Merge branch 'hash' of git://ftp.sciencehorizons.net/linux
Pull string hash improvements from George Spelvin:
"This series does several related things:
- Makes the dcache hash (fs/namei.c) useful for general kernel use.
(Thanks to Bruce for noticing the zero-length corner case)
- Converts the string hashes in <linux/sunrpc/svcauth.h> to use the
above.
- Avoids 64-bit multiplies in hash_64() on 32-bit platforms. Two
32-bit multiplies will do well enough.
- Rids the world of the bad hash multipliers in hash_32.
This finishes the job started in commit 689de1d6ca ("Minimal
fix-up of bad hashing behavior of hash_64()")
The vast majority of Linux architectures have hardware support for
32x32-bit multiply and so derive no benefit from "simplified"
multipliers.
The few processors that do not (68000, h8/300 and some models of
Microblaze) have arch-specific implementations added. Those
patches are last in the series.
- Overhauls the dcache hash mixing.
The patch in commit 0fed3ac866 ("namei: Improve hash mixing if
CONFIG_DCACHE_WORD_ACCESS") was an off-the-cuff suggestion.
Replaced with a much more careful design that's simultaneously
faster and better. (My own invention, as there was noting suitable
in the literature I could find. Comments welcome!)
- Modify the hash_name() loop to skip the initial HASH_MIX(). This
would let us salt the hash if we ever wanted to.
- Sort out partial_name_hash().
The hash function is declared as using a long state, even though
it's truncated to 32 bits at the end and the extra internal state
contributes nothing to the result. And some callers do odd things:
- fs/hfs/string.c only allocates 32 bits of state
- fs/hfsplus/unicode.c uses it to hash 16-bit unicode symbols not bytes
- Modify bytemask_from_count to handle inputs of 1..sizeof(long)
rather than 0..sizeof(long)-1. This would simplify users other
than full_name_hash"
Special thanks to Bruce Fields for testing and finding bugs in v1. (I
learned some humbling lessons about "obviously correct" code.)
On the arch-specific front, the m68k assembly has been tested in a
standalone test harness, I've been in contact with the Microblaze
maintainers who mostly don't care, as the hardware multiplier is never
omitted in real-world applications, and I haven't heard anything from
the H8/300 world"
* 'hash' of git://ftp.sciencehorizons.net/linux:
h8300: Add <asm/hash.h>
microblaze: Add <asm/hash.h>
m68k: Add <asm/hash.h>
<linux/hash.h>: Add support for architecture-specific functions
fs/namei.c: Improve dcache hash function
Eliminate bad hash multipliers from hash_32() and hash_64()
Change hash_64() return value to 32 bits
<linux/sunrpc/svcauth.h>: Define hash_str() in terms of hashlen_string()
fs/namei.c: Add hashlen_string() function
Pull out string hash to <linux/stringhash.h>
This commit is contained in:
Linus Torvalds
commit
7e0fb73c52
17 changed files with 738 additions and 154 deletions
|
|
@ -598,6 +598,14 @@ config HAVE_STACK_VALIDATION
|
|||
Architecture supports the 'objtool check' host tool command, which
|
||||
performs compile-time stack metadata validation.
|
||||
|
||||
config HAVE_ARCH_HASH
|
||||
bool
|
||||
default n
|
||||
help
|
||||
If this is set, the architecture provides an <asm/hash.h>
|
||||
file which provides platform-specific implementations of some
|
||||
functions in <linux/hash.h> or fs/namei.c.
|
||||
|
||||
#
|
||||
# ABI hall of shame
|
||||
#
|
||||
|
|
|
|||
|
|
@ -20,6 +20,7 @@ config H8300
|
|||
select HAVE_KERNEL_GZIP
|
||||
select HAVE_KERNEL_LZO
|
||||
select HAVE_ARCH_KGDB
|
||||
select HAVE_ARCH_HASH
|
||||
select CPU_NO_EFFICIENT_FFS
|
||||
|
||||
config RWSEM_GENERIC_SPINLOCK
|
||||
|
|
|
|||
53
arch/h8300/include/asm/hash.h
Normal file
53
arch/h8300/include/asm/hash.h
Normal file
|
|
@ -0,0 +1,53 @@
|
|||
#ifndef _ASM_HASH_H
|
||||
#define _ASM_HASH_H
|
||||
|
||||
/*
|
||||
* The later H8SX models have a 32x32-bit multiply, but the H8/300H
|
||||
* and H8S have only 16x16->32. Since it's tolerably compact, this is
|
||||
* basically an inlined version of the __mulsi3 code. Since the inputs
|
||||
* are not expected to be small, it's also simplfied by skipping the
|
||||
* early-out checks.
|
||||
*
|
||||
* (Since neither CPU has any multi-bit shift instructions, a
|
||||
* shift-and-add version is a non-starter.)
|
||||
*
|
||||
* TODO: come up with an arch-specific version of the hashing in fs/namei.c,
|
||||
* since that is heavily dependent on rotates. Which, as mentioned, suck
|
||||
* horribly on H8.
|
||||
*/
|
||||
|
||||
#if defined(CONFIG_CPU_H300H) || defined(CONFIG_CPU_H8S)
|
||||
|
||||
#define HAVE_ARCH__HASH_32 1
|
||||
|
||||
/*
|
||||
* Multiply by k = 0x61C88647. Fitting this into three registers requires
|
||||
* one extra instruction, but reducing register pressure will probably
|
||||
* make that back and then some.
|
||||
*
|
||||
* GCC asm note: %e1 is the high half of operand %1, while %f1 is the
|
||||
* low half. So if %1 is er4, then %e1 is e4 and %f1 is r4.
|
||||
*
|
||||
* This has been designed to modify x in place, since that's the most
|
||||
* common usage, but preserve k, since hash_64() makes two calls in
|
||||
* quick succession.
|
||||
*/
|
||||
static inline u32 __attribute_const__ __hash_32(u32 x)
|
||||
{
|
||||
u32 temp;
|
||||
|
||||
asm( "mov.w %e1,%f0"
|
||||
"\n mulxu.w %f2,%0" /* klow * xhigh */
|
||||
"\n mov.w %f0,%e1" /* The extra instruction */
|
||||
"\n mov.w %f1,%f0"
|
||||
"\n mulxu.w %e2,%0" /* khigh * xlow */
|
||||
"\n add.w %e1,%f0"
|
||||
"\n mulxu.w %f2,%1" /* klow * xlow */
|
||||
"\n add.w %f0,%e1"
|
||||
: "=&r" (temp), "=r" (x)
|
||||
: "%r" (GOLDEN_RATIO_32), "1" (x));
|
||||
return x;
|
||||
}
|
||||
|
||||
#endif
|
||||
#endif /* _ASM_HASH_H */
|
||||
|
|
@ -41,6 +41,7 @@ config M68000
|
|||
select CPU_HAS_NO_UNALIGNED
|
||||
select GENERIC_CSUM
|
||||
select CPU_NO_EFFICIENT_FFS
|
||||
select HAVE_ARCH_HASH
|
||||
help
|
||||
The Freescale (was Motorola) 68000 CPU is the first generation of
|
||||
the well known M68K family of processors. The CPU core as well as
|
||||
|
|
|
|||
59
arch/m68k/include/asm/hash.h
Normal file
59
arch/m68k/include/asm/hash.h
Normal file
|
|
@ -0,0 +1,59 @@
|
|||
#ifndef _ASM_HASH_H
|
||||
#define _ASM_HASH_H
|
||||
|
||||
/*
|
||||
* If CONFIG_M68000=y (original mc68000/010), this file is #included
|
||||
* to work around the lack of a MULU.L instruction.
