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2b144498 | 1 | /* |
7b2d81d4 | 2 | * User-space Probes (UProbes) for x86 |
2b144498 SD |
3 | * |
4 | * This program is free software; you can redistribute it and/or modify | |
5 | * it under the terms of the GNU General Public License as published by | |
6 | * the Free Software Foundation; either version 2 of the License, or | |
7 | * (at your option) any later version. | |
8 | * | |
9 | * This program is distributed in the hope that it will be useful, | |
10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
12 | * GNU General Public License for more details. | |
13 | * | |
14 | * You should have received a copy of the GNU General Public License | |
15 | * along with this program; if not, write to the Free Software | |
16 | * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. | |
17 | * | |
18 | * Copyright (C) IBM Corporation, 2008-2011 | |
19 | * Authors: | |
20 | * Srikar Dronamraju | |
21 | * Jim Keniston | |
22 | */ | |
2b144498 SD |
23 | #include <linux/kernel.h> |
24 | #include <linux/sched.h> | |
25 | #include <linux/ptrace.h> | |
26 | #include <linux/uprobes.h> | |
0326f5a9 | 27 | #include <linux/uaccess.h> |
2b144498 SD |
28 | |
29 | #include <linux/kdebug.h> | |
0326f5a9 | 30 | #include <asm/processor.h> |
2b144498 | 31 | #include <asm/insn.h> |
b0e9b09b | 32 | #include <asm/mmu_context.h> |
2b144498 SD |
33 | |
34 | /* Post-execution fixups. */ | |
35 | ||
2b144498 | 36 | /* Adjust IP back to vicinity of actual insn */ |
78d9af4c | 37 | #define UPROBE_FIX_IP 0x01 |
0326f5a9 | 38 | |
2b144498 | 39 | /* Adjust the return address of a call insn */ |
78d9af4c | 40 | #define UPROBE_FIX_CALL 0x02 |
2b144498 | 41 | |
bdc1e472 | 42 | /* Instruction will modify TF, don't change it */ |
78d9af4c | 43 | #define UPROBE_FIX_SETF 0x04 |
bdc1e472 | 44 | |
1ea30fb6 DV |
45 | #define UPROBE_FIX_RIP_SI 0x08 |
46 | #define UPROBE_FIX_RIP_DI 0x10 | |
47 | #define UPROBE_FIX_RIP_BX 0x20 | |
48 | #define UPROBE_FIX_RIP_MASK \ | |
49 | (UPROBE_FIX_RIP_SI | UPROBE_FIX_RIP_DI | UPROBE_FIX_RIP_BX) | |
2b144498 | 50 | |
0326f5a9 SD |
51 | #define UPROBE_TRAP_NR UINT_MAX |
52 | ||
2b144498 | 53 | /* Adaptations for mhiramat x86 decoder v14. */ |
7b2d81d4 IM |
54 | #define OPCODE1(insn) ((insn)->opcode.bytes[0]) |
55 | #define OPCODE2(insn) ((insn)->opcode.bytes[1]) | |
56 | #define OPCODE3(insn) ((insn)->opcode.bytes[2]) | |
ddb69f27 | 57 | #define MODRM_REG(insn) X86_MODRM_REG((insn)->modrm.value) |
2b144498 SD |
58 | |
59 | #define W(row, b0, b1, b2, b3, b4, b5, b6, b7, b8, b9, ba, bb, bc, bd, be, bf)\ | |
60 | (((b0##UL << 0x0)|(b1##UL << 0x1)|(b2##UL << 0x2)|(b3##UL << 0x3) | \ | |
61 | (b4##UL << 0x4)|(b5##UL << 0x5)|(b6##UL << 0x6)|(b7##UL << 0x7) | \ | |
62 | (b8##UL << 0x8)|(b9##UL << 0x9)|(ba##UL << 0xa)|(bb##UL << 0xb) | \ | |
63 | (bc##UL << 0xc)|(bd##UL << 0xd)|(be##UL << 0xe)|(bf##UL << 0xf)) \ | |
64 | << (row % 32)) | |
65 | ||
04a3d984 SD |
66 | /* |
67 | * Good-instruction tables for 32-bit apps. This is non-const and volatile | |
68 | * to keep gcc from statically optimizing it out, as variable_test_bit makes | |
69 | * some versions of gcc to think only *(unsigned long*) is used. | |
097f4e5e | 70 | * |
097f4e5e DV |
71 | * Opcodes we'll probably never support: |
72 | * 6c-6f - ins,outs. SEGVs if used in userspace | |
73 | * e4-e7 - in,out imm. SEGVs if used in userspace | |
74 | * ec-ef - in,out acc. SEGVs if used in userspace | |
75 | * cc - int3. SIGTRAP if used in userspace | |
76 | * ce - into. Not used in userspace - no kernel support to make it useful. SEGVs | |
77 | * (why we support bound (62) then? it's similar, and similarly unused...) | |
78 | * f1 - int1. SIGTRAP if used in userspace | |
79 | * f4 - hlt. SEGVs if used in userspace | |
80 | * fa - cli. SEGVs if used in userspace | |
81 | * fb - sti. SEGVs if used in userspace | |
82 | * | |
83 | * Opcodes which need some work to be supported: | |
84 | * 07,17,1f - pop es/ss/ds | |
85 | * Normally not used in userspace, but would execute if used. | |
86 | * Can cause GP or stack exception if tries to load wrong segment descriptor. | |
87 | * We hesitate to run them under single step since kernel's handling | |
88 | * of userspace single-stepping (TF flag) is fragile. | |
89 | * We can easily refuse to support push es/cs/ss/ds (06/0e/16/1e) | |
90 | * on the same grounds that they are never used. | |
91 | * cd - int N. | |
92 | * Used by userspace for "int 80" syscall entry. (Other "int N" | |
93 | * cause GP -> SEGV since their IDT gates don't allow calls from CPL 3). | |
94 | * Not supported since kernel's handling of userspace single-stepping | |
95 | * (TF flag) is fragile. | |
96 | * cf - iret. Normally not used in userspace. Doesn't SEGV unless arguments are bad | |
04a3d984 | 97 | */ |
8dbacad9 | 98 | #if defined(CONFIG_X86_32) || defined(CONFIG_IA32_EMULATION) |
04a3d984 | 99 | static volatile u32 good_insns_32[256 / 32] = { |
2b144498 SD |
100 | /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ |
101 | /* ---------------------------------------------- */ | |
67fc8092 | 102 | W(0x00, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1) | /* 00 */ |
2b144498 | 103 | W(0x10, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0) , /* 10 */ |
67fc8092 DV |
104 | W(0x20, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 20 */ |
105 | W(0x30, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 30 */ | |
2b144498 SD |
106 | W(0x40, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 40 */ |
107 | W(0x50, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 50 */ | |
