The patch titled
Subject: scripts/gdb: add lx-fdtdump command
has been added to the -mm tree. Its filename is
scripts-gdb-add-lx-fdtdump-command.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/scripts-gdb-add-lx-fdtdump-command.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/scripts-gdb-add-lx-fdtdump-command.patch
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------------------------------------------------------
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()
_
Patches currently in -mm which might be from peter.griffin@xxxxxxxxxx are
scripts-gdb-add-lx-fdtdump-command.patch
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