|
||||
*/
|
||||
|
||||
#define HAVE_ARCH__HASH_32 1
|
||||
/*
|
||||
* While it would be legal to substitute a different hash operation
|
||||
* entirely, let's keep it simple and just use an optimized multiply
|
||||
* by GOLDEN_RATIO_32 = 0x61C88647.
|
||||
*
|
||||
* The best way to do that appears to be to multiply by 0x8647 with
|
||||
* shifts and adds, and use mulu.w to multiply the high half by 0x61C8.
|
||||
*
|
||||
* Because the 68000 has multi-cycle shifts, this addition chain is
|
||||
* chosen to minimise the shift distances.
|
||||
*
|
||||
* Despite every attempt to spoon-feed it simple operations, GCC
|
||||
* 6.1.1 doggedly insists on doing annoying things like converting
|
||||
* "lsl.l #2,<reg>" (12 cycles) to two adds (8+8 cycles).
|
||||
*
|
||||
* It also likes to notice two shifts in a row, like "a = x << 2" and
|
||||
* "a <<= 7", and convert that to "a = x << 9". But shifts longer
|
||||
* than 8 bits are extra-slow on m68k, so that's a lose.
|
||||
*
|
||||
* Since the 68000 is a very simple in-order processor with no
|
||||
* instruction scheduling effects on execution time, we can safely
|
||||
* take it out of GCC's hands and write one big asm() block.
|
||||
*
|
||||
* Without calling overhead, this operation is 30 bytes (14 instructions
|
||||
* plus one immediate constant) and 166 cycles.
|
||||
*
|
||||
* (Because %2 is fetched twice, it can't be postincrement, and thus it
|
||||
* can't be a fully general "g" or "m". Register is preferred, but
|
||||
* offsettable memory or immediate will work.)
|
||||
*/
|
||||
static inline u32 __attribute_const__ __hash_32(u32 x)
|
||||
{
|
||||
u32 a, b;
|
||||
|
||||
asm( "move.l %2,%0" /* a = x * 0x0001 */
|
||||
"\n lsl.l #2,%0" /* a = x * 0x0004 */
|
||||
"\n move.l %0,%1"
|
||||
"\n lsl.l #7,%0" /* a = x * 0x0200 */
|
||||
"\n add.l %2,%0" /* a = x * 0x0201 */
|
||||
"\n add.l %0,%1" /* b = x * 0x0205 */
|
||||
"\n add.l %0,%0" /* a = x * 0x0402 */
|
||||
"\n add.l %0,%1" /* b = x * 0x0607 */
|
||||
"\n lsl.l #5,%0" /* a = x * 0x8040 */
|
||||
: "=&d,d" (a), "=&r,r" (b)
|
||||
: "r,roi?" (x)); /* a+b = x*0x8647 */
|
||||
|
||||
return ((u16)(x*0x61c8) << 16) + a + b;
|
||||
}
|
||||
|
||||
#endif /* _ASM_HASH_H */
|
||||
|
|
@ -16,6 +16,7 @@ config MICROBLAZE
|
|||
select GENERIC_IRQ_SHOW
|
||||
select GENERIC_PCI_IOMAP
|
||||
select GENERIC_SCHED_CLOCK
|
||||
select HAVE_ARCH_HASH
|
||||
select HAVE_ARCH_KGDB
|
||||
select HAVE_DEBUG_KMEMLEAK
|
||||
select HAVE_DMA_API_DEBUG
|
||||
|
|
|
|||
81
arch/microblaze/include/asm/hash.h
Normal file
81
arch/microblaze/include/asm/hash.h
Normal file
|
|
@ -0,0 +1,81 @@
|
|||
#ifndef _ASM_HASH_H
|
||||
#define _ASM_HASH_H
|
||||
|
||||
/*
|
||||
* Fortunately, most people who want to run Linux on Microblaze enable
|
||||
* both multiplier and barrel shifter, but omitting them is technically
|
||||
* a supported configuration.
|
||||
*
|
||||
* With just a barrel shifter, we can implement an efficient constant
|
||||
* multiply using shifts and adds. GCC can find a 9-step solution, but
|
||||
* this 6-step solution was found by Yevgen Voronenko's implementation
|
||||
* of the Hcub algorithm at http://spiral.ece.cmu.edu/mcm/gen.html.
|
||||
*
|
||||
* That software is really not designed for a single multiplier this large,
|
||||
* but if you run it enough times with different seeds, it'll find several
|
||||
* 6-shift, 6-add sequences for computing x * 0x61C88647. They are all
|
||||
* c = (x << 19) + x;
|
||||
* a = (x << 9) + c;
|
||||
* b = (x << 23) + a;
|
||||
* return (a<<11) + (b<<6) + (c<<3) - b;
|
||||
* with variations on the order of the final add.
|
||||
*
|
||||
* Without even a shifter, it's hopless; any hash function will suck.
|
||||
*/
|
||||
|
||||
#if CONFIG_XILINX_MICROBLAZE0_USE_HW_MUL == 0
|
||||
|
||||
#define HAVE_ARCH__HASH_32 1
|
||||
|
||||
/* Multiply by GOLDEN_RATIO_32 = 0x61C88647 */
|
||||
static inline u32 __attribute_const__ __hash_32(u32 a)
|
||||
{
|
||||
#if CONFIG_XILINX_MICROBLAZE0_USE_BARREL
|
||||
unsigned int b, c;
|
||||
|
||||
/* Phase 1: Compute three intermediate values */
|
||||
b = a << 23;
|
||||
c = (a << 19) + a;
|
||||
a = (a << 9) + c;
|
||||
b += a;
|
||||
|
||||
/* Phase 2: Compute (a << 11) + (b << 6) + (c << 3) - b */
|
||||
a <<= 5;
|
||||
a += b; /* (a << 5) + b */
|
||||
a <<= 3;
|
||||
a += c; /* (a << 8) + (b << 3) + c */
|
||||
a <<= 3;
|
||||
return a - b; /* (a << 11) + (b << 6) + (c << 3) - b */
|
||||
#else
|
||||
/*
|
||||
* "This is really going to hurt."
|
||||
*
|
||||
* Without a barrel shifter, left shifts are implemented as
|
||||
* repeated additions, and the best we can do is an optimal
|
||||
* addition-subtraction chain. This one is not known to be
|
||||
* optimal, but at 37 steps, it's decent for a 31-bit multiplier.
