diff options
Diffstat (limited to 'arch/x86/include/asm/fpu/xstate.h')
| -rw-r--r-- | arch/x86/include/asm/fpu/xstate.h | 36 |
1 files changed, 36 insertions, 0 deletions
diff --git a/arch/x86/include/asm/fpu/xstate.h b/arch/x86/include/asm/fpu/xstate.h index 422d8369012a..1559554af931 100644 --- a/arch/x86/include/asm/fpu/xstate.h +++ b/arch/x86/include/asm/fpu/xstate.h @@ -21,6 +21,8 @@ #define XSAVE_YMM_SIZE 256 #define XSAVE_YMM_OFFSET (XSAVE_HDR_SIZE + XSAVE_HDR_OFFSET) +#define XSAVE_ALIGNMENT 64 + /* All currently supported user features */ #define XFEATURE_MASK_USER_SUPPORTED (XFEATURE_MASK_FP | \ XFEATURE_MASK_SSE | \ @@ -36,6 +38,27 @@ #define XFEATURE_MASK_SUPERVISOR_SUPPORTED (0) /* + * A supervisor state component may not always contain valuable information, + * and its size may be huge. Saving/restoring such supervisor state components + * at each context switch can cause high CPU and space overhead, which should + * be avoided. Such supervisor state components should only be saved/restored + * on demand. The on-demand dynamic supervisor features are set in this mask. + * + * Unlike the existing supported supervisor features, a dynamic supervisor + * feature does not allocate a buffer in task->fpu, and the corresponding + * supervisor state component cannot be saved/restored at each context switch. + * + * To support a dynamic supervisor feature, a developer should follow the + * dos and don'ts as below: + * - Do dynamically allocate a buffer for the supervisor state component. + * - Do manually invoke the XSAVES/XRSTORS instruction to save/restore the + * state component to/from the buffer. + * - Don't set the bit corresponding to the dynamic supervisor feature in + * IA32_XSS at run time, since it has been set at boot time. + */ +#define XFEATURE_MASK_DYNAMIC (XFEATURE_MASK_LBR) + +/* * Unsupported supervisor features. When a supervisor feature in this mask is * supported in the future, move it to the supported supervisor feature mask. */ @@ -43,6 +66,7 @@ /* All supervisor states including supported and unsupported states. */ #define XFEATURE_MASK_SUPERVISOR_ALL (XFEATURE_MASK_SUPERVISOR_SUPPORTED | \ + XFEATURE_MASK_DYNAMIC | \ XFEATURE_MASK_SUPERVISOR_UNSUPPORTED) #ifdef CONFIG_X86_64 @@ -63,6 +87,14 @@ static inline u64 xfeatures_mask_user(void) return xfeatures_mask_all & XFEATURE_MASK_USER_SUPPORTED; } +static inline u64 xfeatures_mask_dynamic(void) +{ + if (!boot_cpu_has(X86_FEATURE_ARCH_LBR)) + return XFEATURE_MASK_DYNAMIC & ~XFEATURE_MASK_LBR; + + return XFEATURE_MASK_DYNAMIC; +} + extern u64 xstate_fx_sw_bytes[USER_XSTATE_FX_SW_WORDS]; extern void __init update_regset_xstate_info(unsigned int size, @@ -71,11 +103,15 @@ extern void __init update_regset_xstate_info(unsigned int size, void *get_xsave_addr(struct xregs_state *xsave, int xfeature_nr); const void *get_xsave_field_ptr(int xfeature_nr); int using_compacted_format(void); +int xfeature_size(int xfeature_nr); int copy_xstate_to_kernel(void *kbuf, struct xregs_state *xsave, unsigned int offset, unsigned int size); int copy_xstate_to_user(void __user *ubuf, struct xregs_state *xsave, unsigned int offset, unsigned int size); int copy_kernel_to_xstate(struct xregs_state *xsave, const void *kbuf); int copy_user_to_xstate(struct xregs_state *xsave, const void __user *ubuf); void copy_supervisor_to_kernel(struct xregs_state *xsave); +void copy_dynamic_supervisor_to_kernel(struct xregs_state *xstate, u64 mask); +void copy_kernel_to_dynamic_supervisor(struct xregs_state *xstate, u64 mask); + /* Validate an xstate header supplied by userspace (ptrace or sigreturn) */ int validate_user_xstate_header(const struct xstate_header *hdr); |