Mailing List Archive

[PATCH 2/2] GCM: move look-up table to .data section and unshare between processes
* cipher/cipher-gcm.c (ATTR_ALIGNED_64): New.
(gcmR): Move to 'gcm_table' structure.
(gcm_table): New structure for look-up table with counters before and
after.
(gcmR): New macro.
(prefetch_table): Handle input with length not multiple of 256.
(do_prefetch_tables): Modify pre- and post-table counters to unshare
look-up table pages between processes.
--

GnuPG-bug-id: 4541
Signed-off-by: Jussi Kivilinna <jussi.kivilinna@iki.fi>
---
cipher/cipher-gcm.c | 106 ++++++++++++++++++++++++++++++++++-----------------
1 file changed, 70 insertions(+), 36 deletions(-)

diff --git a/cipher/cipher-gcm.c b/cipher/cipher-gcm.c
index 11f119aa7..194e2ec9d 100644
--- a/cipher/cipher-gcm.c
+++ b/cipher/cipher-gcm.c
@@ -30,6 +30,14 @@
#include "./cipher-internal.h"


+/* Helper macro to force alignment to 16 or 64 bytes. */
+#ifdef HAVE_GCC_ATTRIBUTE_ALIGNED
+# define ATTR_ALIGNED_64 __attribute__ ((aligned (64)))
+#else
+# define ATTR_ALIGNED_64
+#endif
+
+
#ifdef GCM_USE_INTEL_PCLMUL
extern void _gcry_ghash_setup_intel_pclmul (gcry_cipher_hd_t c);

@@ -83,40 +91,54 @@ ghash_armv7_neon (gcry_cipher_hd_t c, byte *result, const byte *buf,


