Remove the PPC_SHA1 implementation added in a6ef3518f9a ([PATCH] PPC assembly implementation of SHA1, 2005-04-22). When this was added Apple consumer hardware used the PPC architecture, and the implementation was intended to improve SHA-1 speed there. Since it was added we've moved to using sha1collisiondetection by default, and anyone wanting hard-rolled non-DC SHA-1 implementation can use OpenSSL's via the OPENSSL_SHA1 knob. The PPC_SHA1 originally originally targeted 32 bit PPC, and later the 64 bit PPC 970 (a.k.a. Apple PowerPC G5). See 926172c5e48 (block-sha1: improve code on large-register-set machines, 2009-08-10) for a reference about the performance on G5 (a comment in block-sha1/sha1.c being removed here). I can't get it to do anything but segfault on both the BE and LE POWER machines in the GCC compile farm[1]. Anyone who's concerned about performance on PPC these days is likely to be using the IBM POWER processors. There have been proposals to entirely remove non-sha1collisiondetection implementations from the tree[2]. I think per [3] that would be a bit overzealous. I.e. there are various set-ups git's speed is going to be more important than the relatively implausible SHA-1 collision attack, or where such attacks are entirely mitigated by other means (e.g. by incoming objects being checked with DC_SHA1). But that really doesn't apply to PPC_SHA1 in particular, which seems to have outlived its usefulness. As this gets rid of the only in-tree *.S assembly file we can remove the small bits of logic from the Makefile needed to build objects from *.S (as opposed to *.c) The code being removed here was also throwing warnings with the "-pedantic" flag, it could have been fixed as 544d93bc3b4 (block-sha1: remove use of obsolete x86 assembly, 2022-03-10) did for block-sha1/*, but as noted above let's remove it instead. 1. https://cfarm.tetaneutral.net/machines/list/ Tested on gcc{110,112,135,203}, a mixture of POWER [789] ppc64 and ppc64le. All segfault in anything needing object hashing (e.g. t/t1007-hash-object.sh) when compiled with PPC_SHA1=Y. 2. https://lore.kernel.org/git/20200223223758.120941-1-mh@xxxxxxxxxxxx/ 3. https://lore.kernel.org/git/20200224044732.GK1018190@xxxxxxxxxxxxxxxxxxxxxxx/ Acked-by: brian m. carlson" <sandals@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@xxxxxxxxx> --- INSTALL | 3 +- Makefile | 18 ++-- block-sha1/sha1.c | 4 - configure.ac | 3 - hash.h | 6 +- ppc/sha1.c | 72 --------------- ppc/sha1.h | 25 ------ ppc/sha1ppc.S | 224 ---------------------------------------------- 8 files changed, 8 insertions(+), 347 deletions(-) delete mode 100644 ppc/sha1.c delete mode 100644 ppc/sha1.h delete mode 100644 ppc/sha1ppc.S diff --git a/INSTALL b/INSTALL index 4140a3f5c8b..89b15d71df5 100644 --- a/INSTALL +++ b/INSTALL @@ -135,8 +135,7 @@ Issues of note: By default, git uses OpenSSL for SHA1 but it will use its own library (inspired by Mozilla's) with either NO_OPENSSL or - BLK_SHA1. Also included is a version optimized for PowerPC - (PPC_SHA1). + BLK_SHA1. - "libcurl" library is used for fetching and pushing repositories over http:// or https://, as well as by diff --git a/Makefile b/Makefile index eac30126e29..7feda7e79be 100644 --- a/Makefile +++ b/Makefile @@ -155,9 +155,6 @@ include shared.mak # Define BLK_SHA1 environment variable to make use of the bundled # optimized C SHA1 routine. # -# Define PPC_SHA1 environment