linux-kernel - Re: linux-next: build failure after merge of the aio tree

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Date:	Thu, 4 Feb 2016 11:01:01 -0500
From:	Benjamin LaHaise <bcrl@...ck.org>
To:	Russell King - ARM Linux <linux@....linux.org.uk>
Cc:	Stephen Rothwell <sfr@...b.auug.org.au>,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	Linux-Next <linux-next@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: linux-next: build failure after merge of the aio tree

On Thu, Feb 04, 2016 at 02:39:07PM +0000, Russell King - ARM Linux wrote:
> However, this one should warn:
> 
> int test_wrong(char **v, const char **p)
> { return __get_user(*v, p); }
> 
> Good luck (I think you'll need lots of it to get a working solution)! :)

This works with your test cases on x86-32.  Note that it's only compile + 
link tested at present.

		-ben
-- 
"Thought is the essence of where you are now."

diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index 09b1b0a..d8834c2 100644
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -326,7 +326,21 @@ do {									\
 } while (0)
 
 #ifdef CONFIG_X86_32
-#define __get_user_asm_u64(x, ptr, retval, errret)	(x) = __get_user_bad()
+#define __get_user_asm_u64(x, addr, err, errret)			\
+	asm volatile(ASM_STAC "\n"					\
+		     "1:	movl %2,%%eax\n"			\
+		     "		movl %3,%%edx\n"			\
+		     "2: " ASM_CLAC "\n"				\
+		     ".section .fixup,\"ax\"\n"				\
+		     "3:	mov %4,%0\n"				\
+		     "	xorl %%eax,%%eax\n"				\
+		     "	xorl %%edx,%%edx\n"				\
+		     "	jmp 2b\n"					\
+		     ".previous\n"					\
+		     _ASM_EXTABLE(1b, 3b)				\
+		     : "=r" (err), "=A"(x)				\
+		     : "m" (__m(addr)), "m" __m(((u32 *)addr) + 1), "i" (errret), "0" (err))
+
 #define __get_user_asm_ex_u64(x, ptr)			(x) = __get_user_bad()
 #else
 #define __get_user_asm_u64(x, ptr, retval, errret) \