diff options
Diffstat (limited to 'arch/x86/include/asm/special_insns.h')
-rw-r--r-- | arch/x86/include/asm/special_insns.h | 70 |
1 files changed, 70 insertions, 0 deletions
diff --git a/arch/x86/include/asm/special_insns.h b/arch/x86/include/asm/special_insns.h index 59a3e13204c3..94624fb06fac 100644 --- a/arch/x86/include/asm/special_insns.h +++ b/arch/x86/include/asm/special_insns.h @@ -234,6 +234,76 @@ static inline void clwb(volatile void *__p) #define nop() asm volatile ("nop") +static inline void serialize(void) +{ + /* Instruction opcode for SERIALIZE; supported in binutils >= 2.35. */ + asm volatile(".byte 0xf, 0x1, 0xe8" ::: "memory"); +} + +/* The dst parameter must be 64-bytes aligned */ +static inline void movdir64b(void *dst, const void *src) +{ + const struct { char _[64]; } *__src = src; + struct { char _[64]; } *__dst = dst; + + /* + * MOVDIR64B %(rdx), rax. + * + * Both __src and __dst must be memory constraints in order to tell the + * compiler that no other memory accesses should be reordered around + * this one. + * + * Also, both must be supplied as lvalues because this tells + * the compiler what the object is (its size) the instruction accesses. + * I.e., not the pointers but what they point to, thus the deref'ing '*'. + */ + asm volatile(".byte 0x66, 0x0f, 0x38, 0xf8, 0x02" + : "+m" (*__dst) + : "m" (*__src), "a" (__dst), "d" (__src)); +} + +/** + * enqcmds - Enqueue a command in supervisor (CPL0) mode + * @dst: destination, in MMIO space (must be 512-bit aligned) + * @src: 512 bits memory operand + * + * The ENQCMDS instruction allows software to write a 512-bit command to + * a 512-bit-aligned special MMIO region that supports the instruction. + * A return status is loaded into the ZF flag in the RFLAGS register. + * ZF = 0 equates to success, and ZF = 1 indicates retry or error. + * + * This function issues the ENQCMDS instruction to submit data from + * kernel space to MMIO space, in a unit of 512 bits. Order of data access + * is not guaranteed, nor is a memory barrier performed afterwards. It + * returns 0 on success and -EAGAIN on failure. + * + * Warning: Do not use this helper unless your driver has checked that the + * ENQCMDS instruction is supported on the platform and the device accepts + * ENQCMDS. + */ +static inline int enqcmds(void __iomem *dst, const void *src) +{ + const struct { char _[64]; } *__src = src; + struct { char _[64]; } *__dst = dst; + int zf; + + /* + * ENQCMDS %(rdx), rax + * + * See movdir64b()'s comment on operand specification. + */ + asm volatile(".byte 0xf3, 0x0f, 0x38, 0xf8, 0x02, 0x66, 0x90" + CC_SET(z) + : CC_OUT(z) (zf), "+m" (*__dst) + : "m" (*__src), "a" (__dst), "d" (__src)); + + /* Submission failure is indicated via EFLAGS.ZF=1 */ + if (zf) + return -EAGAIN; + + return 0; +} + #endif /* __KERNEL__ */ #endif /* _ASM_X86_SPECIAL_INSNS_H */ |