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Date: Tue, 22 Jan 2013 11:24:12 +0000 From: "Jan Beulich" <JBeulich@...e.com> To: <mingo@...e.hu>, <tglx@...utronix.de>, <hpa@...or.com> Cc: <roland@...k.frob.com>, <linux-kernel@...r.kernel.org>, <viro@...iv.linux.org.uk> Subject: [PATCH] ix86: tighten asmlinkage_protect() 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 <jbeulich@...e.com> --- arch/x86/include/asm/linkage.h | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) --- 3.8-rc4/arch/x86/include/asm/linkage.h +++ 3.8-rc4-ix86-asmlinkage-protect/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 */ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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