#ifdef GCM_USE_TABLES
-static const u16 gcmR[256] = {
- 0x0000, 0x01c2, 0x0384, 0x0246, 0x0708, 0x06ca, 0x048c, 0x054e,
- 0x0e10, 0x0fd2, 0x0d94, 0x0c56, 0x0918, 0x08da, 0x0a9c, 0x0b5e,
- 0x1c20, 0x1de2, 0x1fa4, 0x1e66, 0x1b28, 0x1aea, 0x18ac, 0x196e,
- 0x1230, 0x13f2, 0x11b4, 0x1076, 0x1538, 0x14fa, 0x16bc, 0x177e,
- 0x3840, 0x3982, 0x3bc4, 0x3a06, 0x3f48, 0x3e8a, 0x3ccc, 0x3d0e,
- 0x3650, 0x3792, 0x35d4, 0x3416, 0x3158, 0x309a, 0x32dc, 0x331e,
- 0x2460, 0x25a2, 0x27e4, 0x2626, 0x2368, 0x22aa, 0x20ec, 0x212e,
- 0x2a70, 0x2bb2, 0x29f4, 0x2836, 0x2d78, 0x2cba, 0x2efc, 0x2f3e,
- 0x7080, 0x7142, 0x7304, 0x72c6, 0x7788, 0x764a, 0x740c, 0x75ce,
- 0x7e90, 0x7f52, 0x7d14, 0x7cd6, 0x7998, 0x785a, 0x7a1c, 0x7bde,
- 0x6ca0, 0x6d62, 0x6f24, 0x6ee6, 0x6ba8, 0x6a6a, 0x682c, 0x69ee,
- 0x62b0, 0x6372, 0x6134, 0x60f6, 0x65b8, 0x647a, 0x663c, 0x67fe,
- 0x48c0, 0x4902, 0x4b44, 0x4a86, 0x4fc8, 0x4e0a, 0x4c4c, 0x4d8e,
- 0x46d0, 0x4712, 0x4554, 0x4496, 0x41d8, 0x401a, 0x425c, 0x439e,
- 0x54e0, 0x5522, 0x5764, 0x56a6, 0x53e8, 0x522a, 0x506c, 0x51ae,
- 0x5af0, 0x5b32, 0x5974, 0x58b6, 0x5df8, 0x5c3a, 0x5e7c, 0x5fbe,
- 0xe100, 0xe0c2, 0xe284, 0xe346, 0xe608, 0xe7ca, 0xe58c, 0xe44e,
- 0xef10, 0xeed2, 0xec94, 0xed56, 0xe818, 0xe9da, 0xeb9c, 0xea5e,
- 0xfd20, 0xfce2, 0xfea4, 0xff66, 0xfa28, 0xfbea, 0xf9ac, 0xf86e,
- 0xf330, 0xf2f2, 0xf0b4, 0xf176, 0xf438, 0xf5fa, 0xf7bc, 0xf67e,
- 0xd940, 0xd882, 0xdac4, 0xdb06, 0xde48, 0xdf8a, 0xddcc, 0xdc0e,
- 0xd750, 0xd692, 0xd4d4, 0xd516, 0xd058, 0xd19a, 0xd3dc, 0xd21e,
- 0xc560, 0xc4a2, 0xc6e4, 0xc726, 0xc268, 0xc3aa, 0xc1ec, 0xc02e,
- 0xcb70, 0xcab2, 0xc8f4, 0xc936, 0xcc78, 0xcdba, 0xcffc, 0xce3e,
- 0x9180, 0x9042, 0x9204, 0x93c6, 0x9688, 0x974a, 0x950c, 0x94ce,
- 0x9f90, 0x9e52, 0x9c14, 0x9dd6, 0x9898, 0x995a, 0x9b1c, 0x9ade,
- 0x8da0, 0x8c62, 0x8e24, 0x8fe6, 0x8aa8, 0x8b6a, 0x892c, 0x88ee,
- 0x83b0, 0x8272, 0x8034, 0x81f6, 0x84b8, 0x857a, 0x873c, 0x86fe,
- 0xa9c0, 0xa802, 0xaa44, 0xab86, 0xaec8, 0xaf0a, 0xad4c, 0xac8e,
- 0xa7d0, 0xa612, 0xa454, 0xa596, 0xa0d8, 0xa11a, 0xa35c, 0xa29e,
- 0xb5e0, 0xb422, 0xb664, 0xb7a6, 0xb2e8, 0xb32a, 0xb16c, 0xb0ae,
- 0xbbf0, 0xba32, 0xb874, 0xb9b6, 0xbcf8, 0xbd3a, 0xbf7c, 0xbebe,
-};
+static struct
+{
+ volatile u32 counter_head;
+ u32 cacheline_align[64 / 4 - 1];
+ u16 R[256];
+ volatile u32 counter_tail;
+} gcm_table ATTR_ALIGNED_64 =
+ {
+ 0,
+ { 0, },
+ {
+ 0x0000, 0x01c2, 0x0384, 0x0246, 0x0708, 0x06ca, 0x048c, 0x054e,
+ 0x0e10, 0x0fd2, 0x0d94, 0x0c56, 0x0918, 0x08da, 0x0a9c, 0x0b5e,
+ 0x1c20, 0x1de2, 0x1fa4, 0x1e66, 0x1b28, 0x1aea, 0x18ac, 0x196e,
+ 0x1230, 0x13f2, 0x11b4, 0x1076, 0x1538, 0x14fa, 0x16bc, 0x177e,
+ 0x3840, 0x3982, 0x3bc4, 0x3a06, 0x3f48, 0x3e8a, 0x3ccc, 0x3d0e,
+ 0x3650, 0x3792, 0x35d4, 0x3416, 0x3158, 0x309a, 0x32dc, 0x331e,
+ 0x2460, 0x25a2, 0x27e4, 0x2626, 0x2368, 0x22aa, 0x20ec, 0x212e,
+ 0x2a70, 0x2bb2, 0x29f4, 0x2836, 0x2d78, 0x2cba, 0x2efc, 0x2f3e,
+ 0x7080, 0x7142, 0x7304, 0x72c6, 0x7788, 0x764a, 0x740c, 0x75ce,
+ 0x7e90, 0x7f52, 0x7d14, 0x7cd6, 0x7998, 0x785a, 0x7a1c, 0x7bde,
+ 0x6ca0, 0x6d62, 0x6f24, 0x6ee6, 0x6ba8, 0x6a6a, 0x682c, 0x69ee,
+ 0x62b0, 0x6372, 0x6134, 0x60f6, 0x65b8, 0x647a, 0x663c, 0x67fe,
+ 0x48c0, 0x4902, 0x4b44, 0x4a86, 0x4fc8, 0x4e0a, 0x4c4c, 0x4d8e,
+ 0x46d0, 0x4712, 0x4554, 0x4496, 0x41d8, 0x401a, 0x425c, 0x439e,
+ 0x54e0, 0x5522, 0x5764, 0x56a6, 0x53e8, 0x522a, 0x506c, 0x51ae,
+ 0x5af0, 0x5b32, 0x5974, 0x58b6, 0x5df8, 0x5c3a, 0x5e7c, 0x5fbe,
+ 0xe100, 0xe0c2, 0xe284, 0xe346, 0xe608, 0xe7ca, 0xe58c, 0xe44e,
+ 0xef10, 0xeed2, 0xec94, 0xed56, 0xe818, 0xe9da, 0xeb9c, 0xea5e,
+ 0xfd20, 0xfce2, 0xfea4, 0xff66, 0xfa28, 0xfbea, 0xf9ac, 0xf86e,
+ 0xf330, 0xf2f2, 0xf0b4, 0xf176, 0xf438, 0xf5fa, 0xf7bc, 0xf67e,
+ 0xd940, 0xd882, 0xdac4, 0xdb06, 0xde48, 0xdf8a, 0xddcc, 0xdc0e,
+ 0xd750, 0xd692, 0xd4d4, 0xd516, 0xd058, 0xd19a, 0xd3dc, 0xd21e,
+ 0xc560, 0xc4a2, 0xc6e4, 0xc726, 0xc268, 0xc3aa, 0xc1ec, 0xc02e,
+ 0xcb70, 0xcab2, 0xc8f4, 0xc936, 0xcc78, 0xcdba, 0xcffc, 0xce3e,
+ 0x9180, 0x9042, 0x9204, 0x93c6, 0x9688, 0x974a, 0x950c, 0x94ce,
+ 0x9f90, 0x9e52, 0x9c14, 0x9dd6, 0x9898, 0x995a, 0x9b1c, 0x9ade,
+ 0x8da0, 0x8c62, 0x8e24, 0x8fe6, 0x8aa8, 0x8b6a, 0x892c, 0x88ee,
+ 0x83b0, 0x8272, 0x8034, 0x81f6, 0x84b8, 0x857a, 0x873c, 0x86fe,
+ 0xa9c0, 0xa802, 0xaa44, 0xab86, 0xaec8, 0xaf0a, 0xad4c, 0xac8e,
+ 0xa7d0, 0xa612, 0xa454, 0xa596, 0xa0d8, 0xa11a, 0xa35c, 0xa29e,
+ 0xb5e0, 0xb422, 0xb664, 0xb7a6, 0xb2e8, 0xb32a, 0xb16c, 0xb0ae,
+ 0xbbf0, 0xba32, 0xb874, 0xb9b6, 0xbcf8, 0xbd3a, 0xbf7c, 0xbebe,
+ },
+ 0
+ };
+
+#define gcmR gcm_table.R

