On Tue, Jun 04, 2019 at 04:38:53PM +0200, Rouven Czerwinski wrote:
> Add a gdb script with two helper functions which use the new
> pbl_barebox_break symbol to calculate the current barebox load address
> on the device and loads a barebox ELF file to this address.
>
> Signed-off-by: Rouven Czerwinski <r.czerwinski@xxxxxxxxxxxxxx>
> ---
> Documentation/user/debugging.rst | 21 +++++++++++
> Documentation/user/user-manual.rst | 1 +
> common/Kconfig | 9 +++++
> scripts/gdb/helper.py | 60 ++++++++++++++++++++++++++++++
> 4 files changed, 91 insertions(+)
> create mode 100644 Documentation/user/debugging.rst
> create mode 100644 scripts/gdb/helper.py
>
> diff --git a/Documentation/user/debugging.rst b/Documentation/user/debugging.rst
> new file mode 100644
> index 0000000000..15cb439043
> --- /dev/null
> +++ b/Documentation/user/debugging.rst
> @@ -0,0 +1,21 @@
> +Debugging with OpenOCD
> +======================
> +
> +Barebox can be configured to break on prebootloader and main barebox entry. This
> +breakpoint can not be resumed and will stop the board to allow the user to
> +attach a JTAG debugger with OpenOCD. Additionally, barebox provides helper
> +scripts to load the symbols from the ELF binaries.
> +The python scripts require `pyelftools`.
> +To load the scripts into your gdb session, run the following command in the
> +barebox directory:
> +
> +.. code-block:: none
> +
> + (gdb) source scripts/gdb/helper.py
> +
> +This makes two new commands available in gdb, `bb-load-symbols` and
> +`bb-skip-break`. `bb-load-symbols` can load either the main `barebox` file or
> +one of the .pbl files in the image directories. The board needs to be stopped in
> +either the prebootloader or main barebox breakpoint, and gdb needs to be
> +connected to OpenOCD. To continue booting the board, `bb-skip-break` jumps over
> +the breakpoint and continues the barebox execution.
> diff --git a/Documentation/user/user-manual.rst b/Documentation/user/user-manual.rst
> index 516b760b1b..f04981c3f0 100644
> --- a/Documentation/user/user-manual.rst
> +++ b/Documentation/user/user-manual.rst
> @@ -33,6 +33,7 @@ Contents:
> system-reset
> state
> random
> + debugging
>
> * :ref:`search`
> * :ref:`genindex`
> diff --git a/common/Kconfig b/common/Kconfig
> index 4124857a0a..c766e1ef64 100644
> --- a/common/Kconfig
> +++ b/common/Kconfig
> @@ -1252,6 +1252,15 @@ config PBL_BREAK
> If this enabled, barebox will be compiled with BKPT instruction
> on early pbl init. This option be used only with JTAG debugger!
>
> +config GDB_SCRIPTS
> + bool "Provide GDB scripts for barebox debugging"
> + help
> + This creates the required links to GDB helper scripts in the
> + build directory. If you load barebox into gdb, the helper
> + scripts will be automatically imported by gdb as well, and
> + additional functions are available to analyze a Linux kernel
> + instance.
> +
> endmenu
This symbol is not used in any way, as far as I can see.
- Roland
>
> config HAS_DEBUG_LL
> diff --git a/scripts/gdb/helper.py b/scripts/gdb/helper.py
> new file mode 100644
> index 0000000000..4041789890
> --- /dev/null
> +++ b/scripts/gdb/helper.py
> @@ -0,0 +1,60 @@
> +#!/usr/bin/env python
> +
> +import gdb
> +
> +try:
> + from elftools.elf.elffile import ELFFile
> + from elftools.common.exceptions import ELFError
> +except ImportError:
> + gdb.write("The barebox helper requires pyelftools\n", gdb.STDERR)
> + exit(1)
> +
> +
> +class BBSymbols(gdb.Command):
> +
> + def __init__(self):
> + super(BBSymbols, self).__init__("bb-load-symbols", gdb.COMMAND_FILES,
> + gdb.COMPLETE_FILENAME)
> +
> + def invoke(self, argument, from_tty):
> + path = argument
> + f = open(path, 'rb')
> +
> + try:
> + elf = ELFFile(f)
> + except ELFError:
> + gdb.write("Selected file is not an ELF file\n", gdb.STDERR)
> + return
> +
> + section = elf.get_section_by_name(".symtab")
> + if section is None:
> + gdb.write("Section .symtab not found\n", gdb.STDERR)
> + return
> + symbol = section.get_symbol_by_name("pbl_barebox_break")
> + if not symbol:
> + gdb.write("Symbol pbl_barebox_break in section {} in file {} not found\n"
> + .format(section.name, self.path), gdb.STDERR)
> + return
> + symbol = symbol[0]
> + pc = gdb.parse_and_eval("$pc")
> + symbol_address = int(symbol.entry.st_value)
> + address = int(pc) - symbol_address + 1
> + gdb.execute("symbol-file")
> + gdb.execute("add-symbol-file {} {}".format(path, address))
> +
> +
> +BBSymbols()
> +
> +
> +class BBSkip(gdb.Command):
> +
> + def __init__(self):
> + super(BBSkip, self).__init__("bb-skip-break", gdb.COMMAND_BREAKPOINTS)
> +
> + def invoke(self, arg, from_tty):
> + pc = gdb.parse_and_eval("$pc")
> + nop_address = int(pc) + 2
> + gdb.execute("jump *{}".format(nop_address))
> +
> +
> +BBSkip()
> --
> 2.21.0
>
>
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> http://lists.infradead.org/mailman/listinfo/barebox
>
--
Roland Hieber | r.hieber@xxxxxxxxxxxxxx |
Pengutronix e.K. | https://www.pengutronix.de/ |
Peiner Str. 6-8, 31137 Hildesheim | Phone: +49-5121-206917-5086 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
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