|
||||
*
|
||||
* Question: given its size (37*4 = 148 bytes per instance),
|
||||
* and slowness, is this worth having inline?
|
||||
*/
|
||||
unsigned int b, c, d;
|
||||
|
||||
b = a << 4; /* 4 */
|
||||
c = b << 1; /* 1 5 */
|
||||
b += a; /* 1 6 */
|
||||
c += b; /* 1 7 */
|
||||
c <<= 3; /* 3 10 */
|
||||
c -= a; /* 1 11 */
|
||||
d = c << 7; /* 7 18 */
|
||||
d += b; /* 1 19 */
|
||||
d <<= 8; /* 8 27 */
|
||||
d += a; /* 1 28 */
|
||||
d <<= 1; /* 1 29 */
|
||||
d += b; /* 1 30 */
|
||||
d <<= 6; /* 6 36 */
|
||||
return d + c; /* 1 37 total instructions*/
|
||||
#endif
|
||||
}
|
||||
|
||||
#endif /* !CONFIG_XILINX_MICROBLAZE0_USE_HW_MUL */
|
||||
#endif /* _ASM_HASH_H */
|
||||
|
|
@ -398,6 +398,8 @@ static int af9015_download_firmware(struct dvb_usb_device *d,
|
|||
}
|
||||
|
||||
#define AF9015_EEPROM_SIZE 256
|
||||
/* 2^31 + 2^29 - 2^25 + 2^22 - 2^19 - 2^16 + 1 */
|
||||
#define GOLDEN_RATIO_PRIME_32 0x9e370001UL
|
||||
|
||||
/* hash (and dump) eeprom */
|
||||
static int af9015_eeprom_hash(struct dvb_usb_device *d)
|
||||
|
|
|
|||
|
|
@ -1670,8 +1670,7 @@ struct dentry *d_alloc_name(struct dentry *parent, const char *name)
|
|||
struct qstr q;
|
||||
|
||||
q.name = name;
|
||||
q.len = strlen(name);
|
||||
q.hash = full_name_hash(q.name, q.len);
|
||||
q.hash_len = hashlen_string(name);
|
||||
return d_alloc(parent, &q);
|
||||
}
|
||||
EXPORT_SYMBOL(d_alloc_name);
|
||||
|
|
|
|||
162
fs/namei.c
162
fs/namei.c
|
|
@ -35,6 +35,7 @@
|
|||
#include <linux/fs_struct.h>
|
||||
#include <linux/posix_acl.h>
|
||||
#include <linux/hash.h>
|
||||
#include <linux/bitops.h>
|
||||
#include <asm/uaccess.h>
|
||||
|
||||
#include "internal.h"
|
||||
|
|
@ -1797,74 +1798,144 @@ static int walk_component(struct nameidata *nd, int flags)
|
|||
|
||||
#include <asm/word-at-a-time.h>
|
||||
|
||||
#ifdef CONFIG_64BIT
|
||||
#ifdef HASH_MIX
|
||||
|
||||
static inline unsigned int fold_hash(unsigned long hash)
|
||||
{
|
||||
return hash_64(hash, 32);
|
||||
}
|
||||
/* Architecture provides HASH_MIX and fold_hash() in <asm/hash.h> */
|
||||
|
||||
#elif defined(CONFIG_64BIT)
|
||||
/*
|
||||
* Register pressure in the mixing function is an issue, particularly
|
||||
* on 32-bit x86, but almost any function requires one state value and
|
||||
* one temporary. Instead, use a function designed for two state values
|
||||
* and no temporaries.
|
||||
*
|
||||
* This function cannot create a collision in only two iterations, so
|
||||
* we have two iterations to achieve avalanche. In those two iterations,
|
||||
* we have six layers of mixing, which is enough to spread one bit's
|
||||
* influence out to 2^6 = 64 state bits.
|
||||
*
|
||||
* Rotate constants are scored by considering either 64 one-bit input
|
||||
* deltas or 64*63/2 = 2016 two-bit input deltas, and finding the
|
||||
* probability of that delta causing a change to each of the 128 output
|
||||
* bits, using a sample of random initial states.
|
||||
*
|
||||
* The Shannon entropy of the computed probabilities is then summed
|
||||
* to produce a score. Ideally, any input change has a 50% chance of
|
||||
* toggling any given output bit.
|
||||
*
|
||||
* Mixing scores (in bits) for (12,45):
|
||||
* Input delta: 1-bit 2-bit
|
||||
* 1 round: 713.3 42542.6
|
||||
* 2 rounds: 2753.7 140389.8
|
||||
* 3 rounds: 5954.1 233458.2
|
||||
* 4 rounds: 7862.6 256672.2
|
||||
* Perfect: 8192 258048
|
||||
* (64*128) (64*63/2 * 128)
|
||||
*/
|
||||
#define HASH_MIX(x, y, a) \
|
||||
( x ^= (a), \
|
||||
y ^= x, x = rol64(x,12),\
|
||||
x += y, y = rol64(y,45),\
|
||||
y *= 9 )
|
||||
|
||||
/*
|
||||
* This is George Marsaglia's XORSHIFT generator.
|
||||
* It implements a maximum-period LFSR in only a few
|
||||
* instructions. It also has the property (required
|
||||
* by hash_name()) that mix_hash(0) = 0.
|
||||
* Fold two longs into one 32-bit hash value. This must be fast, but
|
||||
* latency isn't quite as critical, as there is a fair bit of additional
|
||||
* work done before the hash value is used.
|
||||
*/
|
||||
static inline unsigned long mix_hash(unsigned long hash)
|
||||
static inline unsigned int fold_hash(unsigned long x, unsigned long y)
|
||||
{
|
||||
hash ^= hash << 13;
|
||||
hash ^= hash >> 7;
|
||||
hash ^= hash << 17;
|
||||
return hash;
|
||||
y ^= x * GOLDEN_RATIO_64;
|
||||
y *= GOLDEN_RATIO_64;
|
||||
return y >> 32;
|
||||
}
|
||||
|
||||
#else /* 32-bit case */
|
||||
|
||||
#define fold_hash(x) (x)
|
||||
/*
|
||||
* Mixing scores (in bits) for (7,20):
|
||||
* Input delta: 1-bit 2-bit
|
||||
* 1 round: 330.3 9201.6
|
||||
* 2 rounds: 1246.4 25475.4
|
||||
* 3 rounds: 1907.1 31295.1
|
||||
* 4 rounds: 2042.3 31718.6
|
||||
* Perfect: 2048 31744
|
||||
* (32*64) (32*31/2 * 64)
|
||||
*/
|
||||
#define HASH_MIX(x, y, a) \
|
||||
( x ^= (a), \
|
||||
y ^= x, x = rol32(x, 7),\
|
||||
x += y, y = rol32(y,20),\
|
||||
y *= 9 )
|
||||
|
||||
static inline unsigned long mix_hash(unsigned long hash)
|
||||
static inline unsigned int fold_hash(unsigned long x, unsigned long y)
|
||||
{
|
||||
hash ^= hash << 13;
|
||||
hash ^= hash >> 17;
|
||||
hash ^= hash << 5;
|
||||
return hash;
|
||||
/* Use arch-optimized multiply if one exists */
|
||||
return __hash_32(y ^ __hash_32(x));
|
||||
}
|
||||
|
||||
#endif
|
||||
|
||||
unsigned int full_name_hash(const unsigned char *name, unsigned int len)
|
||||
/*
|
||||
* Return the hash of a string of known length. This is carfully
|
||||
* designed to match hash_name(), which is the more critical function.