67fc8092 | 108 | W(0x60, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0) | /* 60 */ |
2b144498 SD |
109 | W(0x70, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 70 */ |
110 | W(0x80, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 80 */ | |
111 | W(0x90, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 90 */ | |
112 | W(0xa0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* a0 */ | |
113 | W(0xb0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* b0 */ | |
114 | W(0xc0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0) | /* c0 */ | |
67fc8092 | 115 | W(0xd0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* d0 */ |
2b144498 | 116 | W(0xe0, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0) | /* e0 */ |
67fc8092 | 117 | W(0xf0, 1, 0, 1, 1, 0, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1) /* f0 */ |
2b144498 SD |
118 | /* ---------------------------------------------- */ |
119 | /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ | |
120 | }; | |
8dbacad9 ON |
121 | #else |
122 | #define good_insns_32 NULL | |
123 | #endif | |
2b144498 | 124 | |
097f4e5e | 125 | /* Good-instruction tables for 64-bit apps. |
097f4e5e DV |
126 | * |
127 | * Genuinely invalid opcodes: | |
128 | * 06,07 - formerly push/pop es | |
129 | * 0e - formerly push cs | |
130 | * 16,17 - formerly push/pop ss | |
131 | * 1e,1f - formerly push/pop ds | |
132 | * 27,2f,37,3f - formerly daa/das/aaa/aas | |
133 | * 60,61 - formerly pusha/popa | |
67fc8092 | 134 | * 62 - formerly bound. EVEX prefix for AVX512 (not yet supported) |
097f4e5e | 135 | * 82 - formerly redundant encoding of Group1 |
67fc8092 | 136 | * 9a - formerly call seg:ofs |
097f4e5e DV |
137 | * ce - formerly into |
138 | * d4,d5 - formerly aam/aad | |
139 | * d6 - formerly undocumented salc | |
67fc8092 | 140 | * ea - formerly jmp seg:ofs |
097f4e5e DV |
141 | * |
142 | * Opcodes we'll probably never support: | |
143 | * 6c-6f - ins,outs. SEGVs if used in userspace | |
144 | * e4-e7 - in,out imm. SEGVs if used in userspace | |
145 | * ec-ef - in,out acc. SEGVs if used in userspace | |
146 | * cc - int3. SIGTRAP if used in userspace | |
147 | * f1 - int1. SIGTRAP if used in userspace | |
148 | * f4 - hlt. SEGVs if used in userspace | |
149 | * fa - cli. SEGVs if used in userspace | |
150 | * fb - sti. SEGVs if used in userspace | |
151 | * | |
152 | * Opcodes which need some work to be supported: | |
153 | * cd - int N. | |
154 | * Used by userspace for "int 80" syscall entry. (Other "int N" | |
155 | * cause GP -> SEGV since their IDT gates don't allow calls from CPL 3). | |
156 | * Not supported since kernel's handling of userspace single-stepping | |
157 | * (TF flag) is fragile. | |
158 | * cf - iret. Normally not used in userspace. Doesn't SEGV unless arguments are bad | |
159 | */ | |
8dbacad9 | 160 | #if defined(CONFIG_X86_64) |
04a3d984 SD |
161 | static volatile u32 good_insns_64[256 / 32] = { |
162 | /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ | |
163 | /* ---------------------------------------------- */ | |
67fc8092 | 164 | W(0x00, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 1) | /* 00 */ |
04a3d984 | 165 | W(0x10, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0) , /* 10 */ |
67fc8092 DV |
166 | W(0x20, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0) | /* 20 */ |
167 | W(0x30, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0) , /* 30 */ | |
168 | W(0x40, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 40 */ | |
04a3d984 | 169 | W(0x50, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 50 */ |
67fc8092 | 170 | W(0x60, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0) | /* 60 */ |
04a3d984 SD |
171 | W(0x70, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 70 */ |
172 | W(0x80, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 80 */ | |
67fc8092 | 173 | W(0x90, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1) , /* 90 */ |
04a3d984 SD |
174 | W(0xa0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* a0 */ |
175 | W(0xb0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* b0 */ | |
67fc8092 | 176 | W(0xc0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0) | /* c0 */ |
04a3d984 | 177 | W(0xd0, 1, 1, 1, 1, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* d0 */ |
67fc8092 DV |
178 | W(0xe0, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 0, 1, 0, 0, 0, 0) | /* e0 */ |
179 | W(0xf0, 1, 0, 1, 1, 0, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1) /* f0 */ | |
04a3d984 SD |
180 | /* ---------------------------------------------- */ |
181 | /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ | |
182 | }; | |
8dbacad9 ON |
183 | #else |
184 | #define good_insns_64 NULL | |
185 | #endif | |
186 | ||
097f4e5e DV |
187 | /* Using this for both 64-bit and 32-bit apps. |
188 | * Opcodes we don't support: | |
189 | * 0f 00 - SLDT/STR/LLDT/LTR/VERR/VERW/-/- group. System insns | |
190 | * 0f 01 - SGDT/SIDT/LGDT/LIDT/SMSW/-/LMSW/INVLPG group. | |
191 | * Also encodes tons of other system insns if mod=11. | |
192 | * Some are in fact non-system: xend, xtest, rdtscp, maybe more | |
097f4e5e DV |
193 | * 0f 05 - syscall |
194 | * 0f 06 - clts (CPL0 insn) | |
195 | * 0f 07 - sysret | |
196 | * 0f 08 - invd (CPL0 insn) | |
197 | * 0f 09 - wbinvd (CPL0 insn) | |
097f4e5e | 198 | * 0f 0b - ud2 |
5154d4f2 | 199 | * 0f 30 - wrmsr (CPL0 insn) (then why rdmsr is allowed, it's also CPL0 insn?) |
097f4e5e DV |
200 | * 0f 34 - sysenter |
201 | * 0f 35 - sysexit | |
097f4e5e | 202 | * 0f 37 - getsec |
5154d4f2 DV |
203 | * 0f 78 - vmread (Intel VMX. CPL0 insn) |
204 | * 0f 79 - vmwrite (Intel VMX. CPL0 insn) | |
