From: Peter Griffin <peter.griffin@xxxxxxxxxx> Subject: scripts/gdb: add lx-fdtdump command lx-fdtdump dumps the flattened device tree passed to the kernel from the bootloader to the filename specified as the command argument. If no argument is provided it defaults to fdtdump.dtb. This then allows further post processing on the machine running GDB. The fdt header is also also printed in the GDB console. For example: (gdb) lx-fdtdump fdt_magic: 0xD00DFEED fdt_totalsize: 0xC108 off_dt_struct: 0x38 off_dt_strings: 0x3804 off_mem_rsvmap: 0x28 version: 17 last_comp_version: 16 Dumped fdt to fdtdump.dtb >fdtdump fdtdump.dtb | less This command is useful as the bootloader can often re-write parts of the device tree, and this can sometimes cause the kernel to not boot. Link: http://lkml.kernel.org/r/1481280065-5336-2-git-send-email-kbingham@xxxxxxxxxx Signed-off-by: Peter Griffin <peter.griffin@xxxxxxxxxx> Signed-off-by: Kieran Bingham <kbingham@xxxxxxxxxx> Cc: Jason Wessel <jason.wessel@xxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- scripts/gdb/linux/constants.py.in | 7 ++ scripts/gdb/linux/proc.py | 73 ++++++++++++++++++++++++++++ 2 files changed, 80 insertions(+) diff -puN scripts/gdb/linux/constants.py.in~scripts-gdb-add-lx-fdtdump-command scripts/gdb/linux/constants.py.in --- a/scripts/gdb/linux/constants.py.in~scripts-gdb-add-lx-fdtdump-command +++ a/scripts/gdb/linux/constants.py.in @@ -14,6 +14,7 @@ #include <linux/fs.h> #include <linux/mount.h> +#include <linux/of_fdt.h> /* We need to stringify expanded macros so that they can be parsed */ @@ -50,3 +51,9 @@ LX_VALUE(MNT_NOEXEC) LX_VALUE(MNT_NOATIME) LX_VALUE(MNT_NODIRATIME) LX_VALUE(MNT_RELATIME) + +/* linux/of_fdt.h> */ +LX_VALUE(OF_DT_HEADER) + +/* Kernel Configs */ +LX_CONFIG(CONFIG_OF) diff -puN scripts/gdb/linux/proc.py~scripts-gdb-add-lx-fdtdump-command scripts/gdb/linux/proc.py --- a/scripts/gdb/linux/proc.py~scripts-gdb-add-lx-fdtdump-command +++ a/scripts/gdb/linux/proc.py @@ -16,6 +16,7 @@ from linux import constants from linux import utils from linux import tasks from linux import lists +from struct import * class LxCmdLine(gdb.Command): @@ -195,3 +196,75 @@ values of that process namespace""" info_opts(MNT_INFO, m_flags))) LxMounts() + + +class LxFdtDump(gdb.Command): + """Output Flattened Device Tree header and dump FDT blob to the filename + specified as the command argument. Equivalent to + 'cat /proc/fdt > fdtdump.dtb' on a running target""" + + def __init__(self): + super(LxFdtDump, self).__init__("lx-fdtdump", gdb.COMMAND_DATA, + gdb.COMPLETE_FILENAME) + + def fdthdr_to_cpu(self, fdt_header): + + fdt_header_be = ">IIIIIII" + fdt_header_le = "<IIIIIII" + + if utils.get_target_endianness() == 1: + output_fmt = fdt_header_le + else: + output_fmt = fdt_header_be + + return unpack(output_fmt, pack(fdt_header_be, + fdt_header['magic'], + fdt_header['totalsize'], + fdt_header['off_dt_struct'], + fdt_header['off_dt_strings'], + fdt_header['off_mem_rsvmap'], + fdt_header['version'], + fdt_header['last_comp_version'])) + + def invoke(self, arg, from_tty): + + if not constants.LX_CONFIG_OF: + raise gdb.GdbError("Kernel not compiled with CONFIG_OF\n") + + if len(arg) == 0: + filename = "fdtdump.dtb" + else: + filename = arg + + py_fdt_header_ptr = gdb.parse_and_eval( + "(const struct fdt_header *) initial_boot_params") + py_fdt_header = py_fdt_header_ptr.dereference() + + fdt_header = self.fdthdr_to_cpu(py_fdt_header) + + if fdt_header[0] != constants.LX_OF_DT_HEADER: + raise gdb.GdbError("No flattened device tree magic found\n") + + gdb.write("fdt_magic: 0x{:02X}\n".format(fdt_header[0])) + gdb.write("fdt_totalsize: 0x{:02X}\n".format(fdt_header[1])) + gdb.write("off_dt_struct: 0x{:02X}\n".format(fdt_header[2])) + gdb.write("off_dt_strings: 0x{:02X}\n".format(fdt_header[3])) + gdb.write("off_mem_rsvmap: 0x{:02X}\n".format(fdt_header[4])) + gdb.write("version: {}\n".format(fdt_header[5])) + gdb.write("last_comp_version: {}\n".format(fdt_header[6])) + + inf = gdb.inferiors()[0] + fdt_buf = utils.read_memoryview(inf, py_fdt_header_ptr, + fdt_header[1]).tobytes() + + try: + f = open(filename, 'wb') + except: + raise gdb.GdbError("Could not open file to dump fdt") + + f.write(fdt_buf) + f.close() + + gdb.write("Dumped fdt blob to " + filename + "\n") + +LxFdtDump() _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
