Commit 821f7440 authored by Peter Griffin's avatar Peter Griffin Committed by Linus Torvalds

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@kernel.orgSigned-off-by: default avatarPeter Griffin <peter.griffin@linaro.org>
Signed-off-by: default avatarKieran Bingham <kbingham@kernel.org>
Cc: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 59224ac1
...@@ -14,6 +14,7 @@ ...@@ -14,6 +14,7 @@
#include <linux/fs.h> #include <linux/fs.h>
#include <linux/mount.h> #include <linux/mount.h>
#include <linux/of_fdt.h>
/* We need to stringify expanded macros so that they can be parsed */ /* We need to stringify expanded macros so that they can be parsed */
...@@ -50,3 +51,9 @@ LX_VALUE(MNT_NOEXEC) ...@@ -50,3 +51,9 @@ LX_VALUE(MNT_NOEXEC)
LX_VALUE(MNT_NOATIME) LX_VALUE(MNT_NOATIME)
LX_VALUE(MNT_NODIRATIME) LX_VALUE(MNT_NODIRATIME)
LX_VALUE(MNT_RELATIME) LX_VALUE(MNT_RELATIME)
/* linux/of_fdt.h> */
LX_VALUE(OF_DT_HEADER)
/* Kernel Configs */
LX_CONFIG(CONFIG_OF)
...@@ -16,6 +16,7 @@ from linux import constants ...@@ -16,6 +16,7 @@ from linux import constants
from linux import utils from linux import utils
from linux import tasks from linux import tasks
from linux import lists from linux import lists
from struct import *
class LxCmdLine(gdb.Command): class LxCmdLine(gdb.Command):
...@@ -195,3 +196,75 @@ values of that process namespace""" ...@@ -195,3 +196,75 @@ values of that process namespace"""
info_opts(MNT_INFO, m_flags))) info_opts(MNT_INFO, m_flags)))
LxMounts() 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()
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