Re: [PATCH v7 02/26] x86/mm: Relocate page fault error codes to traps.h

From: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
To: Borislav Petkov <bp@suse.de>
Cc: Ingo Molnar <mingo@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Andy Lutomirski <luto@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Brian Gerst <brgerst@gmail.com>,
	Chris Metcalf <cmetcalf@mellanox.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Liang Z Li <liang.z.li@intel.com>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	Huang Rui <ray.huang@amd.com>, Jiri Slaby <jslaby@suse.cz>,
	Jonathan Corbet <corbet@lwn.net>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	Paul Gortmaker <paul.gortmaker@windriver.com>,
	Vlastimil Babka <vbabka@suse.cz>, Chen Yucong <slaoub@gmail.com>,
	Alexandre Julliard <julliard@winehq.org>,
	Stas Sergeev <stsp@list.ru>, Fenghua Yu <fenghua.yu@intel.com>,
	"Ravi V. Shankar" <ravi.v.shankar@intel.com>,
	Shuah Khan <shuah@kernel.org>,
	linux-kernel@vger.kernel.org, x86@kernel.org,
	linux-msdos@vger.kernel.org, wine-devel@winehq.org,
	"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	Josh Poimboeuf <jpoimboe@redhat.com>
Subject: Re: [PATCH v7 02/26] x86/mm: Relocate page fault error codes to traps.h
Date: Fri, 26 May 2017 20:40:26 -0700	[thread overview]
Message-ID: <1495856426.24288.47.camel@ranerica-desktop> (raw)
In-Reply-To: <20170521142330.GC5676@nazgul.tnic>

On Sun, 2017-05-21 at 16:23 +0200, Borislav Petkov wrote:
> On Fri, May 05, 2017 at 11:17:00AM -0700, Ricardo Neri wrote:
> > Up to this point, only fault.c used the definitions of the page fault error
> > codes. Thus, it made sense to keep them within such file. Other portions of
> > code might be interested in those definitions too. For instance, the User-
> > Mode Instruction Prevention emulation code will use such definitions to
> > emulate a page fault when it is unable to successfully copy the results
> > of the emulated instructions to user space.
> > 
> > While relocating the error code enumeration, the prefix X86_ is used to
> > make it consistent with the rest of the definitions in traps.h. Of course,
> > code using the enumeration had to be updated as well. No functional changes
> > were performed.
> > 
> > Cc: Thomas Gleixner <tglx@linutronix.de>
> > Cc: Ingo Molnar <mingo@redhat.com>
> > Cc: "H. Peter Anvin" <hpa@zytor.com>
> > Cc: Andy Lutomirski <luto@kernel.org>
> > Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
> > Cc: Josh Poimboeuf <jpoimboe@redhat.com>
> > Cc: Dave Hansen <dave.hansen@linux.intel.com>
> > Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
> > Cc: x86@kernel.org
> > Reviewed-by: Andy Lutomirski <luto@kernel.org>
> > Signed-off-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
> > ---
> >  arch/x86/include/asm/traps.h | 18 +++++++++
> >  arch/x86/mm/fault.c          | 88 +++++++++++++++++---------------------------
> >  2 files changed, 52 insertions(+), 54 deletions(-)
> 
> ...
> 
> > @@ -1382,7 +1362,7 @@ __do_page_fault(struct pt_regs *regs, unsigned long error_code,
> >  	 * space check, thus avoiding the deadlock:
> >  	 */
> >  	if (unlikely(!down_read_trylock(&mm->mmap_sem))) {
> > -		if ((error_code & PF_USER) == 0 &&
> > +		if ((error_code & X86_PF_USER) == 0 &&
> 
> 	if (!(error_code & X86_PF_USER))

This change was initially intended to only rename the error codes,
without functional changes. Would making change be considered a change
in functionality? The behavior would be preserved, though.

Thanks and BR,
Ricardo

> 
> With that fixed:
> 
> Reviewed-by: Borislav Petkov <bp@suse.de>

Thank you for your review!

BR,
Ricardo
> 
> -- 
> Regards/Gruss,
>     Boris.
> 
> SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)