From 3b290398638ee4e57f1fb2e35c02005cba9a737f Mon Sep 17 00:00:00 2001 From: "H. Peter Anvin" Date: Wed, 8 Jun 2016 12:38:46 -0700 Subject: [PATCH] x86, asm: Use CC_SET()/CC_OUT() and static_cpu_has() in archrandom.h Use CC_SET()/CC_OUT() and static_cpu_has(). This produces code good enough to eliminate ad hoc use of alternatives in , greatly simplifying the code. While we are at it, make x86_init_rdrand() compile out completely if we don't need it. Signed-off-by: H. Peter Anvin Link: http://lkml.kernel.org/r/1465414726-197858-11-git-send-email-hpa@linux.intel.com v2: fix a conflict between and discovered by Ingo Molnar. There are a few places in x86-specific code where we need all of even when CONFIG_ARCH_RANDOM is disabled, so does not suffice. --- arch/x86/include/asm/archrandom.h | 128 ++++++++++++++---------------- arch/x86/kernel/cpu/rdrand.c | 4 +- 2 files changed, 62 insertions(+), 70 deletions(-) diff --git a/arch/x86/include/asm/archrandom.h b/arch/x86/include/asm/archrandom.h index ab6f599ce2fd..5b0579abb398 100644 --- a/arch/x86/include/asm/archrandom.h +++ b/arch/x86/include/asm/archrandom.h @@ -25,8 +25,6 @@ #include #include -#include -#include #define RDRAND_RETRY_LOOPS 10 @@ -40,97 +38,91 @@ # 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 +/* + * These are the generic interfaces; they must not be declared if the + * stubs in are to be invoked, + * i.e. CONFIG_ARCH_RANDOM is not defined. + */ +#ifdef CONFIG_ARCH_RANDOM -static inline bool rdrand_long(unsigned long *v) +static inline bool arch_get_random_long(unsigned long *v) { - return 0; + return arch_has_random() ? rdrand_long(v) : false; } -static inline bool rdseed_long(unsigned long *v) +static inline bool arch_get_random_int(unsigned int *v) { - return 0; + return arch_has_random() ? rdrand_int(v) : false; } -#endif /* CONFIG_ARCH_RANDOM */ +static inline bool arch_get_random_seed_long(unsigned long *v) +{ + return arch_has_random_seed() ? rdseed_long(v) : false; +} + +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); +#else /* !CONFIG_ARCH_RANDOM */ + +static inline void x86_init_rdrand(struct cpuinfo_x86 *c) { } + +#endif /* !CONFIG_ARCH_RANDOM */ + #endif /* ASM_X86_ARCHRANDOM_H */ diff --git a/arch/x86/kernel/cpu/rdrand.c b/arch/x86/kernel/cpu/rdrand.c index f6f50c4ceaec..cfa97ff67bda 100644 --- a/arch/x86/kernel/cpu/rdrand.c +++ b/arch/x86/kernel/cpu/rdrand.c @@ -39,9 +39,9 @@ __setup("nordrand", x86_rdrand_setup); */ #define SANITY_CHECK_LOOPS 8 +#ifdef CONFIG_ARCH_RANDOM void x86_init_rdrand(struct cpuinfo_x86 *c) { -#ifdef CONFIG_ARCH_RANDOM unsigned long tmp; int i; @@ -55,5 +55,5 @@ void x86_init_rdrand(struct cpuinfo_x86 *c) return; } } -#endif } +#endif -- 2.20.1