From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753400AbcEJXgy (ORCPT ); Tue, 10 May 2016 19:36:54 -0400 Received: from mga03.intel.com ([134.134.136.65]:54247 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753189AbcEJXeu (ORCPT ); Tue, 10 May 2016 19:34:50 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.24,606,1455004800"; d="scan'208";a="100873243" From: Yu-cheng Yu To: linux-kernel@vger.kernel.org, x86@kernel.org, "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar Cc: Dave Hansen , Andy Lutomirski , Borislav Petkov , Sai Praneeth Prakhya , "Ravi V. Shankar" , Fenghua Yu , Yu-cheng Yu Subject: [PATCH v6 01/13] x86/xsaves: Define and use fpu_user_xstate_size Date: Tue, 10 May 2016 16:29:53 -0700 Message-Id: X-Mailer: git-send-email 1.9.1 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The XSAVE area of kernel can be in standard or compacted format; it is always in standard format for user mode. When XSAVES is enabled, the kernel uses the compacted format and it is necessary to use a separate fpu_user_xstate_size for signal/ptrace frames. Based on an earlier patch from Fenghua Yu Signed-off-by: Fenghua Yu [yu-cheng.yu@intel.com: rebase to current, rename to fpu_user_xstate_size] Signed-off-by: Yu-cheng Yu Reviewed-by: Dave Hansen --- arch/x86/include/asm/fpu/xstate.h | 1 - arch/x86/include/asm/processor.h | 1 + arch/x86/kernel/fpu/init.c | 5 ++- arch/x86/kernel/fpu/signal.c | 27 ++++++++++---- arch/x86/kernel/fpu/xstate.c | 76 ++++++++++++++++++++++++--------------- 5 files changed, 73 insertions(+), 37 deletions(-) diff --git a/arch/x86/include/asm/fpu/xstate.h b/arch/x86/include/asm/fpu/xstate.h index 38951b0..16df2c4 100644 --- a/arch/x86/include/asm/fpu/xstate.h +++ b/arch/x86/include/asm/fpu/xstate.h @@ -39,7 +39,6 @@ #define REX_PREFIX #endif -extern unsigned int xstate_size; extern u64 xfeatures_mask; extern u64 xstate_fx_sw_bytes[USER_XSTATE_FX_SW_WORDS]; diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index 9264476..8d5df3f 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -368,6 +368,7 @@ DECLARE_PER_CPU(struct irq_stack *, softirq_stack); #endif /* X86_64 */ extern unsigned int xstate_size; +extern unsigned int fpu_user_xstate_size; struct perf_event; diff --git a/arch/x86/kernel/fpu/init.c b/arch/x86/kernel/fpu/init.c index 54c86ff..824d422 100644 --- a/arch/x86/kernel/fpu/init.c +++ b/arch/x86/kernel/fpu/init.c @@ -195,7 +195,7 @@ static void __init fpu__init_task_struct_size(void) } /* - * Set up the xstate_size based on the legacy FPU context size. + * Set up the user and kernel xstate_size based on the legacy FPU context size. * * We set this up first, and later it will be overwritten by * fpu__init_system_xstate() if the CPU knows about xstates. @@ -226,6 +226,9 @@ static void __init fpu__init_system_xstate_size_legacy(void) else xstate_size = sizeof(struct fregs_state); } + + fpu_user_xstate_size = xstate_size; + /* * Quirk: we don't yet handle the XSAVES* instructions * correctly, as we don't correctly convert between diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c index 31c6a60..23572a9 100644 --- a/arch/x86/kernel/fpu/signal.c +++ b/arch/x86/kernel/fpu/signal.c @@ -31,7 +31,7 @@ static inline int check_for_xstate(struct fxregs_state __user *buf, /* Check for the first magic field and other error scenarios. */ if (fx_sw->magic1 != FP_XSTATE_MAGIC1 || fx_sw->xstate_size < min_xstate_size || - fx_sw->xstate_size > xstate_size || + fx_sw->xstate_size > fpu_user_xstate_size || fx_sw->xstate_size > fx_sw->extended_size) return -1; @@ -88,7 +88,8 @@ static inline int save_xstate_epilog(void __user *buf, int ia32_frame) if (!use_xsave()) return err; - err |= __put_user(FP_XSTATE_MAGIC2, (__u32 *)(buf + xstate_size)); + err |= __put_user(FP_XSTATE_MAGIC2, + (__u32 *)(buf + fpu_user_xstate_size)); /* * Read the xfeatures which we copied (directly from the cpu or @@ -125,7 +126,7 @@ static inline int copy_fpregs_to_sigframe(struct xregs_state __user *buf) else err = copy_fregs_to_user((struct fregs_state __user *) buf); - if (unlikely(err) && __clear_user(buf, xstate_size)) + if (unlikely(err) && __clear_user(buf, fpu_user_xstate_size)) err = -EFAULT; return err; } @@ -175,8 +176,19 @@ int copy_fpstate_to_sigframe(void __user *buf, void __user *buf_fx, int size) if (ia32_fxstate) copy_fxregs_to_kernel(&tsk->thread.fpu); } else { + /* + * It is a *bug* if kernel uses compacted-format for xsave + * area and we copy it out directly to a signal frame. It + * should have been handled above by saving the registers + * directly. + */ + if (boot_cpu_has(X86_FEATURE_XSAVES)) { + WARN_ONCE(1, "x86/fpu: saving compacted-format xsave area to a signal frame!