|
||||
* In particular, we must end by hashing a final word containing 0..7
|
||||
* payload bytes, to match the way that hash_name() iterates until it
|
||||
* finds the delimiter after the name.
|
||||
*/
|
||||
unsigned int full_name_hash(const char *name, unsigned int len)
|
||||
{
|
||||
unsigned long a, hash = 0;
|
||||
unsigned long a, x = 0, y = 0;
|
||||
|
||||
for (;;) {
|
||||
if (!len)
|
||||
goto done;
|
||||
a = load_unaligned_zeropad(name);
|
||||
if (len < sizeof(unsigned long))
|
||||
break;
|
||||
hash = mix_hash(hash + a);
|
||||
HASH_MIX(x, y, a);
|
||||
name += sizeof(unsigned long);
|
||||
len -= sizeof(unsigned long);
|
||||
if (!len)
|
||||
goto done;
|
||||
}
|
||||
hash += a & bytemask_from_count(len);
|
||||
x ^= a & bytemask_from_count(len);
|
||||
done:
|
||||
return fold_hash(hash);
|
||||
return fold_hash(x, y);
|
||||
}
|
||||
EXPORT_SYMBOL(full_name_hash);
|
||||
|
||||
/* Return the "hash_len" (hash and length) of a null-terminated string */
|
||||
u64 hashlen_string(const char *name)
|
||||
{
|
||||
unsigned long a = 0, x = 0, y = 0, adata, mask, len;
|
||||
const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS;
|
||||
|
||||
len = -sizeof(unsigned long);
|
||||
do {
|
||||
HASH_MIX(x, y, a);
|
||||
len += sizeof(unsigned long);
|
||||
a = load_unaligned_zeropad(name+len);
|
||||
} while (!has_zero(a, &adata, &constants));
|
||||
|
||||
adata = prep_zero_mask(a, adata, &constants);
|
||||
mask = create_zero_mask(adata);
|
||||
x ^= a & zero_bytemask(mask);
|
||||
|
||||
return hashlen_create(fold_hash(x, y), len + find_zero(mask));
|
||||
}
|
||||
EXPORT_SYMBOL(hashlen_string);
|
||||
|
||||
/*
|
||||
* Calculate the length and hash of the path component, and
|
||||
* return the "hash_len" as the result.
|
||||
*/
|
||||
static inline u64 hash_name(const char *name)
|
||||
{
|
||||
unsigned long a, b, adata, bdata, mask, hash, len;
|
||||
unsigned long a = 0, b, x = 0, y = 0, adata, bdata, mask, len;
|
||||
const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS;
|
||||
|
||||
hash = a = 0;
|
||||
len = -sizeof(unsigned long);
|
||||
do {
|
||||
hash = mix_hash(hash + a);
|
||||
HASH_MIX(x, y, a);
|
||||
len += sizeof(unsigned long);
|
||||
a = load_unaligned_zeropad(name+len);
|
||||
b = a ^ REPEAT_BYTE('/');
|
||||
|
|
@ -1872,25 +1943,40 @@ static inline u64 hash_name(const char *name)
|
|||
|
||||
adata = prep_zero_mask(a, adata, &constants);
|
||||
bdata = prep_zero_mask(b, bdata, &constants);
|
||||
|
||||
mask = create_zero_mask(adata | bdata);
|
||||
x ^= a & zero_bytemask(mask);
|
||||
|
||||
hash += a & zero_bytemask(mask);
|
||||
len += find_zero(mask);
|
||||
return hashlen_create(fold_hash(hash), len);
|
||||
return hashlen_create(fold_hash(x, y), len + find_zero(mask));
|
||||
}
|
||||
|
||||
#else
|
||||
#else /* !CONFIG_DCACHE_WORD_ACCESS: Slow, byte-at-a-time version */
|
||||
|
||||
unsigned int full_name_hash(const unsigned char *name, unsigned int len)
|
||||
/* Return the hash of a string of known length */
|
||||
unsigned int full_name_hash(const char *name, unsigned int len)
|
||||
{
|
||||
unsigned long hash = init_name_hash();
|
||||
while (len--)
|
||||
hash = partial_name_hash(*name++, hash);
|
||||
hash = partial_name_hash((unsigned char)*name++, hash);
|
||||
return end_name_hash(hash);
|
||||
}
|
||||
EXPORT_SYMBOL(full_name_hash);
|
||||
|
||||
/* Return the "hash_len" (hash and length) of a null-terminated string */
|
||||
u64 hash_string(const char *name)
|
||||
{
|
||||
unsigned long hash = init_name_hash();
|
||||
unsigned long len = 0, c;
|
||||
|
||||
c = (unsigned char)*name;
|
||||
do {
|
||||
len++;
|
||||
hash = partial_name_hash(c, hash);
|
||||
c = (unsigned char)name[len];
|
||||
} while (c);
|
||||
return hashlen_create(end_name_hash(hash), len);
|
||||
}
|
||||
EXPORT_SYMBOL(hash_string);
|
||||
|
||||
/*
|
||||
* We know there's a real path component here of at least
|
||||
* one character.
