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arithmetic internals: Further clarify bn_mul_mont ABI. #2254

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arithmetic internals: Further clarify bn_mul_mont ABI. #2254

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13 changes: 4 additions & 9 deletions crypto/fipsmodule/bn/asm/armv4-mont.pl
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Original file line number Diff line number Diff line change
Expand Up @@ -118,14 +118,9 @@
bn_mul_mont_nohw:
ldr ip,[sp,#4] @ load num
stmdb sp!,{r0,r2} @ sp points at argument block
cmp ip,#2
@ No return value in *ring*. Instead, the caller must ensure num >= 2
mov $num,ip @ load num
#ifdef __thumb2__
ittt lt
#endif
movlt r0,#0
addlt sp,sp,#2*4
blt .Labrt
@ No return value in *ring*

stmdb sp!,{r4-r12,lr} @ save 10 registers

Expand Down Expand Up @@ -259,8 +254,7 @@
add sp,sp,#4 @ skip over tp[num+1]
ldmia sp!,{r4-r12,lr} @ restore registers
add sp,sp,#2*4 @ skip over {r0,r2}
mov r0,#1
.Labrt:
@ No return value in *ring*
#if __ARM_ARCH>=5
ret @ bx lr
#else
Expand Down Expand Up @@ -714,6 +708,7 @@
mov sp,ip
vldmia sp!,{d8-d15}
ldmia sp!,{r4-r11}
@ No return value in *ring*
ret @ bx lr
.size bn_mul8x_mont_neon,.-bn_mul8x_mont_neon
#endif
Expand Down
8 changes: 4 additions & 4 deletions crypto/fipsmodule/bn/asm/armv8-mont.pl
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Original file line number Diff line number Diff line change
Expand Up @@ -55,7 +55,7 @@
$lo1,$hi1,$nj,$m1,$nlo,$nhi,
$ovf, $i,$j,$tp,$tj) = map("x$_",6..17,19..24);

# int bn_mul_mont(
# void bn_mul_mont(
$rp="x0"; # BN_ULONG *rp,
$ap="x1"; # const BN_ULONG *ap,
$bp="x2"; # const BN_ULONG *bp,
Expand Down Expand Up @@ -267,7 +267,7 @@
ldp x19,x20,[x29,#16]
mov sp,x29
ldp x21,x22,[x29,#32]
mov x0,#1
// No return value in *ring*.
ldp x23,x24,[x29,#48]
ldr x29,[sp],#64
AARCH64_VALIDATE_LINK_REGISTER
Expand Down Expand Up @@ -1041,7 +1041,7 @@
ldp x19,x20,[x29,#16]
mov sp,x29
ldp x21,x22,[x29,#32]
mov x0,#1
// No return value in *ring*.
ldp x23,x24,[x29,#48]
ldp x25,x26,[x29,#64]
ldp x27,x28,[x29,#80]
Expand Down Expand Up @@ -1502,7 +1502,7 @@
ldp x19,x20,[x29,#16]
mov sp,x29
ldp x21,x22,[x29,#32]
mov x0,#1
// No return value in *ring*.
ldp x23,x24,[x29,#48]
ldp x25,x26,[x29,#64]
ldp x27,x28,[x29,#80]
Expand Down
5 changes: 3 additions & 2 deletions crypto/fipsmodule/bn/asm/x86-mont.pl
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Original file line number Diff line number Diff line change
Expand Up @@ -65,8 +65,9 @@
$_bpend=&DWP(4*7,"esp");
$frame=32; # size of above frame rounded up to 16n

&xor ("eax","eax");
# No return value in *ring*. Instead, the caller must ensure num >= 4
&mov ("edi",&wparam(5)); # int num
# No return value in *ring*.

