gdb/testsuite/gdb.base/jit-main.c

   1 /* This test program is part of GDB, the GNU debugger.
   2
   3    Copyright 2011-2017 Free Software Foundation, Inc.
   4
   5    This program is free software; you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 3 of the License, or
   8    (at your option) any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  17
  18 /* Simulate loading of JIT code.  */
  19
  20 #include <elf.h>
  21 #include <link.h>
  22 #include <errno.h>
  23 #include <fcntl.h>
  24 #include <stdint.h>
  25 #include <stdio.h>
  26 #include <stdlib.h>
  27 #include <string.h>
  28 #include <sys/mman.h>
  29 #include <sys/stat.h>
  30 #include <unistd.h>
  31
  32 /* ElfW is coming from linux. On other platforms it does not exist.
  33    Let us define it here. */
  34 #ifndef ElfW
  35 # if (defined  (_LP64) || defined (__LP64__))
  36 #   define WORDSIZE 64
  37 # else
  38 #   define WORDSIZE 32
  39 # endif /* _LP64 || __LP64__  */
  40 #define ElfW(type)      _ElfW (Elf, WORDSIZE, type)
  41 #define _ElfW(e,w,t)    _ElfW_1 (e, w, _##t)
  42 #define _ElfW_1(e,w,t)  e##w##t
  43 #endif /* !ElfW  */
  44
  45 typedef enum
  46 {
  47   JIT_NOACTION = 0,
  48   JIT_REGISTER_FN,
  49   JIT_UNREGISTER_FN
  50 } jit_actions_t;
  51
  52 struct jit_code_entry
  53 {
  54   struct jit_code_entry *next_entry;
  55   struct jit_code_entry *prev_entry;
  56   const char *symfile_addr;
  57   uint64_t symfile_size;
  58 };
  59
  60 struct jit_descriptor
  61 {
  62   uint32_t version;
  63   /* This type should be jit_actions_t, but we use uint32_t
  64      to be explicit about the bitwidth.  */
  65   uint32_t action_flag;
  66   struct jit_code_entry *relevant_entry;
  67   struct jit_code_entry *first_entry;
  68 };
  69
  70 /* GDB puts a breakpoint in this function.  */
  71 void __attribute__((noinline)) __jit_debug_register_code () { }
  72
  73 /* Make sure to specify the version statically, because the
  74    debugger may check the version before we can set it.  */
  75 struct jit_descriptor __jit_debug_descriptor = { 1, 0, 0, 0 };
  76
  77 static void
  78 usage (const char *const argv0)
  79 {
  80   fprintf (stderr, "Usage: %s library [count]\n", argv0);
  81   exit (1);
  82 }
  83
  84 /* Update .p_vaddr and .sh_addr as if the code was JITted to ADDR.  */
  85
  86 static void
  87 update_locations (const void *const addr, int idx)
  88 {
  89   const ElfW (Ehdr) *const ehdr = (ElfW (Ehdr) *)addr;
  90   ElfW (Shdr) *const shdr = (ElfW (Shdr) *)((char *)addr + ehdr->e_shoff);
  91   ElfW (Phdr) *const phdr = (ElfW (Phdr) *)((char *)addr + ehdr->e_phoff);
  92   int i;
  93
  94   for (i = 0; i < ehdr->e_phnum; ++i)
  95     if (phdr[i].p_type == PT_LOAD)
  96       phdr[i].p_vaddr += (ElfW (Addr))addr;
  97
  98   for (i = 0; i < ehdr->e_shnum; ++i)
  99     {
 100       if (shdr[i].sh_type == SHT_STRTAB)
 101         {
 102           /* Note: we update both .strtab and .dynstr.  The latter would
 103              not be correct if this were a regular shared library (.hash
 104              would be wrong), but this is a simulation -- the library is
 105              never exposed to the dynamic loader, so it all ends up ok.  */
 106           char *const strtab = (char *)((ElfW (Addr))addr + shdr[i].sh_offset);
 107           char *const strtab_end = strtab + shdr[i].sh_size;
 108           char *p;
 109
 110           for (p = strtab; p < strtab_end; p += strlen (p) + 1)
 111             if (strcmp (p, "jit_function_XXXX") == 0)
 112               sprintf (p, "jit_function_%04d", idx);
 113         }
 114