static inline
void prefetch_table(const void *tab, size_t len)
@@ -124,7 +146,7 @@ void prefetch_table(const void *tab, size_t len)
const volatile byte *vtab = tab;
size_t i;

- for (i = 0; i < len; i += 8 * 32)
+ for (i = 0; len - i >= 8 * 32; i += 8 * 32)
{
(void)vtab[i + 0 * 32];
(void)vtab[i + 1 * 32];
@@ -135,6 +157,10 @@ void prefetch_table(const void *tab, size_t len)
(void)vtab[i + 6 * 32];
(void)vtab[i + 7 * 32];
}
+ for (; i < len; i += 32)
+ {
+ (void)vtab[i];
+ }

(void)vtab[len - 1];
}
@@ -142,8 +168,16 @@ void prefetch_table(const void *tab, size_t len)
static inline void
do_prefetch_tables (const void *gcmM, size_t gcmM_size)
{
+ /* Modify counters to trigger copy-on-write and unsharing if physical pages
+ * of look-up table are shared between processes. Modifying counters also
+ * causes checksums for pages to change and hint same-page merging algorithm
+ * that these pages are frequently changing. */
+ gcm_table.counter_head++;
+ gcm_table.counter_tail++;
+
+ /* Prefetch look-up tables to cache. */
prefetch_table(gcmM, gcmM_size);
- prefetch_table(gcmR, sizeof(gcmR));
+ prefetch_table(&gcm_table, sizeof(gcm_table));
}

#ifdef GCM_TABLES_USE_U64


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