205 | * Note: with prefixes, these two opcodes are | |
206 | * extrq/insertq/AVX512 convert vector ops. | |
207 | * 0f ae - group15: [f]xsave,[f]xrstor,[v]{ld,st}mxcsr,clflush[opt], | |
208 | * {rd,wr}{fs,gs}base,{s,l,m}fence. | |
209 | * Why? They are all user-executable. | |
097f4e5e | 210 | */ |
8dbacad9 ON |
211 | static volatile u32 good_2byte_insns[256 / 32] = { |
212 | /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ | |
213 | /* ---------------------------------------------- */ | |
5154d4f2 DV |
214 | W(0x00, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 1, 0, 1, 1, 1, 1) | /* 00 */ |
215 | W(0x10, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 10 */ | |
216 | W(0x20, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 20 */ | |
217 | W(0x30, 0, 1, 1, 1, 0, 0, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1) , /* 30 */ | |
8dbacad9 ON |
218 | W(0x40, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 40 */ |
219 | W(0x50, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 50 */ | |
220 | W(0x60, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 60 */ | |
5154d4f2 | 221 | W(0x70, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1) , /* 70 */ |
8dbacad9 ON |
222 | W(0x80, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 80 */ |
223 | W(0x90, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 90 */ | |
5154d4f2 DV |
224 | W(0xa0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1) | /* a0 */ |
225 | W(0xb0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* b0 */ | |
8dbacad9 | 226 | W(0xc0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* c0 */ |
5154d4f2 | 227 | W(0xd0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* d0 */ |
8dbacad9 | 228 | W(0xe0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* e0 */ |
5154d4f2 | 229 | W(0xf0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) /* f0 */ |
8dbacad9 ON |
230 | /* ---------------------------------------------- */ |
231 | /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ | |
232 | }; | |
2b144498 SD |
233 | #undef W |
234 | ||
235 | /* | |
2b144498 | 236 | * opcodes we may need to refine support for: |
7b2d81d4 IM |
237 | * |
238 | * 0f - 2-byte instructions: For many of these instructions, the validity | |
239 | * depends on the prefix and/or the reg field. On such instructions, we | |
240 | * just consider the opcode combination valid if it corresponds to any | |
241 | * valid instruction. | |
242 | * | |
243 | * 8f - Group 1 - only reg = 0 is OK | |
244 | * c6-c7 - Group 11 - only reg = 0 is OK | |
245 | * d9-df - fpu insns with some illegal encodings | |
246 | * f2, f3 - repnz, repz prefixes. These are also the first byte for | |
247 | * certain floating-point instructions, such as addsd. | |
248 | * | |
249 | * fe - Group 4 - only reg = 0 or 1 is OK | |
250 | * ff - Group 5 - only reg = 0-6 is OK | |
2b144498 SD |
251 | * |
252 | * others -- Do we need to support these? | |
7b2d81d4 IM |
253 | * |
254 | * 0f - (floating-point?) prefetch instructions | |
255 | * 07, 17, 1f - pop es, pop ss, pop ds | |
256 | * 26, 2e, 36, 3e - es:, cs:, ss:, ds: segment prefixes -- | |
2b144498 | 257 | * but 64 and 65 (fs: and gs:) seem to be used, so we support them |
7b2d81d4 IM |
258 | * 67 - addr16 prefix |
259 | * ce - into | |
260 | * f0 - lock prefix | |
2b144498 SD |
261 | */ |
262 | ||
263 | /* | |
264 | * TODO: | |
265 | * - Where necessary, examine the modrm byte and allow only valid instructions | |
266 | * in the different Groups and fpu instructions. | |
267 | */ | |
268 | ||
269 | static bool is_prefix_bad(struct insn *insn) | |
270 | { | |
271 | int i; | |
272 | ||
273 | for (i = 0; i < insn->prefixes.nbytes; i++) { | |
ed40a104 RN |
274 | insn_attr_t attr; |
275 | ||
276 | attr = inat_get_opcode_attribute(insn->prefixes.bytes[i]); | |
277 | switch (attr) { | |
278 | case INAT_MAKE_PREFIX(INAT_PFX_ES): | |
279 | case INAT_MAKE_PREFIX(INAT_PFX_CS): | |
280 | case INAT_MAKE_PREFIX(INAT_PFX_DS): | |
281 | case INAT_MAKE_PREFIX(INAT_PFX_SS): | |
282 | case INAT_MAKE_PREFIX(INAT_PFX_LOCK): | |
2b144498 SD |
283 | return true; |
284 | } | |
285 | } | |
286 | return false; | |
287 | } | |
288 | ||
73175d0d | 289 | static int uprobe_init_insn(struct arch_uprobe *auprobe, struct insn *insn, bool x86_64) |
2b144498 | 290 | { |
73175d0d ON |
291 | u32 volatile *good_insns; |
292 | ||
6ba48ff4 | 293 | insn_init(insn, auprobe->insn, sizeof(auprobe->insn), x86_64); |
ff261964 ON |
294 | /* has the side-effect of processing the entire instruction */ |
295 | insn_get_length(insn); | |
296 | if (WARN_ON_ONCE(!insn_complete(insn))) | |
297 | return -ENOEXEC; | |
2b144498 | 298 | |
2b144498 SD |
299 | if (is_prefix_bad(insn)) |
300 | return -ENOTSUPP; | |
7b2d81d4 | 301 | |
73175d0d ON |
302 | if (x86_64) |
303 | good_insns = good_insns_64; | |
304 | else | |
305 | good_insns = good_insns_32; | |
306 | ||
307 | if (test_bit(OPCODE1(insn), (unsigned long *)good_insns)) | |
2b144498 | 308 | return 0; |
7b2d81d4 | 309 | |
2b144498 SD |
310 | if (insn->opcode.nbytes == 2) { |
311 | if (test_bit(OPCODE2(insn), (unsigned long *)good_2byte_insns)) | |
312 | return 0; | |
313 | } | |
7b2d81d4 | 314 | |
2b144498 SD |
315 | return -ENOTSUPP; |
316 | } | |
317 | ||
2b144498 SD |
318 | #ifdef CONFIG_X86_64 |
319 | /* | |
3ff54efd | 320 | * If arch_uprobe->insn doesn't use rip-relative addressing, return |
2b144498 SD |
321 | * immediately. Otherwise, rewrite the instruction so that it accesses |
322 | * its memory operand indirectly through a scratch register. Set | |
5cdb76d6 | 323 | * defparam->fixups accordingly. (The contents of the scratch register |
50204c6f DV |
