Use CC_SET()/CC_OUT() and static_cpu_has(). This produces code good enough to eliminate ad hoc use of alternatives in <asm/archrandom.h>, greatly simplifying the code.
Signed-off-by: H. Peter Anvin <[email protected]> --- arch/x86/include/asm/archrandom.h | 113 ++++++++++++++++---------------------- 1 file changed, 47 insertions(+), 66 deletions(-) diff --git a/arch/x86/include/asm/archrandom.h b/arch/x86/include/asm/archrandom.h index ab6f599..654da36 100644 --- a/arch/x86/include/asm/archrandom.h +++ b/arch/x86/include/asm/archrandom.h @@ -40,96 +40,77 @@ # define RDSEED_LONG RDSEED_INT #endif -#ifdef CONFIG_ARCH_RANDOM +/* Unconditional execution of RDRAND and RDSEED */ -/* Instead of arch_get_random_long() when alternatives haven't run. */ static inline bool rdrand_long(unsigned long *v) { - int ok; - asm volatile("1: " RDRAND_LONG "\n\t" - "jc 2f\n\t" - "decl %0\n\t" - "jnz 1b\n\t" - "2:" - : "=r" (ok), "=a" (*v) - : "0" (RDRAND_RETRY_LOOPS)); - return !!ok; + bool ok; + unsigned int retry = RDRAND_RETRY_LOOPS; + do { + asm volatile(RDRAND_LONG "\n\t" + CC_SET(c) + : CC_OUT(c) (ok), "=a" (*v)); + if (ok) + return true; + } while (--retry); + return false; +} + +static inline bool rdrand_int(unsigned int *v) +{ + bool ok; + unsigned int retry = RDRAND_RETRY_LOOPS; + do { + asm volatile(RDRAND_INT "\n\t" + CC_SET(c) + : CC_OUT(c) (ok), "=a" (*v)); + if (ok) + return true; + } while (--retry); + return false; } -/* A single attempt at RDSEED */ static inline bool rdseed_long(unsigned long *v) { bool ok; asm volatile(RDSEED_LONG "\n\t" - "setc %0" - : "=qm" (ok), "=a" (*v)); + CC_SET(c) + : CC_OUT(c) (ok), "=a" (*v)); return ok; } -#define GET_RANDOM(name, type, rdrand, nop) \ -static inline bool name(type *v) \ -{ \ - int ok; \ - alternative_io("movl $0, %0\n\t" \ - nop, \ - "\n1: " rdrand "\n\t" \ - "jc 2f\n\t" \ - "decl %0\n\t" \ - "jnz 1b\n\t" \ - "2:", \ - X86_FEATURE_RDRAND, \ - ASM_OUTPUT2("=r" (ok), "=a" (*v)), \ - "0" (RDRAND_RETRY_LOOPS)); \ - return !!ok; \ -} - -#define GET_SEED(name, type, rdseed, nop) \ -static inline bool name(type *v) \ -{ \ - bool ok; \ - alternative_io("movb $0, %0\n\t" \ - nop, \ - rdseed "\n\t" \ - "setc %0", \ - X86_FEATURE_RDSEED, \ - ASM_OUTPUT2("=q" (ok), "=a" (*v))); \ - return ok; \ +static inline bool rdseed_int(unsigned int *v) +{ + bool ok; + asm volatile(RDSEED_INT "\n\t" + CC_SET(c) + : CC_OUT(c) (ok), "=a" (*v)); + return ok; } -#ifdef CONFIG_X86_64 - -GET_RANDOM(arch_get_random_long, unsigned long, RDRAND_LONG, ASM_NOP5); -GET_RANDOM(arch_get_random_int, unsigned int, RDRAND_INT, ASM_NOP4); - -GET_SEED(arch_get_random_seed_long, unsigned long, RDSEED_LONG, ASM_NOP5); -GET_SEED(arch_get_random_seed_int, unsigned int, RDSEED_INT, ASM_NOP4); - -#else - -GET_RANDOM(arch_get_random_long, unsigned long, RDRAND_LONG, ASM_NOP3); -GET_RANDOM(arch_get_random_int, unsigned int, RDRAND_INT, ASM_NOP3); - -GET_SEED(arch_get_random_seed_long, unsigned long, RDSEED_LONG, ASM_NOP4); -GET_SEED(arch_get_random_seed_int, unsigned int, RDSEED_INT, ASM_NOP4); - -#endif /* CONFIG_X86_64 */ - +/* Conditional execution based on CPU type */ #define arch_has_random() static_cpu_has(X86_FEATURE_RDRAND) #define arch_has_random_seed() static_cpu_has(X86_FEATURE_RDSEED) -#else +static inline bool arch_get_random_long(unsigned long *v) +{ + return arch_has_random() ? rdrand_long(v) : false; +} -static inline bool rdrand_long(unsigned long *v) +static inline bool arch_get_random_int(unsigned int *v) { - return 0; + return arch_has_random() ? rdrand_int(v) : false; } -static inline bool rdseed_long(unsigned long *v) +static inline bool arch_get_random_seed_long(unsigned long *v) { - return 0; + return arch_has_random_seed() ? rdseed_long(v) : false; } -#endif /* CONFIG_ARCH_RANDOM */ +static inline bool arch_get_random_seed_int(unsigned int *v) +{ + return arch_has_random_seed() ? rdseed_int(v) : false; +} extern void x86_init_rdrand(struct cpuinfo_x86 *c); -- 2.7.3.0.11.gd79db92
