| 1 | /* Target-dependent code for GNU/Linux SPARC. |
| 2 | |
| 3 | Copyright 2003 Free Software Foundation, Inc. |
| 4 | |
| 5 | This file is part of GDB. |
| 6 | |
| 7 | This program is free software; you can redistribute it and/or modify |
| 8 | it under the terms of the GNU General Public License as published by |
| 9 | the Free Software Foundation; either version 2 of the License, or |
| 10 | (at your option) any later version. |
| 11 | |
| 12 | This program is distributed in the hope that it will be useful, |
| 13 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 15 | GNU General Public License for more details. |
| 16 | |
| 17 | You should have received a copy of the GNU General Public License |
| 18 | along with this program; if not, write to the Free Software |
| 19 | Foundation, Inc., 59 Temple Place - Suite 330, |
| 20 | Boston, MA 02111-1307, USA. */ |
| 21 | |
| 22 | #include "defs.h" |
| 23 | #include "floatformat.h" |
| 24 | #include "frame.h" |
| 25 | #include "frame-unwind.h" |
| 26 | #include "gdbarch.h" |
| 27 | #include "gdbcore.h" |
| 28 | #include "osabi.h" |
| 29 | #include "regcache.h" |
| 30 | #include "solib-svr4.h" |
| 31 | #include "symtab.h" |
| 32 | #include "trad-frame.h" |
| 33 | |
| 34 | #include "gdb_assert.h" |
| 35 | #include "gdb_string.h" |
| 36 | |
| 37 | #include "sparc-tdep.h" |
| 38 | |
| 39 | /* Recognizing signal handler frames. */ |
| 40 | |
| 41 | /* GNU/Linux has two flavors of signals. Normal signal handlers, and |
| 42 | "realtime" (RT) signals. The RT signals can provide additional |
| 43 | information to the signal handler if the SA_SIGINFO flag is set |
| 44 | when establishing a signal handler using `sigaction'. It is not |
| 45 | unlikely that future versions of GNU/Linux will support SA_SIGINFO |
| 46 | for normal signals too. */ |
| 47 | |
| 48 | /* When the sparc Linux kernel calls a signal handler and the |
| 49 | SA_RESTORER flag isn't set, the return address points to a bit of |
| 50 | code on the stack. This function returns whether the PC appears to |
| 51 | be within this bit of code. |
| 52 | |
| 53 | The instruction sequence for normal signals is |
| 54 | mov __NR_sigreturn, %g1 ! hex: 0x821020d8 |
| 55 | ta 0x10 ! hex: 0x91d02010 |
| 56 | |
| 57 | Checking for the code sequence should be somewhat reliable, because |
| 58 | the effect is to call the system call sigreturn. This is unlikely |
| 59 | to occur anywhere other than a signal trampoline. |
| 60 | |
| 61 | It kind of sucks that we have to read memory from the process in |
| 62 | order to identify a signal trampoline, but there doesn't seem to be |
| 63 | any other way. However, sparc32_linux_pc_in_sigtramp arranges to |
| 64 | only call us if no function name could be identified, which should |
| 65 | be the case since the code is on the stack. */ |
| 66 | |
| 67 | #define LINUX32_SIGTRAMP_INSN0 0x821020d8 /* mov __NR_sigreturn, %g1 */ |
| 68 | #define LINUX32_SIGTRAMP_INSN1 0x91d02010 /* ta 0x10 */ |
| 69 | |
| 70 | /* The instruction sequence for RT signals is |
