Commit 3d81b3d1 authored by Uros Bizjak's avatar Uros Bizjak Committed by Borislav Petkov
Browse files

x86/cpu: Use RDRAND and RDSEED mnemonics in archrandom.h 



Current minimum required version of binutils is 2.23,
which supports RDRAND and RDSEED instruction mnemonics.

Replace the byte-wise specification of RDRAND and
RDSEED with these proper mnemonics.

Signed-off-by: default avatarUros Bizjak <ubizjak@gmail.com>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Reviewed-by: default avatarH. Peter Anvin (Intel) <hpa@zytor.com>
Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200508105817.207887-1-ubizjak@gmail.com
parent 7e32a9da

arch/x86/include/asm/archrandom.h

+8 −18
Original line number Diff line number Diff line
@@ -15,16 +15,6 @@ 


#define RDRAND_RETRY_LOOPS	10



#define RDRAND_INT	".byte 0x0f,0xc7,0xf0"

#define RDSEED_INT	".byte 0x0f,0xc7,0xf8"

#ifdef CONFIG_X86_64

# define RDRAND_LONG	".byte 0x48,0x0f,0xc7,0xf0"

# define RDSEED_LONG	".byte 0x48,0x0f,0xc7,0xf8"

#else

# define RDRAND_LONG	RDRAND_INT

# define RDSEED_LONG	RDSEED_INT

#endif



/* Unconditional execution of RDRAND and RDSEED */



static inline bool __must_check rdrand_long(unsigned long *v)
@@ -32,9 +22,9 @@ static inline bool __must_check rdrand_long(unsigned long *v) 
	bool ok;

	unsigned int retry = RDRAND_RETRY_LOOPS;

	do {

		asm volatile(RDRAND_LONG

		asm volatile("rdrand %[out]"

			     CC_SET(c)

			     : CC_OUT(c) (ok), "=a" (*v));

			     : CC_OUT(c) (ok), [out] "=r" (*v));

		if (ok)

			return true;

	} while (--retry);
@@ -46,9 +36,9 @@ static inline bool __must_check rdrand_int(unsigned int *v) 
	bool ok;

	unsigned int retry = RDRAND_RETRY_LOOPS;

	do {

		asm volatile(RDRAND_INT

		asm volatile("rdrand %[out]"

			     CC_SET(c)

			     : CC_OUT(c) (ok), "=a" (*v));

			     : CC_OUT(c) (ok), [out] "=r" (*v));

		if (ok)

			return true;

	} while (--retry);
@@ -58,18 +48,18 @@ static inline bool __must_check rdrand_int(unsigned int *v) 
static inline bool __must_check rdseed_long(unsigned long *v)

{

	bool ok;

	asm volatile(RDSEED_LONG

	asm volatile("rdseed %[out]"

		     CC_SET(c)

		     : CC_OUT(c) (ok), "=a" (*v));

		     : CC_OUT(c) (ok), [out] "=r" (*v));

	return ok;

}



static inline bool __must_check rdseed_int(unsigned int *v)

{

	bool ok;

	asm volatile(RDSEED_INT

	asm volatile("rdseed %[out]"

		     CC_SET(c)

		     : CC_OUT(c) (ok), "=a" (*v));

		     : CC_OUT(c) (ok), [out] "=r" (*v));

	return ok;

}

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