324 | * will be saved before we single-step the modified instruction, |
325 | * and restored afterward). | |
2b144498 SD |
326 | * |
327 | * We do this because a rip-relative instruction can access only a | |
328 | * relatively small area (+/- 2 GB from the instruction), and the XOL | |
329 | * area typically lies beyond that area. At least for instructions | |
330 | * that store to memory, we can't execute the original instruction | |
331 | * and "fix things up" later, because the misdirected store could be | |
332 | * disastrous. | |
333 | * | |
334 | * Some useful facts about rip-relative instructions: | |
7b2d81d4 | 335 | * |
50204c6f | 336 | * - There's always a modrm byte with bit layout "00 reg 101". |
7b2d81d4 IM |
337 | * - There's never a SIB byte. |
338 | * - The displacement is always 4 bytes. | |
50204c6f DV |
339 | * - REX.B=1 bit in REX prefix, which normally extends r/m field, |
340 | * has no effect on rip-relative mode. It doesn't make modrm byte | |
341 | * with r/m=101 refer to register 1101 = R13. | |
2b144498 | 342 | */ |
1475ee7f | 343 | static void riprel_analyze(struct arch_uprobe *auprobe, struct insn *insn) |
2b144498 SD |
344 | { |
345 | u8 *cursor; | |
346 | u8 reg; | |
1ea30fb6 | 347 | u8 reg2; |
2b144498 | 348 | |
2b144498 SD |
349 | if (!insn_rip_relative(insn)) |
350 | return; | |
351 | ||
352 | /* | |
1ea30fb6 | 353 | * insn_rip_relative() would have decoded rex_prefix, vex_prefix, modrm. |
2b144498 | 354 | * Clear REX.b bit (extension of MODRM.rm field): |
1ea30fb6 | 355 | * we want to encode low numbered reg, not r8+. |
2b144498 SD |
356 | */ |
357 | if (insn->rex_prefix.nbytes) { | |
3ff54efd | 358 | cursor = auprobe->insn + insn_offset_rex_prefix(insn); |
1ea30fb6 DV |
359 | /* REX byte has 0100wrxb layout, clearing REX.b bit */ |
360 | *cursor &= 0xfe; | |
2b144498 | 361 | } |
1ea30fb6 | 362 | /* |
68187872 DV |
363 | * Similar treatment for VEX3/EVEX prefix. |
364 | * TODO: add XOP treatment when insn decoder supports them | |
1ea30fb6 | 365 | */ |
68187872 | 366 | if (insn->vex_prefix.nbytes >= 3) { |
1ea30fb6 DV |
367 | /* |
368 | * vex2: c5 rvvvvLpp (has no b bit) | |
369 | * vex3/xop: c4/8f rxbmmmmm wvvvvLpp | |
370 | * evex: 62 rxbR00mm wvvvv1pp zllBVaaa | |
68187872 DV |
371 | * Setting VEX3.b (setting because it has inverted meaning). |
372 | * Setting EVEX.x since (in non-SIB encoding) EVEX.x | |
373 | * is the 4th bit of MODRM.rm, and needs the same treatment. | |
374 | * For VEX3-encoded insns, VEX3.x value has no effect in | |
375 | * non-SIB encoding, the change is superfluous but harmless. | |
1ea30fb6 DV |
376 | */ |
377 | cursor = auprobe->insn + insn_offset_vex_prefix(insn) + 1; | |
68187872 | 378 | *cursor |= 0x60; |
1ea30fb6 DV |
379 | } |
380 | ||
381 | /* | |
382 | * Convert from rip-relative addressing to register-relative addressing | |
383 | * via a scratch register. | |
384 | * | |
385 | * This is tricky since there are insns with modrm byte | |
386 | * which also use registers not encoded in modrm byte: | |
387 | * [i]div/[i]mul: implicitly use dx:ax | |
388 | * shift ops: implicitly use cx | |
389 | * cmpxchg: implicitly uses ax | |
390 | * cmpxchg8/16b: implicitly uses dx:ax and bx:cx | |
391 | * Encoding: 0f c7/1 modrm | |
392 | * The code below thinks that reg=1 (cx), chooses si as scratch. | |
393 | * mulx: implicitly uses dx: mulx r/m,r1,r2 does r1:r2 = dx * r/m. | |
394 | * First appeared in Haswell (BMI2 insn). It is vex-encoded. | |
395 | * Example where none of bx,cx,dx can be used as scratch reg: | |
396 | * c4 e2 63 f6 0d disp32 mulx disp32(%rip),%ebx,%ecx | |
397 | * [v]pcmpistri: implicitly uses cx, xmm0 | |
398 | * [v]pcmpistrm: implicitly uses xmm0 | |
399 | * [v]pcmpestri: implicitly uses ax, dx, cx, xmm0 | |
400 | * [v]pcmpestrm: implicitly uses ax, dx, xmm0 | |
401 | * Evil SSE4.2 string comparison ops from hell. | |
402 | * maskmovq/[v]maskmovdqu: implicitly uses (ds:rdi) as destination. | |
403 | * Encoding: 0f f7 modrm, 66 0f f7 modrm, vex-encoded: c5 f9 f7 modrm. | |
404 | * Store op1, byte-masked by op2 msb's in each byte, to (ds:rdi). | |
405 | * AMD says it has no 3-operand form (vex.vvvv must be 1111) | |
406 | * and that it can have only register operands, not mem | |
407 | * (its modrm byte must have mode=11). | |
408 | * If these restrictions will ever be lifted, | |
409 | * we'll need code to prevent selection of di as scratch reg! | |
410 | * | |
411 | * Summary: I don't know any insns with modrm byte which | |
412 | * use SI register implicitly. DI register is used only | |
413 | * by one insn (maskmovq) and BX register is used | |
414 | * only by one too (cmpxchg8b). | |
415 | * BP is stack-segment based (may be a problem?). | |
416 | * AX, DX, CX are off-limits (many implicit users). | |
417 | * SP is unusable (it's stack pointer - think about "pop mem"; | |
418 | * also, rsp+disp32 needs sib encoding -> insn length change). | |
419 | */ | |
2b144498 | 420 | |
1ea30fb6 DV |
421 | reg = MODRM_REG(insn); /* Fetch modrm.reg */ |
422 | reg2 = 0xff; /* Fetch vex.vvvv */ | |
68187872 | 423 | if (insn->vex_prefix.nbytes) |
1ea30fb6 DV |
424 | reg2 = insn->vex_prefix.bytes[2]; |
425 | /* | |
68187872 | 426 | * TODO: add XOP vvvv reading. |
1ea30fb6 DV |
427 | * |
428 | * vex.vvvv field is in bits 6-3, bits are inverted. | |
429 | * But in 32-bit mode, high-order bit may be ignored. | |
430 | * Therefore, let's consider only 3 low-order bits. | |
431 | */ | |
432 | reg2 = ((reg2 >> 3) & 0x7) ^ 0x7; | |
433 | /* | |
434 | * Register numbering is ax,cx,dx,bx, sp,bp,si,di, r8..r15. | |
435 | * | |
436 | * Choose scratch reg. Order is important: must not select bx | |
