diff options
Diffstat (limited to 'arch/x86/kernel/fpu/xstate.c')
| -rw-r--r-- | arch/x86/kernel/fpu/xstate.c | 287 |
1 files changed, 202 insertions, 85 deletions
diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index 32b153d38748..bda2e5eaca0e 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -54,13 +54,15 @@ static short xsave_cpuid_features[] __initdata = { }; /* - * Mask of xstate features supported by the CPU and the kernel: + * This represents the full set of bits that should ever be set in a kernel + * XSAVE buffer, both supervisor and user xstates. */ -u64 xfeatures_mask __read_mostly; +u64 xfeatures_mask_all __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[XFEATURE_MAX] = { [ 0 ... XFEATURE_MAX - 1] = -1}; +static unsigned int xstate_supervisor_only_offsets[XFEATURE_MAX] = { [ 0 ... XFEATURE_MAX - 1] = -1}; /* * The XSAVE area of kernel can be in standard or compacted format; @@ -76,7 +78,7 @@ 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_all; if (unlikely(feature_name)) { long xfeature_idx, max_idx; @@ -150,7 +152,7 @@ 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_all) == xfeatures_mask_all) return; /* @@ -177,7 +179,7 @@ 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 @@ -205,30 +207,39 @@ void fpstate_sanitize_xstate(struct fpu *fpu) */ void fpu__init_cpu_xstate(void) { - if (!boot_cpu_has(X86_FEATURE_XSAVE) || !xfeatures_mask) + u64 unsup_bits; + + if (!boot_cpu_has(X86_FEATURE_XSAVE) || !xfeatures_mask_all) 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. + * Unsupported supervisor xstates should not be found in + * the xfeatures mask. */ - WARN_ONCE((xfeatures_mask & XFEATURE_MASK_SUPERVISOR), - "x86/fpu: XSAVES supervisor states are not yet implemented.\n"); + unsup_bits = xfeatures_mask_all & XFEATURE_MASK_SUPERVISOR_UNSUPPORTED; + WARN_ONCE(unsup_bits, "x86/fpu: Found unsupported supervisor xstates: 0x%llx\n", + unsup_bits); - xfeatures_mask &= ~XFEATURE_MASK_SUPERVISOR; + xfeatures_mask_all &= ~XFEATURE_MASK_SUPERVISOR_UNSUPPORTED; cr4_set_bits(X86_CR4_OSXSAVE); - xsetbv(XCR_XFEATURE_ENABLED_MASK, xfeatures_mask); + + /* + * XCR_XFEATURE_ENABLED_MASK (aka. XCR0) sets user features + * managed by XSAVE{C, OPT, S} and XRSTOR{S}. Only XSAVE user + * states can be set here. + */ + xsetbv(XCR_XFEATURE_ENABLED_MASK, xfeatures_mask_user()); + + /* + * MSR_IA32_XSS sets supervisor states managed by XSAVES. + */ + if (boot_cpu_has(X86_FEATURE_XSAVES)) + wrmsrl(MSR_IA32_XSS, xfeatures_mask_supervisor()); } -/* - * Note that in the future we will likely need a pair of - * functions here: one for user xstates and the other for - * system xstates. For now, they are the same. - */ -static int xfeature_enabled(enum xfeature xfeature) +static bool xfeature_enabled(enum xfeature xfeature) { - return !!(xfeatures_mask & (1UL << xfeature)); + return xfeatures_mask_all & BIT_ULL(xfeature); } /* @@ -383,6 +394,33 @@ static void __init setup_xstate_comp_offsets(void) } /* + * Setup offsets of a supervisor-state-only XSAVES buffer: + * + * The offsets stored in xstate_comp_offsets[] only work for one specific + * value of the Requested Feature BitMap (RFBM). In cases where a different + * RFBM value is used, a different set of offsets is required. This set of + * offsets is for when RFBM=xfeatures_mask_supervisor(). + */ +static void __init setup_supervisor_only_offsets(void) +{ + unsigned int next_offset; + int i; + + next_offset = FXSAVE_SIZE + XSAVE_HDR_SIZE; + + for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) { + if (!xfeature_enabled(i) || !xfeature_is_supervisor(i)) + continue; + + if (xfeature_is_aligned(i)) + next_offset = ALIGN(next_offset, 64); + + xstate_supervisor_only_offsets[i] = next_offset; + next_offset += xstate_sizes[i]; + } +} + +/* * Print out xstate component offsets and sizes */ static void __init print_xstate_offset_size(void) @@ -415,7 +453,7 @@ static void __init setup_init_fpu_buf(void) if (boot_cpu_has(X86_FEATURE_XSAVES)) init_fpstate.xsave.header.xcomp_bv = XCOMP_BV_COMPACTED_FORMAT | - xfeatures_mask; + xfeatures_mask_all; /* * Init all the features state with header.xfeatures being 0x0 @@ -438,7 +476,7 @@ static int xfeature_uncompacted_offset(int xfeature_nr) * format. Checking a supervisor state's uncompacted offset is * an error. */ - if (XFEATURE_MASK_SUPERVISOR & BIT_ULL(xfeature_nr)) { + if (XFEATURE_MASK_SUPERVISOR_ALL & BIT_ULL(xfeature_nr)) { WARN_ONCE(1, "No fixed offset for xstate %d\n", xfeature_nr); return -1; } @@ -472,10 +510,10 @@ int using_compacted_format(void) } /* Validate an xstate header supplied by userspace (ptrace or sigreturn) */ -int validate_xstate_header(const struct xstate_header *hdr) +int validate_user_xstate_header(const struct xstate_header *hdr) { /* No unknown or supervisor features may be set */ - if (hdr->xfeatures & (~xfeatures_mask | XFEATURE_MASK_SUPERVISOR)) + if (hdr->xfeatures & ~xfeatures_mask_user()) return -EINVAL; /* Userspace must use the uncompacted format */ @@ -610,15 +648,12 @@ 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 | IA32_XSS. * * 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 * that we use 'XSAVES' on, we could potentially overflow the * buffer because 'XSAVES' saves system states too. - * - * Note that we do not currently set any bits on IA32_XSS so - * 'XCR0 | IA32_XSS == XCR0' for now. */ static unsigned int __init get_xsaves_size(void) { @@ -700,7 +735,7 @@ static int __init init_xstate_size(void) */ static void fpu__init_disable_system_xstate(void) { - xfeatures_mask = 0; + xfeatures_mask_all = 0; cr4_clear_bits(X86_CR4_OSXSAVE); setup_clear_cpu_cap(X86_FEATURE_XSAVE); } @@ -735,16 +770,26 @@ void __init fpu__init_system_xstate(void) return; } + /* + * Find user xstates supported by the processor. + */ cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx); - xfeatures_mask = eax + ((u64)edx << 32); + xfeatures_mask_all = eax + ((u64)edx << 32); - if ((xfeatures_mask & XFEATURE_MASK_FPSSE) != XFEATURE_MASK_FPSSE) { + /* + * Find supervisor xstates supported by the processor. + */ + cpuid_count(XSTATE_CPUID, 1, &eax, &ebx, &ecx, &edx); + xfeatures_mask_all |= ecx + ((u64)edx << 32); + + 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_all); goto out_disable; } @@ -753,10 +798,10 @@ 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_all &= ~BIT_ULL(i); } - xfeatures_mask &= fpu__get_supported_xfeatures_mask(); + xfeatures_mask_all &= fpu__get_supported_xfeatures_mask(); /* Enable xstate instructions to be able to continue with initialization: */ fpu__init_cpu_xstate(); @@ -768,15 +813,16 @@ void __init fpu__init_system_xstate(void) * Update info used for ptrace frames; use standard-format size and no * supervisor 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()); fpu__init_prepare_fx_sw_frame(); setup_init_fpu_buf(); setup_xstate_comp_offsets(); + setup_supervisor_only_offsets(); 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_all, fpu_kernel_xstate_size, boot_cpu_has(X86_FEATURE_XSAVES) ? "compacted" : "standard"); return; @@ -795,7 +841,14 @@ 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()); + + /* + * Restore IA32_XSS. The same CPUID bit enumerates support + * of XSAVES and MSR_IA32_XSS. + */ + if (boot_cpu_has(X86_FEATURE_XSAVES)) + wrmsrl(MSR_IA32_XSS, xfeatures_mask_supervisor()); } /* @@ -840,10 +893,9 @@ void *get_xsave_addr(struct xregs_state *xsave, int xfeature_nr) /* * We should not ever be requesting features that we - * have not enabled. Remember that xfeatures_mask is - * what we write to the XCR0 register. + * have not enabled. */ - WARN_ONCE(!