variable when running make to make use of -# a bundled SHA1 routine optimized for PowerPC. -# # Define DC_SHA1 to unconditionally enable the collision-detecting sha1 # algorithm. This is slower, but may detect attempted collision attacks. # Takes priority over other *_SHA1 knobs. @@ -1802,6 +1799,10 @@ ifdef APPLE_COMMON_CRYPTO SHA1_MAX_BLOCK_SIZE = 1024L*1024L*1024L endif +ifdef PPC_SHA1 +$(error the PPC_SHA1 flag has been removed along with the PowerPC-specific SHA-1 implementation.) +endif + ifdef OPENSSL_SHA1 EXTLIBS += $(LIB_4_CRYPTO) BASIC_CFLAGS += -DSHA1_OPENSSL @@ -1810,10 +1811,6 @@ ifdef BLK_SHA1 LIB_OBJS += block-sha1/sha1.o BASIC_CFLAGS += -DSHA1_BLK else -ifdef PPC_SHA1 - LIB_OBJS += ppc/sha1.o ppc/sha1ppc.o - BASIC_CFLAGS += -DSHA1_PPC -else ifdef APPLE_COMMON_CRYPTO COMPAT_CFLAGS += -DCOMMON_DIGEST_FOR_OPENSSL BASIC_CFLAGS += -DSHA1_APPLE @@ -1847,7 +1844,6 @@ endif endif endif endif -endif ifdef OPENSSL_SHA256 EXTLIBS += $(LIB_4_CRYPTO) @@ -2594,14 +2590,10 @@ missing_compdb_dir = compdb_args = endif -ASM_SRC := $(wildcard $(OBJECTS:o=S)) -ASM_OBJ := $(ASM_SRC:S=o) -C_OBJ := $(filter-out $(ASM_OBJ),$(OBJECTS)) +C_OBJ := $(OBJECTS) $(C_OBJ): %.o: %.c GIT-CFLAGS $(missing_dep_dirs) $(missing_compdb_dir) $(QUIET_CC)$(CC) -o $*.o -c $(dep_args) $(compdb_args) $(ALL_CFLAGS) $(EXTRA_CPPFLAGS) $< -$(ASM_OBJ): %.o: %.S GIT-CFLAGS $(missing_dep_dirs) $(missing_compdb_dir) - $(QUIET_CC)$(CC) -o $*.o -c $(dep_args) $(compdb_args) $(ALL_CFLAGS) $(EXTRA_CPPFLAGS) $< %.s: %.c GIT-CFLAGS FORCE $(QUIET_CC)$(CC) -o $@ -S $(ALL_CFLAGS) $(EXTRA_CPPFLAGS) $< diff --git a/block-sha1/sha1.c b/block-sha1/sha1.c index 5974cd7dd3c..80cebd27564 100644 --- a/block-sha1/sha1.c +++ b/block-sha1/sha1.c @@ -28,10 +28,6 @@ * try to do the silly "optimize away loads" part because it won't * see what the value will be). * - * Ben Herrenschmidt reports that on PPC, the C version comes close - * to the optimized asm with this (ie on PPC you don't want that - * 'volatile', since there are lots of registers). - * * On ARM we get the best code generation by forcing a full memory barrier * between each SHA_ROUND, otherwise gcc happily get wild with spilling and * the stack frame size simply explode and performance goes down the drain. diff --git a/configure.ac b/configure.ac index 7dcd0482042..38ff86678a0 100644 --- a/configure.ac +++ b/configure.ac @@ -237,9 +237,6 @@ AC_MSG_NOTICE([CHECKS for site configuration]) # tests. These tests take up a significant amount of the total test time # but are not needed unless you plan to talk to SVN repos. # -# Define PPC_SHA1 environment variable when running make to make use of -# a bundled SHA1 routine optimized for PowerPC. -# # Define NO_OPENSSL environment variable if you do not have OpenSSL. # # Define OPENSSLDIR=/foo/bar if your openssl header and library files are in diff --git a/hash.h b/hash.h index ea87ae9d92f..36b64165fc9 100644 --- a/hash.h +++ b/hash.h @@ -4,9 +4,7 @@ #include "git-compat-util.h" #include "repository.h" -#if defined(SHA1_PPC) -#include "ppc/sha1.h" -#elif defined(SHA1_APPLE) +#if defined(SHA1_APPLE) #include <CommonCrypto/CommonDigest.h> #elif defined(SHA1_OPENSSL) #include <openssl/sha.h> @@ -32,7 +30,7 @@ * platform's underlying implementation of SHA-1; could be OpenSSL, * blk_SHA, Apple CommonCrypto, etc... Note that the relevant * SHA-1 header may have already defined platform_SHA_CTX for our - * own implementations like block-sha1 and ppc-sha1, so we list + * own implementations like block-sha1, so we list * the default for OpenSSL compatible SHA-1 implementations here. */ #define platform_SHA_CTX SHA_CTX diff --git a/ppc/sha1.c b/ppc/sha1.c deleted file mode 100644 index 1b705cee1fe..00000000000 --- a/ppc/sha1.c +++ /dev/null @@ -1,72 +0,0 @@ -/* - * SHA-1 implementation. - * - * Copyright (C) 2005 Paul Mackerras <paulus@xxxxxxxxx> - * - * This version assumes we are running on a big-endian machine. - * It calls an external sha1_core() to process blocks of 64 bytes. - */ -#include <stdio.h> -#include <string.h> -#include "sha1.h" - -void ppc_sha1_core(uint32_t *hash, const unsigned char *p, - unsigned int nblocks); - -int ppc_SHA1_Init(ppc_SHA_CTX *c) -{ - c->hash[0] = 0x67452301; - c->hash[1] = 0xEFCDAB89; - c->hash[2] = 0x98BADCFE; - c->hash[3] = 0x10325476; - c->hash[4] = 0xC3D2E1F0; - c->len = 0; - c->cnt = 0; - return 0; -} - -int ppc_SHA1_Update(ppc_SHA_CTX *c, const void *ptr, unsigned long n) -{ - unsigned long nb; - const unsigned char *p = ptr; - - c->len += (uint64_t) n << 3; - while (n != 0) { - if (c->cnt || n < 64) { - nb = 64 - c->cnt; - if (nb > n) - nb = n; - memcpy(&c->buf.b[c->cnt], p, nb); - if ((c->cnt += nb) == 64) { - ppc_sha1_core(c->hash, c->buf.b, 1); - c->cnt = 0; - } - } else { - nb = n >> 6; - ppc_sha1_core(c->hash, p, nb); - nb <<= 6; - } - n -= nb; - p += nb; - } - return 0; -} - -int ppc_SHA1_Final(unsigned char *hash, ppc_SHA_CTX *c) -{ - unsigned int cnt = c->cnt; - - c->buf.b[cnt++] = 0x80; - if (cnt > 56) { - if (cnt < 64) - memset(&c->buf.b[cnt], 0, 64 - cnt); - ppc_sha1_core(c->hash, c->buf.b, 1); - cnt = 0; - } - if (cnt < 56) - memset(&c->buf.b[cnt], 0, 56 - cnt); - c->buf.l[7] = c->len; - ppc_sha1_core(c->hash, c->buf.b, 1); - memcpy(hash, c->hash, 20); - return 0; -} diff --git a/ppc/sha1.h b/ppc/sha1.h deleted file mode 100644 index 9b24b326159..00000000000 --- a/ppc/sha1.h +++ /dev/null @@ -1,25 +0,0 @@ -/* - * SHA-1 implementation. - * - * Copyright (C) 2005 Paul Mackerras <paulus@xxxxxxxxx> - */ -#include <stdint.h> - -typedef struct { - uint32_t hash[5]; - uint32_t cnt; - uint64_t len; - union { - unsigned char b[64]; - uint64_t l[8]; - } buf; -} ppc_SHA_CTX; - -int ppc_SHA1_Init(ppc_SHA_CTX *c); -int ppc_SHA1_Update(ppc_SHA_CTX *c, const void *p, unsigned long n); -int ppc_SHA1_Final(unsigned char *hash, ppc_SHA_CTX *c); - -#define platform_SHA_CTX ppc_SHA_CTX -#define platform_SHA1_Init ppc_SHA1_Init -#define platform_SHA1_Update ppc_SHA1_Update -#define platform_SHA1_Final ppc_SHA1_Final diff --git a/ppc/sha1ppc.S b/ppc/sha1ppc.S deleted file mode 100644 index 1711eef6e71..00000000000 --- a/ppc/sha1ppc.S +++ /dev/null @@ -1,224 +0,0 @@ -/* - * SHA-1 implementation for PowerPC. - * - * Copyright (C) 2005 Paul Mackerras <paulus@xxxxxxxxx> - */ - -/* - * PowerPC calling convention: - * %r0 - volatile temp - * %r1 - stack pointer. - * %r2 - reserved - * %r3-%r12 - Incoming arguments & return values; volatile. - * %r13-%r31 - Callee-save registers - * %lr - Return address, volatile - * %ctr - volatile - * - * Register usage in this routine: - * %r0 - temp - * %r3 - argument (pointer to 5 words of SHA state) - * %r4 - argument (pointer to data to hash) - * %r5 - Constant K in SHA round (initially number of blocks to hash) - * %r6-%r10 - Working copies of SHA variables A..E (actually E..A