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Date: Tue, 2 May 2017 11:52:12 -0700 From: Matthias Kaehlcke <mka@...omium.org> To: Mark Rutland <mark.rutland@....com> Cc: Catalin Marinas <catalin.marinas@....com>, Will Deacon <will.deacon@....com>, Ard Biesheuvel <ard.biesheuvel@...aro.org>, Christoffer Dall <christoffer.dall@...aro.org>, Marc Zyngier <marc.zyngier@....com>, Vladimir Murzin <vladimir.murzin@....com>, linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, Grant Grundler <grundler@...omium.org>, Greg Hackmann <ghackmann@...gle.com>, Michael Davidson <md@...gle.com> Subject: Re: [PATCH] arm64: Fix multiple 'asm-operand-widths' warnings Hi, El Tue, May 02, 2017 at 06:29:48PM +0100 Mark Rutland ha dit: > On Mon, May 01, 2017 at 02:26:22PM -0700, Matthias Kaehlcke wrote: > > diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h > > index 5308d696311b..7db143689694 100644 > > --- a/arch/arm64/include/asm/uaccess.h > > +++ b/arch/arm64/include/asm/uaccess.h > > @@ -302,7 +302,7 @@ do { \ > > " .previous\n" \ > > _ASM_EXTABLE(1b, 3b) \ > > : "+r" (err) \ > > - : "r" (x), "r" (addr), "i" (-EFAULT)) > > + : "r" ((__u64)x), "r" (addr), "i" (-EFAULT)) > > > > For reference, do you have the warning for this case to hand? > > In __put_user_err() we make __pu_val the same type as *ptr, then we > switch on sizeof(*ptr), and pass __pu_val to __put_user_asm(), as x. > For cases 1, 2, and 4, we use "%w" as the register template. > > So I can't see why we'd need this cast in __put_user_err(). > > I must be missing something. This is one of many instances: ./include/linux/pagemap.h:554:10: warning: value size does not match register size specified by the constraint and modifier [-Wasm-operand-widths] return __put_user(0, end); ^ ./arch/arm64/include/asm/uaccess.h:338:2: note: expanded from macro '__put_user' __put_user_err((x), (ptr), __pu_err); \ ^ ./arch/arm64/include/asm/uaccess.h:326:38: note: expanded from macro '__put_user_err' __put_user_asm("str", "sttr", "%", __pu_val, (ptr), \ ^ ./include/linux/pagemap.h:554:10: note: use constraint modifier "w" ./arch/arm64/include/asm/uaccess.h:338:2: note: expanded from macro '__put_user' __put_user_err((x), (ptr), __pu_err); \ ^ ./arch/arm64/include/asm/uaccess.h:326:34: note: expanded from macro '__put_user_err' __put_user_asm("str", "sttr", "%", __pu_val, (ptr), \ ^ 'end' is a char pointer, it is not clear to me why we would end up in the width == 8 branch. Matthias
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