437 | * if we can use si (cmpxchg8b case!) | |
438 | */ | |
439 | if (reg != 6 && reg2 != 6) { | |
440 | reg2 = 6; | |
5cdb76d6 | 441 | auprobe->defparam.fixups |= UPROBE_FIX_RIP_SI; |
1ea30fb6 DV |
442 | } else if (reg != 7 && reg2 != 7) { |
443 | reg2 = 7; | |
5cdb76d6 | 444 | auprobe->defparam.fixups |= UPROBE_FIX_RIP_DI; |
1ea30fb6 DV |
445 | /* TODO (paranoia): force maskmovq to not use di */ |
446 | } else { | |
447 | reg2 = 3; | |
5cdb76d6 | 448 | auprobe->defparam.fixups |= UPROBE_FIX_RIP_BX; |
1ea30fb6 | 449 | } |
2b144498 SD |
450 | /* |
451 | * Point cursor at the modrm byte. The next 4 bytes are the | |
452 | * displacement. Beyond the displacement, for some instructions, | |
453 | * is the immediate operand. | |
454 | */ | |
3ff54efd | 455 | cursor = auprobe->insn + insn_offset_modrm(insn); |
2b144498 | 456 | /* |
1ea30fb6 DV |
457 | * Change modrm from "00 reg 101" to "10 reg reg2". Example: |
458 | * 89 05 disp32 mov %eax,disp32(%rip) becomes | |
459 | * 89 86 disp32 mov %eax,disp32(%rsi) | |
2b144498 | 460 | */ |
1ea30fb6 | 461 | *cursor = 0x80 | (reg << 3) | reg2; |
2b144498 SD |
462 | } |
463 | ||
c90a6950 ON |
464 | static inline unsigned long * |
465 | scratch_reg(struct arch_uprobe *auprobe, struct pt_regs *regs) | |
466 | { | |
5cdb76d6 | 467 | if (auprobe->defparam.fixups & UPROBE_FIX_RIP_SI) |
1ea30fb6 | 468 | return ®s->si; |
5cdb76d6 | 469 | if (auprobe->defparam.fixups & UPROBE_FIX_RIP_DI) |
1ea30fb6 DV |
470 | return ®s->di; |
471 | return ®s->bx; | |
c90a6950 ON |
472 | } |
473 | ||
d20737c0 ON |
474 | /* |
475 | * If we're emulating a rip-relative instruction, save the contents | |
476 | * of the scratch register and store the target address in that register. | |
477 | */ | |
7f55e82b | 478 | static void riprel_pre_xol(struct arch_uprobe *auprobe, struct pt_regs *regs) |
d20737c0 | 479 | { |
5cdb76d6 | 480 | if (auprobe->defparam.fixups & UPROBE_FIX_RIP_MASK) { |
c90a6950 ON |
481 | struct uprobe_task *utask = current->utask; |
482 | unsigned long *sr = scratch_reg(auprobe, regs); | |
483 | ||
484 | utask->autask.saved_scratch_register = *sr; | |
5cdb76d6 | 485 | *sr = utask->vaddr + auprobe->defparam.ilen; |
d20737c0 ON |
486 | } |
487 | } | |
488 | ||
50204c6f | 489 | static void riprel_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs) |
d20737c0 | 490 | { |
5cdb76d6 | 491 | if (auprobe->defparam.fixups & UPROBE_FIX_RIP_MASK) { |
c90a6950 ON |
492 | struct uprobe_task *utask = current->utask; |
493 | unsigned long *sr = scratch_reg(auprobe, regs); | |
d20737c0 | 494 | |
c90a6950 | 495 | *sr = utask->autask.saved_scratch_register; |
d20737c0 ON |
496 | } |
497 | } | |
2ae1f49a | 498 | #else /* 32-bit: */ |
d20737c0 ON |
499 | /* |
500 | * No RIP-relative addressing on 32-bit | |
501 | */ | |
1475ee7f | 502 | static void riprel_analyze(struct arch_uprobe *auprobe, struct insn *insn) |
2b144498 | 503 | { |
d20737c0 | 504 | } |
7f55e82b | 505 | static void riprel_pre_xol(struct arch_uprobe *auprobe, struct pt_regs *regs) |
d20737c0 ON |
506 | { |
507 | } | |
50204c6f | 508 | static void riprel_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs) |
d20737c0 | 509 | { |
2b144498 | 510 | } |
2b144498 SD |
511 | #endif /* CONFIG_X86_64 */ |
512 | ||
8ad8e9d3 ON |
513 | struct uprobe_xol_ops { |
514 | bool (*emulate)(struct arch_uprobe *, struct pt_regs *); | |
515 | int (*pre_xol)(struct arch_uprobe *, struct pt_regs *); | |
516 | int (*post_xol)(struct arch_uprobe *, struct pt_regs *); | |
588fbd61 | 517 | void (*abort)(struct arch_uprobe *, struct pt_regs *); |
8ad8e9d3 ON |
518 | }; |
519 | ||
8faaed1b ON |
520 | static inline int sizeof_long(void) |
521 | { | |
abfb9498 | 522 | return in_ia32_syscall() ? 4 : 8; |
8faaed1b ON |
523 | } |
524 | ||
8ad8e9d3 ON |
525 | static int default_pre_xol_op(struct arch_uprobe *auprobe, struct pt_regs *regs) |
526 | { | |
7f55e82b | 527 | riprel_pre_xol(auprobe, regs); |
8ad8e9d3 ON |
528 | return 0; |
529 | } | |
530 | ||
2b82cadf ON |
531 | static int push_ret_address(struct pt_regs *regs, unsigned long ip) |
532 | { | |
533 | unsigned long new_sp = regs->sp - sizeof_long(); | |
534 | ||
535 | if (copy_to_user((void __user *)new_sp, &ip, sizeof_long())) | |
536 | return -EFAULT; | |
537 | ||
538 | regs->sp = new_sp; | |
539 | return 0; | |
540 | } | |
541 | ||
1ea30fb6 DV |
542 | /* |
543 | * We have to fix things up as follows: | |
544 | * | |
545 | * Typically, the new ip is relative to the copied instruction. We need | |
546 | * to make it relative to the original instruction (FIX_IP). Exceptions | |
547 | * are return instructions and absolute or indirect jump or call instructions. | |
548 | * | |
549 | * If the single-stepped instruction was a call, the return address that | |
550 | * is atop the stack is the address following the copied instruction. We | |
551 | * need to make it the address following the original instruction (FIX_CALL). | |
552 | * | |
553 | * If the original instruction was a rip-relative instruction such as | |
554 | * "movl %edx,0xnnnn(%rip)", we have instead executed an equivalent | |
555 | * instruction using a scratch register -- e.g., "movl %edx,0xnnnn(%rsi)". | |
556 | * We need to restore the contents of the scratch register | |
557 | * (FIX_RIP_reg). | |
558 | */ | |
8ad8e9d3 ON |
559 | static int default_post_xol_op(struct arch_uprobe *auprobe, struct pt_regs *regs) |
560 | { | |
561 | struct uprobe_task *utask = current->utask; | |
8ad8e9d3 | 562 | |
50204c6f | 563 | riprel_post_xol(auprobe, regs); |
5cdb76d6 | 564 | if (auprobe->defparam.fixups & UPROBE_FIX_IP) { |
50204c6f | 565 | long correction = utask->vaddr - utask->xol_vaddr; |