order) - * %r11-%r26 - Data being hashed W[]. - * %r27-%r31 - Previous copies of A..E, for final add back. - * %ctr - loop count - */ - - -/* - * We roll the registers for A, B, C, D, E around on each - * iteration; E on iteration t is D on iteration t+1, and so on. - * We use registers 6 - 10 for this. (Registers 27 - 31 hold - * the previous values.) - */ -#define RA(t) (((t)+4)%5+6) -#define RB(t) (((t)+3)%5+6) -#define RC(t) (((t)+2)%5+6) -#define RD(t) (((t)+1)%5+6) -#define RE(t) (((t)+0)%5+6) - -/* We use registers 11 - 26 for the W values */ -#define W(t) ((t)%16+11) - -/* Register 5 is used for the constant k */ - -/* - * The basic SHA-1 round function is: - * E += ROTL(A,5) + F(B,C,D) + W[i] + K; B = ROTL(B,30) - * Then the variables are renamed: (A,B,C,D,E) = (E,A,B,C,D). - * - * Every 20 rounds, the function F() and the constant K changes: - * - 20 rounds of f0(b,c,d) = "bit wise b ? c : d" = (^b & d) + (b & c) - * - 20 rounds of f1(b,c,d) = b^c^d = (b^d)^c - * - 20 rounds of f2(b,c,d) = majority(b,c,d) = (b&d) + ((b^d)&c) - * - 20 more rounds of f1(b,c,d) - * - * These are all scheduled for near-optimal performance on a G4. - * The G4 is a 3-issue out-of-order machine with 3 ALUs, but it can only - * *consider* starting the oldest 3 instructions per cycle. So to get - * maximum performance out of it, you have to treat it as an in-order - * machine. Which means interleaving the computation round t with the - * computation of W[t+4]. - * - * The first 16 rounds use W values loaded directly from memory, while the - * remaining 64 use values computed from those first 16. We preload - * 4 values before starting, so there are three kinds of rounds: - * - The first 12 (all f0) also load the W values from memory. - * - The next 64 compute W(i+4) in parallel. 8*f0, 20*f1, 20*f2, 16*f1. - * - The last 4 (all f1) do not do anything with W. - * - * Therefore, we have 6 different round functions: - * STEPD0_LOAD(t,s) - Perform round t and load W(s). s < 16 - * STEPD0_UPDATE(t,s) - Perform round t and compute W(s). s >= 16. - * STEPD1_UPDATE(t,s) - * STEPD2_UPDATE(t,s) - * STEPD1(t) - Perform round t with no load or update. - * - * The G5 is more fully out-of-order, and can find the parallelism - * by itself. The big limit is that it has a 2-cycle ALU latency, so - * even though it's 2-way, the code has to be scheduled as if it's - * 4-way, which can be a limit. To help it, we try to schedule the - * read of RA(t) as late as possible so it doesn't stall waiting for - * the previous round's RE(t-1), and we try to rotate RB(t) as early - * as possible while reading RC(t) (= RB(t-1)) as late as possible. - */ - -/* the initial loads. */ -#define LOADW(s) \ - lwz W(s),(s)*4(%r4) - -/* - * Perform a step with F0, and load W(s). Uses W(s) as a temporary - * before loading it. - * This is actually 10 instructions, which is an awkward fit. - * It can execute grouped as listed, or delayed one instruction. - * (If delayed two instructions, there is a stall before the start of the - * second line.) Thus, two iterations take 7 cycles, 3.5 cycles per round. - */ -#define STEPD0_LOAD(t,s) \ -add RE(t),RE(t),W(t); andc %r0,RD(t),RB(t); and W(s),RC(t),RB(t); \ -add RE(t),RE(t),%r0; rotlwi %r0,RA(t),5; rotlwi RB(t),RB(t),30; \ -add RE(t),RE(t),W(s); add %r0,%r0,%r5; lwz W(s),(s)*4(%r4); \ -add RE(t),RE(t),%r0 - -/* - * This is likewise awkward, 13 instructions. However, it