(xfeatures_mask & BIT_ULL(xfeature_nr)), + WARN_ONCE(!(xfeatures_mask_all & BIT_ULL(xfeature_nr)), "get of unsupported state"); /* * This assumes the last 'xsave*' instruction to @@ -957,18 +1009,31 @@ static inline bool xfeatures_mxcsr_quirk(u64 xfeatures) return true; } -/* - * This is similar to user_regset_copyout(), but will not add offset to - * the source data pointer or increment pos, count, kbuf, and ubuf. - */ -static inline void -__copy_xstate_to_kernel(void *kbuf, const void *data, - unsigned int offset, unsigned int size, unsigned int size_total) +static void fill_gap(unsigned to, void **kbuf, unsigned *pos, unsigned *count) { - if (offset < size_total) { - unsigned int copy = min(size, size_total - offset); + if (*pos < to) { + unsigned size = to - *pos; + + if (size > *count) + size = *count; + memcpy(*kbuf, (void *)&init_fpstate.xsave + *pos, size); + *kbuf += size; + *pos += size; + *count -= size; + } +} - memcpy(kbuf + offset, data, copy); +static void copy_part(unsigned offset, unsigned size, void *from, + void **kbuf, unsigned *pos, unsigned *count) +{ + fill_gap(offset, kbuf, pos, count); + if (size > *count) + size = *count; + if (size) { + memcpy(*kbuf, from, size); + *kbuf += size; + *pos += size; + *count -= size; } } @@ -981,8 +1046,9 @@ __copy_xstate_to_kernel(void *kbuf, const void *data, */ int copy_xstate_to_kernel(void *kbuf, struct xregs_state *xsave, unsigned int offset_start, unsigned int size_total) { - unsigned int offset, size; struct xstate_header header; + const unsigned off_mxcsr = offsetof(struct fxregs_state, mxcsr); + unsigned count = size_total; int i; /* @@ -996,48 +1062,44 @@ int copy_xstate_to_kernel(void *kbuf, struct xregs_state *xsave, unsigned int of */ memset(&header, 0, sizeof(header)); header.xfeatures = xsave->header.xfeatures; - header.xfeatures &= ~XFEATURE_MASK_SUPERVISOR; - + header.xfeatures &= xfeatures_mask_user(); + + if (header.xfeatures & XFEATURE_MASK_FP) + copy_part(0, off_mxcsr, + &xsave->i387, &kbuf, &offset_start, &count); + if (header.xfeatures & (XFEATURE_MASK_SSE | XFEATURE_MASK_YMM)) + copy_part(off_mxcsr, MXCSR_AND_FLAGS_SIZE, + &xsave->i387.mxcsr, &kbuf, &offset_start, &count); + if (header.xfeatures & XFEATURE_MASK_FP) + copy_part(offsetof(struct fxregs_state, st_space), 128, + &xsave->i387.st_space, &kbuf, &offset_start, &count); + if (header.xfeatures & XFEATURE_MASK_SSE) + copy_part(xstate_offsets[XFEATURE_MASK_SSE], 256, + &xsave->i387.xmm_space, &kbuf, &offset_start, &count); + /* + * Fill xsave->i387.sw_reserved value for ptrace frame: + */ + copy_part(offsetof(struct fxregs_state, sw_reserved), 48, + xstate_fx_sw_bytes, &kbuf, &offset_start, &count); /* * Copy xregs_state->header: */ - offset = offsetof(struct xregs_state, header); - size = sizeof(header); + copy_part(offsetof(struct xregs_state, header), sizeof(header), + &header, &kbuf, &offset_start, &count); - __copy_xstate_to_kernel(kbuf, &header, offset, size, size_total); - - for (i = 0; i < XFEATURE_MAX; i++) { + for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) { /* * Copy only in-use xstates: */ if ((header.xfeatures >> i) & 1) { void *src = __raw_xsave_addr(xsave, i); - offset = xstate_offsets[i]; - size = xstate_sizes[i]; - - /* The next component has to fit fully into the output buffer: */ - if (offset + size > size_total) - break; - - __copy_xstate_to_kernel(kbuf, src, offset, size, size_total); + copy_part(xstate_offsets[i], xstate_sizes[i], + src, &kbuf, &offset_start, &count); } } - - if (xfeatures_mxcsr_quirk(header.xfeatures)) { - offset = offsetof(struct fxregs_state, mxcsr); - size = MXCSR_AND_FLAGS_SIZE; - __copy_xstate_to_kernel(kbuf, &xsave->i387.mxcsr, offset, size, size_total); - } - - /* - * Fill xsave->i387.sw_reserved value for ptrace frame: - */ - offset = offsetof(struct fxregs_state, sw_reserved); - size = sizeof(xstate_fx_sw_bytes); - - __copy_xstate_to_kernel(kbuf, xstate_fx_sw_bytes, offset, size, size_total); + fill_gap(size_total, &kbuf, &offset_start, &count); return 0; } @@ -1080,7 +1142,7 @@ int copy_xstate_to_user(void __user *ubuf, struct xregs_state *xsave, unsigned i */ memset(&header, 0, sizeof(header)); header.xfeatures = xsave->header.xfeatures; - header.xfeatures &= ~XFEATURE_MASK_SUPERVISOR; + header.xfeatures &= xfeatures_mask_user(); /* * Copy xregs_state->header: @@ -1147,7 +1209,7 @@ int copy_kernel_to_xstate(struct xregs_state *xsave, const void *kbuf) memcpy(&hdr, kbuf + offset, size); - if (validate_xstate_header(&hdr)) + if (validate_user_xstate_header(&hdr)) return -EINVAL; for (i = 0; i < XFEATURE_MAX; i++) { @@ -1173,7 +1235,7 @@ int copy_kernel_to_xstate(struct xregs_state *xsave, const void *kbuf) * The state that came in from userspace was user-state only. * Mask all the user states out of 'xfeatures': */ - xsave->header.xfeatures &= XFEATURE_MASK_SUPERVISOR; + xsave->header.xfeatures &= XFEATURE_MASK_SUPERVISOR_ALL; /* * Add back in the features that came in from userspace: @@ -1201,7 +1263,7 @@ int copy_user_to_xstate(struct xregs_state *xsave, const void __user *ubuf) if (__copy_from_user(&hdr, ubuf + offset, size)) return -EFAULT; - if (validate_xstate_header(&hdr)) + if (validate_user_xstate_header(&hdr)) return -EINVAL; for (i = 0; i < XFEATURE_MAX; i++) { @@ -1229,7 +1291,7 @@ int copy_user_to_xstate(struct xregs_state *xsave, const void __user *ubuf) * The state that came in from userspace was user-state only. * Mask all the user states out of 'xfeatures': */ - xsave->header.xfeatures &= XFEATURE_MASK_SUPERVISOR; + xsave->header.xfeatures &= XFEATURE_MASK_SUPERVISOR_ALL; /* * Add back in the features that came in from userspace: @@ -1239,6 +1301,61 @@ int copy_user_to_xstate(struct xregs_state *xsave, const void __user *ubuf) return 0; } +/* + * Save only supervisor states to the kernel buffer. This blows away all + * old states, and is intended to be used only in __fpu__restore_sig(), where + * user states are restored from the user buffer. + */ +void copy_supervisor_to_kernel(struct xregs_state *xstate) +{ + struct xstate_header *header; + u64 max_bit, min_bit; + u32 lmask, hmask; + int err, i; + + if (WARN_ON(!boot_cpu_has(X86_FEATURE_XSAVES))) + return; + + if (!xfeatures_mask_supervisor()) + return; + + max_bit = __fls(xfeatures_mask_supervisor()); + min_bit = __ffs(xfeatures_mask_supervisor()); + + lmask = xfeatures_mask_supervisor(); + hmask = xfeatures_mask_supervisor() >> 32; + XSTATE_OP(XSAVES, xstate, lmask, hmask, err); + + /* We should never fault when copying to a kernel buffer: */ + if (WARN_ON_FPU(err)) + return; + + /* + * At this point, the buffer has only supervisor states and must be + * converted back to normal kernel format. + */ + header = &xstate->header; + header->xcomp_bv |= xfeatures_mask_all; + + /* + * This only moves states up in the buffer. Start with + * the last state and move backwards so that states are + * not overwritten until after they are moved. Note: + * memmove() allows overlapping src/dst buffers. + */ + for (i = max_bit; i >= min_bit; i--) { + u8 *xbuf = (u8 *)xstate; + + if (!((header->xfeatures >> i) & 1)) + continue; + + /* Move xfeature 'i' into its normal location */ + memmove(xbuf + xstate_comp_offsets[i], + xbuf + xstate_supervisor_only_offsets[i], + xstate_sizes[i]); + } +} + #ifdef CONFIG_PROC_PID_ARCH_STATUS /* * Report the amount of time elapsed in millisecond since last AVX512 |