|
||||
|
|
@ -1934,7 +2020,7 @@ static int link_path_walk(const char *name, struct nameidata *nd)
|
|||
int type;
|
||||
|
||||
err = may_lookup(nd);
|
||||
if (err)
|
||||
if (err)
|
||||
return err;
|
||||
|
||||
hash_len = hash_name(name);
|
||||
|
|
|
|||
|
|
@ -10,6 +10,7 @@
|
|||
#include <linux/cache.h>
|
||||
#include <linux/rcupdate.h>
|
||||
#include <linux/lockref.h>
|
||||
#include <linux/stringhash.h>
|
||||
|
||||
struct path;
|
||||
struct vfsmount;
|
||||
|
|
@ -52,9 +53,6 @@ struct qstr {
|
|||
};
|
||||
|
||||
#define QSTR_INIT(n,l) { { { .len = l } }, .name = n }
|
||||
#define hashlen_hash(hashlen) ((u32) (hashlen))
|
||||
#define hashlen_len(hashlen) ((u32)((hashlen) >> 32))
|
||||
#define hashlen_create(hash,len) (((u64)(len)<<32)|(u32)(hash))
|
||||
|
||||
struct dentry_stat_t {
|
||||
long nr_dentry;
|
||||
|
|
@ -65,29 +63,6 @@ struct dentry_stat_t {
|
|||
};
|
||||
extern struct dentry_stat_t dentry_stat;
|
||||
|
||||
/* Name hashing routines. Initial hash value */
|
||||
/* Hash courtesy of the R5 hash in reiserfs modulo sign bits */
|
||||
#define init_name_hash() 0
|
||||
|
||||
/* partial hash update function. Assume roughly 4 bits per character */
|
||||
static inline unsigned long
|
||||
partial_name_hash(unsigned long c, unsigned long prevhash)
|
||||
{
|
||||
return (prevhash + (c << 4) + (c >> 4)) * 11;
|
||||
}
|
||||
|
||||
/*
|
||||
* Finally: cut down the number of bits to a int value (and try to avoid
|
||||
* losing bits)
|
||||
*/
|
||||
static inline unsigned long end_name_hash(unsigned long hash)
|
||||
{
|
||||
return (unsigned int) hash;
|
||||
}
|
||||
|
||||
/* Compute the hash for a name string. */
|
||||
extern unsigned int full_name_hash(const unsigned char *, unsigned int);
|
||||
|
||||
/*
|
||||
* Try to keep struct dentry aligned on 64 byte cachelines (this will
|
||||
* give reasonable cacheline footprint with larger lines without the
|
||||
|
|
|
|||
|
|
@ -3,92 +3,94 @@
|
|||
/* Fast hashing routine for ints, longs and pointers.
|
||||
(C) 2002 Nadia Yvette Chambers, IBM */
|
||||
|
||||
/*
|
||||
* Knuth recommends primes in approximately golden ratio to the maximum
|
||||
* integer representable by a machine word for multiplicative hashing.
|
||||
* Chuck Lever verified the effectiveness of this technique:
|
||||
* http://www.citi.umich.edu/techreports/reports/citi-tr-00-1.pdf
|
||||
*
|
||||
* These primes are chosen to be bit-sparse, that is operations on
|
||||
* them can use shifts and additions instead of multiplications for
|
||||
* machines where multiplications are slow.
|
||||
*/
|
||||
|
||||
#include <asm/types.h>
|
||||
#include <linux/compiler.h>
|
||||
|
||||
/* 2^31 + 2^29 - 2^25 + 2^22 - 2^19 - 2^16 + 1 */
|
||||
#define GOLDEN_RATIO_PRIME_32 0x9e370001UL
|
||||
/* 2^63 + 2^61 - 2^57 + 2^54 - 2^51 - 2^18 + 1 */
|
||||
#define GOLDEN_RATIO_PRIME_64 0x9e37fffffffc0001UL
|
||||
|
||||
/*
|
||||
* The "GOLDEN_RATIO_PRIME" is used in ifs/btrfs/brtfs_inode.h and
|
||||
* fs/inode.c. It's not actually prime any more (the previous primes
|
||||
* were actively bad for hashing), but the name remains.
|
||||
*/
|
||||
#if BITS_PER_LONG == 32
|
||||
#define GOLDEN_RATIO_PRIME GOLDEN_RATIO_PRIME_32
|
||||
#define GOLDEN_RATIO_PRIME GOLDEN_RATIO_32
|
||||
#define hash_long(val, bits) hash_32(val, bits)
|
||||
#elif BITS_PER_LONG == 64
|
||||
#define hash_long(val, bits) hash_64(val, bits)
|
||||
#define GOLDEN_RATIO_PRIME GOLDEN_RATIO_PRIME_64
|
||||
#define GOLDEN_RATIO_PRIME GOLDEN_RATIO_64
|
||||
#else
|
||||
#error Wordsize not 32 or 64
|
||||
#endif
|
||||
|
||||
/*
|
||||
* The above primes are actively bad for hashing, since they are
|
||||
* too sparse. The 32-bit one is mostly ok, the 64-bit one causes
|
||||
* real problems. Besides, the "prime" part is pointless for the
|
||||
* multiplicative hash.
|
||||
* This hash multiplies the input by a large odd number and takes the
|
||||
* high bits. Since multiplication propagates changes to the most
|
||||
* significant end only, it is essential that the high bits of the
|
||||
* product be used for the hash value.
|
||||
*
|
||||
* Chuck Lever verified the effectiveness of this technique:
|
||||
* http://www.citi.umich.edu/techreports/reports/citi-tr-00-1.pdf
|
||||
*
|
||||
* Although a random odd number will do, it turns out that the golden
|
||||
* ratio phi = (sqrt(5)-1)/2, or its negative, has particularly nice
|
||||
* properties.
|
||||
* properties. (See Knuth vol 3, section 6.4, exercise 9.)
|
||||
*
|
||||
* These are the negative, (1 - phi) = (phi^2) = (3 - sqrt(5))/2.
|
||||
* (See Knuth vol 3, section 6.4, exercise 9.)
|
||||
* These are the negative, (1 - phi) = phi**2 = (3 - sqrt(5))/2,
|
||||
* which is very slightly easier to multiply by and makes no
|
||||
* difference to the hash distribution.
|
||||
*/
|
||||
#define GOLDEN_RATIO_32 0x61C88647
|
||||
#define GOLDEN_RATIO_64 0x61C8864680B583EBull
|
||||
|
||||
static __always_inline u64 hash_64(u64 val, unsigned int bits)
|
||||
{
|
||||
u64 hash = val;
|
||||
|
||||
#if BITS_PER_LONG == 64
|
||||
hash = hash * GOLDEN_RATIO_64;
|
||||
#else
|
||||
/* Sigh, gcc can't optimise this alone like it does for 32 bits. */
|
||||
u64 n = hash;
|
||||
n <<= 18;
|
||||
hash -= n;
|
||||
n <<= 33;
|
||||
hash -= n;
|
||||
n <<= 3;
|
||||
hash += n;
|
||||
n <<= 3;
|
||||
hash -= n;
|
||||
n <<= 4;
|
||||
hash += n;
|
||||
n <<= 2;
|
||||
hash += n;
|
||||
#ifdef CONFIG_HAVE_ARCH_HASH
|
||||
/* This header may use the GOLDEN_RATIO_xx constants */
|
||||
#include <asm/hash.h>
|
||||
#endif
|
||||
|
||||
/* High bits are more random, so use them. */
|
||||
return hash >> (64 - bits);
|
||||
}
|
||||
|
||||
static inline u32 hash_32(u32 val, unsigned int bits)
|
||||
/*
|
||||
* The _generic versions exist only so lib/test_hash.c can compare
|
||||
* the arch-optimized versions with the generic.
|
||||
*
|
||||
* Note that if you change these, any <asm/hash.h> that aren't updated
|
||||
* to match need to have their HAVE_ARCH_* define values updated so the
|
||||
* self-test will not false-positive.