can also - * execute starting with 2 out of 3 possible moduli, so it does 2 rounds - * in 9 cycles, 4.5 cycles/round. - */ -#define STEPD0_UPDATE(t,s,loadk...) \ -add RE(t),RE(t),W(t); andc %r0,RD(t),RB(t); xor W(s),W((s)-16),W((s)-3); \ -add RE(t),RE(t),%r0; and %r0,RC(t),RB(t); xor W(s),W(s),W((s)-8); \ -add RE(t),RE(t),%r0; rotlwi %r0,RA(t),5; xor W(s),W(s),W((s)-14); \ -add RE(t),RE(t),%r5; loadk; rotlwi RB(t),RB(t),30; rotlwi W(s),W(s),1; \ -add RE(t),RE(t),%r0 - -/* Nicely optimal. Conveniently, also the most common. */ -#define STEPD1_UPDATE(t,s,loadk...) \ -add RE(t),RE(t),W(t); xor %r0,RD(t),RB(t); xor W(s),W((s)-16),W((s)-3); \ -add RE(t),RE(t),%r5; loadk; xor %r0,%r0,RC(t); xor W(s),W(s),W((s)-8); \ -add RE(t),RE(t),%r0; rotlwi %r0,RA(t),5; xor W(s),W(s),W((s)-14); \ -add RE(t),RE(t),%r0; rotlwi RB(t),RB(t),30; rotlwi W(s),W(s),1 - -/* - * The naked version, no UPDATE, for the last 4 rounds. 3 cycles per. - * We could use W(s) as a temp register, but we don't need it. - */ -#define STEPD1(t) \ - add RE(t),RE(t),W(t); xor %r0,RD(t),RB(t); \ -rotlwi RB(t),RB(t),30; add RE(t),RE(t),%r5; xor %r0,%r0,RC(t); \ -add RE(t),RE(t),%r0; rotlwi %r0,RA(t),5; /* spare slot */ \ -add RE(t),RE(t),%r0 - -/* - * 14 instructions, 5 cycles per. The majority function is a bit - * awkward to compute. This can execute with a 1-instruction delay, - * but it causes a 2-instruction delay, which triggers a stall. - */ -#define STEPD2_UPDATE(t,s,loadk...) \ -add RE(t),RE(t),W(t); and %r0,RD(t),RB(t); xor W(s),W((s)-16),W((s)-3); \ -add RE(t),RE(t),%r0; xor %r0,RD(t),RB(t); xor W(s),W(s),W((s)-8); \ -add RE(t),RE(t),%r5; loadk; and %r0,%r0,RC(t); xor W(s),W(s),W((s)-14); \ -add RE(t),RE(t),%r0; rotlwi %r0,RA(t),5; rotlwi W(s),W(s),1; \ -add RE(t),RE(t),%r0; rotlwi RB(t),RB(t),30 - -#define STEP0_LOAD4(t,s) \ - STEPD0_LOAD(t,s); \ - STEPD0_LOAD((t+1),(s)+1); \ - STEPD0_LOAD((t)+2,(s)+2); \ - STEPD0_LOAD((t)+3,(s)+3) - -#define STEPUP4(fn, t, s, loadk...) \ - STEP##fn##_UPDATE(t,s,); \ - STEP##fn##_UPDATE((t)+1,(s)+1,); \ - STEP##fn##_UPDATE((t)+2,(s)+2,); \ - STEP##fn##_UPDATE((t)+3,(s)+3,loadk) - -#define STEPUP20(fn, t, s, loadk...) \ - STEPUP4(fn, t, s,); \ - STEPUP4(fn, (t)+4, (s)+4,); \ - STEPUP4(fn, (t)+8, (s)+8,); \ - STEPUP4(fn, (t)+12, (s)+12,); \ - STEPUP4(fn, (t)+16, (s)+16, loadk) - - .globl ppc_sha1_core -ppc_sha1_core: - stwu %r1,-80(%r1) - stmw %r13,4(%r1) - - /* Load up A - E */ - lmw %r27,0(%r3) - - mtctr %r5 - -1: - LOADW(0) - lis %r5,0x5a82 - mr RE(0),%r31 - LOADW(1) - mr RD(0),%r30 - mr RC(0),%r29 - LOADW(2) - ori %r5,%r5,0x7999 /* K0-19 */ - mr RB(0),%r28 - LOADW(3) - mr RA(0),%r27 - - STEP0_LOAD4(0, 4) - STEP0_LOAD4(4, 8) - STEP0_LOAD4(8, 12) - STEPUP4(D0, 12, 16,) - STEPUP4(D0, 16, 20, lis %r5,0x6ed9) - - ori %r5,%r5,0xeba1 /* K20-39 */ - STEPUP20(D1, 20, 24, lis %r5,0x8f1b) - - ori %r5,%r5,0xbcdc /* K40-59 */ - STEPUP20(D2, 40, 44, lis %r5,0xca62) - - ori %r5,%r5,0xc1d6 /* K60-79 */ - STEPUP4(D1, 60, 64,) - STEPUP4(D1, 64, 68,) - STEPUP4(D1, 68, 72,) - STEPUP4(D1, 72, 76,) - addi %r4,%r4,64 - STEPD1(76) - STEPD1(77) - STEPD1(78) - STEPD1(79) - - /* Add results to original values */ - add %r31,%r31,RE(0) - add %r30,%r30,RD(0) - add %r29,%r29,RC(0) - add %r28,%r28,RB(0) - add %r27,%r27,RA(0) - - bdnz 1b - - /* Save final hash, restore registers, and return */ - stmw %r27,0(%r3) - lmw %r13,4(%r1) - addi %r1,%r1,80 - blr -- 2.37.3.1406.g184357183a6
