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