| From 3a92d687c8015860a19213e3c102cad6b722f83c Mon Sep 17 00:00:00 2001 |
| From: Herbert Xu <herbert@gondor.apana.org.au> |
| Date: Sun, 5 Feb 2012 15:09:28 +1100 |
| Subject: crypto: sha512 - Avoid stack bloat on i386 |
| |
| From: Herbert Xu <herbert@gondor.apana.org.au> |
| |
| commit 3a92d687c8015860a19213e3c102cad6b722f83c upstream. |
| |
| Unfortunately in reducing W from 80 to 16 we ended up unrolling |
| the loop twice. As gcc has issues dealing with 64-bit ops on |
| i386 this means that we end up using even more stack space (>1K). |
| |
| This patch solves the W reduction by moving LOAD_OP/BLEND_OP |
| into the loop itself, thus avoiding the need to duplicate it. |
| |
| While the stack space still isn't great (>0.5K) it is at least |
| in the same ball park as the amount of stack used for our C sha1 |
| implementation. |
| |
| Note that this patch basically reverts to the original code so |
| the diff looks bigger than it really is. |
| |
| Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| crypto/sha512_generic.c | 68 ++++++++++++++++++++++-------------------------- |
| 1 file changed, 32 insertions(+), 36 deletions(-) |
| |
| --- a/crypto/sha512_generic.c |
| +++ b/crypto/sha512_generic.c |
| @@ -89,46 +89,42 @@ sha512_transform(u64 *state, const u8 *i |
| int i; |
| u64 W[16]; |
| |
| - /* load the input */ |
| - for (i = 0; i < 16; i++) |
| - LOAD_OP(i, W, input); |
| - |
| /* load the state into our registers */ |
| a=state[0]; b=state[1]; c=state[2]; d=state[3]; |
| e=state[4]; f=state[5]; g=state[6]; h=state[7]; |
| |
| -#define SHA512_0_15(i, a, b, c, d, e, f, g, h) \ |
| - t1 = h + e1(e) + Ch(e, f, g) + sha512_K[i] + W[i]; \ |
| - t2 = e0(a) + Maj(a, b, c); \ |
| - d += t1; \ |
| - h = t1 + t2 |
| - |
| -#define SHA512_16_79(i, a, b, c, d, e, f, g, h) \ |
| - BLEND_OP(i, W); \ |
| - t1 = h + e1(e) + Ch(e, f, g) + sha512_K[i] + W[(i)&15]; \ |
| - t2 = e0(a) + Maj(a, b, c); \ |
| - d += t1; \ |
| - h = t1 + t2 |
| - |
| - for (i = 0; i < 16; i += 8) { |
| - SHA512_0_15(i, a, b, c, d, e, f, g, h); |
| - SHA512_0_15(i + 1, h, a, b, c, d, e, f, g); |
| - SHA512_0_15(i + 2, g, h, a, b, c, d, e, f); |
| - SHA512_0_15(i + 3, f, g, h, a, b, c, d, e); |
| - SHA512_0_15(i + 4, e, f, g, h, a, b, c, d); |
| - SHA512_0_15(i + 5, d, e, f, g, h, a, b, c); |
| - SHA512_0_15(i + 6, c, d, e, f, g, h, a, b); |
| - SHA512_0_15(i + 7, b, c, d, e, f, g, h, a); |
| - } |
| - for (i = 16; i < 80; i += 8) { |
| - SHA512_16_79(i, a, b, c, d, e, f, g, h); |
| - SHA512_16_79(i + 1, h, a, b, c, d, e, f, g); |
| - SHA512_16_79(i + 2, g, h, a, b, c, d, e, f); |
| - SHA512_16_79(i + 3, f, g, h, a, b, c, d, e); |
| - SHA512_16_79(i + 4, e, f, g, h, a, b, c, d); |
| - SHA512_16_79(i + 5, d, e, f, g, h, a, b, c); |
| - SHA512_16_79(i + 6, c, d, e, f, g, h, a, b); |
| - SHA512_16_79(i + 7, b, c, d, e, f, g, h, a); |
| + /* now iterate */ |
| + for (i=0; i<80; i+=8) { |
| + if (!(i & 8)) { |
| + int j; |
| + |
| + if (i < 16) { |
| + /* load the input */ |
| + for (j = 0; j < 16; j++) |
| + LOAD_OP(i + j, W, input); |
| + } else { |
| + for (j = 0; j < 16; j++) { |
| + BLEND_OP(i + j, W); |
| + } |
| + } |
| + } |
| + |
| + t1 = h + e1(e) + Ch(e,f,g) + sha512_K[i ] + W[(i & 15)]; |
| + t2 = e0(a) + Maj(a,b,c); d+=t1; h=t1+t2; |
| + t1 = g + e1(d) + Ch(d,e,f) + sha512_K[i+1] + W[(i & 15) + 1]; |
| + t2 = e0(h) + Maj(h,a,b); c+=t1; g=t1+t2; |
| + t1 = f + e1(c) + Ch(c,d,e) + sha512_K[i+2] + W[(i & 15) + 2]; |
| + t2 = e0(g) + Maj(g,h,a); b+=t1; f=t1+t2; |
| + t1 = e + e1(b) + Ch(b,c,d) + sha512_K[i+3] + W[(i & 15) + 3]; |
| + t2 = e0(f) + Maj(f,g,h); a+=t1; e=t1+t2; |
| + t1 = d + e1(a) + Ch(a,b,c) + sha512_K[i+4] + W[(i & 15) + 4]; |
| + t2 = e0(e) + Maj(e,f,g); h+=t1; d=t1+t2; |
| + t1 = c + e1(h) + Ch(h,a,b) + sha512_K[i+5] + W[(i & 15) + 5]; |
| + t2 = e0(d) + Maj(d,e,f); g+=t1; c=t1+t2; |
| + t1 = b + e1(g) + Ch(g,h,a) + sha512_K[i+6] + W[(i & 15) + 6]; |
| + t2 = e0(c) + Maj(c,d,e); f+=t1; b=t1+t2; |
| + t1 = a + e1(f) + Ch(f,g,h) + sha512_K[i+7] + W[(i & 15) + 7]; |
| + t2 = e0(b) + Maj(b,c,d); e+=t1; a=t1+t2; |
| } |
| |
| state[0] += a; state[1] += b; state[2] += c; state[3] += d; |