMP_REG_1 ", %[" __rseq_str(var) "]\n"
124
125 #define RSEQ_ASM_OP_R_LOAD_OFF(offset) \
126 "add " RSEQ_ASM_TMP_REG_1 ", %[" __rseq_str(offset) "], " \
127 RSEQ_ASM_TMP_REG_1 "\n" \
128 REG_L RSEQ_ASM_TMP_REG_1 ", (" RSEQ_ASM_TMP_REG_1 ")\n"
129
130 #define RSEQ_ASM_OP_R_ADD(count) \
131 "add " RSEQ_ASM_TMP_REG_1 ", " RSEQ_ASM_TMP_REG_1 \
132 ", %[" __rseq_str(count) "]\n"
133
134 #define RSEQ_ASM_OP_FINAL_STORE(value, var, post_commit_label) \
135 RSEQ_ASM_OP_STORE(value, var) \
136 __rseq_str(post_commit_label) ":\n"
137
138 #define RSEQ_ASM_OP_FINAL_STORE_RELEASE(value, var, post_commit_label) \
139 "fence rw, w\n" \
140 RSEQ_ASM_OP_STORE(value, var) \
141 __rseq_str(post_commit_label) ":\n"
142
143 #define RSEQ_ASM_OP_R_FINAL_STORE(var, post_commit_label) \
144 REG_S RSEQ_ASM_TMP_REG_1 ", %[" __rseq_str(var) "]\n" \
145 __rseq_str(post_commit_label) ":\n"
146
147 #define RSEQ_ASM_OP_R_BAD_MEMCPY(dst, src, len) \
148 "beqz %[" __rseq_str(len) "], 333f\n" \
149 "mv " RSEQ_ASM_TMP_REG_1 ", %[" __rseq_str(len) "]\n" \
150 "mv " RSEQ_ASM_TMP_REG_2 ", %[" __rseq_str(src) "]\n" \
151 "mv " RSEQ_ASM_TMP_REG_3 ", %[" __rseq_str(dst) "]\n" \
152 "222:\n" \
153 "lb " RSEQ_ASM_TMP_REG_4 ", 0(" RSEQ_ASM_TMP_REG_2 ")\n" \
154 "sb " RSEQ_ASM_TMP_REG_4 ", 0(" RSEQ_ASM_TMP_REG_3 ")\n" \
155 "addi " RSEQ_ASM_TMP_REG_1 ", " RSEQ_ASM_TMP_REG_1 ", -1\n" \
156 "addi " RSEQ_ASM_TMP_REG_2 ", " RSEQ_ASM_TMP_REG_2 ", 1\n" \
157 "addi " RSEQ_ASM_TMP_REG_3 ", " RSEQ_ASM_TMP_REG_3 ", 1\n" \
158 "bnez " RSEQ_ASM_TMP_REG_1 ", 222b\n" \
159 "333:\n"
160
161 #define RSEQ_ASM_OP_R_DEREF_ADDV(ptr, off, post_commit_label) \
162 "mv " RSEQ_ASM_TMP_REG_1 ", %[" __rseq_str(ptr) "]\n" \
163 RSEQ_ASM_OP_R_ADD(off) \
164 REG_L RSEQ_ASM_TMP_REG_1 ", 0(" RSEQ_ASM_TMP_REG_1 ")\n" \
165 RSEQ_ASM_OP_R_ADD(inc) \
166 __rseq_str(post_commit_label) ":\n"
167
168 /* Per-cpu-id indexing. */
169
170 #define RSEQ_TEMPLATE_CPU_ID
171 #define RSEQ_TEMPLATE_MO_RELAXED
172 #include "rseq-riscv-bits.h"
173 #undef RSEQ_TEMPLATE_MO_RELAXED
174
175 #define RSEQ_TEMPLATE_MO_RELEASE
176 #include "rseq-riscv-bits.h"
177 #undef RSEQ_TEMPLATE_MO_RELEASE
178 #undef RSEQ_TEMPLATE_CPU_ID
179
180 /* Per-mm-cid indexing. */
181
182 #define RSEQ_TEMPLATE_MM_CID
183 #define RSEQ_TEMPLATE_MO_RELAXED
184 #include "rseq-riscv-bits.h"
185 #undef RSEQ_TEMPLATE_MO_RELAXED
186
187 #define RSEQ_TEMPLATE_MO_RELEASE
188 #include "rseq-riscv-bits.h"
189 #undef RSEQ_TEMPLATE_MO_RELEASE
190 #undef RSEQ_TEMPLATE_MM_CID
191
192 /* APIs which are not based on cpu ids. */
193
194 #define RSEQ_TEMPLATE_CPU_ID_NONE
195 #define RSEQ_TEMPLATE_MO_RELAXED
196 #include "rseq-riscv-bits.h"
197 #undef RSEQ_TEMPLATE_MO_RELAXED
198 #undef RSEQ_TEMPLATE_CPU_ID_NONE
199
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