diff options
Diffstat (limited to 'arch')
-rw-r--r-- | arch/x86/include/asm/i387.h | 15 | ||||
-rw-r--r-- | arch/x86/include/asm/xsave.h | 24 | ||||
-rw-r--r-- | arch/x86/kernel/cpu/common.c | 16 | ||||
-rw-r--r-- | arch/x86/kernel/i387.c | 39 | ||||
-rw-r--r-- | arch/x86/kernel/xsave.c | 170 |
5 files changed, 222 insertions, 42 deletions
diff --git a/arch/x86/include/asm/i387.h b/arch/x86/include/asm/i387.h index f1accc6..a73a8d5 100644 --- a/arch/x86/include/asm/i387.h +++ b/arch/x86/include/asm/i387.h @@ -31,7 +31,6 @@ extern void mxcsr_feature_mask_init(void); extern int init_fpu(struct task_struct *child); extern asmlinkage void math_state_restore(void); extern void __math_state_restore(void); -extern void init_thread_xstate(void); extern int dump_fpu(struct pt_regs *, struct user_i387_struct *); extern user_regset_active_fn fpregs_active, xfpregs_active; @@ -58,11 +57,25 @@ extern int restore_i387_xstate_ia32(void __user *buf); #define X87_FSW_ES (1 << 7) /* Exception Summary */ +static __always_inline __pure bool use_xsaveopt(void) +{ + return static_cpu_has(X86_FEATURE_XSAVEOPT); +} + static __always_inline __pure bool use_xsave(void) { return static_cpu_has(X86_FEATURE_XSAVE); } +extern void __sanitize_i387_state(struct task_struct *); + +static inline void sanitize_i387_state(struct task_struct *tsk) +{ + if (!use_xsaveopt()) + return; + __sanitize_i387_state(tsk); +} + #ifdef CONFIG_X86_64 /* Ignore delayed exceptions from user space */ diff --git a/arch/x86/include/asm/xsave.h b/arch/x86/include/asm/xsave.h index 06acdbd..c6ce245 100644 --- a/arch/x86/include/asm/xsave.h +++ b/arch/x86/include/asm/xsave.h @@ -3,7 +3,8 @@ #include <linux/types.h> #include <asm/processor.h> -#include <asm/i387.h> + +#define XSTATE_CPUID 0x0000000d #define XSTATE_FP 0x1 #define XSTATE_SSE 0x2 @@ -32,10 +33,8 @@ extern unsigned int xstate_size; extern u64 pcntxt_mask; -extern struct xsave_struct *init_xstate_buf; extern u64 xstate_fx_sw_bytes[USER_XSTATE_FX_SW_WORDS]; -extern void xsave_cntxt_init(void); extern void xsave_init(void); extern void update_regset_xstate_info(unsigned int size, u64 xstate_mask); extern int init_fpu(struct task_struct *child); @@ -127,12 +126,25 @@ static inline void xrstor_state(struct xsave_struct *fx, u64 mask) : "memory"); } +static inline void xsave_state(struct xsave_struct *fx, u64 mask) +{ + u32 lmask = mask; + u32 hmask = mask >> 32; + + asm volatile(".byte " REX_PREFIX "0x0f,0xae,0x27\n\t" + : : "D" (fx), "m" (*fx), "a" (lmask), "d" (hmask) + : "memory"); +} + static inline void fpu_xsave(struct fpu *fpu) { /* This, however, we can work around by forcing the compiler to select an addressing mode that doesn't require extended registers. */ - __asm__ __volatile__(".byte " REX_PREFIX "0x0f,0xae,0x27" - : : "D" (&(fpu->state->xsave)), - "a" (-1), "d"(-1) : "memory"); + alternative_input( + ".byte " REX_PREFIX "0x0f,0xae,0x27", + ".byte " REX_PREFIX "0x0f,0xae,0x37", + X86_FEATURE_XSAVEOPT, + [fx] "D" (&fpu->state->xsave), "a" (-1), "d" (-1) : + "memory"); } #endif diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index f102731..490dac6 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -140,10 +140,18 @@ EXPORT_PER_CPU_SYMBOL_GPL(gdt_page); static int __init x86_xsave_setup(char *s) { setup_clear_cpu_cap(X86_FEATURE_XSAVE); + setup_clear_cpu_cap(X86_FEATURE_XSAVEOPT); return 1; } __setup("noxsave", x86_xsave_setup); +static int __init x86_xsaveopt_setup(char *s) +{ + setup_clear_cpu_cap(X86_FEATURE_XSAVEOPT); + return 1; +} +__setup("noxsaveopt", x86_xsaveopt_setup); + #ifdef CONFIG_X86_32 static int cachesize_override __cpuinitdata = -1; static int disable_x86_serial_nr __cpuinitdata = 1; @@ -1202,6 +1210,7 @@ void __cpuinit cpu_init(void) dbg_restore_debug_regs(); fpu_init(); + xsave_init(); raw_local_save_flags(kernel_eflags); @@ -1262,12 +1271,7 @@ void __cpuinit cpu_init(void) clear_used_math(); mxcsr_feature_mask_init(); - /* - * Boot processor to setup the FP and extended state context info. - */ - if (smp_processor_id() == boot_cpu_id) - init_thread_xstate(); - + fpu_init(); xsave_init(); } #endif diff --git a/arch/x86/kernel/i387.c b/arch/x86/kernel/i387.c index c4444bc..1f11f5c 100644 --- a/arch/x86/kernel/i387.c +++ b/arch/x86/kernel/i387.c @@ -59,18 +59,18 @@ void __cpuinit mxcsr_feature_mask_init(void) stts(); } -void __cpuinit init_thread_xstate(void) +static void __cpuinit init_thread_xstate(void) { + /* + * Note that xstate_size might be overwriten later during + * xsave_init(). + */ + if (!HAVE_HWFP) { xstate_size = sizeof(struct i387_soft_struct); return; } - if (cpu_has_xsave) { - xsave_cntxt_init(); - return; - } - if (cpu_has_fxsr) xstate_size = sizeof(struct i387_fxsave_struct); #ifdef CONFIG_X86_32 @@ -84,6 +84,7 @@ void __cpuinit init_thread_xstate(void) * Called at bootup to set up the initial FPU state that is later cloned * into all processes. */ + void __cpuinit fpu_init(void) { unsigned long oldcr0 = read_cr0(); @@ -93,19 +94,24 @@ void __cpuinit fpu_init(void) write_cr0(oldcr0 & ~(X86_CR0_TS|X86_CR0_EM)); /* clear TS and EM */ - /* - * Boot processor to setup the FP and extended state context info. - */ if (!smp_processor_id()) init_thread_xstate(); - xsave_init(); mxcsr_feature_mask_init(); /* clean state in init */ current_thread_info()->status = 0; clear_used_math(); } -#endif /* CONFIG_X86_64 */ + +#else /* CONFIG_X86_64 */ + +void __cpuinit fpu_init(void) +{ + if (!smp_processor_id()) + init_thread_xstate(); +} + +#endif /* CONFIG_X86_32 */ void fpu_finit(struct fpu *fpu) { @@ -191,6 +197,8 @@ int xfpregs_get(struct task_struct *target, const struct user_regset *regset, if (ret) return ret; + sanitize_i387_state(target); + return user_regset_copyout(&pos, &count, &kbuf, &ubuf, &target->thread.fpu.state->fxsave, 0, -1); } @@ -208,6 +216,8 @@ int xfpregs_set(struct task_struct *target, const struct user_regset *regset, if (ret) return ret; + sanitize_i387_state(target); + ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &target->thread.fpu.state->fxsave, 0, -1); @@ -447,6 +457,8 @@ int fpregs_get(struct task_struct *target, const struct user_regset *regset, -1); } + sanitize_i387_state(target); + if (kbuf && pos == 0 && count == sizeof(env)) { convert_from_fxsr(kbuf, target); return 0; @@ -468,6 +480,8 @@ int fpregs_set(struct task_struct *target, const struct user_regset *regset, if (ret) return