[PATCH 1/1] doc: add more details for crash dump analysis

[Sean Anderson]

On 8/2/22 9:29 AM, Heinrich Schuchardt wrote:
> * describe crashs in UEFI binaries
> * provide architechture specific information for the sandbox and RISC-V
> 
> Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt at canonical.com>
> ---
>  doc/develop/crash_dumps.rst | 52 +++++++++++++++++++++++++++++++++++++
>  1 file changed, 52 insertions(+)
> 
> diff --git a/doc/develop/crash_dumps.rst b/doc/develop/crash_dumps.rst
> index 85030b4e36..9e7ae3d751 100644
> --- a/doc/develop/crash_dumps.rst
> +++ b/doc/develop/crash_dumps.rst
> @@ -122,3 +122,55 @@ 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
> +-----------------------------
> +
> +RISC-V
> +~~~~~~
> +
> +On the RISC-V architecture CONFIG_SHOW_REGS=y has to be specified to show
> +all registers in crash dumps.

See also: CONFIG_ARMV8_SPL_EXCEPTION_VECTORS

> +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.
>