superrob1500
/
mirror-linux
mirror of https://github.com/torvalds/linux
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

lib/crypto: gf128mul: Remove unused 4k_lle functions 

Remove the 4k_lle multiplication functions and the associated
gf128mul_table_le data table.  Their only user was the generic
implementation of GHASH, which has now been changed to use a different
implementation based on standard integer multiplication.

Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20260319061723.1140720-18-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
master
Eric Biggers 2026-03-18 23:17:18 -07:00
parent 662a05a245
commit 07241d6c92
2 changed files with 4 additions and 86 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
include/crypto/gf128mul.h
View File

@ -215,25 +215,14 @@ static inline void gf128mul_x_ble(le128 *r, const le128 *x)
r->b = cpu_to_le64((b << 1) ^ _tt);
}
/* 4k table optimization */
struct gf128mul_4k {
be128 t[256];
};
struct gf128mul_4k *gf128mul_init_4k_lle(const be128 *g);
void gf128mul_4k_lle(be128 *a, const struct gf128mul_4k *t);
void gf128mul_x8_ble(le128 *r, const le128 *x);
static inline void gf128mul_free_4k(struct gf128mul_4k *t)
{
kfree_sensitive(t);
}
/* 64k table optimization, implemented for bbe */
struct gf128mul_64k {
struct gf128mul_4k *t[16];
struct {
be128 t[256];
} *t[16];
};
/* First initialize with the constant factor with which you

73
lib/crypto/gf128mul.c
View File

@ -127,27 +127,9 @@
(i & 0x02 ? 0x0384 : 0) ^ (i & 0x01 ? 0x01c2 : 0) \
)
static const u16 gf128mul_table_le[256] = gf128mul_dat(xda_le);
static const u16 gf128mul_table_be[256] = gf128mul_dat(xda_be);
/*
* The following functions multiply a field element by x^8 in
* the polynomial field representation. They use 64-bit word operations
* to gain speed but compensate for machine endianness and hence work
* correctly on both styles of machine.
*/
static void gf128mul_x8_lle(be128 *x)
{
u64 a = be64_to_cpu(x->a);
u64 b = be64_to_cpu(x->b);
u64 _tt = gf128mul_table_le[b & 0xff];
x->b = cpu_to_be64((b >> 8) | (a << 56));
x->a = cpu_to_be64((a >> 8) ^ (_tt << 48));
}
/* time invariant version of gf128mul_x8_lle */
/* A table-less implementation of multiplying by x^8 */
static void gf128mul_x8_lle_ti(be128 *x)
{
u64 a = be64_to_cpu(x->a);
@ -305,58 +287,5 @@ void gf128mul_64k_bbe(be128 *a, const struct gf128mul_64k *t)
}
EXPORT_SYMBOL(gf128mul_64k_bbe);
/* This version uses 4k bytes of table space.
A 16 byte buffer has to be multiplied by a 16 byte key
value in GF(2^128). If we consider a GF(2^128) value in a
single byte, we can construct a table of the 256 16 byte
values that result from the 256 values of this byte.
This requires 4096 bytes. If we take the highest byte in
the buffer and use this table to get the result, we then
have to multiply by x^120 to get the final value. For the
next highest byte the result has to be multiplied by x^112
and so on. But we can do this by accumulating the result
in an accumulator starting with the result for the top
byte. We repeatedly multiply the accumulator value by
x^8 and then add in (i.e. xor) the 16 bytes of the next
lower byte in the buffer, stopping when we reach the
lowest byte. This requires a 4096 byte table.
*/
struct gf128mul_4k *gf128mul_init_4k_lle(const be128 *g)
{
struct gf128mul_4k *t;
int j, k;
t = kzalloc_obj(*t);
if (!t)
goto out;
t->t[128] = *g;
for (j = 64; j > 0; j >>= 1)
gf128mul_x_lle(&t->t[j], &t->t[j+j]);
for (j = 2; j < 256; j += j)
for (k = 1; k < j; ++k)
be128_xor(&t->t[j + k], &t->t[j], &t->t[k]);
out:
return t;
}
EXPORT_SYMBOL(gf128mul_init_4k_lle);
void gf128mul_4k_lle(be128 *a, const struct gf128mul_4k *t)
{
u8 *ap = (u8 *)a;
be128 r[1];
int i = 15;
*r = t->t[ap[15]];
while (i--) {
gf128mul_x8_lle(r);
be128_xor(r, r, &t->t[ap[i]]);
}
*a = *r;
}
EXPORT_SYMBOL(gf128mul_4k_lle);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Functions for multiplying elements of GF(2^128)");