| 71 | mov __NR_rt_sigreturn, %g1 ! hex: 0x82102065 |
| 72 | ta {0x10,0x6d} ! hex: 0x91d02010 or 0x91d0206d |
| 73 | |
| 74 | The effect is to call the system call rt_sigreturn. The trap number |
| 75 | is variable based upon whether this is a 32-bit or 64-bit sparc binary. |
| 76 | Note that 64-bit binaries only use this RT signal return method. */ |
| 77 | |
| 78 | #define LINUX32_RT_SIGTRAMP_INSN0 0x82102065 |
| 79 | #define LINUX32_RT_SIGTRAMP_INSN1 0x91d02010 |
| 80 | |
| 81 | /* If PC is in a sigtramp routine consisting of the instructions INSN0 |
| 82 | and INSN1, return the address of the start of the routine. |
| 83 | Otherwise, return 0. */ |
| 84 | |
| 85 | CORE_ADDR |
| 86 | sparc_linux_sigtramp_start (CORE_ADDR pc, ULONGEST insn0, ULONGEST insn1) |
| 87 | { |
| 88 | ULONGEST word0, word1; |
| 89 | char buf[8]; /* Two instructions. */ |
| 90 | |
| 91 | /* We only recognize a signal trampoline if PC is at the start of |
| 92 | one of the instructions. We optimize for finding the PC at the |
| 93 | start of the instruction sequence, as will be the case when the |
| 94 | trampoline is not the first frame on the stack. We assume that |
| 95 | in the case where the PC is not at the start of the instruction |
| 96 | sequence, there will be a few trailing readable bytes on the |
| 97 | stack. */ |
| 98 | |
| 99 | if (read_memory_nobpt (pc, buf, sizeof buf) != 0) |
| 100 | return 0; |
| 101 | |
| 102 | word0 = extract_unsigned_integer (buf, 4); |
| 103 | if (word0 != insn0) |
| 104 | { |
| 105 | if (word0 != insn1) |
| 106 | return 0; |
| 107 | |
| 108 | pc -= 4; |
| 109 | if (read_memory_nobpt (pc, buf, sizeof buf) != 0) |
| 110 | return 0; |
| 111 | |
| 112 | word0 = extract_unsigned_integer (buf, 4); |
| 113 | } |
| 114 | |
| 115 | word1 = extract_unsigned_integer (buf + 4, 4); |
| 116 | if (word0 != insn0 || word1 != insn1) |
| 117 | return 0; |
| 118 | |
| 119 | return pc; |
| 120 | } |
| 121 | |
| 122 | static CORE_ADDR |
| 123 | sparc32_linux_sigtramp_start (CORE_ADDR pc) |
| 124 | { |
| 125 | return sparc_linux_sigtramp_start (pc, LINUX32_SIGTRAMP_INSN0, |
| 126 | LINUX32_SIGTRAMP_INSN1); |
| 127 | } |
| 128 | |
| 129 | static CORE_ADDR |
| 130 | sparc32_linux_rt_sigtramp_start (CORE_ADDR pc) |
| 131 | { |
| 132 | return sparc_linux_sigtramp_start (pc, LINUX32_RT_SIGTRAMP_INSN0, |
| 133 | LINUX32_RT_SIGTRAMP_INSN1); |
| 134 | } |
| 135 | |
| 136 | static int |
| 137 | sparc32_linux_pc_in_sigtramp (CORE_ADDR pc, char *name) |
| 138 | { |
| 139 | /* If we have NAME, we can optimize the search. The trampolines are |
| 140 | named __restore and __restore_rt. However, they aren't dynamically |
| 141 | exported from the shared C library, so the trampoline may appear to |
| 142 | be part of the preceding function. This should always be sigaction, |
| 143 | __sigaction, or __libc_sigaction (all aliases to the same function). */ |
| 144 | if (name == NULL || strstr (name, "sigaction") != NULL) |
| 145 | return (sparc32_linux_sigtramp_start (pc) != 0 |
| 146 | || sparc32_linux_rt_sigtramp_start (pc) != 0); |
