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-rw-r--r--payloads/libpayload/arch/arm64/gdb.c96
1 files changed, 88 insertions, 8 deletions
diff --git a/payloads/libpayload/arch/arm64/gdb.c b/payloads/libpayload/arch/arm64/gdb.c
index 29a037095f..10ae675fe4 100644
--- a/payloads/libpayload/arch/arm64/gdb.c
+++ b/payloads/libpayload/arch/arm64/gdb.c
@@ -18,40 +18,120 @@
struct gdb_regs
{
- u64 x[32];
+ u64 x[31];
+ u64 sp; /* shares encoding 0b11111 with XZR in insns */
+ u64 pc; /* no longer encoded as a GPR in AArch64! */
+ u32 spsr;
struct fp_reg
{
- u64 quad[2];
- } __packed f[32];
- u32 fpcr;
+ u64 low;
+ u64 high;
+ } __packed v[32];
u32 fpsr;
- u32 spsr;
+ u32 fpcr;
} __packed;
+/* 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)
{
- return -1;
+ if (!gdb_handle_reentrant_exception()) {
+ u8 signal;
+
+ if (type >= EXC_SYNC_SPX) {
+ printf("Impossible exception type: %d!\n", type);
+ return 0;
+ }
+
+ if (type == EXC_IRQ_SP0 || type == EXC_FIQ_SP0)
+ signal = GDB_SIGINT;
+ else switch (exception_state.ec) {
+ case ESR_EC_UNKNOWN:
+ signal = GDB_SIGILL;
+ break;
+ case ESR_EC_SVC_64: /* gdb_arch_enter() uses SVC */
+ case ESR_EC_SS_SAME: /* single-step causes this one */
+ case ESR_EC_BKPT_64: /* GDB itself likes to insert BRKs */
+ signal = GDB_SIGTRAP;
+ break;
+ default:
+ /* We mostly expect INSN_ABT, DATA_ABT and SERROR here,
+ but it makes for a good catchall signal anyway. */
+ signal = GDB_SIGSEGV;
+ /* GDB itself doesn't read out the ESR, so print it to
+ help people understand unexpected exceptions. But we
+ can't print anything if GDB is not connected yet. */
+ if (gdb_state.connected)
+ printf("Remote-GDB Exception %d, ESR: %#08x\n",
+ type, (uint32_t)exception_state.esr);
+ }
+
+ exception_set_state_ptr(&sentinel_exception_state);
+ gdb_command_loop(signal);
+ }
+
+ exception_set_state_ptr(&exception_state);
+
+ return 1;
}
void gdb_arch_init(void)
{
exception_install_hook(&gdb_exception_hook);
+ raw_write_oslar_el1(0); /* Disable OS lock (whatever that is) */
+ raw_write_mdcr_el2(MDCR_TDE); /* Route debug exceptions to EL2 */
+ raw_write_mdscr_el1(MDSCR_KDE); /* Enable debugging of current EL */
}
void gdb_arch_enter(void)
{
+ u64 *sp;
+
+ asm volatile ("mov %0, sp" : "=r"(sp) );
+
+ /* Avoid reentrant exceptions, just call the hook if in one already.
+ This is mostly important when gdb_enter() is called as result of an
+ exception (as part of the halt() at the end). */
+ if (sp >= exception_stack && sp <= exception_stack_end)
+ gdb_exception_hook(EXC_SYNC_SP0);
+ else /* BRK doesn't adjust ELR, so using SVC makes things easier. */
+ 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;
+ raw_write_mdscr_el1(MDSCR_KDE | (on ? MDSCR_SS : 0));
+ exception_state.pstate.ss = !!on;
+ return 0;
}
void gdb_arch_encode_regs(struct gdb_message *message)
{
+ gdb_message_encode_bytes(message, &exception_state.regs,
+ sizeof(exception_state.regs));
+ gdb_message_encode_bytes(message, &exception_state.sp,
+ sizeof(exception_state.sp));
+ gdb_message_encode_bytes(message, &exception_state.elr,
+ sizeof(exception_state.elr));
+ gdb_message_encode_bytes(message, &exception_state.spsr,
+ sizeof(exception_state.spsr));
+ gdb_message_encode_zero_bytes(message,
+ sizeof(struct gdb_regs) - offsetof(struct gdb_regs, v));
}
void gdb_arch_decode_regs(int offset, struct gdb_message *message)
{
+ gdb_message_decode_bytes(message, offset,
+ &exception_state.regs, sizeof(exception_state.regs));
+ offset += sizeof(exception_state.regs) * 2;
+ gdb_message_decode_bytes(message, offset,
+ &exception_state.sp, sizeof(exception_state.sp));
+ offset += sizeof(exception_state.sp) * 2;
+ gdb_message_decode_bytes(message, offset,
+ &exception_state.elr, sizeof(exception_state.elr));
+ offset += sizeof(exception_state.elr) * 2;
+ gdb_message_decode_bytes(message, offset,
+ &exception_state.spsr, sizeof(exception_state.spsr));
+ offset += sizeof(exception_state.spsr) * 2;
}