arch/riscv/include/asm/vendor_extensions/thead.h

Source file repositories/reference/linux-study-clean/arch/riscv/include/asm/vendor_extensions/thead.h

File Facts

System
Linux kernel
Corpus path
arch/riscv/include/asm/vendor_extensions/thead.h
Extension
.h
Size
1554 bytes
Lines
48
Domain
Architecture Layer
Bucket
arch/riscv
Inferred role
Architecture Layer: implementation source
Status
source implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

static inline void disable_xtheadvector(void) { }
#endif

/* Extension specific helpers */

/*
 * Vector 0.7.1 as used for example on T-Head Xuantie cores, uses an older
 * encoding for vsetvli (ta, ma vs. d1), so provide an instruction for
 * vsetvli	t4, x0, e8, m8, d1
 */
#define THEAD_VSETVLI_T4X0E8M8D1	".long	0x00307ed7\n\t"

/*
 * While in theory, the vector-0.7.1 vsb.v and vlb.v result in the same
 * encoding as the standard vse8.v and vle8.v, compilers seem to optimize
 * the call resulting in a different encoding and then using a value for
 * the "mop" field that is not part of vector-0.7.1
 * So encode specific variants for vstate_save and _restore.
 */
#define THEAD_VSB_V_V0T0		".long	0x02028027\n\t"
#define THEAD_VSB_V_V8T0		".long	0x02028427\n\t"
#define THEAD_VSB_V_V16T0		".long	0x02028827\n\t"
#define THEAD_VSB_V_V24T0		".long	0x02028c27\n\t"
#define THEAD_VLB_V_V0T0		".long	0x012028007\n\t"
#define THEAD_VLB_V_V8T0		".long	0x012028407\n\t"
#define THEAD_VLB_V_V16T0		".long	0x012028807\n\t"
#define THEAD_VLB_V_V24T0		".long	0x012028c07\n\t"

#endif

Annotation

Implementation Notes