Hi Lianbo,
Thank you for the fix.
On 2023/07/21 13:36, Lianbo Jiang wrote:
> Currently, the symbol ".rodata" may not be found in some vmlinux, and
> the strings command will still be used to get the linux banner string,
> but this gets two strings as below:
>
> # strings /usr/lib/debug/usr/lib/modules/6.5.0-0.rc2.17.fc39.x86_64/vmlinux |grep "Linux version"
> Linux version 6.5.0-0.rc2.17.fc39.x86_64 (mockbuild@23a79bad375e4c2c8c60f2d40df7df49) (gcc (GCC) 13.1.1 20230614 (Red Hat 13.1.1-4), GNU ld version 2.40-9.fc39) # SMP PREEMPT_DYNAMIC
> Linux version 6.5.0-0.rc2.17.fc39.x86_64 (mockbuild@23a79bad375e4c2c8c60f2d40df7df49) (gcc (GCC) 13.1.1 20230614 (Red Hat 13.1.1-4), GNU ld version 2.40-9.fc39) #1 SMP PREEMPT_DYNAMIC Mon Jul 17 14:57:35 UTC 2023
>
> In the verify_namelist(), the while-loop will only determine if the
> above first string(linux banner) matches and break the loop. But
> actually the above second string is correct one. Eventually, crash
> startup with the following warning:
>
> # ./crash -s /usr/lib/debug/usr/lib/modules/6.5.0-0.rc2.17.fc39.x86_64/vmlinux /var/crash/127.0.0.1-2023-07-20-20\:50\:50/vmcore
> WARNING: kernel version inconsistency between vmlinux and dumpfile
>
> # ./crash -s
> WARNING: kernel version inconsistency between vmlinux and live memory
>
> Let's always try to match the correct one, otherwise still prints a
> warning as before.
>
> Signed-off-by: Lianbo Jiang <lijiang@xxxxxxxxxx>
> ---
> kernel.c | 2 --
> 1 file changed, 2 deletions(-)
>
> diff --git a/kernel.c b/kernel.c
> index 546eed95eebd..9801812387bd 100644
> --- a/kernel.c
> +++ b/kernel.c
> @@ -1375,8 +1375,6 @@ verify_namelist()
> buffer3[i++] = *p1++;
> buffer3[i] = NULLCHAR;
> }
> -
> - break;
> }
> pclose(pipe);
>
I think you are fixing the fallback routine and that's good, but it's
better to fix get_linux_banner_from_vmlinux() first if possible. It's
much faster. Isn't it possible?
What do you see in "sections:" in "help -s"? And probably you can
determine the section where linux_banner is located, with the address of
linux_banner and KASLR offset.
crash> help -s
...
sections:
.text vma: ffffffff81000000 size: 14686984
.rodata vma: ffffffff82000000 size: 5366231
.pci_fixup vma: ffffffff8251e1e0 size: 14112
...
crash> sym linux_banner
ffffffffb5200a40 (D) linux_banner
crash> help -D | grep KERNELOFFSET
KERNELOFFSET=33200000
crash> eval ffffffffb5200a40 - 0x33200000
hexadecimal: ffffffff82000a40 --> linux_banner is in ".rodata"
Thanks,
Kazu
--
Crash-utility mailing list
Crash-utility@xxxxxxxxxx
https://listman.redhat.com/mailman/listinfo/crash-utility
Contribution Guidelines: https://github.com/crash-utility/crash/wiki
