jsix/assets/debugging/jsix.elf-gdb.py

import gdb

class PrintStackCommand(gdb.Command):
    def __init__(self):
        super().__init__("j6stack", gdb.COMMAND_DATA)

    def invoke(self, arg, from_tty):
        args = gdb.string_to_argv(arg)

        base = "$rsp"
        if len(args) > 0:
            base = args[0]
        base = int(gdb.parse_and_eval(base))

        depth = 22
        if len(args) > 1:
            depth = int(args[1])

        for i in range(depth-1, -1, -1):
            try:
                offset = i * 8
                value = gdb.parse_and_eval(f"*(uint64_t*)({base:#x} + {offset:#x})")
                print("{:016x} (+{:04x}): {:016x}".format(base + offset, offset, int(value)))
            except Exception as e:
                print(e)
                continue


def stack_walk(frame, depth):
    for i in range(depth-1, -1, -1):
        ret = gdb.parse_and_eval(f"*(uint64_t*)({frame:#x} + 0x8)")

        name = ""
        try:
            block = gdb.block_for_pc(int(ret))
            if block:
                name = block.function or ""
        except RuntimeError:
            pass

        try:
            print("{:016x}: {:016x} {}".format(int(frame), int(ret), name))
            frame = int(gdb.parse_and_eval(f"*(uint64_t*)({frame:#x})"))
        except gdb.MemoryError:
            return

        if frame == 0 or ret == 0:
            return


class PrintBacktraceCommand(gdb.Command):
    def __init__(self):
        super().__init__("j6bt", gdb.COMMAND_DATA)

    def invoke(self, arg, from_tty):
        args = gdb.string_to_argv(arg)

        frame = "$rbp"
        if len(args) > 0:
            frame = args[0]

        frame = int(gdb.parse_and_eval(f"{frame}"))

        depth = 30
        if len(args) > 1:
            depth = int(gdb.parse_and_eval(args[1]))

        stack_walk(frame, depth)


class TableWalkCommand(gdb.Command):
    def __init__(self):
        super().__init__("j6tw", gdb.COMMAND_DATA)

    def invoke(self, arg, from_tty):
        args = gdb.string_to_argv(arg)
        if len(args) < 2:
            raise Exception("Must be: j6tw <pml4> <addr>")

        pml4 = int(gdb.parse_and_eval(args[0]))
        addr = int(gdb.parse_and_eval(args[1]))

        indices = [
            (addr >> 39) & 0x1ff,
            (addr >> 30) & 0x1ff,
            (addr >> 21) & 0x1ff,
            (addr >> 12) & 0x1ff,
            ]

        names = ["PML4", "PDP", "PD", "PT"]

        table_flags = [
            (0x0001, "present"),
            (0x0002, "write"),
            (0x0004, "user"),
            (0x0008, "pwt"),
            (0x0010, "pcd"),
            (0x0020, "accessed"),
            (0x0040, "dirty"),
            (0x0080, "largepage"),
            (0x0100, "global"),
            (0x1080, "pat"),
            ((1<<63), "xd"),
        ]

        page_flags = [
            (0x0001, "present"),
            (0x0002, "write"),
            (0x0004, "user"),
            (0x0008, "pwt"),
            (0x0010, "pcd"),
            (0x0020, "accessed"),
            (0x0040, "dirty"),
            (0x0080, "pat"),
            (0x0100, "global"),
            ((1<<63), "xd"),
        ]

        flagsets = [table_flags, table_flags, table_flags, page_flags]

        table = pml4
        entry = 0
        for i in range(len(indices)):
            entry = int(gdb.parse_and_eval(f'((uint64_t*)0x{table:x})[0x{indices[i]:x}]'))
            flagset = flagsets[i]
            flag_names = " | ".join([f[1] for f in flagset if (entry & f[0]) == f[0]])

            print(f"{names[i]:>4}: {table:016x}")
            print(f"      index: {indices[i]:3} {entry:016x}")
            print(f"      flags: {flag_names}")

            if (entry & 1) == 0 or (i < 3 and (entry & 0x80)):
                break

            table = (entry & 0x7ffffffffffffe00) | 0xffffc00000000000


class GetThreadsCommand(gdb.Command):
    FLAGS = {
        "ready":    0x01,
        "loading":  0x02,
        "exited":   0x04,
        "constant": 0x80,
    }

    def __init__(self):
        super().__init__("j6threads", gdb.COMMAND_DATA)

    def get_flags(self, bitset):
        flags = []
        for k, v in GetThreadsCommand.FLAGS.items():
            if bitset & v:
                flags.append(k)
        return " ".join(flags)

    def print_thread(self, addr):
        if addr == 0:
            print("  <no thread>\n")
            return

        tcb = f"((TCB*){addr:#x})"
        thread = f"({tcb}->thread)"
        stack = int(gdb.parse_and_eval(f"{tcb}->kernel_stack"))
        rsp = int(gdb.parse_and_eval(f"{tcb}->rsp"))
        pri = int(gdb.parse_and_eval(f"{tcb}->priority"))
        flags = int(gdb.parse_and_eval(f"{thread}->m_state"))
        koid = int(gdb.parse_and_eval(f"{thread}->m_koid"))
        proc = int(gdb.parse_and_eval(f"{thread}->m_parent.m_koid"))

        creator = int(gdb.parse_and_eval(f"{thread}->m_creator"))
        if creator != 0:
            creator_koid = int(gdb.parse_and_eval(f"{thread}->m_creator->m_koid"))
            creator = f"{creator_koid:x}"
        else:
            creator = "<no thread>"

        print(f"  Thread {proc:x}:{koid:x}")
        print(f"         creator: {creator}")
        print(f"        priority: {pri}")
        print(f"           flags: {self.get_flags(flags)}")
        print(f"          kstack: {stack:#x}")
        print(f"             rsp: {rsp:#x}")
        print("------------------------------------")

        if stack != 0:
            rsp = int(gdb.parse_and_eval(f"{tcb}->rsp"))
            stack_walk(rsp + 5*8, 5)

        print("")

    def print_thread_list(self, addr, name):
        if addr == 0:
            return

        print(f"=== {name} ===")

        while addr != 0:
            self.print_thread(addr)
            addr = int(gdb.parse_and_eval(f"((tcb_node*){addr:#x})->m_next"))


    def invoke(self, arg, from_tty):
        args = gdb.string_to_argv(arg)
        if len(args) != 1:
            raise RuntimeError("Usage: j6threads <cpu>")

        ncpu = int(args[0])
        runlist = f"scheduler::s_instance->m_run_queues.m_elements[{ncpu:#x}]"

        print("CURRENT:")
        current = int(gdb.parse_and_eval(f"{runlist}.current"))
        self.print_thread(current)

        for pri in range(8):
            ready = int(gdb.parse_and_eval(f"{runlist}.ready[{pri:#x}].m_head"))
            self.print_thread_list(ready, f"PRIORITY {pri}")

        blocked = int(gdb.parse_and_eval(f"{runlist}.blocked.m_head"))
        self.print_thread_list(blocked, "BLOCKED")

PrintStackCommand()
PrintBacktraceCommand()
TableWalkCommand()
GetThreadsCommand()

gdb.execute("display/i $rip")
if not gdb.selected_inferior().was_attached:
    gdb.execute("add-symbol-file build/panic.serial.elf")
    gdb.execute("target remote :1234")