8ad8e9d3 | 566 | regs->ip += correction; |
5cdb76d6 ON |
567 | } else if (auprobe->defparam.fixups & UPROBE_FIX_CALL) { |
568 | regs->sp += sizeof_long(); /* Pop incorrect return address */ | |
569 | if (push_ret_address(regs, utask->vaddr + auprobe->defparam.ilen)) | |
75f9ef0b | 570 | return -ERESTART; |
75f9ef0b | 571 | } |
220ef8dc | 572 | /* popf; tell the caller to not touch TF */ |
5cdb76d6 | 573 | if (auprobe->defparam.fixups & UPROBE_FIX_SETF) |
220ef8dc | 574 | utask->autask.saved_tf = true; |
8ad8e9d3 | 575 | |
75f9ef0b | 576 | return 0; |
8ad8e9d3 ON |
577 | } |
578 | ||
588fbd61 ON |
579 | static void default_abort_op(struct arch_uprobe *auprobe, struct pt_regs *regs) |
580 | { | |
50204c6f | 581 | riprel_post_xol(auprobe, regs); |
588fbd61 ON |
582 | } |
583 | ||
dac42987 | 584 | static const struct uprobe_xol_ops default_xol_ops = { |
8ad8e9d3 ON |
585 | .pre_xol = default_pre_xol_op, |
586 | .post_xol = default_post_xol_op, | |
588fbd61 | 587 | .abort = default_abort_op, |
8ad8e9d3 ON |
588 | }; |
589 | ||
8e89c0be ON |
590 | static bool branch_is_call(struct arch_uprobe *auprobe) |
591 | { | |
592 | return auprobe->branch.opc1 == 0xe8; | |
593 | } | |
594 | ||
8f95505b ON |
595 | #define CASE_COND \ |
596 | COND(70, 71, XF(OF)) \ | |
597 | COND(72, 73, XF(CF)) \ | |
598 | COND(74, 75, XF(ZF)) \ | |
599 | COND(78, 79, XF(SF)) \ | |
600 | COND(7a, 7b, XF(PF)) \ | |
601 | COND(76, 77, XF(CF) || XF(ZF)) \ | |
602 | COND(7c, 7d, XF(SF) != XF(OF)) \ | |
603 | COND(7e, 7f, XF(ZF) || XF(SF) != XF(OF)) | |
604 | ||
605 | #define COND(op_y, op_n, expr) \ | |
606 | case 0x ## op_y: DO((expr) != 0) \ | |
607 | case 0x ## op_n: DO((expr) == 0) | |
608 | ||
609 | #define XF(xf) (!!(flags & X86_EFLAGS_ ## xf)) | |
610 | ||
611 | static bool is_cond_jmp_opcode(u8 opcode) | |
612 | { | |
613 | switch (opcode) { | |
614 | #define DO(expr) \ | |
615 | return true; | |
616 | CASE_COND | |
617 | #undef DO | |
618 | ||
619 | default: | |
620 | return false; | |
621 | } | |
622 | } | |
623 | ||
624 | static bool check_jmp_cond(struct arch_uprobe *auprobe, struct pt_regs *regs) | |
625 | { | |
626 | unsigned long flags = regs->flags; | |
627 | ||
628 | switch (auprobe->branch.opc1) { | |
629 | #define DO(expr) \ | |
630 | return expr; | |
631 | CASE_COND | |
632 | #undef DO | |
633 | ||
634 | default: /* not a conditional jmp */ | |
635 | return true; | |
636 | } | |
637 | } | |
638 | ||
639 | #undef XF | |
640 | #undef COND | |
641 | #undef CASE_COND | |
642 | ||
7ba6db2d ON |
643 | static bool branch_emulate_op(struct arch_uprobe *auprobe, struct pt_regs *regs) |
644 | { | |
8e89c0be | 645 | unsigned long new_ip = regs->ip += auprobe->branch.ilen; |
8f95505b | 646 | unsigned long offs = (long)auprobe->branch.offs; |
8e89c0be ON |
647 | |
648 | if (branch_is_call(auprobe)) { | |
8e89c0be ON |
649 | /* |
650 | * If it fails we execute this (mangled, see the comment in | |
651 | * branch_clear_offset) insn out-of-line. In the likely case | |
652 | * this should trigger the trap, and the probed application | |
653 | * should die or restart the same insn after it handles the | |
654 | * signal, arch_uprobe_post_xol() won't be even called. | |
655 | * | |
656 | * But there is corner case, see the comment in ->post_xol(). | |
657 | */ | |
2b82cadf | 658 | if (push_ret_address(regs, new_ip)) |
8e89c0be | 659 | return false; |
8f95505b ON |
660 | } else if (!check_jmp_cond(auprobe, regs)) { |
661 | offs = 0; | |
8e89c0be ON |
662 | } |
663 | ||
8f95505b | 664 | regs->ip = new_ip + offs; |
7ba6db2d ON |
665 | return true; |
666 | } | |
667 | ||
8e89c0be ON |
668 | static int branch_post_xol_op(struct arch_uprobe *auprobe, struct pt_regs *regs) |
669 | { | |
670 | BUG_ON(!branch_is_call(auprobe)); | |
671 | /* | |
672 | * We can only get here if branch_emulate_op() failed to push the ret | |
673 | * address _and_ another thread expanded our stack before the (mangled) | |
674 | * "call" insn was executed out-of-line. Just restore ->sp and restart. | |
675 | * We could also restore ->ip and try to call branch_emulate_op() again. | |
676 | */ | |
677 | regs->sp += sizeof_long(); | |
678 | return -ERESTART; | |
679 | } | |
680 | ||
681 | static void branch_clear_offset(struct arch_uprobe *auprobe, struct insn *insn) | |
682 | { | |
683 | /* | |
684 | * Turn this insn into "call 1f; 1:", this is what we will execute | |
685 | * out-of-line if ->emulate() fails. We only need this to generate | |
686 | * a trap, so that the probed task receives the correct signal with | |
687 | * the properly filled siginfo. | |
688 | * | |
689 | * But see the comment in ->post_xol(), in the unlikely case it can | |
690 | * succeed. So we need to ensure that the new ->ip can not fall into | |
691 | * the non-canonical area and trigger #GP. | |
692 | * | |
693 | * We could turn it into (say) "pushf", but then we would need to | |
694 | * divorce ->insn[] and ->ixol[]. We need to preserve the 1st byte | |
695 | * of ->insn[] for set_orig_insn(). | |
696 | */ | |
697 | memset(auprobe->insn + insn_offset_immediate(insn), | |
698 | 0, insn->immediate.nbytes); | |
699 | } | |
700 | ||
dac42987 | 701 | static const struct uprobe_xol_ops branch_xol_ops = { |
7ba6db2d | 702 | .emulate = branch_emulate_op, |
8e89c0be | 703 | .post_xol = branch_post_xol_op, |
7ba6db2d ON |
704 | }; |
705 | ||
706 | /* Returns -ENOSYS if branch_xol_ops doesn't handle this insn */ | |
707 | static int branch_setup_xol_ops(struct arch_uprobe *auprobe, struct insn *insn) | |
708 | { | |
8e89c0be | 709 | u8 opc1 = OPCODE1(insn); |
250bbd12 | 710 | int i; |
8e89c0be | 711 | |
8e89c0be | 712 | switch (opc1) { |
