generic-library/openssl
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

Add volatile qualifications to two blocks of inline asm to stop GCC from

Browse Source 
eliminating them as dead code.

Both volatile and "memory" are used because of some concern that the compiler
may still cache values across the asm block without it, and because this was
such a painful debugging session that I wanted to ensure that it's never
repeated.

(cherry picked from commit 7753a3a684)

Conflicts:
	crypto/bn/asm/x86_64-gcc.c

Reviewed-by: Rich Salz <rsalz@openssl.org>
This commit is contained in:
Adam Langley
2013-06-03 15:45:11 -04:00
committed by Emilia Kasper
parent 0ed8e95c4b
commit a90b1e32d2
1 changed files with 4 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

8
crypto/bn/asm/x86_64-gcc.c
View File

@@ -189,7 +189,7 @@ BN_ULONG bn_add_words (BN_ULONG *rp, const BN_ULONG *ap, const BN_ULONG *bp,int
if (n <= 0) return 0; if (n <= 0) return 0;
asm ( asm volatile (
" subq %2,%2 \n" " subq %2,%2 \n"
".p2align 4 \n" ".p2align 4 \n"
"1: movq (%4,%2,8),%0 \n" "1: movq (%4,%2,8),%0 \n"
@@ -200,7 +200,7 @@ BN_ULONG bn_add_words (BN_ULONG *rp, const BN_ULONG *ap, const BN_ULONG *bp,int
" sbbq %0,%0 \n" " sbbq %0,%0 \n"
: "=&a"(ret),"+c"(n),"=&r"(i) : "=&a"(ret),"+c"(n),"=&r"(i)
: "r"(rp),"r"(ap),"r"(bp) : "r"(rp),"r"(ap),"r"(bp)
: "cc" : "cc", "memory"
); );
return ret&1; return ret&1;
@@ -212,7 +212,7 @@ BN_ULONG bn_sub_words (BN_ULONG *rp, const BN_ULONG *ap, const BN_ULONG *bp,int
if (n <= 0) return 0; if (n <= 0) return 0;
asm ( asm volatile (
" subq %2,%2 \n" " subq %2,%2 \n"
".p2align 4 \n" ".p2align 4 \n"
"1: movq (%4,%2,8),%0 \n" "1: movq (%4,%2,8),%0 \n"
@@ -223,7 +223,7 @@ BN_ULONG bn_sub_words (BN_ULONG *rp, const BN_ULONG *ap, const BN_ULONG *bp,int
" sbbq %0,%0 \n" " sbbq %0,%0 \n"
: "=&a"(ret),"+c"(n),"=&r"(i) : "=&a"(ret),"+c"(n),"=&r"(i)
: "r"(rp),"r"(ap),"r"(bp) : "r"(rp),"r"(ap),"r"(bp)
: "cc" : "cc", "memory"
); );
return ret&1; return ret&1;