Re: [BUG] general protection fault when reading /proc/kcore

[David Hildenbrand]

On 16.08.21 19:49, David Hildenbrand wrote:
> On 16.08.21 19:34, Jiri Olsa wrote:
> > hi,
> > I'm getting fault below when running:
> >
> > 	# cat /proc/kallsyms | grep ksys_read
> > 	ffffffff8136d580 T ksys_read
> > 	# objdump -d --start-address=0xffffffff8136d580 --stop-address=0xffffffff8136d590 /proc/kcore
> >
> > 	/proc/kcore:     file format elf64-x86-64
> >
> > 	Segmentation fault
> >
> > any idea? config is attached
>
> Just tried with a different config on 5.14.0-rc6+
>
> [root@localhost ~]# cat /proc/kallsyms | grep ksys_read
> ffffffff8927a800 T ksys_readahead
> ffffffff89333660 T ksys_read
>
> [root@localhost ~]# objdump -d --start-address=0xffffffff89333660
> --stop-address=0xffffffff89333670
>
> a.out:     file format elf64-x86-64


Sorry, missed the /proc/kcore part:

[root@localhost ~]# cat /proc/kallsyms | grep ksys_read
ffffffffba27a800 T ksys_readahead
ffffffffba333660 T ksys_read
[root@localhost ~]# objdump -d --start-address=0xffffffffba333660 
--stop-address=0xffffffffba333670 /proc/kcore

/proc/kcore:     file format elf64-x86-64


Disassembly of section load1:

ffffffffba333660 <load1+0x333660>:
ffffffffba333660:       0f 1f 44 00 00          nopl   0x0(%rax,%rax,1)
ffffffffba333665:       41 55                   push   %r13
ffffffffba333667:       49 89 d5                mov    %rdx,%r13
ffffffffba33366a:       41 54                   push   %r12
ffffffffba33366c:       49 89 f4                mov    %rsi,%r12
ffffffffba33366f:       55                      push   %rbp


--
Thanks,

David / dhildenb