|
||||
*/
|
||||
#ifndef HAVE_ARCH__HASH_32
|
||||
#define __hash_32 __hash_32_generic
|
||||
#endif
|
||||
static inline u32 __hash_32_generic(u32 val)
|
||||
{
|
||||
/* On some cpus multiply is faster, on others gcc will do shifts */
|
||||
u32 hash = val * GOLDEN_RATIO_PRIME_32;
|
||||
|
||||
/* High bits are more random, so use them. */
|
||||
return hash >> (32 - bits);
|
||||
return val * GOLDEN_RATIO_32;
|
||||
}
|
||||
|
||||
static inline unsigned long hash_ptr(const void *ptr, unsigned int bits)
|
||||
#ifndef HAVE_ARCH_HASH_32
|
||||
#define hash_32 hash_32_generic
|
||||
#endif
|
||||
static inline u32 hash_32_generic(u32 val, unsigned int bits)
|
||||
{
|
||||
/* High bits are more random, so use them. */
|
||||
return __hash_32(val) >> (32 - bits);
|
||||
}
|
||||
|
||||
#ifndef HAVE_ARCH_HASH_64
|
||||
#define hash_64 hash_64_generic
|
||||
#endif
|
||||
static __always_inline u32 hash_64_generic(u64 val, unsigned int bits)
|
||||
{
|
||||
#if BITS_PER_LONG == 64
|
||||
/* 64x64-bit multiply is efficient on all 64-bit processors */
|
||||
return val * GOLDEN_RATIO_64 >> (64 - bits);
|
||||
#else
|
||||
/* Hash 64 bits using only 32x32-bit multiply. */
|
||||
return hash_32((u32)val ^ __hash_32(val >> 32), bits);
|
||||
#endif
|
||||
}
|
||||
|
||||
static inline u32 hash_ptr(const void *ptr, unsigned int bits)
|
||||
{
|
||||
return hash_long((unsigned long)ptr, bits);
|
||||
}
|
||||
|
||||
/* This really should be called fold32_ptr; it does no hashing to speak of. */
|
||||
static inline u32 hash32_ptr(const void *ptr)
|
||||
{
|
||||
unsigned long val = (unsigned long)ptr;
|
||||
|
|
|
|||
76
include/linux/stringhash.h
Normal file
76
include/linux/stringhash.h
Normal file
|
|
@ -0,0 +1,76 @@
|
|||
#ifndef __LINUX_STRINGHASH_H
|
||||
#define __LINUX_STRINGHASH_H
|
||||
|
||||
#include <linux/compiler.h> /* For __pure */
|
||||
#include <linux/types.h> /* For u32, u64 */
|
||||
|
||||
/*
|
||||
* Routines for hashing strings of bytes to a 32-bit hash value.
|
||||
*
|
||||
* These hash functions are NOT GUARANTEED STABLE between kernel
|
||||
* versions, architectures, or even repeated boots of the same kernel.
|
||||
* (E.g. they may depend on boot-time hardware detection or be
|
||||
* deliberately randomized.)
|
||||
*
|
||||
* They are also not intended to be secure against collisions caused by
|
||||
* malicious inputs; much slower hash functions are required for that.
|
||||
*
|
||||
* They are optimized for pathname components, meaning short strings.
|
||||
* Even if a majority of files have longer names, the dynamic profile of
|
||||
* pathname components skews short due to short directory names.
|
||||
* (E.g. /usr/lib/libsesquipedalianism.so.3.141.)
|
||||
*/
|
||||
|
||||
/*
|
||||
* Version 1: one byte at a time. Example of use:
|
||||
*
|
||||
* unsigned long hash = init_name_hash;
|
||||
* while (*p)
|
||||
* hash = partial_name_hash(tolower(*p++), hash);
|
||||
* hash = end_name_hash(hash);
|
||||
*
|
||||
* Although this is designed for bytes, fs/hfsplus/unicode.c
|
||||
* abuses it to hash 16-bit values.
|
||||
*/
|
||||
|
||||
/* Hash courtesy of the R5 hash in reiserfs modulo sign bits */
|
||||
#define init_name_hash() 0
|
||||
|
||||
/* partial hash update function. Assume roughly 4 bits per character */
|
||||
static inline unsigned long
|
||||
partial_name_hash(unsigned long c, unsigned long prevhash)
|
||||
{
|
||||
return (prevhash + (c << 4) + (c >> 4)) * 11;
|
||||
}
|
||||
|
||||
/*
|
||||
* Finally: cut down the number of bits to a int value (and try to avoid
|
||||
* losing bits)
|
||||
*/
|
||||
static inline unsigned long end_name_hash(unsigned long hash)
|
||||
{
|
||||
return (unsigned int)hash;
|
||||
}
|
||||
|
||||
/*
|
||||
* Version 2: One word (32 or 64 bits) at a time.
|
||||
* If CONFIG_DCACHE_WORD_ACCESS is defined (meaning <asm/word-at-a-time.h>
|
||||
* exists, which describes major Linux platforms like x86 and ARM), then
|
||||
* this computes a different hash function much faster.
|
||||
*
|
||||
* If not set, this falls back to a wrapper around the preceding.
|
||||
*/
|
||||
extern unsigned int __pure full_name_hash(const char *, unsigned int);
|
||||
|
||||
/*
|
||||
* A hash_len is a u64 with the hash of a string in the low
|
||||
* half and the length in the high half.
|
||||
*/
|
||||
#define hashlen_hash(hashlen) ((u32)(hashlen))
|
||||
#define hashlen_len(hashlen) ((u32)((hashlen) >> 32))
|
||||
#define hashlen_create(hash, len) ((u64)(len)<<32 | (u32)(hash))
|
||||
|
||||
/* Return the "hash_len" (hash and length) of a null-terminated string */
|
||||
extern u64 __pure hashlen_string(const char *name);
|
||||
|
||||
#endif /* __LINUX_STRINGHASH_H */
|
||||
|
|
@ -16,6 +16,7 @@
|
|||
#include <linux/sunrpc/cache.h>
|
||||
#include <linux/sunrpc/gss_api.h>
|
||||
#include <linux/hash.h>
|
||||
#include <linux/stringhash.h>
|
||||
#include <linux/cred.h>
|
||||
|
||||
struct svc_cred {
|
||||
|
|
@ -165,41 +166,18 @@ extern int svcauth_unix_set_client(struct svc_rqst *rqstp);
|
|||
extern int unix_gid_cache_create(struct net *net);
|
||||
extern void unix_gid_cache_destroy(struct net *net);
|
||||
|
||||
static inline unsigned long hash_str(char *name, int bits)
|
||||
/*
|
||||
* The <stringhash.h> functions are good enough that we don't need to
|
||||
* use hash_32() on them; just extracting the high bits is enough.
