Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752445AbbDBNN1 (ORCPT ); Thu, 2 Apr 2015 09:13:27 -0400 Received: from mail.skyhub.de ([78.46.96.112]:38814 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751102AbbDBNNY (ORCPT ); Thu, 2 Apr 2015 09:13:24 -0400 From: Borislav Petkov To: X86 ML Cc: LKML , "H. Peter Anvin" , Ingo Molnar , Thomas Gleixner , Quentin Casasnovas , Oleg Nesterov , Andy Lutomirski Subject: [PATCH] x86/xsave: Robustify and merge macros Date: Thu, 2 Apr 2015 15:11:22 +0200 Message-Id: <1427980282-25929-1-git-send-email-bp@alien8.de> X-Mailer: git-send-email 2.3.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6660 Lines: 226 From: Borislav Petkov Previously, we did call an XSAVE/XRSTOR variant through alternatives and did potential exception handling resulting from the instruction execution in a second inline asm. Which was misleading and error prone, see 06c8173eb92b ("x86/fpu/xsaves: Fix improper uses of __ex_table") for an example. Add single macros which combine the alternatives and the exception handling. While at it, remove the SYSTEM_BOOTING checks in favor of static_cpu_has_safe() which works regardless of system state. Cleanup comments. Signed-off-by: Borislav Petkov Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: Thomas Gleixner Cc: Quentin Casasnovas Cc: Oleg Nesterov Cc: Andy Lutomirski --- arch/x86/include/asm/xsave.h | 141 ++++++++++++++++++++++--------------------- 1 file changed, 73 insertions(+), 68 deletions(-) diff --git a/arch/x86/include/asm/xsave.h b/arch/x86/include/asm/xsave.h index c9a6d68b8d62..e6c7986c95df 100644 --- a/arch/x86/include/asm/xsave.h +++ b/arch/x86/include/asm/xsave.h @@ -67,6 +67,66 @@ extern int init_fpu(struct task_struct *child); _ASM_EXTABLE(1b, 3b) \ : [err] "=r" (err) +#define XSTATE_OP(op, st, lmask, hmask, err) \ + asm volatile("1:" op "\n\t" \ + "2:\n\t" \ + "xor %[err], %[err]\n" \ + ".pushsection .fixup,\"ax\"\n\t" \ + "3: movl $-1,%[err]\n\t" \ + "jmp 2b\n\t" \ + ".popsection\n\t" \ + _ASM_EXTABLE(1b, 3b) \ + : [err] "=r" (err) \ + : "D" (st), "m" (*st), "a" (lmask), "d" (hmask) \ + : "memory") + +/* + * If XSAVES is enabled, it replaces XSAVEOPT because it supports a compact + * format and supervisor states in addition to modified optimization in + * XSAVEOPT. + * + * Otherwise, if XSAVEOPT is enabled, XSAVEOPT replaces XSAVE because XSAVEOPT + * supports modified optimization which is not supported by XSAVE. + * + * We use XSAVE as a fallback. + * + * 661 and alt_end_marker labels below are defined in ALTERNATIVE* and we're + * reusing them here so as not to clutter this macro unnecessarily. + */ +#define XSTATE_XSAVE(st, lmask, hmask, err) \ + asm volatile(ALTERNATIVE_2(XSAVE, \ + XSAVEOPT, X86_FEATURE_XSAVEOPT, \ + XSAVES, X86_FEATURE_XSAVES) \ + "\n" \ + "xor %[err], %[err]\n" \ + ".pushsection .fixup,\"ax\"\n" \ + "3: movl $-1, %[err]\n" \ + "jmp " alt_end_marker "b\n" \ + ".popsection\n" \ + _ASM_EXTABLE(661b, 3b) \ + : [err] "=r" (err) \ + : "D" (st), "a" (lmask), "d" (hmask) \ + : "memory") + +/* + * Use XRSTORS to restore context if it is enabled. XRSTORS supports compact + * XSAVE area format. + */ +#define XSTATE_XRESTORE(st, lmask, hmask, err) \ + asm volatile(ALTERNATIVE(XRSTOR, \ + XRSTORS, X86_FEATURE_XSAVES) \ + "\n" \ + "xor %[err], %[err]\n" \ + ".pushsection .fixup,\"ax\"\n" \ + "3: movl $-1, %[err]\n" \ + "jmp 663b\n" \ + ".popsection\n" \ + _ASM_EXTABLE(661b, 3b) \ + : [err] "=r" (err) \ + : "D" (st), "m" (*st), "a" (lmask), "d" (hmask) \ + : "memory") + + /* * This function is called only during boot time when x86 caps are not set * up and alternative can not be used yet. @@ -75,22 +135,13 @@ static inline int xsave_state_booting(struct xsave_struct *fx, u64 mask) { u32 lmask = mask; u32 hmask = mask >> 32; - int err = 0; - - WARN_ON(system_state != SYSTEM_BOOTING); + int err; - if (boot_cpu_has(X86_FEATURE_XSAVES)) - asm volatile("1:"XSAVES"\n\t" - "2:\n\t" - xstate_fault - : "D" (fx), "m" (*fx), "a" (lmask), "d" (hmask) - : "memory"); + if (static_cpu_has_safe(X86_FEATURE_XSAVES)) + XSTATE_OP(XSAVES, fx, lmask, hmask, err); else - asm volatile("1:"XSAVE"\n\t" - "2:\n\t" - xstate_fault - : "D" (fx), "m" (*fx), "a" (lmask), "d" (hmask) - : "memory"); + XSTATE_OP(XSAVE, fx, lmask, hmask, err); + return err; } @@ -102,22 +153,12 @@ static inline int xrstor_state_booting(struct xsave_struct *fx, u64 mask) { u32 lmask = mask; u32 hmask = mask >> 32; - int err = 0; - - WARN_ON(system_state != SYSTEM_BOOTING); + int err; - if (boot_cpu_has(X86_FEATURE_XSAVES)) - asm volatile("1:"XRSTORS"\n\t" - "2:\n\t" - xstate_fault - : "D" (fx), "m" (*fx), "a" (lmask), "d" (hmask) - : "memory"); + if (static_cpu_has_safe(X86_FEATURE_XSAVES)) + XSTATE_OP(XRSTORS, fx, lmask, hmask, err); else - asm volatile("1:"XRSTOR"\n\t" - "2:\n\t" - xstate_fault - : "D" (fx), "m" (*fx), "a" (lmask), "d" (hmask) - : "memory"); + XSTATE_OP(XRSTOR, fx, lmask, hmask, err); return err; } @@ -128,31 +169,9 @@ static inline int xsave_state(struct xsave_struct *fx, u64 mask) { u32 lmask = mask; u32 hmask = mask >> 32; - int err = 0; + int err; - /* - * If xsaves is enabled, xsaves replaces xsaveopt because - * it supports compact format and supervisor states in addition to - * modified optimization in xsaveopt. - * - * Otherwise, if xsaveopt is enabled, xsaveopt replaces xsave - * because xsaveopt supports modified optimization which is not - * supported by xsave. - * - * If none of xsaves and xsaveopt is enabled, use xsave. - */ - alternative_input_2( - "1:"XSAVE, - XSAVEOPT, - X86_FEATURE_XSAVEOPT, - XSAVES, - X86_FEATURE_XSAVES, - [fx] "D" (fx), "a" (lmask), "d" (hmask) : - "memory"); - asm volatile("2:\n\t" - xstate_fault - : "0" (0) - : "memory"); + XSTATE_XSAVE(fx, lmask, hmask, err); return err; } @@ -162,25 +181,11 @@ static inline int xsave_state(struct xsave_struct *fx, u64 mask) */ static inline int xrstor_state(struct xsave_struct *fx, u64 mask) { - int err = 0; + int err; u32 lmask = mask; u32 hmask = mask >> 32; - /* - * Use xrstors to restore context if it is enabled. xrstors supports - * compacted format of xsave area which is not supported by xrstor. - */ - alternative_input( - "1: " XRSTOR, - XRSTORS, - X86_FEATURE_XSAVES, - "D" (fx), "m" (*fx), "a" (lmask), "d" (hmask) - : "memory"); - - asm volatile("2:\n" - xstate_fault - : "0" (0) - : "memory"); + XSTATE_XRESTORE(fx, lmask, hmask, err); return err; } -- 2.3.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/