7ba6db2d ON |
713 | case 0xeb: /* jmp 8 */ |
714 | case 0xe9: /* jmp 32 */ | |
d2410063 | 715 | case 0x90: /* prefix* + nop; same as jmp with .offs = 0 */ |
7ba6db2d | 716 | break; |
8e89c0be ON |
717 | |
718 | case 0xe8: /* call relative */ | |
719 | branch_clear_offset(auprobe, insn); | |
720 | break; | |
8f95505b | 721 | |
6cc5e7ff ON |
722 | case 0x0f: |
723 | if (insn->opcode.nbytes != 2) | |
724 | return -ENOSYS; | |
725 | /* | |
726 | * If it is a "near" conditional jmp, OPCODE2() - 0x10 matches | |
727 | * OPCODE1() of the "short" jmp which checks the same condition. | |
728 | */ | |
729 | opc1 = OPCODE2(insn) - 0x10; | |
7ba6db2d | 730 | default: |
8f95505b ON |
731 | if (!is_cond_jmp_opcode(opc1)) |
732 | return -ENOSYS; | |
7ba6db2d ON |
733 | } |
734 | ||
250bbd12 DV |
735 | /* |
736 | * 16-bit overrides such as CALLW (66 e8 nn nn) are not supported. | |
737 | * Intel and AMD behavior differ in 64-bit mode: Intel ignores 66 prefix. | |
738 | * No one uses these insns, reject any branch insns with such prefix. | |
739 | */ | |
740 | for (i = 0; i < insn->prefixes.nbytes; i++) { | |
741 | if (insn->prefixes.bytes[i] == 0x66) | |
742 | return -ENOTSUPP; | |
743 | } | |
744 | ||
8e89c0be | 745 | auprobe->branch.opc1 = opc1; |
7ba6db2d ON |
746 | auprobe->branch.ilen = insn->length; |
747 | auprobe->branch.offs = insn->immediate.value; | |
748 | ||
749 | auprobe->ops = &branch_xol_ops; | |
750 | return 0; | |
751 | } | |
752 | ||
2b144498 | 753 | /** |
0326f5a9 | 754 | * arch_uprobe_analyze_insn - instruction analysis including validity and fixups. |
2b144498 | 755 | * @mm: the probed address space. |
3ff54efd | 756 | * @arch_uprobe: the probepoint information. |
7eb9ba5e | 757 | * @addr: virtual address at which to install the probepoint |
2b144498 SD |
758 | * Return 0 on success or a -ve number on error. |
759 | */ | |
7eb9ba5e | 760 | int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long addr) |
2b144498 | 761 | { |
2b144498 | 762 | struct insn insn; |
83cd5914 | 763 | u8 fix_ip_or_call = UPROBE_FIX_IP; |
ddb69f27 | 764 | int ret; |
2b144498 | 765 | |
2ae1f49a | 766 | ret = uprobe_init_insn(auprobe, &insn, is_64bit_mm(mm)); |
ddb69f27 | 767 | if (ret) |
2b144498 | 768 | return ret; |
7b2d81d4 | 769 | |
7ba6db2d ON |
770 | ret = branch_setup_xol_ops(auprobe, &insn); |
771 | if (ret != -ENOSYS) | |
772 | return ret; | |
773 | ||
ddb69f27 | 774 | /* |
97aa5cdd | 775 | * Figure out which fixups default_post_xol_op() will need to perform, |
5cdb76d6 | 776 | * and annotate defparam->fixups accordingly. |
ddb69f27 | 777 | */ |
ddb69f27 ON |
778 | switch (OPCODE1(&insn)) { |
779 | case 0x9d: /* popf */ | |
5cdb76d6 | 780 | auprobe->defparam.fixups |= UPROBE_FIX_SETF; |
ddb69f27 ON |
781 | break; |
782 | case 0xc3: /* ret or lret -- ip is correct */ | |
783 | case 0xcb: | |
784 | case 0xc2: | |
785 | case 0xca: | |
83cd5914 ON |
786 | case 0xea: /* jmp absolute -- ip is correct */ |
787 | fix_ip_or_call = 0; | |
ddb69f27 | 788 | break; |
ddb69f27 | 789 | case 0x9a: /* call absolute - Fix return addr, not ip */ |
83cd5914 | 790 | fix_ip_or_call = UPROBE_FIX_CALL; |
ddb69f27 ON |
791 | break; |
792 | case 0xff: | |
ddb69f27 ON |
793 | switch (MODRM_REG(&insn)) { |
794 | case 2: case 3: /* call or lcall, indirect */ | |
83cd5914 ON |
795 | fix_ip_or_call = UPROBE_FIX_CALL; |
796 | break; | |
ddb69f27 | 797 | case 4: case 5: /* jmp or ljmp, indirect */ |
83cd5914 ON |
798 | fix_ip_or_call = 0; |
799 | break; | |
ddb69f27 | 800 | } |
e55848a4 | 801 | /* fall through */ |
ddb69f27 | 802 | default: |
1475ee7f | 803 | riprel_analyze(auprobe, &insn); |
ddb69f27 ON |
804 | } |
805 | ||
5cdb76d6 ON |
806 | auprobe->defparam.ilen = insn.length; |
807 | auprobe->defparam.fixups |= fix_ip_or_call; | |
7b2d81d4 | 808 | |
8ad8e9d3 | 809 | auprobe->ops = &default_xol_ops; |
2b144498 SD |
810 | return 0; |
811 | } | |
0326f5a9 | 812 | |
0326f5a9 SD |
813 | /* |
814 | * arch_uprobe_pre_xol - prepare to execute out of line. | |
815 | * @auprobe: the probepoint information. | |
816 | * @regs: reflects the saved user state of current task. | |
817 | */ | |
818 | int arch_uprobe_pre_xol(struct arch_uprobe *auprobe, struct pt_regs *regs) | |
819 | { | |
34e7317d | 820 | struct uprobe_task *utask = current->utask; |
0326f5a9 | 821 | |
dd91016d ON |
822 | if (auprobe->ops->pre_xol) { |
823 | int err = auprobe->ops->pre_xol(auprobe, regs); | |
824 | if (err) | |
825 | return err; | |
826 | } | |
827 | ||
34e7317d ON |
828 | regs->ip = utask->xol_vaddr; |
829 | utask->autask.saved_trap_nr = current->thread.trap_nr; | |
0326f5a9 | 830 | current->thread.trap_nr = UPROBE_TRAP_NR; |
0326f5a9 | 831 | |
34e7317d | 832 | utask->autask.saved_tf = !!(regs->flags & X86_EFLAGS_TF); |
4dc316c6 ON |
833 | regs->flags |= X86_EFLAGS_TF; |
834 | if (test_tsk_thread_flag(current, TIF_BLOCKSTEP)) | |
835 | set_task_blockstep(current, false); | |
836 | ||
0326f5a9 SD |
837 | return 0; |
838 | } | |
839 | ||
0326f5a9 SD |
840 | /* |
841 | * If xol insn itself traps and generates a signal(Say, | |
842 | * SIGILL/SIGSEGV/etc), then detect the case where a singlestepped | |
843 | * instruction jumps back to its own address. It is assumed that anything | |
844 | * like do_page_fault/do_trap/etc sets thread.trap_nr != -1. | |
845 | * | |
846 | * arch_uprobe_pre_xol/arch_uprobe_post_xol save/restore thread.trap_nr, | |
847 | * arch_uprobe_xol_was_trapped() simply checks that ->trap_nr is not equal to | |
848 | * UPROBE_TRAP_NR == -1 set by arch_uprobe_pre_xol(). | |
849 | */ | |
850 | bool arch_uprobe_xol_was_trapped(struct task_struct *t) | |
851 | { | |
852 | if (t->thread.trap_nr != UPROBE_TRAP_NR) | |
