1 /* GNU/Linux/x86 specific low level interface, for the in-process
2 agent library for GDB.
3
4 Copyright (C) 2010-2013 Free Software Foundation, Inc.
5
6 This file is part of GDB.
7
8 This program is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 3 of the License, or
11 (at your option) any later version.
12
13 This program is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
17
18 You should have received a copy of the GNU General Public License
19 along with this program. If not, see <http://www.gnu.org/licenses/>. */
20
21 #include "server.h"
22 #include <stdint.h>
23 #include <sys/mman.h>
24
25 /* GDB register numbers. */
26
27 enum i386_gdb_regnum
28 {
29 I386_EAX_REGNUM, /* %eax */
30 I386_ECX_REGNUM, /* %ecx */
31 I386_EDX_REGNUM, /* %edx */
32 I386_EBX_REGNUM, /* %ebx */
33 I386_ESP_REGNUM, /* %esp */
34 I386_EBP_REGNUM, /* %ebp */
35 I386_ESI_REGNUM, /* %esi */
36 I386_EDI_REGNUM, /* %edi */
37 I386_EIP_REGNUM, /* %eip */
38 I386_EFLAGS_REGNUM, /* %eflags */
39 I386_CS_REGNUM, /* %cs */
40 I386_SS_REGNUM, /* %ss */
41 I386_DS_REGNUM, /* %ds */
42 I386_ES_REGNUM, /* %es */
43 I386_FS_REGNUM, /* %fs */
44 I386_GS_REGNUM, /* %gs */
45 I386_ST0_REGNUM /* %st(0) */
46 };
47
48 #define i386_num_regs 16
49
50 /* Defined in auto-generated file i386-linux.c. */
51 void init_registers_i386_linux (void);
52
53 #define FT_CR_EAX 15
54 #define FT_CR_ECX 14
55 #define FT_CR_EDX 13
56 #define FT_CR_EBX 12
57 #define FT_CR_UESP 11
58 #define FT_CR_EBP 10
59 #define FT_CR_ESI 9
60 #define FT_CR_EDI 8
61 #define FT_CR_EIP 7
62 #define FT_CR_EFL 6
63 #define FT_CR_DS 5
64 #define FT_CR_ES 4
65 #define FT_CR_FS 3
66 #define FT_CR_GS 2
67 #define FT_CR_SS 1
68 #define FT_CR_CS 0
69
70 /* Mapping between the general-purpose registers in jump tracepoint
71 format and GDB's register array layout. */
72
73 static const int i386_ft_collect_regmap[] =
74 {
75 FT_CR_EAX * 4, FT_CR_ECX * 4, FT_CR_EDX * 4, FT_CR_EBX * 4,
76 FT_CR_UESP * 4, FT_CR_EBP * 4, FT_CR_ESI * 4, FT_CR_EDI * 4,
77 FT_CR_EIP * 4, FT_CR_EFL * 4, FT_CR_CS * 4, FT_CR_SS * 4,
78 FT_CR_DS * 4, FT_CR_ES * 4, FT_CR_FS * 4, FT_CR_GS * 4
79 };
80
81 void
supply_fast_tracepoint_registers(struct regcache * regcache,const unsigned char * buf)82 supply_fast_tracepoint_registers (struct regcache *regcache,
83 const unsigned char *buf)
84 {
85 int i;
86
87 for (i = 0; i < i386_num_regs; i++)
88 {
89 int regval;
90
91 if (i >= I386_CS_REGNUM && i <= I386_GS_REGNUM)
92 regval = *(short *) (((char *) buf) + i386_ft_collect_regmap[i]);
93 else
94 regval = *(int *) (((char *) buf) + i386_ft_collect_regmap[i]);
95
96 supply_register (regcache, i, ®val);
97 }
98 }
99
100 ULONGEST __attribute__ ((visibility("default"), used))
gdb_agent_get_raw_reg(unsigned char * raw_regs,int regnum)101 gdb_agent_get_raw_reg (unsigned char *raw_regs, int regnum)
102 {
103 /* This should maybe be allowed to return an error code, or perhaps
104 better, have the emit_reg detect this, and emit a constant zero,
105 or something. */
106
107 if (regnum > i386_num_regs)
108 return 0;
109 else if (regnum >= I386_CS_REGNUM && regnum <= I386_GS_REGNUM)
110 return *(short *) (raw_regs + i386_ft_collect_regmap[regnum]);
111 else
112 return *(int *) (raw_regs + i386_ft_collect_regmap[regnum]);
113 }
114
115 #ifdef HAVE_UST
116
117 #include <ust/processor.h>
118
119 /* "struct registers" is the UST object type holding the registers at
120 the time of the static tracepoint marker call. This doesn't
121 contain EIP, but we know what it must have been (the marker
122 address). */
123
