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Diffstat (limited to 'kernel/arch/x86/include/asm/fpu/types.h')
| -rw-r--r-- | kernel/arch/x86/include/asm/fpu/types.h | 355 |
1 files changed, 355 insertions, 0 deletions
diff --git a/kernel/arch/x86/include/asm/fpu/types.h b/kernel/arch/x86/include/asm/fpu/types.h new file mode 100644 index 000000000..1c6f6ac52 --- /dev/null +++ b/kernel/arch/x86/include/asm/fpu/types.h @@ -0,0 +1,355 @@ +/* + * FPU data structures: + */ +#ifndef _ASM_X86_FPU_H +#define _ASM_X86_FPU_H + +/* + * The legacy x87 FPU state format, as saved by FSAVE and + * restored by the FRSTOR instructions: + */ +struct fregs_state { + u32 cwd; /* FPU Control Word */ + u32 swd; /* FPU Status Word */ + u32 twd; /* FPU Tag Word */ + u32 fip; /* FPU IP Offset */ + u32 fcs; /* FPU IP Selector */ + u32 foo; /* FPU Operand Pointer Offset */ + u32 fos; /* FPU Operand Pointer Selector */ + + /* 8*10 bytes for each FP-reg = 80 bytes: */ + u32 st_space[20]; + + /* Software status information [not touched by FSAVE]: */ + u32 status; +}; + +/* + * The legacy fx SSE/MMX FPU state format, as saved by FXSAVE and + * restored by the FXRSTOR instructions. It's similar to the FSAVE + * format, but differs in some areas, plus has extensions at + * the end for the XMM registers. + */ +struct fxregs_state { + u16 cwd; /* Control Word */ + u16 swd; /* Status Word */ + u16 twd; /* Tag Word */ + u16 fop; /* Last Instruction Opcode */ + union { + struct { + u64 rip; /* Instruction Pointer */ + u64 rdp; /* Data Pointer */ + }; + struct { + u32 fip; /* FPU IP Offset */ + u32 fcs; /* FPU IP Selector */ + u32 foo; /* FPU Operand Offset */ + u32 fos; /* FPU Operand Selector */ + }; + }; + u32 mxcsr; /* MXCSR Register State */ + u32 mxcsr_mask; /* MXCSR Mask */ + + /* 8*16 bytes for each FP-reg = 128 bytes: */ + u32 st_space[32]; + + /* 16*16 bytes for each XMM-reg = 256 bytes: */ + u32 xmm_space[64]; + + u32 padding[12]; + + union { + u32 padding1[12]; + u32 sw_reserved[12]; + }; + +} __attribute__((aligned(16))); + +/* Default value for fxregs_state.mxcsr: */ +#define MXCSR_DEFAULT 0x1f80 + +/* + * Software based FPU emulation state. This is arbitrary really, + * it matches the x87 format to make it easier to understand: + */ +struct swregs_state { + u32 cwd; + u32 swd; + u32 twd; + u32 fip; + u32 fcs; + u32 foo; + u32 fos; + /* 8*10 bytes for each FP-reg = 80 bytes: */ + u32 st_space[20]; + u8 ftop; + u8 changed; + u8 lookahead; + u8 no_update; + u8 rm; + u8 alimit; + struct math_emu_info *info; + u32 entry_eip; +}; + +/* + * List of XSAVE features Linux knows about: + */ +enum xfeature { + XFEATURE_FP, + XFEATURE_SSE, + /* + * Values above here are "legacy states". + * Those below are "extended states". + */ + XFEATURE_YMM, + XFEATURE_BNDREGS, + XFEATURE_BNDCSR, + XFEATURE_OPMASK, + XFEATURE_ZMM_Hi256, + XFEATURE_Hi16_ZMM, + + XFEATURE_MAX, +}; + +#define XFEATURE_MASK_FP (1 << XFEATURE_FP) +#define XFEATURE_MASK_SSE (1 << XFEATURE_SSE) +#define XFEATURE_MASK_YMM (1 << XFEATURE_YMM) +#define XFEATURE_MASK_BNDREGS (1 << XFEATURE_BNDREGS) +#define XFEATURE_MASK_BNDCSR (1 << XFEATURE_BNDCSR) +#define XFEATURE_MASK_OPMASK (1 << XFEATURE_OPMASK) +#define XFEATURE_MASK_ZMM_Hi256 (1 << XFEATURE_ZMM_Hi256) +#define XFEATURE_MASK_Hi16_ZMM (1 << XFEATURE_Hi16_ZMM) + +#define XFEATURE_MASK_FPSSE (XFEATURE_MASK_FP | XFEATURE_MASK_SSE) +#define XFEATURE_MASK_AVX512 (XFEATURE_MASK_OPMASK \ + | XFEATURE_MASK_ZMM_Hi256 \ + | XFEATURE_MASK_Hi16_ZMM) + +#define FIRST_EXTENDED_XFEATURE XFEATURE_YMM + +struct reg_128_bit { + u8 regbytes[128/8]; +}; +struct reg_256_bit { + u8 regbytes[256/8]; +}; +struct reg_512_bit { + u8 regbytes[512/8]; +}; + +/* + * State component 2: + * + * There are 16x 256-bit AVX registers named YMM0-YMM15. + * The low 128 bits are aliased to the 16 SSE registers (XMM0-XMM15) + * and are stored in 'struct fxregs_state::xmm_space[]' in the + * "legacy" area. + * + * The high 128 bits are stored here. + */ +struct ymmh_struct { + struct reg_128_bit hi_ymm[16]; +} __packed; + +/* Intel MPX support: */ + +struct mpx_bndreg { + u64 lower_bound; + u64 upper_bound; +} __packed; +/* + * State component 3 is used for the 4 128-bit bounds registers + */ +struct mpx_bndreg_state { + struct mpx_bndreg bndreg[4]; +} __packed; + +/* + * State component 4 is used for the 64-bit user-mode MPX + * configuration register BNDCFGU and the 64-bit MPX status + * register BNDSTATUS. We call the pair "BNDCSR". + */ +struct mpx_bndcsr { + u64 bndcfgu; + u64 bndstatus; +} __packed; + +/* + * The BNDCSR state is padded out to be 64-bytes in size. + */ +struct mpx_bndcsr_state { + union { + struct mpx_bndcsr bndcsr; + u8 pad_to_64_bytes[64]; + }; +} __packed; + +/* AVX-512 Components: */ + +/* + * State component 5 is used for the 8 64-bit opmask registers + * k0-k7 (opmask state). + */ +struct avx_512_opmask_state { + u64 opmask_reg[8]; +} __packed; + +/* + * State component 6 is used for the upper 256 bits of the + * registers ZMM0-ZMM15. These 16 256-bit values are denoted + * ZMM0_H-ZMM15_H (ZMM_Hi256 state). + */ +struct avx_512_zmm_uppers_state { + struct reg_256_bit zmm_upper[16]; +} __packed; + +/* + * State component 7 is used for the 16 512-bit registers + * ZMM16-ZMM31 (Hi16_ZMM state). + */ +struct avx_512_hi16_state { + struct reg_512_bit hi16_zmm[16]; +} __packed; + +struct xstate_header { + u64 xfeatures; + u64 xcomp_bv; + u64 reserved[6]; +} __attribute__((packed)); + +/* + * This is our most modern FPU state format, as saved by the XSAVE + * and restored by the XRSTOR instructions. + * + * It consists of a legacy fxregs portion, an xstate header and + * subsequent areas as defined by the xstate header. Not all CPUs + * support all the extensions, so the size of the extended area + * can vary quite a bit between CPUs. + */ +struct xregs_state { + struct fxregs_state i387; + struct xstate_header header; + u8 extended_state_area[0]; +} __attribute__ ((packed, aligned (64))); + +/* + * This is a union of all the possible FPU state formats + * put together, so that we can pick the right one runtime. + * + * The size of the structure is determined by the largest + * member - which is the xsave area. The padding is there + * to ensure that statically-allocated task_structs (just + * the init_task today) have enough space. + */ +union fpregs_state { + struct fregs_state fsave; + struct fxregs_state fxsave; + struct swregs_state soft; + struct xregs_state xsave; + u8 __padding[PAGE_SIZE]; +}; + +/* + * Highest level per task FPU state data structure that + * contains the FPU register state plus various FPU + * state fields: + */ +struct fpu { + /* + * @last_cpu: + * + * Records the last CPU on which this context was loaded into + * FPU registers. (In the lazy-restore case we might be + * able to reuse FPU registers across multiple context switches + * this way, if no intermediate task used the FPU.) + * + * A value of -1 is used to indicate that the FPU state in context + * memory is newer than the FPU state in registers, and that the + * FPU state should be reloaded next time the task is run. + */ + unsigned int last_cpu; + + /* + * @fpstate_active: + * + * This flag indicates whether this context is active: if the task + * is not running then we can restore from this context, if the task + * is running then we should save into this context. + */ + unsigned char fpstate_active; + + /* + * @fpregs_active: + * + * This flag determines whether a given context is actively + * loaded into the FPU's registers and that those registers + * represent the task's current FPU state. + * + * Note the interaction with fpstate_active: + * + * # task does not use the FPU: + * fpstate_active == 0 + * + * # task uses the FPU and regs are active: + * fpstate_active == 1 && fpregs_active == 1 + * + * # the regs are inactive but still match fpstate: + * fpstate_active == 1 && fpregs_active == 0 && fpregs_owner == fpu + * + * The third state is what we use for the lazy restore optimization + * on lazy-switching CPUs. + */ + unsigned char fpregs_active; + + /* + * @counter: + * + * This counter contains the number of consecutive context switches + * during which the FPU stays used. If this is over a threshold, the + * lazy FPU restore logic becomes eager, to save the trap overhead. + * This is an unsigned char so that after 256 iterations the counter + * wraps and the context switch behavior turns lazy again; this is to + * deal with bursty apps that only use the FPU for a short time: + */ + unsigned char counter; + /* + * @state: + * + * In-memory copy of all FPU registers that we save/restore + * over context switches. If the task is using the FPU then + * the registers in the FPU are more recent than this state + * copy. If the task context-switches away then they get + * saved here and represent the FPU state. + * + * After context switches there may be a (short) time period + * during which the in-FPU hardware registers are unchanged + * and still perfectly match this state, if the tasks + * scheduled afterwards are not using the FPU. + * + * This is the 'lazy restore' window of optimization, which + * we track though 'fpu_fpregs_owner_ctx' and 'fpu->last_cpu'. + * + * We detect whether a subsequent task uses the FPU via setting + * CR0::TS to 1, which causes any FPU use to raise a #NM fault. + * + * During this window, if the task gets scheduled again, we + * might be able to skip having to do a restore from this + * memory buffer to the hardware registers - at the cost of + * incurring the overhead of #NM fault traps. + * + * Note that on modern CPUs that support the XSAVEOPT (or other + * optimized XSAVE instructions), we don't use #NM traps anymore, + * as the hardware can track whether FPU registers need saving + * or not. On such CPUs we activate the non-lazy ('eagerfpu') + * logic, which unconditionally saves/restores all FPU state + * across context switches. (if FPU state exists.) + */ + union fpregs_state state; + /* + * WARNING: 'state' is dynamically-sized. Do not put + * anything after it here. + */ +}; + +#endif /* _ASM_X86_FPU_H */ |