853 | return true; | |
854 | ||
855 | return false; | |
856 | } | |
857 | ||
858 | /* | |
859 | * Called after single-stepping. To avoid the SMP problems that can | |
860 | * occur when we temporarily put back the original opcode to | |
861 | * single-step, we single-stepped a copy of the instruction. | |
862 | * | |
863 | * This function prepares to resume execution after the single-step. | |
0326f5a9 SD |
864 | */ |
865 | int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs) | |
866 | { | |
34e7317d | 867 | struct uprobe_task *utask = current->utask; |
220ef8dc ON |
868 | bool send_sigtrap = utask->autask.saved_tf; |
869 | int err = 0; | |
0326f5a9 SD |
870 | |
871 | WARN_ON_ONCE(current->thread.trap_nr != UPROBE_TRAP_NR); | |
6ded5f38 | 872 | current->thread.trap_nr = utask->autask.saved_trap_nr; |
014940ba ON |
873 | |
874 | if (auprobe->ops->post_xol) { | |
220ef8dc | 875 | err = auprobe->ops->post_xol(auprobe, regs); |
014940ba | 876 | if (err) { |
75f9ef0b | 877 | /* |
6ded5f38 ON |
878 | * Restore ->ip for restart or post mortem analysis. |
879 | * ->post_xol() must not return -ERESTART unless this | |
880 | * is really possible. | |
75f9ef0b | 881 | */ |
6ded5f38 | 882 | regs->ip = utask->vaddr; |
75f9ef0b | 883 | if (err == -ERESTART) |
220ef8dc ON |
884 | err = 0; |
885 | send_sigtrap = false; | |
014940ba ON |
886 | } |
887 | } | |
4dc316c6 ON |
888 | /* |
889 | * arch_uprobe_pre_xol() doesn't save the state of TIF_BLOCKSTEP | |
890 | * so we can get an extra SIGTRAP if we do not clear TF. We need | |
891 | * to examine the opcode to make it right. | |
892 | */ | |
220ef8dc | 893 | if (send_sigtrap) |
4dc316c6 | 894 | send_sig(SIGTRAP, current, 0); |
220ef8dc ON |
895 | |
896 | if (!utask->autask.saved_tf) | |
4dc316c6 ON |
897 | regs->flags &= ~X86_EFLAGS_TF; |
898 | ||
220ef8dc | 899 | return err; |
0326f5a9 SD |
900 | } |
901 | ||
902 | /* callback routine for handling exceptions. */ | |
903 | int arch_uprobe_exception_notify(struct notifier_block *self, unsigned long val, void *data) | |
904 | { | |
905 | struct die_args *args = data; | |
906 | struct pt_regs *regs = args->regs; | |
907 | int ret = NOTIFY_DONE; | |
908 | ||
909 | /* We are only interested in userspace traps */ | |
f39b6f0e | 910 | if (regs && !user_mode(regs)) |
0326f5a9 SD |
911 | return NOTIFY_DONE; |
912 | ||
913 | switch (val) { | |
914 | case DIE_INT3: | |
915 | if (uprobe_pre_sstep_notifier(regs)) | |
916 | ret = NOTIFY_STOP; | |
917 | ||
918 | break; | |
919 | ||
920 | case DIE_DEBUG: | |
921 | if (uprobe_post_sstep_notifier(regs)) | |
922 | ret = NOTIFY_STOP; | |
923 | ||
924 | default: | |
925 | break; | |
926 | } | |
927 | ||
928 | return ret; | |
929 | } | |
930 | ||
931 | /* | |
932 | * This function gets called when XOL instruction either gets trapped or | |
6ded5f38 ON |
933 | * the thread has a fatal signal. Reset the instruction pointer to its |
934 | * probed address for the potential restart or for post mortem analysis. | |
0326f5a9 SD |
935 | */ |
936 | void arch_uprobe_abort_xol(struct arch_uprobe *auprobe, struct pt_regs *regs) | |
937 | { | |
938 | struct uprobe_task *utask = current->utask; | |
939 | ||
588fbd61 ON |
940 | if (auprobe->ops->abort) |
941 | auprobe->ops->abort(auprobe, regs); | |
4dc316c6 | 942 | |
588fbd61 ON |
943 | current->thread.trap_nr = utask->autask.saved_trap_nr; |
944 | regs->ip = utask->vaddr; | |
4dc316c6 ON |
945 | /* clear TF if it was set by us in arch_uprobe_pre_xol() */ |
946 | if (!utask->autask.saved_tf) | |
947 | regs->flags &= ~X86_EFLAGS_TF; | |
0326f5a9 SD |
948 | } |
949 | ||
3a4664aa | 950 | static bool __skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs) |
0326f5a9 | 951 | { |
8ad8e9d3 ON |
952 | if (auprobe->ops->emulate) |
953 | return auprobe->ops->emulate(auprobe, regs); | |
0326f5a9 SD |
954 | return false; |
955 | } | |
bdc1e472 | 956 | |
3a4664aa ON |
957 | bool arch_uprobe_skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs) |
958 | { | |
959 | bool ret = __skip_sstep(auprobe, regs); | |
960 | if (ret && (regs->flags & X86_EFLAGS_TF)) | |
961 | send_sig(SIGTRAP, current, 0); | |
962 | return ret; | |
963 | } | |
791eca10 AA |
964 | |
965 | unsigned long | |
966 | arch_uretprobe_hijack_return_addr(unsigned long trampoline_vaddr, struct pt_regs *regs) | |
967 | { | |
8faaed1b | 968 | int rasize = sizeof_long(), nleft; |
791eca10 AA |
969 | unsigned long orig_ret_vaddr = 0; /* clear high bits for 32-bit apps */ |
970 | ||
8faaed1b | 971 | if (copy_from_user(&orig_ret_vaddr, (void __user *)regs->sp, rasize)) |
791eca10 AA |
972 | return -1; |
973 | ||
974 | /* check whether address has been already hijacked */ | |
975 | if (orig_ret_vaddr == trampoline_vaddr) | |
976 | return orig_ret_vaddr; | |
977 | ||
8faaed1b ON |
978 | nleft = copy_to_user((void __user *)regs->sp, &trampoline_vaddr, rasize); |
979 | if (likely(!nleft)) | |
791eca10 AA |
980 | return orig_ret_vaddr; |
981 | ||
8faaed1b | 982 | if (nleft != rasize) { |
791eca10 AA |
983 | pr_err("uprobe: return address clobbered: pid=%d, %%sp=%#lx, " |
984 | "%%ip=%#lx\n", current->pid, regs->sp, regs->ip); | |
985 | ||
986 | force_sig_info(SIGSEGV, SEND_SIG_FORCED, current); | |
987 | } | |
988 | ||
989 | return -1; | |
990 | } | |
7b868e48 | 991 | |
86dcb702 ON |
992 | bool arch_uretprobe_is_alive(struct return_instance *ret, enum rp_check ctx, |
993 | struct pt_regs *regs) | |
7b868e48 | 994 | { |
db087ef6 ON |
995 | if (ctx == RP_CHECK_CALL) /* sp was just decremented by "call" insn */ |
996 | return regs->sp < ret->stack; | |
997 | else | |
998 | return regs->sp <= ret->stack; | |
7b868e48 | 999 | } |