From: Borislav Petkov <bp@alien8.de>
To: Andy Lutomirski <luto@kernel.org>
Cc: 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 09/11] x86/fault: Rename no_context() to kernelmode_fixup_or_oops()
Date: Wed, 3 Feb 2021 20:39:49 +0100 [thread overview]
Message-ID: <20210203193949.GI13819@zn.tnic> (raw)
In-Reply-To: <5b0ad34afeeee15032393367b0945a5032903162.1612113550.git.luto@kernel.org>
On Sun, Jan 31, 2021 at 09:24:40AM -0800, Andy Lutomirski wrote:
> The name no_context() has never been very clear. It's only called for
> faults from kernel mode, so rename it and change the no-longer-useful
> user_mode(regs) check to a WARN_ON_ONCE.
>
> 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 | 28 ++++++++++------------------
> 1 file changed, 10 insertions(+), 18 deletions(-)
>
> diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
> index 177b612c7f33..04cc98ec2423 100644
> --- a/arch/x86/mm/fault.c
> +++ b/arch/x86/mm/fault.c
> @@ -693,17 +693,10 @@ page_fault_oops(struct pt_regs *regs, unsigned long error_code,
> }
>
> static noinline void
> -no_context(struct pt_regs *regs, unsigned long error_code,
> - unsigned long address, int signal, int si_code)
> +kernelmode_fixup_or_oops(struct pt_regs *regs, unsigned long error_code,
> + unsigned long address, int signal, int si_code)
Ew, I don't like functions with "or" in the name - they're probably not
doing one thing only as they should.
Why not simply "handle_kernel_fault" ?
Also, all the callsites now do:
if (!user_mode(regs)) {
kernelmode_fixup_or_oops
...
I guess you can push the "user_mode" check inside that function for less
hairy code at the callsites.
> {
> - 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;
> - }
> + WARN_ON_ONCE(user_mode(regs));
I guess...
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2021-02-03 19:41 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
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 [this message]
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
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