 115       if (shdr[i].sh_flags & SHF_ALLOC)
 116         shdr[i].sh_addr += (ElfW (Addr))addr;
 117     }
 118 }
 119
 120 /* Defined by the .exp file if testing attach.  */
 121 #ifndef ATTACH
 122 #define ATTACH 0
 123 #endif
 124
 125 #ifndef MAIN
 126 #define MAIN main
 127 #endif
 128
 129 /* Used to spin waiting for GDB.  */
 130 volatile int wait_for_gdb = ATTACH;
 131 #define WAIT_FOR_GDB while (wait_for_gdb)
 132
 133 /* The current process's PID.  GDB retrieves this.  */
 134 int mypid;
 135
 136 int
 137 MAIN (int argc, char *argv[])
 138 {
 139   /* These variables are here so they can easily be set from jit.exp.  */
 140   const char *libname = NULL;
 141   int count = 0, i, fd;
 142   struct stat st;
 143
 144   alarm (300);
 145
 146   mypid = getpid ();
 147
 148   count = count;  /* gdb break here 0  */
 149
 150   if (argc < 2)
 151     {
 152       usage (argv[0]);
 153       exit (1);
 154     }
 155
 156   if (libname == NULL)
 157     /* Only set if not already set from GDB.  */
 158     libname = argv[1];
 159
 160   if (argc > 2 && count == 0)
 161     /* Only set if not already set from GDB.  */
 162     count = atoi (argv[2]);
 163
 164   printf ("%s:%d: libname = %s, count = %d\n", __FILE__, __LINE__,
 165           libname, count);
 166
 167   if ((fd = open (libname, O_RDONLY)) == -1)
 168     {
 169       fprintf (stderr, "open (\"%s\", O_RDONLY): %s\n", libname,
 170                strerror (errno));
 171       exit (1);
 172     }
 173
 174   if (fstat (fd, &st) != 0)
 175     {
 176       fprintf (stderr, "fstat (\"%d\"): %s\n", fd, strerror (errno));
 177       exit (1);
 178     }
 179
 180   for (i = 0; i < count; ++i)
 181     {
 182       const void *const addr = mmap (0, st.st_size, PROT_READ|PROT_WRITE,
 183                                      MAP_PRIVATE, fd, 0);
 184       struct jit_code_entry *const entry = calloc (1, sizeof (*entry));
 185
 186       if (addr == MAP_FAILED)
 187         {
 188           fprintf (stderr, "mmap: %s\n", strerror (errno));
 189           exit (1);
 190         }
 191
 192       update_locations (addr, i);
 193
 194       /* Link entry at the end of the list.  */
 195       entry->symfile_addr = (const char *)addr;
 196       entry->symfile_size = st.st_size;
 197       entry->prev_entry = __jit_debug_descriptor.relevant_entry;
 198       __jit_debug_descriptor.relevant_entry = entry;
 199
 200       if (entry->prev_entry != NULL)
 201         entry->prev_entry->next_entry = entry;
 202       else
 203         __jit_debug_descriptor.first_entry = entry;
 204
 205       /* Notify GDB.  */
 206       __jit_debug_descriptor.action_flag = JIT_REGISTER_FN;
 207       __jit_debug_register_code ();
 208     }
 209
 210   WAIT_FOR_GDB; i = 0;  /* gdb break here 1 */
 211
 212   /* Now unregister them all in reverse order.  */
 213   while (__jit_debug_descriptor.relevant_entry != NULL)
 214     {
 215       struct jit_code_entry *const entry =
 216         __jit_debug_descriptor.relevant_entry;
 217       struct jit_code_entry *const prev_entry = entry->prev_entry;
 218
 219       if (prev_entry != NULL)
 220         {
 221           prev_entry->next_entry = NULL;
 222           entry->prev_entry = NULL;
 223         }
 224       else
 225         __jit_debug_descriptor.first_entry = NULL;
 226
 227       /* Notify GDB.  */
 228       __jit_debug_descriptor.action_flag = JIT_UNREGISTER_FN;
 229       __jit_debug_register_code ();
 230
 231       __jit_debug_descriptor.relevant_entry = prev_entry;
 232       free (entry);
 233     }
 234
 235   WAIT_FOR_GDB; return 0;  /* gdb break here 2  */
 236 }