124 #define ST_REGENTRY(REG) \
125 { \
126 offsetof (struct registers, REG), \
127 sizeof (((struct registers *) NULL)->REG) \
128 }
129
130 static struct
131 {
132 int offset;
133 int size;
134 } i386_st_collect_regmap[] =
135 {
136 ST_REGENTRY(eax),
137 ST_REGENTRY(ecx),
138 ST_REGENTRY(edx),
139 ST_REGENTRY(ebx),
140 ST_REGENTRY(esp),
141 ST_REGENTRY(ebp),
142 ST_REGENTRY(esi),
143 ST_REGENTRY(edi),
144 { -1, 0 }, /* eip */
145 ST_REGENTRY(eflags),
146 ST_REGENTRY(cs),
147 ST_REGENTRY(ss),
148 };
149
150 #define i386_NUM_ST_COLLECT_GREGS \
151 (sizeof (i386_st_collect_regmap) / sizeof (i386_st_collect_regmap[0]))
152
153 void
supply_static_tracepoint_registers(struct regcache * regcache,const unsigned char * buf,CORE_ADDR pc)154 supply_static_tracepoint_registers (struct regcache *regcache,
155 const unsigned char *buf,
156 CORE_ADDR pc)
157 {
158 int i;
159 unsigned int newpc = pc;
160
161 supply_register (regcache, I386_EIP_REGNUM, &newpc);
162
163 for (i = 0; i < i386_NUM_ST_COLLECT_GREGS; i++)
164 if (i386_st_collect_regmap[i].offset != -1)
165 {
166 switch (i386_st_collect_regmap[i].size)
167 {
168 case 4:
169 supply_register (regcache, i,
170 ((char *) buf)
171 + i386_st_collect_regmap[i].offset);
172 break;
173 case 2:
174 {
175 unsigned long reg
176 = * (short *) (((char *) buf)
177 + i386_st_collect_regmap[i].offset);
178 reg &= 0xffff;
179 supply_register (regcache, i, ®);
180 }
181 break;
182 default:
183 internal_error (__FILE__, __LINE__, "unhandled register size: %d",
184 i386_st_collect_regmap[i].size);
185 }
186 }
187 }
188
189 #endif /* HAVE_UST */
190
191
192 /* This is only needed because reg-i386-linux-lib.o references it. We
193 may use it proper at some point. */
194 const char *gdbserver_xmltarget;
195
196 /* Attempt to allocate memory for trampolines in the first 64 KiB of
197 memory to enable smaller jump patches. */
198
199 static void
initialize_fast_tracepoint_trampoline_buffer(void)200 initialize_fast_tracepoint_trampoline_buffer (void)
201 {
202 const CORE_ADDR buffer_end = 64 * 1024;
203 /* Ensure that the buffer will be at least 1 KiB in size, which is
204 enough space for over 200 fast tracepoints. */
205 const int min_buffer_size = 1024;
206 char buf[IPA_BUFSIZ];
207 CORE_ADDR mmap_min_addr = buffer_end + 1;
208 ULONGEST buffer_size;
209 FILE *f = fopen ("/proc/sys/vm/mmap_min_addr", "r");
210
211 if (!f)
212 {
213 snprintf (buf, sizeof (buf), "mmap_min_addr open failed: %s",
214 strerror (errno));
215 set_trampoline_buffer_space (0, 0, buf);
216 return;
217 }
218
219 if (fgets (buf, IPA_BUFSIZ, f))
220 sscanf (buf, "%llu", &mmap_min_addr);
221
222 fclose (f);
223
224 buffer_size = buffer_end - mmap_min_addr;
225
226 if (buffer_size >= min_buffer_size)
227 {
228 if (mmap ((void *) (uintptr_t) mmap_min_addr, buffer_size,
229 PROT_READ | PROT_EXEC | PROT_WRITE,
230 MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS,
231 -1, 0)
232 != MAP_FAILED)
233 set_trampoline_buffer_space (mmap_min_addr, buffer_end, NULL);
234 else
235 {
236 snprintf (buf, IPA_BUFSIZ, "low-64K-buffer mmap() failed: %s",
237 strerror (errno));
238 set_trampoline_buffer_space (0, 0, buf);
239 }
240 }
241 else
242 {
243 snprintf (buf, IPA_BUFSIZ, "mmap_min_addr is %d, must be %d or less",
244 (int) mmap_min_addr, (int) buffer_end - min_buffer_size);
245 set_trampoline_buffer_space (0, 0, buf);
246 }
247 }
248
249 void
initialize_low_tracepoint(void)250 initialize_low_tracepoint (void)
251 {
252 init_registers_i386_linux ();
253 initialize_fast_tracepoint_trampoline_buffer ();
254 }
255