138 lines
4.1 KiB
C
138 lines
4.1 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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u64 x[31];
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u64 sp; /* shares encoding 0b11111 with XZR in insns */
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u64 pc; /* no longer encoded as a GPR in AArch64! */
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u32 spsr;
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struct fp_reg
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{
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u64 low;
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u64 high;
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} __packed v[32];
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u32 fpsr;
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u32 fpcr;
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} __packed;
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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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if (!gdb_handle_reentrant_exception()) {
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u8 signal;
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if (type >= EXC_SYNC_SPX) {
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printf("Impossible exception type: %d!\n", type);
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return 0;
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}
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if (type == EXC_IRQ_SP0 || type == EXC_FIQ_SP0)
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signal = GDB_SIGINT;
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else switch (exception_state.ec) {
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case ESR_EC_UNKNOWN:
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signal = GDB_SIGILL;
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break;
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case ESR_EC_SVC_64: /* gdb_arch_enter() uses SVC */
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case ESR_EC_SS_SAME: /* single-step causes this one */
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case ESR_EC_BKPT_64: /* GDB itself likes to insert BRKs */
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signal = GDB_SIGTRAP;
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break;
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default:
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/* We mostly expect INSN_ABT, DATA_ABT and SERROR here,
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but it makes for a good catchall signal anyway. */
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signal = GDB_SIGSEGV;
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/* GDB itself doesn't read out the ESR, so print it to
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help people understand unexpected exceptions. But we
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can't print anything if GDB is not connected yet. */
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if (gdb_state.connected)
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printf("Remote-GDB Exception %d, ESR: %#08x\n",
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type, (uint32_t)exception_state.esr);
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}
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exception_set_state_ptr(&sentinel_exception_state);
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gdb_command_loop(signal);
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}
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exception_set_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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raw_write_oslar_el1(0); /* Disable OS lock (whatever that is) */
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raw_write_mdcr_el2(MDCR_TDE); /* Route debug exceptions to EL2 */
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raw_write_mdscr_el1(MDSCR_KDE); /* Enable debugging of current EL */
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}
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void gdb_arch_enter(void)
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{
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u64 *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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This is mostly important when gdb_enter() is called as result of an
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exception (as part of the halt() at the end). */
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if (sp >= exception_stack && sp <= exception_stack_end)
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gdb_exception_hook(EXC_SYNC_SP0);
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else /* BRK doesn't adjust ELR, so using SVC makes things easier. */
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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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raw_write_mdscr_el1(MDSCR_KDE | (on ? MDSCR_SS : 0));
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exception_state.pstate.ss = !!on;
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return 0;
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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_bytes(message, &exception_state.sp,
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sizeof(exception_state.sp));
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gdb_message_encode_bytes(message, &exception_state.elr,
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sizeof(exception_state.elr));
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gdb_message_encode_bytes(message, &exception_state.spsr,
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sizeof(exception_state.spsr));
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gdb_message_encode_zero_bytes(message,
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sizeof(struct gdb_regs) - offsetof(struct gdb_regs, v));
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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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gdb_message_decode_bytes(message, offset,
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&exception_state.regs, sizeof(exception_state.regs));
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offset += sizeof(exception_state.regs) * 2;
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gdb_message_decode_bytes(message, offset,
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&exception_state.sp, sizeof(exception_state.sp));
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offset += sizeof(exception_state.sp) * 2;
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gdb_message_decode_bytes(message, offset,
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&exception_state.elr, sizeof(exception_state.elr));
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offset += sizeof(exception_state.elr) * 2;
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gdb_message_decode_bytes(message, offset,
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&exception_state.spsr, sizeof(exception_state.spsr));
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offset += sizeof(exception_state.spsr) * 2;
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}
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