From d59fe3f13d070489e63d04e1c9bfd819d5f71542 Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Tue, 22 Jan 2013 11:24:12 +0000 Subject: [PATCH] ix86: Tighten asmlinkage_protect() constraints While the description of the commit that originally introduced asmlinkage_protect() validly says that this doesn't guarantee clobbering of the function arguments, using "m" constraints rather than "g" ones reduces the risk (by making it less attractive to the compiler to move those variables into registers) and generally results in better code (because we know the arguments are in memory anyway, and are frequently - if not always - used just once, with the second [compiler visible] use in asmlinkage_protect() itself being a fake one). Signed-off-by: Jan Beulich Cc: Cc: Cc: Linus Torvalds Cc: Andrew Morton Link: http://lkml.kernel.org/r/50FE84EC02000078000B83B7@nat28.tlf.novell.com Signed-off-by: Ingo Molnar --- arch/x86/include/asm/linkage.h | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) diff --git a/arch/x86/include/asm/linkage.h b/arch/x86/include/asm/linkage.h index 48142971b25d..79327e9483a3 100644 --- a/arch/x86/include/asm/linkage.h +++ b/arch/x86/include/asm/linkage.h @@ -27,20 +27,20 @@ #define __asmlinkage_protect0(ret) \ __asmlinkage_protect_n(ret) #define __asmlinkage_protect1(ret, arg1) \ - __asmlinkage_protect_n(ret, "g" (arg1)) + __asmlinkage_protect_n(ret, "m" (arg1)) #define __asmlinkage_protect2(ret, arg1, arg2) \ - __asmlinkage_protect_n(ret, "g" (arg1), "g" (arg2)) + __asmlinkage_protect_n(ret, "m" (arg1), "m" (arg2)) #define __asmlinkage_protect3(ret, arg1, arg2, arg3) \ - __asmlinkage_protect_n(ret, "g" (arg1), "g" (arg2), "g" (arg3)) + __asmlinkage_protect_n(ret, "m" (arg1), "m" (arg2), "m" (arg3)) #define __asmlinkage_protect4(ret, arg1, arg2, arg3, arg4) \ - __asmlinkage_protect_n(ret, "g" (arg1), "g" (arg2), "g" (arg3), \ - "g" (arg4)) + __asmlinkage_protect_n(ret, "m" (arg1), "m" (arg2), "m" (arg3), \ + "m" (arg4)) #define __asmlinkage_protect5(ret, arg1, arg2, arg3, arg4, arg5) \ - __asmlinkage_protect_n(ret, "g" (arg1), "g" (arg2), "g" (arg3), \ - "g" (arg4), "g" (arg5)) + __asmlinkage_protect_n(ret, "m" (arg1), "m" (arg2), "m" (arg3), \ + "m" (arg4), "m" (arg5)) #define __asmlinkage_protect6(ret, arg1, arg2, arg3, arg4, arg5, arg6) \ - __asmlinkage_protect_n(ret, "g" (arg1), "g" (arg2), "g" (arg3), \ - "g" (arg4), "g" (arg5), "g" (arg6)) + __asmlinkage_protect_n(ret, "m" (arg1), "m" (arg2), "m" (arg3), \ + "m" (arg4), "m" (arg5), "m" (arg6)) #endif /* CONFIG_X86_32 */ -- 2.39.5