http://repzret.org/p/repzret/

My read of this:  Long time ago (Think Conan, not dinasaurs) during the race
to make speedier processors, a cpu vendor built a pipeline with a bad stall,
and proposed a tremendously hasky workaround.  A wizard adopted this into his
perl scroll, and failed to reflect later when no compiler adopted the practice.
This relic remains at the tail end of some functions in OpenSSL as
".byte 0xf3,0xc3".  Banish it straight to hell.
ok mlarkin, others also stared blankly

diff --git a/lib/libcrypto/aes/asm/aes-x86_64.pl b/lib/libcrypto/aes/asm/aes-x86_64.pl
index c37fd55..9072f60 100755 (executable)
--- a/lib/libcrypto/aes/asm/aes-x86_64.pl
+++ b/lib/libcrypto/aes/asm/aes-x86_64.pl
@@ -352,7 +352,7 @@ ___
 ___
        }
 $code.=<<___;
-       .byte   0xf3,0xc3                       # rep ret
+       retq
 .size  _x86_64_AES_encrypt,.-_x86_64_AES_encrypt
 ___
 
@@ -580,7 +580,7 @@ $code.=<<___;
        xor     4($key),$s1
        xor     8($key),$s2
        xor     12($key),$s3
-       .byte   0xf3,0xc3                       # rep ret
+       retq
 .size  _x86_64_AES_encrypt_compact,.-_x86_64_AES_encrypt_compact
 ___
 
@@ -925,7 +925,7 @@ ___
 ___
        }
 $code.=<<___;
-       .byte   0xf3,0xc3                       # rep ret
+       retq
 .size  _x86_64_AES_decrypt,.-_x86_64_AES_decrypt
 ___
 
@@ -1179,7 +1179,7 @@ $code.=<<___;
        xor     4($key),$s1
        xor     8($key),$s2
        xor     12($key),$s3
-       .byte   0xf3,0xc3                       # rep ret
+       retq
 .size  _x86_64_AES_decrypt_compact,.-_x86_64_AES_decrypt_compact
 ___
 
@@ -1496,7 +1496,7 @@ $code.=<<___;
 .Lbadpointer:
        mov     \$-1,%rax
 .Lexit:
-       .byte   0xf3,0xc3                       # rep ret
+       retq
 .size  _x86_64_AES_set_encrypt_key,.-_x86_64_AES_set_encrypt_key
 ___
 

diff --git a/lib/libcrypto/camellia/asm/cmll-x86_64.pl b/lib/libcrypto/camellia/asm/cmll-x86_64.pl
index a171c65..df6bf11 100644 (file)
--- a/lib/libcrypto/camellia/asm/cmll-x86_64.pl
+++ b/lib/libcrypto/camellia/asm/cmll-x86_64.pl
@@ -218,7 +218,7 @@ $code.=<<___;
        mov     $t2,@S[2]
        mov     $t3,@S[3]
 
-       .byte   0xf3,0xc3               # rep ret
+       retq
 .size  _x86_64_Camellia_encrypt,.-_x86_64_Camellia_encrypt
 
 # V1.x API
@@ -329,7 +329,7 @@ $code.=<<___;
        mov     $t0,@S[2]
        mov     $t1,@S[3]
 
-       .byte   0xf3,0xc3               # rep ret
+       retq
 .size  _x86_64_Camellia_decrypt,.-_x86_64_Camellia_decrypt
 ___
 

diff --git a/lib/libcrypto/perlasm/x86_64-xlate.pl b/lib/libcrypto/perlasm/x86_64-xlate.pl
index a8393d2..5f7f585 100755 (executable)
--- a/lib/libcrypto/perlasm/x86_64-xlate.pl
+++ b/lib/libcrypto/perlasm/x86_64-xlate.pl
@@ -149,7 +149,7 @@ my %globals;
                    $epilogue = "movq   8(%rsp),%rdi\n\t" .
                                "movq   16(%rsp),%rsi\n\t";
                }
-               $epilogue . ".byte      0xf3,0xc3";
+               $epilogue . "retq";
            } elsif ($self->{op} eq "call" && !$elf && $current_segment eq ".init") {
                ".p2align\t3\n\t.quad";
            } else {