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Add a control to disable the Poly1305 NEON code.

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Some phones have a buggy NEON unit and the Poly1305 NEON code fails on
them, even though other NEON code appears to work fine.

This change:

1) Fixes a bug where NEON was assumed even when the code wasn't compiled
   in NEON mode.

2) Adds a second NEON control bit that can be disabled in order to run
   NEON code, but not the Poly1305 NEON code.

https://code.google.com/p/chromium/issues/detail?id=341598

Change-Id: Icb121bf8dba47c7a46c7667f676ff7a4bc973625
Reviewed-on: https://boringssl-review.googlesource.com/1351
Reviewed-by: Adam Langley <agl@google.com>
This commit is contained in:
Adam Langley 2014-07-31 12:16:48 -07:00 committed by Adam Langley
parent eb7d2ed1fe
commit 31ebde9e5e
4 changed files with 44 additions and 9 deletions
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15
crypto/arm_arch.h
View File

@ -88,13 +88,22 @@
#endif
#if !__ASSEMBLER__
/* OPENSSL_armcap_P contains flags describing the capabilities of the CPU and
* is easy for assembly code to acesss. For C code, see the functions in
* |cpu.h|. */
extern unsigned int OPENSSL_armcap_P;
extern uint32_t OPENSSL_armcap_P;
#define ARMV7_NEON (1<<0)
#endif
/* ARMV7_NEON is true when a NEON unit is present in the current CPU. */
#define ARMV7_NEON (1 << 0)
/* ARMV7_NEON_FUNCTIONAL is true when the NEON unit doesn't contain subtle bugs.
* The Poly1305 NEON code is known to trigger bugs in the NEON units of some
* phones. If this bit isn't set then the Poly1305 NEON code won't be used.
* See https://code.google.com/p/chromium/issues/detail?id=341598. */
#define ARMV7_NEON_FUNCTIONAL (1 << 1)
#endif /* !__ASSEMBLER__ */
#endif /* OPENSSL_HEADER_THREAD_H */

17
crypto/cpu-arm.c
View File

@ -64,9 +64,9 @@
#include "arm_arch.h"
#if defined(__ARM_NEON__)
uint32_t OPENSSL_armcap_P = ARMV7_NEON;
uint32_t OPENSSL_armcap_P = ARMV7_NEON | ARMV7_NEON_FUNCTIONAL;
#else
uint32_t OPENSSL_armcap_P = ARMV7_NEON;
uint32_t OPENSSL_armcap_P = ARMV7_NEON_FUNCTIONAL;
#endif
char CRYPTO_is_NEON_capable() {
@ -81,4 +81,17 @@ void CRYPTO_set_NEON_capable(char neon_capable) {
}
}
char CRYPTO_is_NEON_functional() {
static const uint32_t kWantFlags = ARMV7_NEON | ARMV7_NEON_FUNCTIONAL;
return (OPENSSL_armcap_P & kWantFlags) == kWantFlags;
}
void CRYPTO_set_NEON_functional(char neon_functional) {
if (neon_functional) {
OPENSSL_armcap_P |= ARMV7_NEON_FUNCTIONAL;
} else {
OPENSSL_armcap_P &= ~ARMV7_NEON_FUNCTIONAL;
}
}
#endif /* defined(OPENSSL_ARM) */

6
crypto/poly1305/poly1305.c
View File

@ -166,7 +166,7 @@ void CRYPTO_poly1305_init(poly1305_state *statep, const uint8_t key[32]) {
uint32_t t0, t1, t2, t3;
#if defined(OPENSSL_ARM)
if (CRYPTO_is_NEON_capable()) {
if (CRYPTO_is_NEON_functional()) {
CRYPTO_poly1305_init_neon(statep, key);
return;
}
@ -213,7 +213,7 @@ void CRYPTO_poly1305_update(poly1305_state *statep, const uint8_t *in,
struct poly1305_state_st *state = (struct poly1305_state_st *)statep;
#if defined(OPENSSL_ARM)
if (CRYPTO_is_NEON_capable()) {
if (CRYPTO_is_NEON_functional()) {
CRYPTO_poly1305_update_neon(statep, in, in_len);
return;
}
@ -256,7 +256,7 @@ void CRYPTO_poly1305_finish(poly1305_state *statep, uint8_t mac[16]) {
uint32_t b, nb;
#if defined(OPENSSL_ARM)
if (CRYPTO_is_NEON_capable()) {
if (CRYPTO_is_NEON_functional()) {
CRYPTO_poly1305_finish_neon(statep, mac);
return;
}

15
include/openssl/cpu.h
View File

@ -91,8 +91,21 @@ OPENSSL_EXPORT char CRYPTO_is_NEON_capable();
/* CRYPTO_set_NEON_capable sets the return value of |CRYPTO_is_NEON_capable|.
* By default, unless the code was compiled with |-mfpu=neon|, NEON is assumed
* not to be present. It is not autodetected. */
* not to be present. It is not autodetected. Calling this with a zero
* argument also causes |CRYPTO_is_NEON_functional| to return false. */
OPENSSL_EXPORT void CRYPTO_set_NEON_capable(char neon_capable);
/* CRYPTO_is_NEON_functional returns true if the current CPU has a /working/
* NEON unit. Some phones have a NEON unit, but the Poly1305 NEON code causes
* it to fail. See https://code.google.com/p/chromium/issues/detail?id=341598 */
OPENSSL_EXPORT char CRYPTO_is_NEON_functional();
/* CRYPTO_set_NEON_functional sets the "NEON functional" flag. For
* |CRYPTO_is_NEON_functional| to return true, both this flag and the NEON flag
* must be true. By default NEON is assumed to be functional if the code was
* compiled with |-mfpu=neon| or if |CRYPTO_set_NEON_capable| has been called
* with a non-zero argument. */
OPENSSL_EXPORT void CRYPTO_set_NEON_functional(char neon_functional);
#endif /* OPENSSL_ARM */