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 <asm/archrandom.h>, 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 <hpa@linux.intel.com> Link: http://lkml.kernel.org/r/1465414726-197858-11-git-send-email-hpa@linux.intel.com v2: fix a conflict between <linux/random.h> and <asm/archrandom.h> discovered by Ingo Molnar. There are a few places in x86-specific code where we need all of <arch/archrandom.h> even when CONFIG_ARCH_RANDOM is disabled, so <linux/random.h> does not suffice.
This commit is contained in:
H. Peter Anvin
Родитель
66928b4eb9
Коммит
3b29039863
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@ -25,8 +25,6 @@
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#include <asm/processor.h>
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#include <asm/cpufeature.h>
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#include <asm/alternative.h>
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#include <asm/nops.h>
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#define RDRAND_RETRY_LOOPS 10
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@ -40,97 +38,91 @@
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# define RDSEED_LONG RDSEED_INT
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#endif
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#ifdef CONFIG_ARCH_RANDOM
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/* Unconditional execution of RDRAND and RDSEED */
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/* Instead of arch_get_random_long() when alternatives haven't run. */
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static inline bool rdrand_long(unsigned long *v)
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{
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int ok;
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asm volatile("1: " RDRAND_LONG "\n\t"
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"jc 2f\n\t"
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"decl %0\n\t"
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"jnz 1b\n\t"
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"2:"
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: "=r" (ok), "=a" (*v)
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: "0" (RDRAND_RETRY_LOOPS));
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return !!ok;
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bool ok;
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unsigned int retry = RDRAND_RETRY_LOOPS;
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do {
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asm volatile(RDRAND_LONG "\n\t"
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CC_SET(c)
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: CC_OUT(c) (ok), "=a" (*v));
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if (ok)
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return true;
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} while (--retry);
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return false;
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}
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static inline bool rdrand_int(unsigned int *v)
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{
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bool ok;
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unsigned int retry = RDRAND_RETRY_LOOPS;
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do {
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asm volatile(RDRAND_INT "\n\t"
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CC_SET(c)
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: CC_OUT(c) (ok), "=a" (*v));
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if (ok)
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return true;
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} while (--retry);
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return false;
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}
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/* A single attempt at RDSEED */
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static inline bool rdseed_long(unsigned long *v)
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{
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bool ok;
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asm volatile(RDSEED_LONG "\n\t"
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"setc %0"
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: "=qm" (ok), "=a" (*v));
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CC_SET(c)
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: CC_OUT(c) (ok), "=a" (*v));
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return ok;
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}
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#define GET_RANDOM(name, type, rdrand, nop) \
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static inline bool name(type *v) \
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{ \
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int ok; \
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alternative_io("movl $0, %0\n\t" \
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nop, \
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"\n1: " rdrand "\n\t" \
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"jc 2f\n\t" \
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"decl %0\n\t" \
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"jnz 1b\n\t" \
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"2:", \
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X86_FEATURE_RDRAND, \
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ASM_OUTPUT2("=r" (ok), "=a" (*v)), \
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"0" (RDRAND_RETRY_LOOPS)); \
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return !!ok; \
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static inline bool rdseed_int(unsigned int *v)
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{
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bool ok;
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asm volatile(RDSEED_INT "\n\t"
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CC_SET(c)
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: CC_OUT(c) (ok), "=a" (*v));
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return ok;
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}
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#define GET_SEED(name, type, rdseed, nop) \
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static inline bool name(type *v) \
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{ \
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bool ok; \
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alternative_io("movb $0, %0\n\t" \
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nop, \
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rdseed "\n\t" \
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"setc %0", \
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X86_FEATURE_RDSEED, \
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ASM_OUTPUT2("=q" (ok), "=a" (*v))); \
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return ok; \
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}
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#ifdef CONFIG_X86_64
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GET_RANDOM(arch_get_random_long, unsigned long, RDRAND_LONG, ASM_NOP5);
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GET_RANDOM(arch_get_random_int, unsigned int, RDRAND_INT, ASM_NOP4);
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GET_SEED(arch_get_random_seed_long, unsigned long, RDSEED_LONG, ASM_NOP5);
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GET_SEED(arch_get_random_seed_int, unsigned int, RDSEED_INT, ASM_NOP4);
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#else
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GET_RANDOM(arch_get_random_long, unsigned long, RDRAND_LONG, ASM_NOP3);
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GET_RANDOM(arch_get_random_int, unsigned int, RDRAND_INT, ASM_NOP3);
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GET_SEED(arch_get_random_seed_long, unsigned long, RDSEED_LONG, ASM_NOP4);
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GET_SEED(arch_get_random_seed_int, unsigned int, RDSEED_INT, ASM_NOP4);
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#endif /* CONFIG_X86_64 */
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/* Conditional execution based on CPU type */
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#define arch_has_random() static_cpu_has(X86_FEATURE_RDRAND)
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#define arch_has_random_seed() static_cpu_has(X86_FEATURE_RDSEED)
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#else
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/*
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* These are the generic interfaces; they must not be declared if the
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* stubs in <linux/random.h> are to be invoked,
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* i.e. CONFIG_ARCH_RANDOM is not defined.
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*/
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#ifdef CONFIG_ARCH_RANDOM
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static inline bool rdrand_long(unsigned long *v)
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static inline bool arch_get_random_long(unsigned long *v)
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{
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return 0;
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return arch_has_random() ? rdrand_long(v) : false;
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}
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static inline bool rdseed_long(unsigned long *v)
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static inline bool arch_get_random_int(unsigned int *v)
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{
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return 0;
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return arch_has_random() ? rdrand_int(v) : false;
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}
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#endif /* CONFIG_ARCH_RANDOM */
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static inline bool arch_get_random_seed_long(unsigned long *v)
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{
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return arch_has_random_seed() ? rdseed_long(v) : false;
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}
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static inline bool arch_get_random_seed_int(unsigned int *v)
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{
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return arch_has_random_seed() ? rdseed_int(v) : false;
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}
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extern void x86_init_rdrand(struct cpuinfo_x86 *c);
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#else /* !CONFIG_ARCH_RANDOM */
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static inline void x86_init_rdrand(struct cpuinfo_x86 *c) { }
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#endif /* !CONFIG_ARCH_RANDOM */
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#endif /* ASM_X86_ARCHRANDOM_H */
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@ -39,9 +39,9 @@ __setup("nordrand", x86_rdrand_setup);
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*/
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#define SANITY_CHECK_LOOPS 8
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#ifdef CONFIG_ARCH_RANDOM
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void x86_init_rdrand(struct cpuinfo_x86 *c)
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{
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#ifdef CONFIG_ARCH_RANDOM
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unsigned long tmp;
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int i;
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@ -55,5 +55,5 @@ void x86_init_rdrand(struct cpuinfo_x86 *c)
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return;
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}
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}
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#endif
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}
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#endif
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