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authorDenys Vlasenko2021-10-06 19:59:39 +0200
committerDenys Vlasenko2021-10-06 19:59:39 +0200
commit87e3f2e9f8a1c99b223b316fbefb5ae49c2a8fe2 (patch)
tree0751b9c52ace20c6cff5297fbf1f955b44f30faf /networking
parent911344a99889319a7dba8a725a64dc324597f9eb (diff)
downloadbusybox-87e3f2e9f8a1c99b223b316fbefb5ae49c2a8fe2.zip
busybox-87e3f2e9f8a1c99b223b316fbefb5ae49c2a8fe2.tar.gz
tls: P256: x86-64 optimized sp_256_sub_8_p256_mod
function old new delta sp_256_sub_8_p256_mod - 53 +53 sp_256_mont_reduce_8 223 217 -6 sp_256_mont_dbl_8 38 32 -6 sp_256_ecc_mulmod_8 1535 1529 -6 sp_256_proj_point_dbl_8 469 454 -15 ------------------------------------------------------------------------------ (add/remove: 1/0 grow/shrink: 0/4 up/down: 53/-33) Total: 20 bytes Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
Diffstat (limited to 'networking')
-rw-r--r--networking/tls_sp_c32.c32
1 files changed, 31 insertions, 1 deletions
diff --git a/networking/tls_sp_c32.c b/networking/tls_sp_c32.c
index 14a7c70..1391cb4 100644
--- a/networking/tls_sp_c32.c
+++ b/networking/tls_sp_c32.c
@@ -346,8 +346,8 @@ static int sp_256_sub_8(sp_digit* r, const sp_digit* a, const sp_digit* b)
#endif
}
-#if ALLOW_ASM && defined(__GNUC__) && defined(__i386__)
/* Sub p256_mod from a into r. (r = a - p256_mod). */
+#if ALLOW_ASM && defined(__GNUC__) && defined(__i386__)
static void sp_256_sub_8_p256_mod(sp_digit* r, const sp_digit* a)
{
sp_digit reg;
@@ -390,6 +390,36 @@ static void sp_256_sub_8_p256_mod(sp_digit* r, const sp_digit* a)
: "memory"
);
}
+#elif ALLOW_ASM && defined(__GNUC__) && defined(__x86_64__)
+static void sp_256_sub_8_p256_mod(sp_digit* r, const sp_digit* a)
+{
+ uint64_t reg;
+ uint64_t ooff;
+//p256_mod[3..0] = ffffffff00000001 0000000000000000 00000000ffffffff ffffffffffffffff
+ asm volatile (
+"\n movq (%0), %3"
+"\n addq $1, %3" // adding 1 is the same as subtracting ffffffffffffffff
+"\n movq %3, (%1)" //
+"\n cmc" // only carry bit needs inverting
+"\n"
+"\n movq 1*8(%0), %3"
+"\n sbbq %2, %3" // %2 holds 00000000ffffffff
+"\n movq %3, 1*8(%1)"
+"\n"
+"\n movq 2*8(%0), %3"
+"\n sbbq $0, %3"
+"\n movq %3, 2*8(%1)"
+"\n"
+"\n movq 3*8(%0), %3"
+"\n sbbq $0, %3" // adding 00000000ffffffff (in %2)
+"\n addq %2, %3" // is the same as subtracting ffffffff00000001
+"\n movq %3, 3*8(%1)"
+"\n"
+ : "=r" (a), "=r" (r), "=r" (ooff), "=r" (reg)
+ : "0" (a), "1" (r), "2" (0x00000000ffffffff)
+ : "memory"
+ );
+}
#else
# define sp_256_sub_8_p256_mod(r, a) sp_256_sub_8((r), (a), p256_mod)
#endif