ret; + sanitize_i387_state(target); + if (!HAVE_HWFP) return fpregs_soft_set(target, regset, pos, count, kbuf, ubuf); @@ -534,6 +548,9 @@ static int save_i387_xsave(void __user *buf) struct _fpstate_ia32 __user *fx = buf; int err = 0; + + sanitize_i387_state(tsk); + /* * For legacy compatible, we always set FP/SSE bits in the bit * vector while saving the state to the user context. diff --git a/arch/x86/kernel/xsave.c b/arch/x86/kernel/xsave.c index a4ae302..9c253bd 100644 --- a/arch/x86/kernel/xsave.c +++ b/arch/x86/kernel/xsave.c @@ -16,11 +16,88 @@ */ u64 pcntxt_mask; +/* + * Represents init state for the supported extended state. + */ +static struct xsave_struct *init_xstate_buf; + struct _fpx_sw_bytes fx_sw_reserved; #ifdef CONFIG_IA32_EMULATION struct _fpx_sw_bytes fx_sw_reserved_ia32; #endif +static unsigned int *xstate_offsets, *xstate_sizes, xstate_features; + +/* + * If a processor implementation discern that a processor state component is + * in its initialized state it may modify the corresponding bit in the + * xsave_hdr.xstate_bv as '0', with out modifying the corresponding memory + * layout in the case of xsaveopt. While presenting the xstate information to + * the user, we always ensure that the memory layout of a feature will be in + * the init state if the corresponding header bit is zero. This is to ensure + * that the user doesn't see some stale state in the memory layout during + * signal handling, debugging etc. + */ +void __sanitize_i387_state(struct task_struct *tsk) +{ + u64 xstate_bv; + int feature_bit = 0x2; + struct i387_fxsave_struct *fx = &tsk->thread.fpu.state->fxsave; + + if (!fx) + return; + + BUG_ON(task_thread_info(tsk)->status & TS_USEDFPU); + + xstate_bv = tsk->thread.fpu.state->xsave.xsave_hdr.xstate_bv; + + /* + * None of the feature bits are in init state. So nothing else + * to do for us, as the memory layout is upto date. + */ + if ((xstate_bv & pcntxt_mask) == pcntxt_mask) + return; + + /* + * FP is in init state + */ + if (!(xstate_bv & XSTATE_FP)) { + fx->cwd = 0x37f; + fx->swd = 0; + fx->twd = 0; + fx->fop = 0; + fx->rip = 0; + fx->rdp = 0; + memset(&fx->st_space[0], 0, 128); + } + + /* + * SSE is in init state + */ + if (!(xstate_bv & XSTATE_SSE)) + memset(&fx->xmm_space[0], 0, 256); + + xstate_bv = (pcntxt_mask & ~xstate_bv) >> 2; + + /* + * Update all the other memory layouts for which the corresponding + * header bit is in the init state. + */ + while (xstate_bv) { + if (xstate_bv & 0x1) { + int offset = xstate_offsets[feature_bit]; + int size = xstate_sizes[feature_bit]; + + memcpy(((void *) fx) + offset, + ((void *) init_xstate_buf) + offset, + size); + } + + xstate_bv >>= 1; + feature_bit++; + } +} + /* * Check for the presence of extended state information in the * user fpstate pointer in the sigcontext. @@ -102,6 +179,7 @@ int save_i387_xstate(void __user *buf) task_thread_info(tsk)->status &= ~TS_USEDFPU; stts(); } else { + sanitize_i387_state(tsk); if (__copy_to_user(buf, &tsk->thread.fpu.state->fxsave, xstate_size)) return -1; @@ -267,11 +345,6 @@ static void prepare_fx_sw_frame(void) #endif } -/* - * Represents init state for the supported extended state. - */ -struct xsave_struct *init_xstate_buf; - #ifdef CONFIG_X86_64 unsigned int sig_xstate_size = sizeof(struct _fpstate); #endif @@ -279,37 +352,77 @@ unsigned int sig_xstate_size = sizeof(struct _fpstate); /* * Enable the extended processor state save/restore feature */ -void __cpuinit xsave_init(void) +static inline void xstate_enable(void) { - if (!cpu_has_xsave) - return; - set_in_cr4(X86_CR4_OSXSAVE); - - /* - * Enable all the features that the HW is capable of - * and the Linux kernel is aware of. - */ xsetbv(XCR_XFEATURE_ENABLED_MASK, pcntxt_mask); } /* + * Record the offsets and sizes of different state managed by the xsave + * memory layout. + */ +static void __init setup_xstate_features(void) +{ + int eax, ebx, ecx, edx, leaf = 0x2; + + xstate_features = fls64(pcntxt_mask); + xstate_offsets = alloc_bootmem(xstate_features * sizeof(int)); + xstate_sizes = alloc_bootmem(xstate_features * sizeof(int)); + + do { + cpuid_count(XSTATE_CPUID, leaf, &eax, &ebx, &ecx, &edx); + + if (eax == 0) + break; + + xstate_offsets[leaf] = ebx; + xstate_sizes[leaf] = eax; + + leaf++; + } while (1); +} + +/* * setup the xstate image representing the init state */ static void __init setup_xstate_init(void) { + setup_xstate_features(); + + /* + * Setup init_xstate_buf to represent the init state of + * all the features managed by the xsave + */ init_xstate_buf = alloc_bootmem(xstate_size); init_xstate_buf->i387.mxcsr = MXCSR_DEFAULT; + + clts(); + /* + * Init all the features state with header_bv being 0x0 + */ + xrstor_state(init_xstate_buf, -1); + /* + * Dump the init state again. This is to identify the init state + * of any feature which is not represented by all zero's. + */ + xsave_state(init_xstate_buf, -1); + stts(); } /* * Enable and initialize the xsave feature. */ -void __ref xsave_cntxt_init(void) +static void __init xstate_enable_boot_cpu(void) { unsigned int eax, ebx, ecx, edx; - cpuid_count(0xd, 0, &eax, &ebx, &ecx, &edx); + if (boot_cpu_data.cpuid_level < XSTATE_CPUID) { + WARN(1, KERN_ERR "XSTATE_CPUID missing\n"); + return; + } + + cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx); pcntxt_mask = eax + ((u64)edx << 32); if ((pcntxt_mask & XSTATE_FPSSE) != XSTATE_FPSSE) { @@ -322,12 +435,13 @@ void __ref xsave_cntxt_init(void) * Support only the state known to OS. */ pcntxt_mask = pcntxt_mask & XCNTXT_MASK; - xsave_init(); + + xstate_enable(); /* * Recompute the context size for enabled features */ - cpuid_count(0xd, 0, &eax, &ebx, &ecx, &edx); + cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx); xstate_size = ebx; update_regset_xstate_info(xstate_size, pcntxt_mask); @@ -339,3 +453,23 @@ void __ref xsave_cntxt_init(void) "cntxt size 0x%x\n", pcntxt_mask, xstate_size); } + +/* + * For the very first instance, this calls xstate_enable_boot_cpu(); + * for all subsequent instances, this calls xstate_enable(). + * + * This is somewhat obfuscated due to the lack of powerful enough + * overrides for the section checks. + */ +void __cpuinit xsave_init(void) +{ + static __refdata void (*next_func)(void) = xstate_enable_boot_cpu; + void (*this_func)(void); + + if (!cpu_has_xsave) + return; + + this_func = next_func; + next_func = xstate_enable; + this_func(); +} |