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From: David Hildenbrand <david@redhat.com>
To: Jiri Olsa <jolsa@redhat.com>, Mike Rapoport <rppt@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Oscar Salvador <osalvador@suse.de>
Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [BUG] general protection fault when reading /proc/kcore
Date: Mon, 16 Aug 2021 19:49:15 +0200	[thread overview]
Message-ID: <1a05d147-e249-7682-2c86-bbd157bc9c7d@redhat.com> (raw)
In-Reply-To: <YRqhqz35tm3hA9CG@krava>

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



The kern_addr_valid(start) seems to fault in your case, which is weird, 
because it merely walks the page tables. But it seems to complain about 
a non-canonical address 0xf887ffcbff000

Can you post your QEMU cmdline? Did you test this on other kernel versions?

Thanks!

-- 
Thanks,

David / dhildenb


  reply	other threads:[~2021-08-16 17:49 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-16 17:34 Jiri Olsa
2021-08-16 17:49 ` David Hildenbrand [this message]
2021-08-16 17:54   ` David Hildenbrand
2021-08-16 18:12   ` Jiri Olsa
2021-08-16 18:38     ` David Hildenbrand
2021-08-16 19:12       ` Mike Rapoport
2021-08-16 19:20         ` David Hildenbrand
2021-08-17  7:56         ` Mike Rapoport
2021-08-17  8:02           ` David Hildenbrand
2021-08-17  8:20             ` Mike Rapoport
2021-08-17  8:09           ` Jiri Olsa
2021-08-17  7:43       ` Jiri Olsa

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