[Crash-utility] [PATCH] arm64: Fix for st->_stext_vmlinux not initialized when set VA_BITS_ACTUAL

Tue Jun 28 01:55:23 UTC 2022

Hi, Kazu and Qianli

On Tue, Jun 28, 2022 at 9:17 AM HAGIO KAZUHITO(萩尾 一仁) <k-hagio-ab at nec.com>
wrote:

> Hi Qianli,
>
> thanks for the patch and explanation.  I was off.
>
> On 2022/06/27 11:24, qianli zhao wrote:
> > Hi,Kazu
> >
> > Would you like to help review this patch?
>
> Sure, I think I can review it this week.
>
> Lianbo, can you possibly reproduce and test this?

OK, I will have a look and give feedback later.

Thanks.
Lianbo

> Kazu
>
> >
> > qianli zhao <zhaoqianligood at gmail.com> 于2022年6月24日周五 10:56写道：
> >
> >>
> >> Hi,all
> >>
> >> Here's some explanation for this patch
> >>
> >> Without patch:
> >> Consider the following scenario
> >> ->arm64_init(PRE_GDB)
> >> case PRE_GDB:
> >> ...
> >>   292                         } else if (ms->VA_BITS_ACTUAL) {
> >>   293                                 ms->modules_vaddr =
> >> (st->_stext_vmlinux & TEXT_OFFSET_MASK) -
> >> ARM64_MODULES_VSIZE;-->//ms->modules_vaddr=0xfffffffff8000000
> >>   294                                 ms->modules_end =
> >> ms->modules_vaddr + ARM64_MODULES_VSIZE
> >> -1;--->//ms->modules_end=0xffffffffffffffff
> >>   295                                 ms->vmalloc_start_addr =
> >> ms->modules_end + 1;--->//ms->vmalloc_start_addr=0
> >> 296                         } else {
> >>                                 ....
> >>                                 }
> >>                                 arm64_calc_kimage_voffset();
> >> .....
> >>
> >> Since arm64_calc_kimage_voffset() depends on vmalloc_start_addr,
> >> kimage_voffset cannot be calculated correctly.
> >>
> >> st->_stext_vmlinux can be initialized in numeric_forward(),just set
> >> st->_stext_vmlinux to UNINITIALIZED.
> >>
> >> ============
> >> log as below:
> >>
> >> $ ~/crash/crash/crash vmlinux DDRCS0.bin at 0x80000000 --machdep
> vabits_actual=48
> >>
> >> crash 8.0.1++
> >> Copyright (C) 2002-2022  Red Hat, Inc.
> >> Copyright (C) 2004, 2005, 2006, 2010  IBM Corporation
> >> Copyright (C) 1999-2006  Hewlett-Packard Co
> >> Copyright (C) 2005, 2006, 2011, 2012  Fujitsu Limited
> >> Copyright (C) 2006, 2007  VA Linux Systems Japan K.K.
> >> Copyright (C) 2005, 2011, 2020-2022  NEC Corporation
> >> Copyright (C) 1999, 2002, 2007  Silicon Graphics, Inc.
> >> Copyright (C) 1999, 2000, 2001, 2002  Mission Critical Linux, Inc.
> >> Copyright (C) 2015, 2021  VMware, Inc.
> >> This program is free software, covered by the GNU General Public
> License,
> >> and you are welcome to change it and/or distribute copies of it under
> >> certain conditions.  Enter "help copying" to see the conditions.
> >> This program has absolutely no warranty.  Enter "help warranty" for
> details.
> >>
> >> NOTE: setting vabits_actual to: 48
> >>
> >> WARNING: kimage_voffset cannot be determined from the dumpfile.
> >>         Try using the command line option: --machdep
> kimage_voffset=<addr>
> >> GNU gdb (GDB) 10.2
> >> Copyright (C) 2021 Free Software Foundation, Inc.
> >> License GPLv3+: GNU GPL version 3 or later <
> http://gnu.org/licenses/gpl.html>
> >> This is free software: you are free to change and redistribute it.
> >> There is NO WARRANTY, to the extent permitted by law.
> >> Type "show copying" and "show warranty" for details.
> >> This GDB was configured as "--host=x86_64-pc-linux-gnu
> >> --target=aarch64-elf-linux".
> >> Type "show configuration" for configuration details.
> >> Find the GDB manual and other documentation resources online at:
> >>      <http://www.gnu.org/software/gdb/documentation/>.
> >>
> >> For help, type "help".
> >> Type "apropos word" to search for commands related to "word"...
> >>
> >> crash: read error: kernel virtual address: ffff80001083d4a0  type:
> >> "kernel_config_data"
> >> WARNING: cannot read kernel_config_data
> >> crash: read error: kernel virtual address: ffff80001170e798  type:
> "possible"
> >> WARNING: cannot read cpu_possible_map
> >> crash: read error: kernel virtual address: ffff80001170e7a8  type:
> "present"
> >> WARNING: cannot read cpu_present_map
> >> crash: read error: kernel virtual address: ffff80001170e788  type:
> "online"
> >> WARNING: cannot read cpu_online_map
> >> crash: read error: kernel virtual address: ffff80001170e7c0  type:
> "active"
> >> WARNING: cannot read cpu_active_map
> >> crash: read error: kernel virtual address: ffff8000122e00f0  type:
> >> "shadow_timekeeper xtime_sec"
> >> crash: read error: kernel virtual address: ffff80001171dc04  type:
> "init_uts_ns"
> >> crash: vmlinux and /var/tmp/ramdump_elf_m2ivkg do not match!
> >>
> >> Usage:
> >>
> >>    crash [OPTION]... NAMELIST MEMORY-IMAGE[@ADDRESS]     (dumpfile form)
> >>    crash [OPTION]... [NAMELIST]                          (live system
> form)
> >>
> >> Enter "crash -h" for details.
> >>
> >> Qianli Zhao <zhaoqianligood at gmail.com> 于2022年6月24日周五 00:14写道：
> >>>
> >>> From: Qianli Zhao <qianli.zhao at horizon.ai>
> >>>
> >>> Setting st->_stext_vmlinux to UNINITIALIZED to search for "_stext"
> from the vmlinux
> >>> Without the patch, if we do not enable kaslr, will get the wrong
> >>> MODULES/VMALLOC ranges, cause parsing dump failure
> >>>
> >>> Signed-off-by: Qianli Zhao <qianli.zhao at horizon.ai>
> >>> ---
> >>>   arm64.c | 3 +++
> >>>   1 file changed, 3 insertions(+)
> >>>
> >>> diff --git a/arm64.c b/arm64.c
> >>> index 0f615cf..4458a66 100644
> >>> --- a/arm64.c
> >>> +++ b/arm64.c
> >>> @@ -149,6 +149,9 @@ arm64_init(int when)
> >>>
> >>>                  ms = machdep->machspec;
> >>>
> >>> +               if (ms->VA_BITS_ACTUAL)
> >>> +                       st->_stext_vmlinux = UNINITIALIZED;
> >>> +
> >>>                  if (!ms->kimage_voffset && STREQ(pc->live_memsrc,
> "/dev/crash"))
> >>>                          ioctl(pc->mfd, DEV_CRASH_ARCH_DATA,
> &ms->kimage_voffset);
> >>>
> >>> --
> >>> 2.17.1
> >>>
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