/* * Copyright 2014 Google Inc. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License as * published by the Free Software Foundation; either version 2 of * the License, or (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but without any warranty; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc. */ #include <exception.h> #include <gdb.h> #include <libpayload.h> struct gdb_regs { u32 r[16]; struct fp_reg { u8 byte[12]; } __attribute__((packed)) f[8]; u32 fps; u32 cpsr; } __attribute__((packed)); static const u8 type_to_signal[] = { [EXC_UNDEF] = GDB_SIGILL, [EXC_SWI] = GDB_SIGTRAP, [EXC_PABORT] = GDB_SIGSEGV, [EXC_DABORT] = GDB_SIGSEGV, }; /* Scratch value to write reentrant exception states to. We never read it. */ static struct exception_state sentinel_exception_state; static int gdb_exception_hook(u32 type) { /* * If we were not resumed we are in deep trouble here. GDB probably told * us to do something stupid and caused a reentrant exception. All we * can do is just blindly send an error code and keep going. Eventually * GDB will tell us to resume and we return right back to the original * exception state ("jumping over" all the nested ones). */ if (gdb_state.connected && !gdb_state.resumed) { static const char error_code[] = "E22"; /* EINVAL? */ static const struct gdb_message tmp_reply = { .buf = (u8 *)error_code, .used = sizeof(error_code), .size = sizeof(error_code), }; gdb_send_reply(&tmp_reply); gdb_command_loop(gdb_state.signal); /* preserve old signal */ } else { if (type >= ARRAY_SIZE(type_to_signal) || !type_to_signal[type]) return 0; exception_state_ptr = &sentinel_exception_state; gdb_command_loop(type_to_signal[type]); } exception_state_ptr = &exception_state; return 1; } void gdb_arch_init(void) { exception_install_hook(&gdb_exception_hook); } void gdb_arch_enter(void) { u32 *sp; asm volatile ("mov %0, %%sp" : "=r"(sp) ); /* Avoid reentrant exceptions, just call the hook if in one already. */ if (sp >= exception_stack && sp <= exception_stack_end) gdb_exception_hook(EXC_SWI); else asm volatile ("svc #0"); } int gdb_arch_set_single_step(int on) { /* GDB seems to only need this on x86, ARM works fine without it. */ return -1; } void gdb_arch_encode_regs(struct gdb_message *message) { gdb_message_encode_bytes(message, exception_state.regs, sizeof(exception_state.regs)); gdb_message_encode_zero_bytes(message, offsetof(struct gdb_regs, cpsr) - offsetof(struct gdb_regs, f)); gdb_message_encode_bytes(message, &exception_state.cpsr, sizeof(exception_state.cpsr)); } void gdb_arch_decode_regs(int offset, struct gdb_message *message) { const int cpsr_hex_offset = offsetof(struct gdb_regs, cpsr) * 2; gdb_message_decode_bytes(message, offset, exception_state.regs, sizeof(exception_state.regs)); gdb_message_decode_bytes(message, offset + cpsr_hex_offset, &exception_state.cpsr, sizeof(exception_state.cpsr)); }