From: Kan Liang <[email protected]> The LBR dynamic supervisor feature will be enabled in the perf subsystem later. A new structure, several helpers, and a macro are added as below to facilitate enabling the feature. - Currently, the structure for each state component is maintained in fpu/types.h. The structure for the new LBR state component should be maintained in the same place, which will be used in the following patch. - The perf subsystem will only need to save/restore the LBR state. However, the existing helpers save all supported supervisor states to a kernel buffer, which will be unnecessary. Two helpers are introduced to only save/restore requested dynamic supervisor states. The supervisor features in XFEATURE_MASK_SUPERVISOR_SUPPORTED and XFEATURE_MASK_SUPERVISOR_UNSUPPORTED mask cannot be saved/restored using these helpers. - The XSAVE buffer must be 64-byte aligned. A new macro is added to reflect the alignment requirement.
The structure, the helpers, and the macro will be used in the following patch. Reviewed-by: Dave Hansen <[email protected]> Signed-off-by: Kan Liang <[email protected]> --- arch/x86/include/asm/fpu/types.h | 19 +++++++++++ arch/x86/include/asm/fpu/xstate.h | 5 +++ arch/x86/kernel/fpu/xstate.c | 72 +++++++++++++++++++++++++++++++++++++++ 3 files changed, 96 insertions(+) diff --git a/arch/x86/include/asm/fpu/types.h b/arch/x86/include/asm/fpu/types.h index 132e9cc..975f078 100644 --- a/arch/x86/include/asm/fpu/types.h +++ b/arch/x86/include/asm/fpu/types.h @@ -236,6 +236,25 @@ struct pkru_state { u32 pad; } __packed; +/* + * State component 15: Architectural LBR configuration state. + * The size of Arch LBR state depends on the number of LBRs (lbr_depth). + */ +struct arch_lbr_entry { + u64 lbr_from; + u64 lbr_to; + u64 lbr_info; +}; + +struct arch_lbr_state { + u64 lbr_ctl; + u64 lbr_depth; + u64 ler_from; + u64 ler_to; + u64 ler_info; + struct arch_lbr_entry entries[0]; +} __packed; + struct xstate_header { u64 xfeatures; u64 xcomp_bv; diff --git a/arch/x86/include/asm/fpu/xstate.h b/arch/x86/include/asm/fpu/xstate.h index 040c4d4..636c3ef 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 | \ @@ -106,6 +108,9 @@ int copy_xstate_to_user(void __user *ubuf, struct xregs_state *xsave, unsigned i 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); diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index 58d79f1..49e0347 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -1352,6 +1352,78 @@ void copy_supervisor_to_kernel(struct xregs_state *xstate) } } +/** + * copy_dynamic_supervisor_to_kernel() - Save dynamic supervisor states to + * an xsave area + * @xstate: A pointer to an xsave area + * @mask: Represent the dynamic supervisor features saved into the xsave area + * + * Only the dynamic supervisor states sets in the mask are saved into the xsave + * area (See the comment in XFEATURE_MASK_DYNAMIC for the details of dynamic + * supervisor feature). Besides the dynamic supervisor states, the legacy + * region and XSAVE header are also saved into the xsave area. The supervisor + * features in the XFEATURE_MASK_SUPERVISOR_SUPPORTED and + * XFEATURE_MASK_SUPERVISOR_UNSUPPORTED are not saved. + * + * The xsave area must be 64-bytes aligned. + */ +void copy_dynamic_supervisor_to_kernel(struct xregs_state *xstate, u64 mask) +{ + u64 dynamic_mask = xfeatures_mask_dynamic() & mask; + u32 lmask, hmask; + int err; + + if (WARN_ON_FPU(!boot_cpu_has(X86_FEATURE_XSAVES))) + return; + + if (WARN_ON_FPU(!dynamic_mask)) + return; + + lmask = dynamic_mask; + hmask = dynamic_mask >> 32; + + XSTATE_OP(XSAVES, xstate, lmask, hmask, err); + + /* Should never fault when copying to a kernel buffer */ + WARN_ON_FPU(err); +} + +/** + * copy_kernel_to_dynamic_supervisor() - Restore dynamic supervisor states from + * an xsave area + * @xstate: A pointer to an xsave area + * @mask: Represent the dynamic supervisor features restored from the xsave area + * + * Only the dynamic supervisor states sets in the mask are restored from the + * xsave area (See the comment in XFEATURE_MASK_DYNAMIC for the details of + * dynamic supervisor feature). Besides the dynamic supervisor states, the + * legacy region and XSAVE header are also restored from the xsave area. The + * supervisor features in the XFEATURE_MASK_SUPERVISOR_SUPPORTED and + * XFEATURE_MASK_SUPERVISOR_UNSUPPORTED are not restored. + * + * The xsave area must be 64-bytes aligned. + */ +void copy_kernel_to_dynamic_supervisor(struct xregs_state *xstate, u64 mask) +{ + u64 dynamic_mask = xfeatures_mask_dynamic() & mask; + u32 lmask, hmask; + int err; + + if (WARN_ON_FPU(!boot_cpu_has(X86_FEATURE_XSAVES))) + return; + + if (WARN_ON_FPU(!dynamic_mask)) + return; + + lmask = dynamic_mask; + hmask = dynamic_mask >> 32; + + XSTATE_OP(XRSTORS, xstate, lmask, hmask, err); + + /* Should never fault when copying from a kernel buffer */ + WARN_ON_FPU(err); +} + #ifdef CONFIG_PROC_PID_ARCH_STATUS /* * Report the amount of time elapsed in millisecond since last AVX512 -- 2.7.4