| 147 | |
| 148 | return (strcmp ("__restore", name) == 0 |
| 149 | || strcmp ("__restore_rt", name) == 0); |
| 150 | } |
| 151 | |
| 152 | static struct sparc_frame_cache * |
| 153 | sparc32_linux_sigtramp_frame_cache (struct frame_info *next_frame, |
| 154 | void **this_cache) |
| 155 | { |
| 156 | struct sparc_frame_cache *cache; |
| 157 | CORE_ADDR sigcontext_addr, addr; |
| 158 | int regnum; |
| 159 | |
| 160 | if (*this_cache) |
| 161 | return *this_cache; |
| 162 | |
| 163 | cache = sparc32_frame_cache (next_frame, this_cache); |
| 164 | gdb_assert (cache == *this_cache); |
| 165 | |
| 166 | /* ??? What about signal trampolines that aren't frameless? */ |
| 167 | regnum = SPARC_SP_REGNUM; |
| 168 | cache->base = frame_unwind_register_unsigned (next_frame, regnum); |
| 169 | |
| 170 | regnum = SPARC_O1_REGNUM; |
| 171 | sigcontext_addr = frame_unwind_register_unsigned (next_frame, regnum); |
| 172 | |
| 173 | cache->pc = frame_pc_unwind (next_frame); |
| 174 | addr = sparc32_linux_sigtramp_start (cache->pc); |
| 175 | if (addr == 0) |
| 176 | { |
| 177 | /* If this is a RT signal trampoline, adjust SIGCONTEXT_ADDR |
| 178 | accordingly. */ |
| 179 | addr = sparc32_linux_rt_sigtramp_start (cache->pc); |
| 180 | if (addr) |
| 181 | sigcontext_addr += 128; |
| 182 | else |
| 183 | addr = frame_func_unwind (next_frame); |
| 184 | } |
| 185 | cache->pc = addr; |
| 186 | |
| 187 | cache->saved_regs = trad_frame_alloc_saved_regs (next_frame); |
| 188 | |
| 189 | cache->saved_regs[SPARC32_PSR_REGNUM].addr = sigcontext_addr + 0; |
| 190 | cache->saved_regs[SPARC32_PC_REGNUM].addr = sigcontext_addr + 4; |
| 191 | cache->saved_regs[SPARC32_NPC_REGNUM].addr = sigcontext_addr + 8; |
| 192 | cache->saved_regs[SPARC32_Y_REGNUM].addr = sigcontext_addr + 12; |
| 193 | |
| 194 | /* Since %g0 is always zero, keep the identity encoding. */ |
| 195 | for (regnum = SPARC_G1_REGNUM, addr = sigcontext_addr + 20; |
| 196 | regnum <= SPARC_O7_REGNUM; regnum++, addr += 4) |
| 197 | cache->saved_regs[regnum].addr = addr; |
| 198 | |
| 199 | for (regnum = SPARC_L0_REGNUM, addr = cache->base; |
| 200 | regnum <= SPARC_I7_REGNUM; regnum++, addr += 4) |
| 201 | cache->saved_regs[regnum].addr = addr; |
| 202 | |
| 203 | return cache; |
| 204 | } |
| 205 | |
| 206 | static void |
| 207 | sparc32_linux_sigtramp_frame_this_id (struct frame_info *next_frame, |
| 208 | void **this_cache, |
| 209 | struct frame_id *this_id) |
| 210 | { |
| 211 | struct sparc_frame_cache *cache = |
| 212 | sparc32_linux_sigtramp_frame_cache (next_frame, this_cache); |
| 213 | |
| 214 | (*this_id) = frame_id_build (cache->base, cache->pc); |
| 215 | } |
| 216 | |
| 217 | static void |
| 218 | sparc32_linux_sigtramp_frame_prev_register (struct frame_info *next_frame, |
| 219 | void **this_cache, |
| 220 | int regnum, int *optimizedp, |
| 221 | enum lval_type *lvalp, |
| 222 | CORE_ADDR *addrp, |
| 223 | int *realnump, void *valuep) |
| 224 | { |
| 225 | struct sparc_frame_cache *cache = |
