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

Ricardo Neri
2017-05-27T03:40:26Z

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)