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doc: add more details for crash dump analysis

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* describe crashs in UEFI binaries
* provide architechture specific information for the sandbox and RISC-V

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
This commit is contained in:
Heinrich Schuchardt 2022-08-02 15:23:32 +02:00
parent 1e120337f9
commit 4d497c8698
1 changed files with 60 additions and 0 deletions
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doc/develop/crash_dumps.rst
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@ -122,3 +122,63 @@ If we want to dive deeper, we can disassemble the U-Boot binary::
This example is based on the ARMv8 architecture but the same procedures can be
used on other architectures as well.
Crashs in UEFI binaries
-----------------------
If UEFI images are loaded when a crash occurs, their load addresses are
displayed. If the process counter points to an address in a loaded UEFI
binary, the relative process counter position is indicated. Here is an
example executed on the U-Boot sandbox::
=> load host 0:1 $kernel_addr_r buggy.efi
5632 bytes read in 0 ms
=> bootefi $kernel_addr_r
Booting /buggy.efi
Buggy world!
Segmentation violation
pc = 0x19fc264c, pc_reloc = 0xffffaa4688b1664c
UEFI image [0x0000000019fc0000:0x0000000019fc6137] pc=0x264c '/buggy.efi'
The crash occured in UEFI binary buggy.efi at relative position 0x264c.
Disassembly may be used to find the actual source code location::
$ x86_64-linux-gnu-objdump -S -D buggy_efi.so
0000000000002640 <memset>:
2640: f3 0f 1e fa endbr64
2644: 48 89 f8 mov %rdi,%rax
2647: 48 89 f9 mov %rdi,%rcx
264a: eb 0b jmp 2657 <memset+0x17>
264c: 40 88 31 mov %sil,(%rcx)
Architecture specific details
-----------------------------
ARMv8
~~~~~
On the ARM 64-bit architecture CONFIG_ARMV8_SPL_EXCEPTION_VECTORS controls
if the exception vector tables are set up in the Secondary Program Loader (SPL).
Without initialization of the tables crash dumps cannot be shown. The feature is
disabled by default on most boards to reduce the size of the SPL.
RISC-V
~~~~~~
On the RISC-V architecture CONFIG_SHOW_REGS=y has to be specified to show
all registers in crash dumps.
Sandbox
~~~~~~~
The sandbox U-Boot binary must be invoked with parameter *-S* to display crash
dumps:
.. code-block:: bash
./u-boot -S -T
Only with CONFIG_SANDBOX_CRASH_RESET=y the sandbox reboots after a crash.