|
||||
*/
|
||||
static inline unsigned long hash_str(char const *name, int bits)
|
||||
{
|
||||
unsigned long hash = 0;
|
||||
unsigned long l = 0;
|
||||
int len = 0;
|
||||
unsigned char c;
|
||||
do {
|
||||
if (unlikely(!(c = *name++))) {
|
||||
c = (char)len; len = -1;
|
||||
}
|
||||
l = (l << 8) | c;
|
||||
len++;
|
||||
if ((len & (BITS_PER_LONG/8-1))==0)
|
||||
hash = hash_long(hash^l, BITS_PER_LONG);
|
||||
} while (len);
|
||||
return hash >> (BITS_PER_LONG - bits);
|
||||
return hashlen_hash(hashlen_string(name)) >> (32 - bits);
|
||||
}
|
||||
|
||||
static inline unsigned long hash_mem(char *buf, int length, int bits)
|
||||
static inline unsigned long hash_mem(char const *buf, int length, int bits)
|
||||
{
|
||||
unsigned long hash = 0;
|
||||
unsigned long l = 0;
|
||||
int len = 0;
|
||||
unsigned char c;
|
||||
do {
|
||||
if (len == length) {
|
||||
c = (char)len; len = -1;
|
||||
} else
|
||||
c = *buf++;
|
||||
l = (l << 8) | c;
|
||||
len++;
|
||||
if ((len & (BITS_PER_LONG/8-1))==0)
|
||||
hash = hash_long(hash^l, BITS_PER_LONG);
|
||||
} while (len);
|
||||
return hash >> (BITS_PER_LONG - bits);
|
||||
return full_name_hash(buf, length) >> (32 - bits);
|
||||
}
|
||||
|
||||
#endif /* __KERNEL__ */
|
||||
|
|
|
|||
|
|
@ -1849,6 +1849,17 @@ config TEST_RHASHTABLE
|
|||
|
||||
If unsure, say N.
|
||||
|
||||
config TEST_HASH
|
||||
tristate "Perform selftest on hash functions"
|
||||
default n
|
||||
help
|
||||
Enable this option to test the kernel's integer (<linux/hash,h>)
|
||||
and string (<linux/stringhash.h>) hash functions on boot
|
||||
(or module load).
|
||||
|
||||
This is intended to help people writing architecture-specific
|
||||
optimized versions. If unsure, say N.
|
||||
|
||||
endmenu # runtime tests
|
||||
|
||||
config PROVIDE_OHCI1394_DMA_INIT
|
||||
|
|
|
|||
|
|
@ -48,6 +48,7 @@ obj-$(CONFIG_TEST_HEXDUMP) += test_hexdump.o
|
|||
obj-y += kstrtox.o
|
||||
obj-$(CONFIG_TEST_BPF) += test_bpf.o
|
||||
obj-$(CONFIG_TEST_FIRMWARE) += test_firmware.o
|
||||
obj-$(CONFIG_TEST_HASH) += test_hash.o
|
||||
obj-$(CONFIG_TEST_KASAN) += test_kasan.o
|
||||
obj-$(CONFIG_TEST_KSTRTOX) += test-kstrtox.o
|
||||
obj-$(CONFIG_TEST_LKM) += test_module.o
|
||||
|
|
|
|||
250
lib/test_hash.c
Normal file
250
lib/test_hash.c
Normal file
|
|
@ -0,0 +1,250 @@
|
|||
/*
|
||||
* Test cases for <linux/hash.h> and <linux/stringhash.h>
|
||||
* This just verifies that various ways of computing a hash
|
||||
* produce the same thing and, for cases where a k-bit hash
|
||||
* value is requested, is of the requested size.
|
||||
*
|
||||
* We fill a buffer with a 255-byte null-terminated string,
|
||||
* and use both full_name_hash() and hashlen_string() to hash the
|
||||
* substrings from i to j, where 0 <= i < j < 256.
|
||||
*
|
||||
* The returned values are used to check that __hash_32() and
|
||||
* __hash_32_generic() compute the same thing. Likewise hash_32()
|
||||
* and hash_64().
|
||||
*/
|
||||
|
||||
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt "\n"
|
||||
|
||||
#include <linux/compiler.h>
|
||||
#include <linux/types.h>
|
||||
#include <linux/module.h>
|
||||
#include <linux/hash.h>
|
||||
#include <linux/stringhash.h>
|
||||
#include <linux/printk.h>
|
||||
|
||||
/* 32-bit XORSHIFT generator. Seed must not be zero. */
|
||||
static u32 __init __attribute_const__
|
||||
xorshift(u32 seed)
|
||||
{
|
||||
seed ^= seed << 13;
|
||||
seed ^= seed >> 17;
|
||||
seed ^= seed << 5;
|
||||
return seed;
|
||||
}
|
||||
|
||||
/* Given a non-zero x, returns a non-zero byte. */
|
||||
static u8 __init __attribute_const__
|
||||
mod255(u32 x)
|
||||
{
|
||||
x = (x & 0xffff) + (x >> 16); /* 1 <= x <= 0x1fffe */
|
||||
x = (x & 0xff) + (x >> 8); /* 1 <= x <= 0x2fd */
|
||||
x = (x & 0xff) + (x >> 8); /* 1 <= x <= 0x100 */
|
||||
x = (x & 0xff) + (x >> 8); /* 1 <= x <= 0xff */
|
||||
return x;
|
||||
}
|
||||
|
||||
/* Fill the buffer with non-zero bytes. */
|
||||
static void __init
|
||||
fill_buf(char *buf, size_t len, u32 seed)
|
||||
{
|
||||
size_t i;
|
||||
|
||||
for (i = 0; i < len; i++) {
|
||||
seed = xorshift(seed);
|
||||
buf[i] = mod255(seed);
|
||||
}
|
||||
}
|
||||
|
||||
/*
|
||||
* Test the various integer hash functions. h64 (or its low-order bits)
|
||||
* is the integer to hash. hash_or accumulates the OR of the hash values,
|
||||
* which are later checked to see that they cover all the requested bits.
|
||||
*
|
||||
* Because these functions (as opposed to the string hashes) are all
|
||||
* inline, the code being tested is actually in the module, and you can
|
||||
* recompile and re-test the module without rebooting.
