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Add an option (LIBSA_CREAD_NOCRC) to disable gunzip CRC32 calculation.

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No obvious sideeffect on booting i386 GENERIC kernels (without the option).
Closes PR/50638 (Extreme slowness on loading gzipped kernels on old CPUs).
This commit is contained in:
tsutsui 2016-01-17 04:35:42 +00:00
parent d943d96739
commit 89a198b4f5
1 changed files with 27 additions and 6 deletions
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33
sys/lib/libsa/cread.c
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@ -1,4 +1,4 @@
/* $NetBSD: cread.c,v 1.27 2015/07/25 07:06:11 isaki Exp $ */
/* $NetBSD: cread.c,v 1.28 2016/01/17 04:35:42 tsutsui Exp $ */
/*
* Copyright (c) 1996
@ -87,10 +87,9 @@ void zcfree(void *, void *);
void zmemcpy(unsigned char *, unsigned char *, unsigned int);
/*
* The libkern version of this function uses an 8K set of tables.
* This is the double-loop version of LE CRC32 from if_ethersubr,
* lightly modified -- it is 200 bytes smaller than the version using
* a 4-bit table and at least 8K smaller than the libkern version.
* lightly modified -- it is ~1KB smaller than libkern version with
* DYNAMIC_CRC_TABLE but too much slower especially on ancient poor CPUs.
*/
#ifndef ETHER_CRC_POLY_LE
#define ETHER_CRC_POLY_LE 0xedb88320
@ -98,6 +97,10 @@ void zmemcpy(unsigned char *, unsigned char *, unsigned int);
uint32_t
crc32(uint32_t crc, const uint8_t *const buf, size_t len)
{
#if defined(LIBSA_CREAD_NOCRC)
/* XXX provide a stub to avoid pulling a larger libkern version */
return crc;
#else
uint32_t c, carry;
size_t i, j;
@ -114,6 +117,7 @@ crc32(uint32_t crc, const uint8_t *const buf, size_t len)
}
}
return (crc ^ 0xffffffffU);
#endif /* defined(LIBSA_CREAD_NOCRC) */
}
/*
@ -317,7 +321,9 @@ ssize_t
read(int fd, void *buf, size_t len)
{
struct sd *s;
#if !defined(LIBSA_CREAD_NOCRC)
unsigned char *start = buf; /* starting point for crc computation */
#endif
s = ss[fd];
@ -373,13 +379,24 @@ read(int fd, void *buf, size_t len)
s->z_err = inflate(&(s->stream), Z_NO_FLUSH);
if (s->z_err == Z_STREAM_END) {
uint32_t total_out;
#if !defined(LIBSA_CREAD_NOCRC)
uint32_t crc;
/* Check CRC and original size */
s->crc = crc32(s->crc, start, (unsigned int)
(s->stream.next_out - start));
start = s->stream.next_out;
crc = getLong(s);
#else
(void)getLong(s);
#endif
total_out = getLong(s);
if (getLong(s) != s->crc ||
getLong(s) != s->stream.total_out) {
if (
#if !defined(LIBSA_CREAD_NOCRC)
crc != s->crc ||
#endif
total_out != s->stream.total_out) {
s->z_err = Z_DATA_ERROR;
} else {
@ -387,7 +404,9 @@ read(int fd, void *buf, size_t len)
check_header(s);
if (s->z_err == Z_OK) {
inflateReset(&(s->stream));
#if !defined(LIBSA_CREAD_NOCRC)
s->crc = crc32(0L, Z_NULL, 0);
#endif
}
}
}
@ -395,8 +414,10 @@ read(int fd, void *buf, size_t len)
break;
}
#if !defined(LIBSA_CREAD_NOCRC)
s->crc = crc32(s->crc, start,
(unsigned int)(s->stream.next_out - start));
#endif
return (int)(len - s->stream.avail_out);
}