xref: /netbsd-src/external/gpl3/gdb.old/dist/gdb/mips-sde-tdep.c (revision bdc22b2e01993381dcefeff2bc9b56ca75a4235c)
1 /* Target-dependent code for SDE on MIPS processors.
2 
3    Copyright (C) 2014-2016 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 3 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, see <http://www.gnu.org/licenses/>.  */
19 
20 #include "defs.h"
21 #include "osabi.h"
22 #include "elf-bfd.h"
23 #include "block.h"
24 #include "symtab.h"
25 
26 #include "frame.h"
27 #include "frame-unwind.h"
28 #include "frame-base.h"
29 #include "trad-frame.h"
30 
31 #include "mips-tdep.h"
32 
33 /* Fill in the register cache *THIS_CACHE for THIS_FRAME for use
34    in the SDE frame unwinder.  */
35 
36 static struct trad_frame_cache *
37 mips_sde_frame_cache (struct frame_info *this_frame, void **this_cache)
38 {
39   struct gdbarch *gdbarch = get_frame_arch (this_frame);
40   const struct mips_regnum *regs = mips_regnum (gdbarch);
41   const int sizeof_reg_t = mips_abi_regsize (gdbarch);
42   enum mips_abi abi = mips_abi (gdbarch);
43   struct trad_frame_cache *cache;
44   CORE_ADDR xcpt_frame;
45   CORE_ADDR start_addr;
46   CORE_ADDR stack_addr;
47   CORE_ADDR pc;
48   int i;
49 
50   if (*this_cache != NULL)
51     return (struct trad_frame_cache *) *this_cache;
52   cache = trad_frame_cache_zalloc (this_frame);
53   *this_cache = cache;
54 
55   /* The previous registers are held in struct xcptcontext
56      which is at $sp+offs
57 
58      struct xcptcontext {
59        reg_t	sr;		CP0 Status
60        reg_t	cr;		CP0 Cause
61        reg_t	epc;		CP0 EPC
62        reg_t	vaddr;		CP0 BadVAddr
63        reg_t	regs[32];	General registers
64        reg_t	mdlo;		LO
65        reg_t	mdhi;		HI
66        reg_t	mdex;		ACX
67        ...
68      };
69   */
70 
71   stack_addr = get_frame_register_signed (this_frame,
72 					  gdbarch_sp_regnum (gdbarch));
73   switch (abi)
74     {
75     case MIPS_ABI_O32:
76       /* 40: XCPTCONTEXT
77 	 24: xcpt_gen() argspace		(16 bytes)
78 	 16: _xcptcall() saved ra, rounded up	( 8 bytes)
79 	 00: _xcptcall() argspace 		(16 bytes)  */
80       xcpt_frame = stack_addr + 40;
81       break;
82     case MIPS_ABI_N32:
83     case MIPS_ABI_N64:
84     default:			/* Wild guess.  */
85       /* 16: XCPTCONTEXT
86 	 16: xcpt_gen() argspace 		( 0 bytes)
87 	 00: _xcptcall() saved ra, rounded up	(16 bytes)  */
88       xcpt_frame = stack_addr + 16;
89       break;
90     }
91 
92   trad_frame_set_reg_addr (cache,
93 			   MIPS_PS_REGNUM + gdbarch_num_regs (gdbarch),
94 			   xcpt_frame + 0 * sizeof_reg_t);
95   trad_frame_set_reg_addr (cache,
96 			   regs->cause + gdbarch_num_regs (gdbarch),
97 			   xcpt_frame + 1 * sizeof_reg_t);
98   trad_frame_set_reg_addr (cache,
99 			   regs->pc + gdbarch_num_regs (gdbarch),
100 			   xcpt_frame + 2 * sizeof_reg_t);
101   trad_frame_set_reg_addr (cache,
102 			   regs->badvaddr + gdbarch_num_regs (gdbarch),
103 			   xcpt_frame + 3 * sizeof_reg_t);
104   for (i = 0; i < MIPS_NUMREGS; i++)
105     trad_frame_set_reg_addr (cache,
106 			     i + MIPS_ZERO_REGNUM + gdbarch_num_regs (gdbarch),
107 			     xcpt_frame + (4 + i) * sizeof_reg_t);
108   trad_frame_set_reg_addr (cache,
109 			   regs->lo + gdbarch_num_regs (gdbarch),
110 			   xcpt_frame + 36 * sizeof_reg_t);
111   trad_frame_set_reg_addr (cache,
112 			   regs->hi + gdbarch_num_regs (gdbarch),
113 			   xcpt_frame + 37 * sizeof_reg_t);
114 
115   pc = get_frame_pc (this_frame);
116   find_pc_partial_function (pc, NULL, &start_addr, NULL);
117   trad_frame_set_id (cache, frame_id_build (start_addr, stack_addr));
118 
119   return cache;
120 }
121 
122 /* Implement the this_id function for the SDE frame unwinder.  */
123 
124 static void
125 mips_sde_frame_this_id (struct frame_info *this_frame, void **this_cache,
126 			struct frame_id *this_id)
127 {
128   struct trad_frame_cache *this_trad_cache
129     = mips_sde_frame_cache (this_frame, this_cache);
130 
131   trad_frame_get_id (this_trad_cache, this_id);
132 }
133 
134 /* Implement the prev_register function for the SDE frame unwinder.  */
135 
136 static struct value *
