linux-kernel - Re: [patch 01/10] x86/fpu/signal: Clarify exception handling in restore_fpregs_from

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Message-ID: <YS06l92erXZDYeNW@zn.tnic>
Date:   Mon, 30 Aug 2021 22:07:51 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     LKML <linux-kernel@...r.kernel.org>, x86@...nel.org,
        Al Viro <viro@...iv.linux.org.uk>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [patch 01/10] x86/fpu/signal: Clarify exception handling in
 restore_fpregs_from_user()

On Mon, Aug 30, 2021 at 09:33:42PM +0200, Borislav Petkov wrote:
> I guess you wanna fixup the comment over XSTATE_OP() too and perhaps
> mention ex_handler_fault() explicitly so that one can make her/his way
> around the code and pinpoint quickly where it sticks that exception
> number into rAX.

Diff ontop. I think it should not say anything about X86_TRAP_PF or
EFAULT or any other error value but simply that it returns one. It is
callers' task to act upon the specific error value returned.

---
diff --git a/arch/x86/include/asm/fpu/internal.h b/arch/x86/include/asm/fpu/internal.h
index 5771af87e4b4..d59bc5df7438 100644
--- a/arch/x86/include/asm/fpu/internal.h
+++ b/arch/x86/include/asm/fpu/internal.h
@@ -199,7 +199,7 @@ static inline void fxsave(struct fxregs_state *fx)
 
 /*
  * After this @err contains 0 on success or the negated trap number when
- * the operation raises an exception. For faults this results in -EFAULT.
+ * the operation raises an exception, see ex_handler_fault().
  */
 #define XSTATE_OP(op, st, lmask, hmask, err)				\
 	asm volatile("1:" op "\n\t"					\

-- 
Regards/Gruss,
    Boris.

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