summaryrefslogtreecommitdiffstats
path: root/src/crypto/rand/asm/rdrand-x86_64.pl
diff options
context:
space:
mode:
Diffstat (limited to 'src/crypto/rand/asm/rdrand-x86_64.pl')
-rw-r--r--src/crypto/rand/asm/rdrand-x86_64.pl52
1 files changed, 51 insertions, 1 deletions
diff --git a/src/crypto/rand/asm/rdrand-x86_64.pl b/src/crypto/rand/asm/rdrand-x86_64.pl
index a917611..c32a55c 100644
--- a/src/crypto/rand/asm/rdrand-x86_64.pl
+++ b/src/crypto/rand/asm/rdrand-x86_64.pl
@@ -1,5 +1,19 @@
#!/usr/bin/env perl
+# Copyright (c) 2015, Google Inc.
+#
+# Permission to use, copy, modify, and/or distribute this software for any
+# purpose with or without fee is hereby granted, provided that the above
+# copyright notice and this permission notice appear in all copies.
+#
+# THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
+# SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
+# OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+# CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
+
$flavour = shift;
$output = shift;
if ($flavour =~ /\./) { $output = $flavour; undef $flavour; }
@@ -14,11 +28,47 @@ open OUT,"| \"$^X\" $xlate $flavour $output";
print<<___;
.text
+# CRYPTO_rdrand writes eight bytes of random data from the hardware RNG to
+# |out|. It returns one on success or zero on hardware failure.
+# int CRYPTO_rdrand(uint8_t out[8]);
.globl CRYPTO_rdrand
.type CRYPTO_rdrand,\@function,1
.align 16
CRYPTO_rdrand:
- .byte 0x48, 0x0f, 0xc7, 0xf0
+ xorq %rax, %rax
+ # This is rdrand %rcx. It sets rcx to a random value and sets the carry
+ # flag on success.
+ .byte 0x48, 0x0f, 0xc7, 0xf1
+ # An add-with-carry of zero effectively sets %rax to the carry flag.
+ adcq %rax, %rax
+ movq %rcx, 0(%rdi)
+ retq
+
+# CRYPTO_rdrand_multiple8_buf fills |len| bytes at |buf| with random data from
+# the hardware RNG. The |len| argument must be a multiple of eight. It returns
+# one on success and zero on hardware failure.
+# int CRYPTO_rdrand_multiple8_buf(uint8_t *buf, size_t len);
+.globl CRYPTO_rdrand_multiple8_buf
+.type CRYPTO_rdrand_multiple8_buf,\@function,2
+.align 16
+CRYPTO_rdrand_multiple8_buf:
+ test %rsi, %rsi
+ jz .Lout
+ movq \$8, %rdx
+.Lloop:
+ # This is rdrand %rcx. It sets rcx to a random value and sets the carry
+ # flag on success.
+ .byte 0x48, 0x0f, 0xc7, 0xf1
+ jnc .Lerr
+ movq %rcx, 0(%rdi)
+ addq %rdx, %rdi
+ subq %rdx, %rsi
+ jnz .Lloop
+.Lout:
+ movq \$1, %rax
+ retq
+.Lerr:
+ xorq %rax, %rax
retq
___