Re: [Crash-utility] [PATCH v2] arm64: fix the "pud page" crash for live system
-----Original Message-----
1.) When I tested live system with "crash vmlinux
/proc/kcore" in kernel v5.7,
I met the following crash issue:
........................................
crash: seek error: kernel virtual address: ffff75e9fffff000 type: "pud
page"
........................................
2.) The root cause is the PTOV does not work correctly for some kernel,
and then arm64_vtop_4level_4k() does not work correctly too.
Why PTOV does not work?
Because the physvirt_offset does not get the correct value.
3.) This patch uses symbol_value_from_proc_kallsyms() to get the
virtual address of "physvirt_offset", and then uses
READMEM(,..,KCORE_USE_VADDR) to get the correct value of
"physvirt_offset".
And also updates the ms->phys_offset which is initialized with
a wrong value in kernel version [5.4, 5.10).
Also add more comments for arm64_calc_physvirt_offset().
Signed-off-by: Huang Shijie <shijie(a)os.amperecomputing.com>
---
v1 --> v2:
v1 tried to get the correct value for phys_offset,
and then get the physvirt_offset correctly.
v2 tried to get the physvirt_offset correctly,
and them update phys_offset correctly.
Tested this patch with kernel 5.7.
Thank you for the change. The code looks good to me.
Acked-by: Kazuhito Hagio <k-hagio-ab(a)nec.com>
Lianbo, can we add the following with this? it's missing in help -m.
@@ -1065,6 +1065,7 @@ arm64_dump_machdep_table(ulong arg)
fprintf(fp, " kimage_voffset: %016lx\n",
ms->kimage_voffset);
}
fprintf(fp, " phys_offset: %lx\n", ms->phys_offset);
+ fprintf(fp, " physvirt_offset: %lx\n", ms->physvirt_offset);
fprintf(fp, "__exception_text_start: %lx\n",
ms->__exception_text_start);
fprintf(fp, " __exception_text_end: %lx\n",
ms->__exception_text_end);
fprintf(fp, " __irqentry_text_start: %lx\n",
ms->__irqentry_text_start);
Thanks,
Kazu