|
||||
*/
|
||||
static bool __init
|
||||
test_int_hash(unsigned long long h64, u32 hash_or[2][33])
|
||||
{
|
||||
int k;
|
||||
u32 h0 = (u32)h64, h1, h2;
|
||||
|
||||
/* Test __hash32 */
|
||||
hash_or[0][0] |= h1 = __hash_32(h0);
|
||||
#ifdef HAVE_ARCH__HASH_32
|
||||
hash_or[1][0] |= h2 = __hash_32_generic(h0);
|
||||
#if HAVE_ARCH__HASH_32 == 1
|
||||
if (h1 != h2) {
|
||||
pr_err("__hash_32(%#x) = %#x != __hash_32_generic() = %#x",
|
||||
h0, h1, h2);
|
||||
return false;
|
||||
}
|
||||
#endif
|
||||
#endif
|
||||
|
||||
/* Test k = 1..32 bits */
|
||||
for (k = 1; k <= 32; k++) {
|
||||
u32 const m = ((u32)2 << (k-1)) - 1; /* Low k bits set */
|
||||
|
||||
/* Test hash_32 */
|
||||
hash_or[0][k] |= h1 = hash_32(h0, k);
|
||||
if (h1 > m) {
|
||||
pr_err("hash_32(%#x, %d) = %#x > %#x", h0, k, h1, m);
|
||||
return false;
|
||||
}
|
||||
#ifdef HAVE_ARCH_HASH_32
|
||||
h2 = hash_32_generic(h0, k);
|
||||
#if HAVE_ARCH_HASH_32 == 1
|
||||
if (h1 != h2) {
|
||||
pr_err("hash_32(%#x, %d) = %#x != hash_32_generic() "
|
||||
" = %#x", h0, k, h1, h2);
|
||||
return false;
|
||||
}
|
||||
#else
|
||||
if (h2 > m) {
|
||||
pr_err("hash_32_generic(%#x, %d) = %#x > %#x",
|
||||
h0, k, h1, m);
|
||||
return false;
|
||||
}
|
||||
#endif
|
||||
#endif
|
||||
/* Test hash_64 */
|
||||
hash_or[1][k] |= h1 = hash_64(h64, k);
|
||||
if (h1 > m) {
|
||||
pr_err("hash_64(%#llx, %d) = %#x > %#x", h64, k, h1, m);
|
||||
return false;
|
||||
}
|
||||
#ifdef HAVE_ARCH_HASH_64
|
||||
h2 = hash_64_generic(h64, k);
|
||||
#if HAVE_ARCH_HASH_64 == 1
|
||||
if (h1 != h2) {
|
||||
pr_err("hash_64(%#llx, %d) = %#x != hash_64_generic() "
|
||||
"= %#x", h64, k, h1, h2);
|
||||
return false;
|
||||
}
|
||||
#else
|
||||
if (h2 > m) {
|
||||
pr_err("hash_64_generic(%#llx, %d) = %#x > %#x",
|
||||
h64, k, h1, m);
|
||||
return false;
|
||||
}
|
||||
#endif
|
||||
#endif
|
||||
}
|
||||
|
||||
(void)h2; /* Suppress unused variable warning */
|
||||
return true;
|
||||
}
|
||||
|
||||
#define SIZE 256 /* Run time is cubic in SIZE */
|
||||
|
||||
static int __init
|
||||
test_hash_init(void)
|
||||
{
|
||||
char buf[SIZE+1];
|
||||
u32 string_or = 0, hash_or[2][33] = { 0 };
|
||||
unsigned tests = 0;
|
||||
unsigned long long h64 = 0;
|
||||
int i, j;
|
||||
|
||||
fill_buf(buf, SIZE, 1);
|
||||
|
||||
/* Test every possible non-empty substring in the buffer. */
|
||||
for (j = SIZE; j > 0; --j) {
|
||||
buf[j] = '\0';
|
||||
|
||||
for (i = 0; i <= j; i++) {
|
||||
u64 hashlen = hashlen_string(buf+i);
|
||||
u32 h0 = full_name_hash(buf+i, j-i);
|
||||
|
||||
/* Check that hashlen_string gets the length right */
|
||||
if (hashlen_len(hashlen) != j-i) {
|
||||
pr_err("hashlen_string(%d..%d) returned length"
|
||||
" %u, expected %d",
|
||||
i, j, hashlen_len(hashlen), j-i);
|
||||
return -EINVAL;
|
||||
}
|
||||
/* Check that the hashes match */
|
||||
if (hashlen_hash(hashlen) != h0) {
|
||||
pr_err("hashlen_string(%d..%d) = %08x != "
|
||||
"full_name_hash() = %08x",
|
||||
i, j, hashlen_hash(hashlen), h0);
|
||||
return -EINVAL;
|
||||
}
|
||||
|
||||
string_or |= h0;
|
||||
h64 = h64 << 32 | h0; /* For use with hash_64 */
|
||||
if (!test_int_hash(h64, hash_or))
|
||||
return -EINVAL;
|
||||
tests++;
|
||||
} /* i */
|
||||
} /* j */
|
||||
|
||||
/* The OR of all the hash values should cover all the bits */
|
||||
if (~string_or) {
|
||||
pr_err("OR of all string hash results = %#x != %#x",
|
||||
string_or, -1u);
|
||||
return -EINVAL;
|
||||
}
|
||||
if (~hash_or[0][0]) {
|
||||
pr_err("OR of all __hash_32 results = %#x != %#x",
|
||||
hash_or[0][0], -1u);
|
||||
return -EINVAL;
|
||||
}
|
||||
#ifdef HAVE_ARCH__HASH_32
|
||||
#if HAVE_ARCH__HASH_32 != 1 /* Test is pointless if results match */
|
||||
if (~hash_or[1][0]) {
|
||||
pr_err("OR of all __hash_32_generic results = %#x != %#x",
|
||||
hash_or[1][0], -1u);
|
||||
return -EINVAL;
|
||||
}
|
||||
#endif
|
||||
#endif
|
||||
|
||||
/* Likewise for all the i-bit hash values */
|
||||
for (i = 1; i <= 32; i++) {
|
||||
u32 const m = ((u32)2 << (i-1)) - 1; /* Low i bits set */
|
||||
|
||||
if (hash_or[0][i] != m) {
|
||||
pr_err("OR of all hash_32(%d) results = %#x "
|
||||
"(%#x expected)", i, hash_or[0][i], m);
|
||||
return -EINVAL;
|
||||
}
|
||||
if (hash_or[1][i] != m) {
|
||||
pr_err("OR of all hash_64(%d) results = %#x "
|
||||
"(%#x expected)", i, hash_or[1][i], m);
|
||||
return -EINVAL;
|
||||
}
|
||||
}
|
||||
|
||||
/* Issue notices about skipped tests. */
|
||||
#ifndef HAVE_ARCH__HASH_32
|
||||
pr_info("__hash_32() has no arch implementation to test.");
|
||||
#elif HAVE_ARCH__HASH_32 != 1
|
||||
pr_info("__hash_32() is arch-specific; not compared to generic.");
|
||||
#endif
|
||||
#ifndef HAVE_ARCH_HASH_32
|
||||
pr_info("hash_32() has no arch implementation to test.");
|
||||
#elif HAVE_ARCH_HASH_32 != 1
|
||||
pr_info("hash_32() is arch-specific; not compared to generic.");
|
||||
#endif
|
||||
#ifndef HAVE_ARCH_HASH_64
|
||||
pr_info("hash_64() has no arch implementation to test.");
|
||||
#elif HAVE_ARCH_HASH_64 != 1
|
||||
pr_info("hash_64() is arch-specific; not compared to generic.");
|
||||
#endif
|
||||
|
||||
pr_notice("%u tests passed.", tests);
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
static void __exit test_hash_exit(void)
|
||||
{
|
||||
}
|
||||
|
||||
module_init(test_hash_init); /* Does everything */
|
||||
module_exit(test_hash_exit); /* Does nothing */
|
||||
|
||||
MODULE_LICENSE("GPL");
|
||||
Loading…
Reference in a new issue