From: Andy Lutomirski <luto@amacapital.net>
To: Borislav Petkov <bp@alien8.de>
Cc: Andy Lutomirski <luto@kernel.org>,
x86@kernel.org, LKML <linux-kernel@vger.kernel.org>,
Dave Hansen <dave.hansen@linux.intel.com>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Yonghong Song <yhs@fb.com>,
Masami Hiramatsu <mhiramat@kernel.org>,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH 07/11] x86/fault: Split the OOPS code out from no_context()
Date: Wed, 3 Feb 2021 11:29:39 -0800 [thread overview]
Message-ID: <78B808CF-16E2-4C41-B680-0AFD1428ED4A@amacapital.net> (raw)
In-Reply-To: <20210203185517.GH13819@zn.tnic>
> On Feb 3, 2021, at 10:56 AM, Borislav Petkov <bp@alien8.de> wrote:
>
> On Sun, Jan 31, 2021 at 09:24:38AM -0800, Andy Lutomirski wrote:
>> Not all callers of no_context() want to run exception fixups.
>> Separate the OOPS code out from the fixup code in no_context().
>>
>> Cc: Dave Hansen <dave.hansen@linux.intel.com>
>> Cc: Peter Zijlstra <peterz@infradead.org>
>> Signed-off-by: Andy Lutomirski <luto@kernel.org>
>> ---
>> arch/x86/mm/fault.c | 116 +++++++++++++++++++++++---------------------
>> 1 file changed, 62 insertions(+), 54 deletions(-)
>>
>> diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
>> index 1939e546beae..6f43d080e1e8 100644
>> --- a/arch/x86/mm/fault.c
>> +++ b/arch/x86/mm/fault.c
>> @@ -618,53 +618,20 @@ static void set_signal_archinfo(unsigned long address,
>> }
>>
>> static noinline void
>> -no_context(struct pt_regs *regs, unsigned long error_code,
>> - unsigned long address, int signal, int si_code)
>> +page_fault_oops(struct pt_regs *regs, unsigned long error_code,
>
> Not sure about this name - it still tries to recover:
> efi_recover_from_page_fault().
>
That function is a lie. It tries to keep the system alive but it doesn’t return if it “recovers”. Maybe I should add a comment?
> Judging by where it is called, maybe no_context_tail() or
> no_context_oops() or no_context_finish_me_already()...
>
> Yah, I haz no better idea. :-\
>
> ...
>
>> @@ -739,6 +692,61 @@ no_context(struct pt_regs *regs, unsigned long error_code,
>> oops_end(flags, regs, sig);
>> }
>>
>> +static noinline void
>> +no_context(struct pt_regs *regs, unsigned long error_code,
>> + unsigned long address, int signal, int si_code)
>> +{
>> + if (user_mode(regs)) {
>> + /*
>> + * This is an implicit supervisor-mode access from user
>> + * mode. Bypass all the kernel-mode recovery code and just
>> + * OOPS.
>> + */
>> + goto oops;
>
> Just do
>
> return page_fault_oops(...);
>
> here and get rid of the label.
>
> --
> Regards/Gruss,
> Boris.
>
> https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2021-02-03 19:30 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-31 17:24 [PATCH 00/11] x86/fault: Cleanups and robustifications Andy Lutomirski
2021-01-31 17:24 ` [PATCH 01/11] x86/fault: Fix AMD erratum #91 errata fixup for user code Andy Lutomirski
2021-02-01 9:05 ` Christoph Hellwig
2021-02-01 20:31 ` Borislav Petkov
2021-01-31 17:24 ` [PATCH 02/11] x86/fault: Fold mm_fault_error() into do_user_addr_fault() Andy Lutomirski
2021-01-31 17:24 ` [PATCH 03/11] x86/fault/32: Move is_f00f_bug() do do_kern_addr_fault() Andy Lutomirski
2021-02-03 14:44 ` Borislav Petkov
2021-01-31 17:24 ` [PATCH 04/11] x86/fault: Document the locking in the fault_signal_pending() path Andy Lutomirski
2021-01-31 17:24 ` [PATCH 05/11] x86/fault: Correct a few user vs kernel checks wrt WRUSS Andy Lutomirski
2021-02-03 15:48 ` Borislav Petkov
2021-01-31 17:24 ` [PATCH 06/11] x86/fault: Improve kernel-executing-user-memory handling Andy Lutomirski
2021-02-01 9:08 ` Christoph Hellwig
2021-02-02 1:00 ` Andy Lutomirski
2021-02-03 16:01 ` Borislav Petkov
2021-02-03 16:23 ` Borislav Petkov
2021-01-31 17:24 ` [PATCH 07/11] x86/fault: Split the OOPS code out from no_context() Andy Lutomirski
2021-02-03 18:56 ` Borislav Petkov
2021-02-03 19:29 ` Andy Lutomirski [this message]
2021-02-03 19:46 ` Borislav Petkov
2021-02-09 20:09 ` Andy Lutomirski
2021-01-31 17:24 ` [PATCH 08/11] x86/fault: Bypass no_context() for implicit kernel faults from usermode Andy Lutomirski
2021-01-31 17:24 ` [PATCH 09/11] x86/fault: Rename no_context() to kernelmode_fixup_or_oops() Andy Lutomirski
2021-02-01 9:14 ` Christoph Hellwig
2021-02-02 1:01 ` Andy Lutomirski
2021-02-03 19:39 ` Borislav Petkov
2021-02-03 19:53 ` Andy Lutomirski
2021-02-03 20:07 ` Borislav Petkov
2021-02-03 20:14 ` Andy Lutomirski
2021-02-03 20:25 ` Borislav Petkov
2021-01-31 17:24 ` [PATCH 10/11] x86/fault: Don't run fixups for SMAP violations Andy Lutomirski
2021-02-03 19:50 ` Borislav Petkov
2021-01-31 17:24 ` [PATCH 11/11] x86/fault: Don't look for extable entries for SMEP violations Andy Lutomirski
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=78B808CF-16E2-4C41-B680-0AFD1428ED4A@amacapital.net \
--to=luto@amacapital.net \
--cc=ast@kernel.org \
--cc=bp@alien8.de \
--cc=daniel@iogearbox.net \
--cc=dave.hansen@linux.intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=luto@kernel.org \
--cc=mhiramat@kernel.org \
--cc=peterz@infradead.org \
--cc=x86@kernel.org \
--cc=yhs@fb.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).