From mboxrd@z Thu Jan 1 00:00:00 1970 From: Yu-cheng Yu Subject: [PATCH v8 03/27] x86/fpu/xstate: Change names to separate XSAVES system and user states Date: Tue, 13 Aug 2019 13:52:01 -0700 Message-ID: <20190813205225.12032-4-yu-cheng.yu@intel.com> References: <20190813205225.12032-1-yu-cheng.yu@intel.com> Return-path: In-Reply-To: <20190813205225.12032-1-yu-cheng.yu@intel.com> Sender: linux-kernel-owner@vger.kernel.org To: x86@kernel.org, "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, Arnd Bergmann , Andy Lutomirski , Balbir Singh , Borislav Petkov , Cyrill Gorcunov , Dave Hansen , Eugene Syromiatnikov , Florian Weimer , "H.J. Lu" , Jann Horn , Jonathan Corbet , Kees Cook , Mike Kravetz , Nadav Amit Cc: Yu-cheng Yu List-Id: linux-api@vger.kernel.org Control-flow Enforcement (CET) MSR contents are XSAVES system states. To support CET, introduce XSAVES system states first. XSAVES is a "supervisor" instruction and, comparing to XSAVE, saves additional "supervisor" states that can be modified only from CPL 0. However, these states are per-task and not kernel's own. Rename "supervisor" states to "system" states to clearly separate them from "user" states. Signed-off-by: Yu-cheng Yu --- arch/x86/include/asm/fpu/internal.h | 4 +- arch/x86/include/asm/fpu/xstate.h | 20 +++---- arch/x86/kernel/fpu/init.c | 2 +- arch/x86/kernel/fpu/signal.c | 10 ++-- arch/x86/kernel/fpu/xstate.c | 86 ++++++++++++++--------------- 5 files changed, 60 insertions(+), 62 deletions(-) diff --git a/arch/x86/include/asm/fpu/internal.h b/arch/x86/include/asm/fpu/internal.h index 4c95c365058a..652be3853b40 100644 --- a/arch/x86/include/asm/fpu/internal.h +++ b/arch/x86/include/asm/fpu/internal.h @@ -92,7 +92,7 @@ static inline void fpstate_init_xstate(struct xregs_state *xsave) * XRSTORS requires these bits set in xcomp_bv, or it will * trigger #GP: */ - xsave->header.xcomp_bv = XCOMP_BV_COMPACTED_FORMAT | xfeatures_mask; + xsave->header.xcomp_bv = XCOMP_BV_COMPACTED_FORMAT | xfeatures_mask_user; } static inline void fpstate_init_fxstate(struct fxregs_state *fx) @@ -225,7 +225,7 @@ static inline void copy_fxregs_to_kernel(struct fpu *fpu) /* * If XSAVES is enabled, it replaces XSAVEOPT because it supports a compact - * format and supervisor states in addition to modified optimization in + * format and system states in addition to modified optimization in * XSAVEOPT. * * Otherwise, if XSAVEOPT is enabled, XSAVEOPT replaces XSAVE because XSAVEOPT diff --git a/arch/x86/include/asm/fpu/xstate.h b/arch/x86/include/asm/fpu/xstate.h index c6136d79f8c0..9ded9532257d 100644 --- a/arch/x86/include/asm/fpu/xstate.h +++ b/arch/x86/include/asm/fpu/xstate.h @@ -25,15 +25,15 @@ #define XFEATURE_MASK_SUPERVISOR (XFEATURE_MASK_PT) /* All currently supported features */ -#define XCNTXT_MASK (XFEATURE_MASK_FP | \ - XFEATURE_MASK_SSE | \ - XFEATURE_MASK_YMM | \ - XFEATURE_MASK_OPMASK | \ - XFEATURE_MASK_ZMM_Hi256 | \ - XFEATURE_MASK_Hi16_ZMM | \ - XFEATURE_MASK_PKRU | \ - XFEATURE_MASK_BNDREGS | \ - XFEATURE_MASK_BNDCSR) +#define SUPPORTED_XFEATURES_MASK (XFEATURE_MASK_FP | \ + XFEATURE_MASK_SSE | \ + XFEATURE_MASK_YMM | \ + XFEATURE_MASK_OPMASK | \ + XFEATURE_MASK_ZMM_Hi256 | \ + XFEATURE_MASK_Hi16_ZMM | \ + XFEATURE_MASK_PKRU | \ + XFEATURE_MASK_BNDREGS | \ + XFEATURE_MASK_BNDCSR) #ifdef CONFIG_X86_64 #define REX_PREFIX "0x48, " @@ -41,7 +41,7 @@ #define REX_PREFIX #endif -extern u64 xfeatures_mask; +extern u64 xfeatures_mask_user; extern u64 xstate_fx_sw_bytes[USER_XSTATE_FX_SW_WORDS]; extern void __init update_regset_xstate_info(unsigned int size, diff --git a/arch/x86/kernel/fpu/init.c b/arch/x86/kernel/fpu/init.c index 6ce7e0a23268..73fed33e5bda 100644 --- a/arch/x86/kernel/fpu/init.c +++ b/arch/x86/kernel/fpu/init.c @@ -224,7 +224,7 @@ static void __init fpu__init_system_xstate_size_legacy(void) */ u64 __init fpu__get_supported_xfeatures_mask(void) { - return XCNTXT_MASK; + return SUPPORTED_XFEATURES_MASK; } /* Legacy code to initialize eager fpu mode. */ diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c index 0071b794ed19..8a63f07cf400 100644 --- a/arch/x86/kernel/fpu/signal.c +++ b/arch/x86/kernel/fpu/signal.c @@ -254,11 +254,11 @@ static int copy_user_to_fpregs_zeroing(void __user *buf, u64 xbv, int fx_only) { if (use_xsave()) { if (fx_only) { - u64 init_bv = xfeatures_mask & ~XFEATURE_MASK_FPSSE; + u64 init_bv = xfeatures_mask_user & ~XFEATURE_MASK_FPSSE; copy_kernel_to_xregs(&init_fpstate.xsave, init_bv); return copy_user_to_fxregs(buf); } else { - u64 init_bv = xfeatures_mask & ~xbv; + u64 init_bv = xfeatures_mask_user & ~xbv; if (unlikely(init_bv)) copy_kernel_to_xregs(&init_fpstate.xsave, init_bv); return copy_user_to_xregs(buf, xbv); @@ -357,7 +357,7 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size) if (use_xsave() && !fx_only) { - u64 init_bv = xfeatures_mask & ~xfeatures; + u64 init_bv = xfeatures_mask_user & ~xfeatures; if (using_compacted_format()) { ret = copy_user_to_xstate(&fpu->state.xsave, buf_fx); @@ -388,7 +388,7 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size) fpregs_lock(); if (use_xsave()) { - u64 init_bv = xfeatures_mask & ~XFEATURE_MASK_FPSSE; + u64 init_bv = xfeatures_mask_user & ~XFEATURE_MASK_FPSSE; copy_kernel_to_xregs(&init_fpstate.xsave, init_bv); } @@ -462,7 +462,7 @@ void fpu__init_prepare_fx_sw_frame(void) fx_sw_reserved.magic1 = FP_XSTATE_MAGIC1; fx_sw_reserved.extended_size = size; - fx_sw_reserved.xfeatures = xfeatures_mask; + fx_sw_reserved.xfeatures = xfeatures_mask_user; fx_sw_reserved.xstate_size = fpu_user_xstate_size; if (IS_ENABLED(CONFIG_IA32_EMULATION) || diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index e5cb67d67c03..d560e8861a3c 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -54,13 +54,16 @@ static short xsave_cpuid_features[] __initdata = { }; /* - * Mask of xstate features supported by the CPU and the kernel: + * XSAVES system states can only be modified from CPL 0 and saved by + * XSAVES. The rest are user states. The following is a mask of + * supported user state features derived from boot_cpu_has() and + * SUPPORTED_XFEATURES_MASK. */ -u64 xfeatures_mask __read_mostly; +u64 xfeatures_mask_user __read_mostly; static unsigned int xstate_offsets[XFEATURE_MAX] = { [ 0 ... XFEATURE_MAX - 1] = -1}; static unsigned int xstate_sizes[XFEATURE_MAX] = { [ 0 ... XFEATURE_MAX - 1] = -1}; -static unsigned int xstate_comp_offsets[sizeof(xfeatures_mask)*8]; +static unsigned int xstate_comp_offsets[sizeof(xfeatures_mask_user)*8]; /* * The XSAVE area of kernel can be in standard or compacted format; @@ -76,7 +79,7 @@ unsigned int fpu_user_xstate_size; */ int cpu_has_xfeatures(u64 xfeatures_needed, const char **feature_name) { - u64 xfeatures_missing = xfeatures_needed & ~xfeatures_mask; + u64 xfeatures_missing = xfeatures_needed & ~xfeatures_mask_user; if (unlikely(feature_name)) { long xfeature_idx, max_idx; @@ -107,15 +110,12 @@ int cpu_has_xfeatures(u64 xfeatures_needed, const char **feature_name) } EXPORT_SYMBOL_GPL(cpu_has_xfeatures); -static int xfeature_is_supervisor(int xfeature_nr) +static int xfeature_is_system(int xfeature_nr) { /* - * We currently do not support supervisor states, but if - * we did, we could find out like this. - * * SDM says: If state component 'i' is a user state component, - * ECX[0] return 0; if state component i is a supervisor - * state component, ECX[0] returns 1. + * ECX[0] is 0; if state component i is a system state component, + * ECX[0] is 1. */ u32 eax, ebx, ecx, edx; @@ -125,7 +125,7 @@ static int xfeature_is_supervisor(int xfeature_nr) static int xfeature_is_user(int xfeature_nr) { - return !xfeature_is_supervisor(xfeature_nr); + return !xfeature_is_system(xfeature_nr); } /* @@ -158,7 +158,7 @@ void fpstate_sanitize_xstate(struct fpu *fpu) * None of the feature bits are in init state. So nothing else * to do for us, as the memory layout is up to date. */ - if ((xfeatures & xfeatures_mask) == xfeatures_mask) + if ((xfeatures & xfeatures_mask_user) == xfeatures_mask_user) return; /* @@ -185,7 +185,7 @@ void fpstate_sanitize_xstate(struct fpu *fpu) * in a special way already: */ feature_bit = 0x2; - xfeatures = (xfeatures_mask & ~xfeatures) >> 2; + xfeatures = (xfeatures_mask_user & ~xfeatures) >> 2; /* * Update all the remaining memory layouts according to their @@ -213,20 +213,18 @@ void fpstate_sanitize_xstate(struct fpu *fpu) */ void fpu__init_cpu_xstate(void) { - if (!boot_cpu_has(X86_FEATURE_XSAVE) || !xfeatures_mask) + if (!boot_cpu_has(X86_FEATURE_XSAVE) || !xfeatures_mask_user) return; /* - * Make it clear that XSAVES supervisor states are not yet - * implemented should anyone expect it to work by changing - * bits in XFEATURE_MASK_* macros and XCR0. + * XCR_XFEATURE_ENABLED_MASK sets the features that are managed + * by XSAVE{C, OPT} and XRSTOR. Only XSAVE user states can be + * set here. */ - WARN_ONCE((xfeatures_mask & XFEATURE_MASK_SUPERVISOR), - "x86/fpu: XSAVES supervisor states are not yet implemented.\n"); - xfeatures_mask &= ~XFEATURE_MASK_SUPERVISOR; + xfeatures_mask_user &= ~XFEATURE_MASK_SUPERVISOR; cr4_set_bits(X86_CR4_OSXSAVE); - xsetbv(XCR_XFEATURE_ENABLED_MASK, xfeatures_mask); + xsetbv(XCR_XFEATURE_ENABLED_MASK, xfeatures_mask_user); } /* @@ -236,7 +234,7 @@ void fpu__init_cpu_xstate(void) */ static int xfeature_enabled(enum xfeature xfeature) { - return !!(xfeatures_mask & (1UL << xfeature)); + return !!(xfeatures_mask_user & BIT_ULL(xfeature)); } /* @@ -266,7 +264,7 @@ static void __init setup_xstate_features(void) cpuid_count(XSTATE_CPUID, i, &eax, &ebx, &ecx, &edx); /* - * If an xfeature is supervisor state, the offset + * If an xfeature is a system state, the offset * in EBX is invalid. We leave it to -1. */ if (xfeature_is_user(i)) @@ -342,7 +340,7 @@ static int xfeature_is_aligned(int xfeature_nr) */ static void __init setup_xstate_comp(void) { - unsigned int xstate_comp_sizes[sizeof(xfeatures_mask)*8]; + unsigned int xstate_comp_sizes[sizeof(xfeatures_mask_user)*8]; int i; /* @@ -415,7 +413,7 @@ static void __init setup_init_fpu_buf(void) print_xstate_features(); if (boot_cpu_has(X86_FEATURE_XSAVES)) - init_fpstate.xsave.header.xcomp_bv = (u64)1 << 63 | xfeatures_mask; + init_fpstate.xsave.header.xcomp_bv = BIT_ULL(63) | xfeatures_mask_user; /* * Init all the features state with header.xfeatures being 0x0 @@ -434,8 +432,8 @@ static int xfeature_uncompacted_offset(int xfeature_nr) u32 eax, ebx, ecx, edx; /* - * Only XSAVES supports supervisor states and it uses compacted - * format. Checking a supervisor state's uncompacted offset is + * Only XSAVES supports system states and it uses compacted + * format. Checking a system state's uncompacted offset is * an error. */ if (XFEATURE_MASK_SUPERVISOR & BIT_ULL(xfeature_nr)) { @@ -459,7 +457,7 @@ static int xfeature_size(int xfeature_nr) /* * 'XSAVES' implies two different things: - * 1. saving of supervisor/system state + * 1. saving of system state * 2. using the compacted format * * Use this function when dealing with the compacted format so @@ -474,8 +472,8 @@ int using_compacted_format(void) /* Validate an xstate header supplied by userspace (ptrace or sigreturn) */ int validate_xstate_header(const struct xstate_header *hdr) { - /* No unknown or supervisor features may be set */ - if (hdr->xfeatures & (~xfeatures_mask | XFEATURE_MASK_SUPERVISOR)) + /* No unknown or system features may be set */ + if (hdr->xfeatures & ~xfeatures_mask_user) return -EINVAL; /* Userspace must use the uncompacted format */ @@ -582,11 +580,11 @@ static void do_extra_xstate_size_checks(void) check_xstate_against_struct(i); /* - * Supervisor state components can be managed only by + * System state components can be managed only by * XSAVES, which is compacted-format only. */ if (!using_compacted_format()) - XSTATE_WARN_ON(xfeature_is_supervisor(i)); + XSTATE_WARN_ON(xfeature_is_system(i)); /* Align from the end of the previous feature */ if (xfeature_is_aligned(i)) @@ -610,7 +608,7 @@ static void do_extra_xstate_size_checks(void) /* - * Get total size of enabled xstates in XCR0/xfeatures_mask. + * Get total size of enabled xstates in XCR0/xfeatures_mask_user. * * 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 @@ -700,7 +698,7 @@ static int __init init_xstate_size(void) */ static void fpu__init_disable_system_xstate(void) { - xfeatures_mask = 0; + xfeatures_mask_user = 0; cr4_clear_bits(X86_CR4_OSXSAVE); setup_clear_cpu_cap(X86_FEATURE_XSAVE); } @@ -736,15 +734,15 @@ void __init fpu__init_system_xstate(void) } cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx); - xfeatures_mask = eax + ((u64)edx << 32); + xfeatures_mask_user = eax + ((u64)edx << 32); - if ((xfeatures_mask & XFEATURE_MASK_FPSSE) != XFEATURE_MASK_FPSSE) { + if ((xfeatures_mask_user & XFEATURE_MASK_FPSSE) != XFEATURE_MASK_FPSSE) { /* * This indicates that something really unexpected happened * with the enumeration. Disable XSAVE and try to continue * booting without it. This is too early to BUG(). */ - pr_err("x86/fpu: FP/SSE not present amongst the CPU's xstate features: 0x%llx.\n", xfeatures_mask); + pr_err("x86/fpu: FP/SSE not present amongst the CPU's xstate features: 0x%llx.\n", xfeatures_mask_user); goto out_disable; } @@ -753,10 +751,10 @@ void __init fpu__init_system_xstate(void) */ for (i = 0; i < ARRAY_SIZE(xsave_cpuid_features); i++) { if (!boot_cpu_has(xsave_cpuid_features[i])) - xfeatures_mask &= ~BIT(i); + xfeatures_mask_user &= ~BIT_ULL(i); } - xfeatures_mask &= fpu__get_supported_xfeatures_mask(); + xfeatures_mask_user &= fpu__get_supported_xfeatures_mask(); /* Enable xstate instructions to be able to continue with initialization: */ fpu__init_cpu_xstate(); @@ -766,9 +764,9 @@ void __init fpu__init_system_xstate(void) /* * Update info used for ptrace frames; use standard-format size and no - * supervisor xstates: + * system xstates: */ - update_regset_xstate_info(fpu_user_xstate_size, xfeatures_mask & ~XFEATURE_MASK_SUPERVISOR); + update_regset_xstate_info(fpu_user_xstate_size, xfeatures_mask_user & ~XFEATURE_MASK_SUPERVISOR); fpu__init_prepare_fx_sw_frame(); setup_init_fpu_buf(); @@ -776,7 +774,7 @@ void __init fpu__init_system_xstate(void) print_xstate_offset_size(); pr_info("x86/fpu: Enabled xstate features 0x%llx, context size is %d bytes, using '%s' format.\n", - xfeatures_mask, + xfeatures_mask_user, fpu_kernel_xstate_size, boot_cpu_has(X86_FEATURE_XSAVES) ? "compacted" : "standard"); return; @@ -795,7 +793,7 @@ void fpu__resume_cpu(void) * Restore XCR0 on xsave capable CPUs: */ if (boot_cpu_has(X86_FEATURE_XSAVE)) - xsetbv(XCR_XFEATURE_ENABLED_MASK, xfeatures_mask); + xsetbv(XCR_XFEATURE_ENABLED_MASK, xfeatures_mask_user); } /* @@ -843,7 +841,7 @@ void *get_xsave_addr(struct xregs_state *xsave, int xfeature_nr) * have not enabled. Remember that pcntxt_mask is * what we write to the XCR0 register. */ - WARN_ONCE(!(xfeatures_mask & BIT_ULL(xfeature_nr)), + WARN_ONCE(!(xfeatures_mask_user & BIT_ULL(xfeature_nr)), "get of unsupported state"); /* * This assumes the last 'xsave*' instruction to -- 2.17.1