From mboxrd@z Thu Jan 1 00:00:00 1970 From: Feng Wu Subject: [PATCH v2 5/5] x86: Use alternative mechanism to define CLAC/STAC Date: Thu, 29 May 2014 13:34:29 +0800 Message-ID: <1401341669-5237-6-git-send-email-feng.wu@intel.com> References: <1401341669-5237-1-git-send-email-feng.wu@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1401341669-5237-1-git-send-email-feng.wu@intel.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: xen-devel@lists.xen.org Cc: Feng Wu , ian.campbell@citrix.com, andrew.cooper3@citrix.com, tim@xen.org, keir.xen@gmail.com, stefano.stabellini@citrix.com, JBeulich@suse.com List-Id: xen-devel@lists.xenproject.org This patch use alternative mechanism to define CLAC/STAC. Signed-off-by: Feng Wu --- xen/include/asm-x86/asm_defns.h | 24 +++++++++++++----------- 1 file changed, 13 insertions(+), 11 deletions(-) diff --git a/xen/include/asm-x86/asm_defns.h b/xen/include/asm-x86/asm_defns.h index 0b9f898..dd50b97 100644 --- a/xen/include/asm-x86/asm_defns.h +++ b/xen/include/asm-x86/asm_defns.h @@ -9,6 +9,7 @@ #include #include #include +#include #ifndef __ASSEMBLY__ void ret_from_intr(void); @@ -165,26 +166,27 @@ void ret_from_intr(void); #define __ASM_STAC .byte 0x0f,0x01,0xcb #ifdef __ASSEMBLY__ -#define ASM_AC(op) \ - btl $X86_FEATURE_SMAP & 31, \ - CPUINFO_FEATURE_OFFSET(X86_FEATURE_SMAP)+boot_cpu_data(%rip); \ - jnc 881f; \ - __ASM_##op; \ -881: - +#define ASM_AC(op) \ + 661: ASM_NOP3; \ + .pushsection .altinstr_replacement, "ax"; \ + 662: __ASM_##op; \ + .popsection; \ + .pushsection .altinstructions, "a"; \ + altinstruction_entry 661b, 662b, X86_FEATURE_SMAP, 3, 3; \ + .popsection #define ASM_STAC ASM_AC(STAC) #define ASM_CLAC ASM_AC(CLAC) #else static inline void clac(void) { - if ( boot_cpu_has(X86_FEATURE_SMAP) ) - asm volatile (STR(__ASM_CLAC) : : : "memory"); + /* Note: a barrier is implicit in alternative() */ + alternative(ASM_NOP3, STR(__ASM_CLAC), X86_FEATURE_SMAP); } static inline void stac(void) { - if ( boot_cpu_has(X86_FEATURE_SMAP) ) - asm volatile (STR(__ASM_STAC) : : : "memory"); + /* Note: a barrier is implicit in alternative() */ + alternative(ASM_NOP3, STR(__ASM_STAC), X86_FEATURE_SMAP); } #endif -- 1.8.3.1