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selftests/x86/xstate: Refactor XSAVE helpers for general use
The AMX test introduced several XSAVE-related helper functions, but so far, it has been the only user of them. These helpers can be generalized for broader test of multiple xstate features. Move most XSAVE-related code into xsave.h, making it shareable. The restructuring includes: * Establishing low-level XSAVE helpers for saving and restoring register states, as well as handling XSAVE buffers. * Generalizing state data manipuldations: set_rand_data() * Introducing a generic feature query helper: get_xstate_info() While doing so, remove unused defines in amx.c. Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20250226010731.2456-3-chang.seok.bae@intel.com
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Chang S. Bae
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Ingo Molnar
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Feb 26, 2025
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,132 @@ | ||
| // SPDX-License-Identifier: GPL-2.0-only | ||
| #ifndef __SELFTESTS_X86_XSTATE_H | ||
| #define __SELFTESTS_X86_XSTATE_H | ||
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| #include <stdint.h> | ||
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| #include "../kselftest.h" | ||
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| #define XSAVE_HDR_OFFSET 512 | ||
| #define XSAVE_HDR_SIZE 64 | ||
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| struct xsave_buffer { | ||
| union { | ||
| struct { | ||
| char legacy[XSAVE_HDR_OFFSET]; | ||
| char header[XSAVE_HDR_SIZE]; | ||
| char extended[0]; | ||
| }; | ||
| char bytes[0]; | ||
| }; | ||
| }; | ||
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| static inline void xsave(struct xsave_buffer *xbuf, uint64_t rfbm) | ||
| { | ||
| uint32_t rfbm_hi = rfbm >> 32; | ||
| uint32_t rfbm_lo = rfbm; | ||
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| asm volatile("xsave (%%rdi)" | ||
| : : "D" (xbuf), "a" (rfbm_lo), "d" (rfbm_hi) | ||
| : "memory"); | ||
| } | ||
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| static inline void xrstor(struct xsave_buffer *xbuf, uint64_t rfbm) | ||
| { | ||
| uint32_t rfbm_hi = rfbm >> 32; | ||
| uint32_t rfbm_lo = rfbm; | ||
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| asm volatile("xrstor (%%rdi)" | ||
| : : "D" (xbuf), "a" (rfbm_lo), "d" (rfbm_hi)); | ||
| } | ||
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| #define CPUID_LEAF_XSTATE 0xd | ||
| #define CPUID_SUBLEAF_XSTATE_USER 0x0 | ||
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| static inline uint32_t get_xbuf_size(void) | ||
| { | ||
| uint32_t eax, ebx, ecx, edx; | ||
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| __cpuid_count(CPUID_LEAF_XSTATE, CPUID_SUBLEAF_XSTATE_USER, | ||
| eax, ebx, ecx, edx); | ||
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| /* | ||
| * EBX enumerates the size (in bytes) required by the XSAVE | ||
| * instruction for an XSAVE area containing all the user state | ||
| * components corresponding to bits currently set in XCR0. | ||
| */ | ||
| return ebx; | ||
| } | ||
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| struct xstate_info { | ||
| uint32_t num; | ||
| uint32_t mask; | ||
| uint32_t xbuf_offset; | ||
| uint32_t size; | ||
| }; | ||
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| static inline struct xstate_info get_xstate_info(uint32_t xfeature_num) | ||
| { | ||
| struct xstate_info xstate = { }; | ||
| uint32_t eax, ebx, ecx, edx; | ||
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| xstate.num = xfeature_num; | ||
| xstate.mask = 1 << xfeature_num; | ||
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| __cpuid_count(CPUID_LEAF_XSTATE, xfeature_num, | ||
| eax, ebx, ecx, edx); | ||
| xstate.size = eax; | ||
| xstate.xbuf_offset = ebx; | ||
| return xstate; | ||
| } | ||
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| static inline struct xsave_buffer *alloc_xbuf(void) | ||
| { | ||
| uint32_t xbuf_size = get_xbuf_size(); | ||
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| /* XSAVE buffer should be 64B-aligned. */ | ||
| return aligned_alloc(64, xbuf_size); | ||
| } | ||
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| static inline void clear_xstate_header(struct xsave_buffer *xbuf) | ||
| { | ||
| memset(&xbuf->header, 0, sizeof(xbuf->header)); | ||
| } | ||
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| static inline void set_xstatebv(struct xsave_buffer *xbuf, uint64_t bv) | ||
| { | ||
| /* XSTATE_BV is at the beginning of the header: */ | ||
| *(uint64_t *)(&xbuf->header) = bv; | ||
| } | ||
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| /* See 'struct _fpx_sw_bytes' at sigcontext.h */ | ||
| #define SW_BYTES_OFFSET 464 | ||
| /* N.B. The struct's field name varies so read from the offset. */ | ||
| #define SW_BYTES_BV_OFFSET (SW_BYTES_OFFSET + 8) | ||
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| static inline struct _fpx_sw_bytes *get_fpx_sw_bytes(void *xbuf) | ||
| { | ||
| return xbuf + SW_BYTES_OFFSET; | ||
| } | ||
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| static inline uint64_t get_fpx_sw_bytes_features(void *buffer) | ||
| { | ||
| return *(uint64_t *)(buffer + SW_BYTES_BV_OFFSET); | ||
| } | ||
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| static inline void set_rand_data(struct xstate_info *xstate, struct xsave_buffer *xbuf) | ||
| { | ||
| int *ptr = (int *)&xbuf->bytes[xstate->xbuf_offset]; | ||
| int data, i; | ||
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| /* | ||
| * Ensure that 'data' is never 0. This ensures that | ||
| * the registers are never in their initial configuration | ||
| * and thus never tracked as being in the init state. | ||
| */ | ||
| data = rand() | 1; | ||
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| for (i = 0; i < xstate->size / sizeof(int); i++, ptr++) | ||
| *ptr = data; | ||
| } | ||
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| #endif /* __SELFTESTS_X86_XSTATE_H */ |