gdb/testsuite/gdb.base/jithost.c

   1 /* Copyright (C) 2009-2019 Free Software Foundation, Inc.
   2
   3    This file is part of GDB.
   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 #include <stdio.h>
  19 #include <stdlib.h>
  20 #include <string.h>
  21 #include <unistd.h>
  22
  23 #include <sys/mman.h>
  24
  25 #include JIT_READER_H  /* Please see jit-reader.exp for an explanation.  */
  26 #include "jithost.h"
  27 #include "jit-protocol.h"
  28
  29 void __attribute__((noinline)) __jit_debug_register_code () { }
  30
  31 struct jit_descriptor __jit_debug_descriptor = { 1, 0, 0, 0 };
  32 struct jit_code_entry only_entry;
  33
  34 typedef void (jit_function_stack_mangle_t) (void);
  35 typedef long (jit_function_add_t) (long a, long b);
  36
  37 /* The code of the jit_function_00 function that is copied into an
  38    mmapped buffer in the inferior at run time.
  39
  40    The second instruction mangles the stack pointer, meaning that when
  41    stopped at the third instruction, GDB needs assistance from the JIT
  42    unwinder in order to be able to unwind successfully.  */
  43 static const unsigned char jit_function_stack_mangle_code[] = {
  44   0xcc,                         /* int3 */
  45   0x48, 0x83, 0xf4, 0xff,       /* xor $0xffffffffffffffff, %rsp */
  46   0x48, 0x83, 0xf4, 0xff,       /* xor $0xffffffffffffffff, %rsp */
  47   0xc3                          /* ret */
  48 };
  49
  50 /* And another "JIT-ed" function, with the prototype `jit_function_add_t`.  */
  51 static const unsigned char jit_function_add_code[] = {
  52   0x48, 0x01, 0xfe,             /* add %rdi,%rsi */
  53   0x48, 0x89, 0xf0,             /* mov %rsi,%rax */
  54   0xc3,                         /* retq */
  55 };
  56
  57 int
  58 main (int argc, char **argv)
  59 {
  60   struct jithost_abi *symfile = malloc (sizeof (struct jithost_abi));
  61   char *code = mmap (NULL, getpagesize (), PROT_WRITE | PROT_EXEC,
  62                      MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
  63   char *code_end = code;
  64
  65   /* "JIT" function_stack_mangle.  */
  66   memcpy (code_end, jit_function_stack_mangle_code,
  67           sizeof (jit_function_stack_mangle_code));
  68   jit_function_stack_mangle_t *function_stack_mangle
  69     = (jit_function_stack_mangle_t *) code_end;
  70   symfile->function_stack_mangle.begin = code_end;
  71   code_end += sizeof (jit_function_stack_mangle_code);
  72   symfile->function_stack_mangle.end = code_end;
  73
  74   /* "JIT" function_add.  */
  75   memcpy (code_end, jit_function_add_code, sizeof (jit_function_add_code));
  76   jit_function_add_t *function_add = (jit_function_add_t *) code_end;
  77   symfile->function_add.begin = code_end;
  78   code_end += sizeof (jit_function_add_code);
  79   symfile->function_add.end = code_end;
  80
  81   /* Bounds of the whole object.  */
  82   symfile->object.begin = code;
  83   symfile->object.end = code_end;
  84
  85   only_entry.symfile_addr = symfile;
  86   only_entry.symfile_size = sizeof (struct jithost_abi);
  87
  88   __jit_debug_descriptor.first_entry = &only_entry;
  89   __jit_debug_descriptor.relevant_entry = &only_entry;
  90   __jit_debug_descriptor.action_flag = JIT_REGISTER;
  91   __jit_debug_descriptor.version = 1;
  92   __jit_debug_register_code ();
  93
  94   function_stack_mangle ();
  95   function_add (5, 6);
  96
  97   return 0;
  98 }