&lea ("esi",&wparam(0)); # put aside pointer to argument block
&lea ("edx",&wparam(1)); # load ap
Expand Down Expand Up @@ -325,7 +326,7 @@
&jge (&label("copy"));

&mov ("esp",$_sp); # pull saved stack pointer
&mov ("eax",1);
# No return value in *ring*.
&function_end("bn_mul_mont");

&asciz("Montgomery Multiplication for x86, CRYPTOGAMS by <appro\@openssl.org>");
Expand Down
8 changes: 4 additions & 4 deletions crypto/fipsmodule/bn/asm/x86_64-mont.pl
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Expand Up @@ -310,7 +310,7 @@

mov 8(%rsp,$num,8),%rsi # restore %rsp
.cfi_def_cfa %rsi,8
mov \$1,%rax
# No return value in *ring*
mov -48(%rsi),%r15
.cfi_restore %r15
mov -40(%rsi),%r14
Expand Down Expand Up @@ -757,7 +757,7 @@
$code.=<<___;
mov 8(%rsp,$num,8),%rsi # restore %rsp
.cfi_def_cfa %rsi, 8
mov \$1,%rax
# No return value in *ring*
mov -48(%rsi),%r15
.cfi_restore %r15
mov -40(%rsi),%r14
Expand Down Expand Up @@ -971,7 +971,7 @@
add \$32,$num
jnz .Lsqr8x_cond_copy

mov \$1,%rax
# No return value in *ring*
mov -48(%rsi),%r15
.cfi_restore %r15
mov -40(%rsi),%r14
Expand Down Expand Up @@ -1340,7 +1340,7 @@

mov %rdx,($tptr)

mov \$1,%rax
# No return value in *ring*.
mov -48(%rsi),%r15
.cfi_restore %r15
mov -40(%rsi),%r14
Expand Down
11 changes: 2 additions & 9 deletions src/arithmetic/ffi.rs
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Expand Up @@ -12,7 +12,7 @@
// OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
// CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

use super::{inout::AliasingSlices, n0::N0, LimbSliceError, MAX_LIMBS, MIN_LIMBS};
use super::{inout::AliasingSlices, n0::N0, LimbSliceError, MAX_LIMBS};
use crate::{c, limb::Limb, polyfill::usize_from_u32};
use core::mem::size_of;

Expand All @@ -33,7 +33,6 @@ macro_rules! bn_mul_mont_ffi {
use crate::{c, limb::Limb};
prefixed_extern! {
// `r` and/or 'a' and/or 'b' may alias.
// XXX: BoringSSL declares these functions to return `int`.
fn $f(
r: *mut Limb,
a: *const Limb,
Expand Down Expand Up @@ -66,14 +65,8 @@ pub(super) unsafe fn bn_mul_mont_ffi<Cpu, const LEN_MIN: usize, const LEN_MOD: u
len: c::size_t,
),
) -> Result<(), LimbSliceError> {
assert_eq!(n.len() % LEN_MOD, 0); // The caller should guard against this.

/// The x86 implementation of `bn_mul_mont`, at least, requires at least 4
/// limbs. For a long time we have required 4 limbs for all targets, though
/// this may be unnecessary.
const _MIN_LIMBS_AT_LEAST_4: () = assert!(MIN_LIMBS >= 4);
// We haven't tested shorter lengths.
assert!(LEN_MIN >= MIN_LIMBS);
assert!(LEN_MIN >= 4);
if n.len() < LEN_MIN {
return Err(LimbSliceError::too_short(n.len()));
}
Expand Down
3 changes: 3 additions & 0 deletions src/arithmetic/montgomery.rs
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Expand Up @@ -160,6 +160,9 @@ pub(super) fn limbs_mul_mont(
})
}
} else {
// The x86 implementation of `bn_mul_mont`, at least, requires at least 4
// limbs.
const _MIN_LIMBS_AT_LEAST_4: () = assert!(MIN_LIMBS >= 4);
bn_mul_mont_ffi!(in_out, n, n0, cpu, unsafe {
(MIN_LIMBS, MOD_FALLBACK, cpu::Features) => bn_mul_mont
})
Expand Down