137 mips_sde_frame_prev_register (struct frame_info *this_frame,
138 			      void **this_cache,
139 			      int prev_regnum)
140 {
141   struct trad_frame_cache *trad_cache
142     = mips_sde_frame_cache (this_frame, this_cache);
143 
144   return trad_frame_get_register (trad_cache, this_frame, prev_regnum);
145 }
146 
147 /* Implement the sniffer function for the SDE frame unwinder.  */
148 
149 static int
150 mips_sde_frame_sniffer (const struct frame_unwind *self,
151 			struct frame_info *this_frame,
152 			void **this_cache)
153 {
154   CORE_ADDR pc = get_frame_pc (this_frame);
155   const char *name;
156 
157   find_pc_partial_function (pc, &name, NULL, NULL);
158   return (name
159 	  && (strcmp (name, "_xcptcall") == 0
160 	      || strcmp (name, "_sigtramp") == 0));
161 }
162 
163 /* Data structure for the SDE frame unwinder.  */
164 
165 static const struct frame_unwind mips_sde_frame_unwind =
166 {
167   SIGTRAMP_FRAME,
168   default_frame_unwind_stop_reason,
169   mips_sde_frame_this_id,
170   mips_sde_frame_prev_register,
171   NULL,
172   mips_sde_frame_sniffer
173 };
174 
175 /* Implement the this_base, this_locals, and this_args hooks
176    for the normal unwinder.  */
177 
178 static CORE_ADDR
179 mips_sde_frame_base_address (struct frame_info *this_frame, void **this_cache)
180 {
181   struct trad_frame_cache *this_trad_cache
182     = mips_sde_frame_cache (this_frame, this_cache);
183 
184   return trad_frame_get_this_base (this_trad_cache);
185 }
186 
187 static const struct frame_base mips_sde_frame_base =
188 {
189   &mips_sde_frame_unwind,
190   mips_sde_frame_base_address,
191   mips_sde_frame_base_address,
192   mips_sde_frame_base_address
193 };
194 
195 static const struct frame_base *
196 mips_sde_frame_base_sniffer (struct frame_info *this_frame)
197 {
198   if (mips_sde_frame_sniffer (&mips_sde_frame_unwind, this_frame, NULL))
199     return &mips_sde_frame_base;
200   else
201     return NULL;
202 }
203 
204 static void
205 mips_sde_elf_osabi_sniff_abi_tag_sections (bfd *abfd, asection *sect,
206 					   void *obj)
207 {
208   enum gdb_osabi *os_ident_ptr = (enum gdb_osabi *) obj;
209   const char *name;
210 
211   name = bfd_get_section_name (abfd, sect);
212 
213   /* The presence of a section with a ".sde" prefix is indicative
214      of an SDE binary.  */
215   if (startswith (name, ".sde"))
216     *os_ident_ptr = GDB_OSABI_SDE;
217 }
218 
219 /* OSABI sniffer for MIPS SDE.  */
220 
221 static enum gdb_osabi
222 mips_sde_elf_osabi_sniffer (bfd *abfd)
223 {
224   enum gdb_osabi osabi = GDB_OSABI_UNKNOWN;
225   unsigned int elfosabi;
226 
227   /* If the generic sniffer gets a hit, return and let other sniffers
228      get a crack at it.  */
229   bfd_map_over_sections (abfd,
230 			 generic_elf_osabi_sniff_abi_tag_sections,
231 			 &osabi);
232   if (osabi != GDB_OSABI_UNKNOWN)
233     return GDB_OSABI_UNKNOWN;
234 
235   elfosabi = elf_elfheader (abfd)->e_ident[EI_OSABI];
236 
237   if (elfosabi == ELFOSABI_NONE)
238     {
239       /* When elfosabi is ELFOSABI_NONE (0), then the ELF structures in the
240 	 file are conforming to the base specification for that machine
241 	 (there are no OS-specific extensions).  In order to determine the
242 	 real OS in use we must look for OS notes that have been added.
243 
244 	 For SDE, we simply look for sections named with .sde as prefixes.  */
245       bfd_map_over_sections (abfd,
246 			     mips_sde_elf_osabi_sniff_abi_tag_sections,
247 			     &osabi);
248     }
249   return osabi;
250 }
251 
252 static void
253 mips_sde_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
254 {
255   frame_unwind_append_unwinder (gdbarch, &mips_sde_frame_unwind);
256   frame_base_append_sniffer (gdbarch, mips_sde_frame_base_sniffer);
257 }
258 
259 /* Provide a prototype to silence -Wmissing-prototypes.  */
260 extern initialize_file_ftype _initialize_mips_sde_tdep;
261 
262 void
263 _initialize_mips_sde_tdep (void)
264 {
265   gdbarch_register_osabi_sniffer (bfd_arch_mips,
266 				  bfd_target_elf_flavour,
267 				  mips_sde_elf_osabi_sniffer);
268 
269   gdbarch_register_osabi (bfd_arch_mips, 0, GDB_OSABI_SDE, mips_sde_init_abi);
270 }
271