diff options
Diffstat (limited to 'payloads/libpayload/arch/arm/gdb.c')
| -rw-r--r-- | payloads/libpayload/arch/arm/gdb.c | 114 |
1 files changed, 114 insertions, 0 deletions
diff --git a/payloads/libpayload/arch/arm/gdb.c b/payloads/libpayload/arch/arm/gdb.c new file mode 100644 index 0000000000..faf9eb48f2 --- /dev/null +++ b/payloads/libpayload/arch/arm/gdb.c @@ -0,0 +1,114 @@ +/* + * 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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA + */ + +#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)); +} |