\n"); + return -1; + } + fpstate_sanitize_xstate(&tsk->thread.fpu); - if (__copy_to_user(buf_fx, xsave, xstate_size)) + if (__copy_to_user(buf_fx, xsave, fpu_user_xstate_size)) return -1; } @@ -341,7 +353,8 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size) static inline int xstate_sigframe_size(void) { - return use_xsave() ? xstate_size + FP_XSTATE_MAGIC2_SIZE : xstate_size; + return use_xsave() ? fpu_user_xstate_size + FP_XSTATE_MAGIC2_SIZE : + fpu_user_xstate_size; } /* @@ -385,12 +398,12 @@ fpu__alloc_mathframe(unsigned long sp, int ia32_frame, */ void fpu__init_prepare_fx_sw_frame(void) { - int size = xstate_size + FP_XSTATE_MAGIC2_SIZE; + int size = fpu_user_xstate_size + FP_XSTATE_MAGIC2_SIZE; fx_sw_reserved.magic1 = FP_XSTATE_MAGIC1; fx_sw_reserved.extended_size = size; fx_sw_reserved.xfeatures = xfeatures_mask; - fx_sw_reserved.xstate_size = xstate_size; + fx_sw_reserved.xstate_size = fpu_user_xstate_size; if (config_enabled(CONFIG_IA32_EMULATION) || config_enabled(CONFIG_X86_32)) { diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index b48ef35..dfac87d 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -44,6 +44,13 @@ static unsigned int xstate_sizes[XFEATURE_MAX] = { [ 0 ... XFEATURE_MAX - 1] = static unsigned int xstate_comp_offsets[sizeof(xfeatures_mask)*8]; /* + * The XSAVE area of kernel can be in standard or compacted format; + * it is always in standard format for user mode. This is the user + * mode standard format size used for signal and ptrace frames. + */ +unsigned int fpu_user_xstate_size; + +/* * Clear all of the X86_FEATURE_* bits that are unavailable * when the CPU has no XSAVE support. */ @@ -171,7 +178,7 @@ void fpstate_sanitize_xstate(struct fpu *fpu) */ while (xfeatures) { if (xfeatures & 0x1) { - int offset = xstate_offsets[feature_bit]; + int offset = xstate_comp_offsets[feature_bit]; int size = xstate_sizes[feature_bit]; memcpy((void *)fx + offset, @@ -533,8 +540,9 @@ static void do_extra_xstate_size_checks(void) XSTATE_WARN_ON(paranoid_xstate_size != xstate_size); } + /* - * Calculate total size of enabled xstates in XCR0/xfeatures_mask. + * Get total size of enabled xstates in XCR0/xfeatures_mask. * * Note the SDM's wording here. "sub-function 0" only enumerates * the size of the *user* states. If we use it to size a buffer @@ -544,34 +552,33 @@ static void do_extra_xstate_size_checks(void) * Note that we do not currently set any bits on IA32_XSS so * 'XCR0 | IA32_XSS == XCR0' for now. */ -static unsigned int __init calculate_xstate_size(void) +static unsigned int __init get_xsaves_size(void) { unsigned int eax, ebx, ecx, edx; - unsigned int calculated_xstate_size; + /* + * - CPUID function 0DH, sub-function 1: + * EBX enumerates the size (in bytes) required by + * the XSAVES instruction for an XSAVE area + * containing all the state components + * corresponding to bits currently set in + * XCR0 | IA32_XSS. + */ + cpuid_count(XSTATE_CPUID, 1, &eax, &ebx, &ecx, &edx); + return ebx; +} - if (!cpu_has_xsaves) { - /* - * - CPUID function 0DH, sub-function 0: - * EBX enumerates the size (in bytes) required by - * the XSAVE instruction for an XSAVE area - * containing all the *user* state components - * corresponding to bits currently set in XCR0. - */ - cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx); - calculated_xstate_size = ebx; - } else { - /* - * - CPUID function 0DH, sub-function 1: - * EBX enumerates the size (in bytes) required by - * the XSAVES instruction for an XSAVE area - * containing all the state components - * corresponding to bits currently set in - * XCR0 | IA32_XSS. - */ - cpuid_count(XSTATE_CPUID, 1, &eax, &ebx, &ecx, &edx); - calculated_xstate_size = ebx; - } - return calculated_xstate_size; +static unsigned int __init get_xsave_size(void) +{ + unsigned int eax, ebx, ecx, edx; + /* + * - CPUID function 0DH, sub-function 0: + * EBX enumerates the size (in bytes) required by + * the XSAVE instruction for an XSAVE area + * containing all the *user* state components + * corresponding to bits currently set in XCR0. + */ + cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx); + return ebx; } /* @@ -591,7 +598,15 @@ static bool is_supported_xstate_size(unsigned int test_xstate_size) static int init_xstate_size(void) { /* Recompute the context size for enabled features: */ - unsigned int possible_xstate_size = calculate_xstate_size(); + unsigned int possible_xstate_size; + unsigned int xsave_size; + + xsave_size = get_xsave_size(); + + if (cpu_has_xsaves) + possible_xstate_size = get_xsaves_size(); + else + possible_xstate_size = xsave_size; /* Ensure we have the space to store all enabled: */ if (!is_supported_xstate_size(possible_xstate_size)) @@ -603,6 +618,11 @@ static int init_xstate_size(void) */ xstate_size = possible_xstate_size; do_extra_xstate_size_checks(); + + /* + * User space is always in standard format. + */ + fpu_user_xstate_size = xsave_size; return 0; } -- 1.9.1