1 /*
2 * Copyright 2014 Google Inc.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License as
6 * published by the Free Software Foundation; either version 2 of
7 * the License, or (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but without any warranty; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 */
14
15 #include <exception.h>
16 #include <gdb.h>
17 #include <libpayload.h>
18 #include <stddef.h>
19
20 static const u8 type_to_signal[] = {
21 [EXC_DE] = GDB_SIGFPE,
22 [EXC_DB] = GDB_SIGTRAP,
23 [EXC_NMI] = GDB_SIGKILL,
24 [EXC_BP] = GDB_SIGTRAP,
25 [EXC_OF] = GDB_SIGFPE,
26 [EXC_BR] = GDB_SIGSEGV,
27 [EXC_UD] = GDB_SIGILL,
28 [EXC_NM] = GDB_SIGEMT,
29 [EXC_DF] = GDB_SIGKILL,
30 [EXC_TS] = GDB_SIGSEGV,
31 [EXC_NP] = GDB_SIGSEGV,
32 [EXC_SS] = GDB_SIGBUS,
33 [EXC_GP] = GDB_SIGSEGV,
34 [EXC_PF] = GDB_SIGSEGV,
35 [EXC_MF] = GDB_SIGEMT,
36 [EXC_AC] = GDB_SIGBUS,
37 [EXC_MC] = GDB_SIGKILL,
38 [EXC_XF] = GDB_SIGFPE,
39 [EXC_SX] = GDB_SIGFPE,
40 };
41
gdb_exception_hook(u8 vector)42 static void gdb_exception_hook(u8 vector)
43 {
44 gdb_command_loop(type_to_signal[vector]);
45 }
46
gdb_arch_init(void)47 void gdb_arch_init(void)
48 {
49 for (int vector = 0; vector < ARRAY_SIZE(type_to_signal); ++vector) {
50 if (type_to_signal[vector])
51 set_interrupt_handler(vector, &gdb_exception_hook);
52 }
53 }
54
gdb_arch_enter(void)55 void gdb_arch_enter(void)
56 {
57 u8 *stack_pointer;
58 #if CONFIG(LP_ARCH_X86_64)
59 asm volatile ("movq %%rsp, %0" : "=r"(stack_pointer));
60 #else
61 asm volatile ("mov %%esp, %0" : "=r"(stack_pointer));
62 #endif
63
64 /* Avoid reentrant exceptions, just call the hook if in one already. */
65 if (stack_pointer >= exception_stack && stack_pointer <= exception_stack_end)
66 gdb_exception_hook(EXC_BP);
67 else
68 asm volatile ("int3");
69 }
70
gdb_arch_set_single_step(int on)71 int gdb_arch_set_single_step(int on)
72 {
73 const size_t tf_bit = 1 << 8;
74
75 if (on)
76 exception_state->regs.reg_flags |= tf_bit;
77 else
78 exception_state->regs.reg_flags &= ~tf_bit;
79
80 return 0;
81 }
82
gdb_arch_encode_regs(struct gdb_message * message)83 void gdb_arch_encode_regs(struct gdb_message *message)
84 {
85 gdb_message_encode_bytes(message, &exception_state->regs,
86 sizeof(exception_state->regs));
87 }
88
gdb_arch_decode_regs(int offset,struct gdb_message * message)89 void gdb_arch_decode_regs(int offset, struct gdb_message *message)
90 {
91 gdb_message_decode_bytes(message, offset, &exception_state->regs,
92 sizeof(exception_state->regs));
93 }
94