From: Jan-Simon Möller Date: Thu, 29 Aug 2013 19:13:05 +0000 (+0200) Subject: x86, asm: Fix a compilation issue with clang X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=bdfc017eead9bc17cd23317ff42eb7297cb9468a;p=deliverable%2Flinux.git x86, asm: Fix a compilation issue with clang Clang does not support the "shortcut" we're taking here for gcc (see below). The patch uses the macro _ASM_DX to do the job. From arch/x86/include/asm/uaccess.h: /* * Careful: we have to cast the result to the type of the pointer * for sign reasons. * * The use of %edx as the register specifier is a bit of a * simplification, as gcc only cares about it as the starting point * and not size: for a 64-bit value it will use %ecx:%edx on 32 bits * (%ecx being the next register in gcc's x86 register sequence), and * %rdx on 64 bits. */ [ hpa: I consider this a compatibility bug in clang as this reflects a bit of a misunderstanding about how register strings are used by gcc, but the workaround is straightforward and there is no particular reason to not do it. ] Signed-off-by: Jan-Simon Möller Link: http://lkml.kernel.org/r/1377803585-5913-3-git-send-email-dl9pf@gmx.de Signed-off-by: H. Peter Anvin --- diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h index 5ee26875baea..f715fee40821 100644 --- a/arch/x86/include/asm/uaccess.h +++ b/arch/x86/include/asm/uaccess.h @@ -162,7 +162,7 @@ __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL)) #define get_user(x, ptr) \ ({ \ int __ret_gu; \ - register __inttype(*(ptr)) __val_gu asm("%edx"); \ + register __inttype(*(ptr)) __val_gu asm("%"_ASM_DX); \ __chk_user_ptr(ptr); \ might_fault(); \ asm volatile("call __get_user_%P3" \