| 226 | sparc32_linux_sigtramp_frame_cache (next_frame, this_cache); |
| 227 | |
| 228 | trad_frame_prev_register (next_frame, cache->saved_regs, regnum, |
| 229 | optimizedp, lvalp, addrp, realnump, valuep); |
| 230 | } |
| 231 | |
| 232 | static const struct frame_unwind sparc32_linux_sigtramp_frame_unwind = |
| 233 | { |
| 234 | SIGTRAMP_FRAME, |
| 235 | sparc32_linux_sigtramp_frame_this_id, |
| 236 | sparc32_linux_sigtramp_frame_prev_register |
| 237 | }; |
| 238 | |
| 239 | static const struct frame_unwind * |
| 240 | sparc32_linux_sigtramp_frame_sniffer (struct frame_info *next_frame) |
| 241 | { |
| 242 | CORE_ADDR pc = frame_pc_unwind (next_frame); |
| 243 | char *name; |
| 244 | |
| 245 | find_pc_partial_function (pc, &name, NULL, NULL); |
| 246 | if (sparc32_linux_pc_in_sigtramp (pc, name)) |
| 247 | return &sparc32_linux_sigtramp_frame_unwind; |
| 248 | |
| 249 | return NULL; |
| 250 | } |
| 251 | \f |
| 252 | |
| 253 | static struct link_map_offsets * |
| 254 | sparc32_linux_svr4_fetch_link_map_offsets (void) |
| 255 | { |
| 256 | static struct link_map_offsets lmo; |
| 257 | static struct link_map_offsets *lmp = NULL; |
| 258 | |
| 259 | if (lmp == NULL) |
| 260 | { |
| 261 | lmp = &lmo; |
| 262 | |
| 263 | /* Everything we need is in the first 8 bytes. */ |
| 264 | lmo.r_debug_size = 8; |
| 265 | lmo.r_map_offset = 4; |
| 266 | lmo.r_map_size = 4; |
| 267 | |
| 268 | /* Everything we need is in the first 20 bytes. */ |
| 269 | lmo.link_map_size = 20; |
| 270 | lmo.l_addr_offset = 0; |
| 271 | lmo.l_addr_size = 4; |
| 272 | lmo.l_name_offset = 4; |
| 273 | lmo.l_name_size = 4; |
| 274 | lmo.l_next_offset = 12; |
| 275 | lmo.l_next_size = 4; |
| 276 | lmo.l_prev_offset = 16; |
| 277 | lmo.l_prev_size = 4; |
| 278 | } |
| 279 | |
| 280 | return lmp; |
| 281 | } |
| 282 | |
| 283 | static void |
| 284 | sparc32_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch) |
| 285 | { |
| 286 | /* GNU/Linux is very similar to Solaris ... */ |
| 287 | sparc32_sol2_init_abi (info, gdbarch); |
| 288 | |
| 289 | /* ... but doesn't have kernel-assisted single-stepping support. */ |
| 290 | set_gdbarch_software_single_step (gdbarch, sparc_software_single_step); |
| 291 | |
| 292 | /* GNU/Linux doesn't support the 128-bit `long double' from the psABI. */ |
| 293 | set_gdbarch_long_double_bit (gdbarch, 64); |
| 294 | set_gdbarch_long_double_format (gdbarch, &floatformat_ieee_double_big); |
| 295 | |
| 296 | set_gdbarch_pc_in_sigtramp (gdbarch, sparc32_linux_pc_in_sigtramp); |
| 297 | frame_unwind_append_sniffer (gdbarch, sparc32_linux_sigtramp_frame_sniffer); |
| 298 | |
| 299 | set_solib_svr4_fetch_link_map_offsets |
| 300 | (gdbarch, sparc32_linux_svr4_fetch_link_map_offsets); |
| 301 | } |
| 302 | |
| 303 | /* Provide a prototype to silence -Wmissing-prototypes. */ |
| 304 | extern void _initialize_sparc_linux_tdep (void); |
| 305 | |
| 306 | void |
| 307 | _initialize_sparc_linux_tdep (void) |
| 308 | { |
| 309 | gdbarch_register_osabi (bfd_arch_sparc, 0, GDB_OSABI_LINUX, |
| 310 | sparc32_linux_init_abi); |
| 311 | } |