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zfs/module/spl/spl-generic.c

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/*****************************************************************************\
* Copyright (C) 2007-2010 Lawrence Livermore National Security, LLC.
* Copyright (C) 2007 The Regents of the University of California.
* Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
* Written by Brian Behlendorf <behlendorf1@llnl.gov>.
* UCRL-CODE-235197
*
* This file is part of the SPL, Solaris Porting Layer.
* For details, see <http://zfsonlinux.org/>.
*
* The SPL is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version.
*
* The SPL is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* for more details.
*
* You should have received a copy of the GNU General Public License along
* with the SPL. If not, see <http://www.gnu.org/licenses/>.
*****************************************************************************
* Solaris Porting Layer (SPL) Generic Implementation.
\*****************************************************************************/
#include <sys/sysmacros.h>
#include <sys/systeminfo.h>
#include <sys/vmsystm.h>
#include <sys/kobj.h>
#include <sys/kmem.h>
#include <sys/kmem_cache.h>
#include <sys/vmem.h>
#include <sys/mutex.h>
#include <sys/rwlock.h>
#include <sys/taskq.h>
#include <sys/tsd.h>
#include <sys/zmod.h>
#include <sys/debug.h>
#include <sys/proc.h>
#include <sys/kstat.h>
#include <sys/file.h>
#include <linux/ctype.h>
#include <sys/disp.h>
#include <sys/random.h>
#include <linux/kmod.h>
#include <linux/math64_compat.h>
#include <linux/proc_compat.h>
char spl_version[32] = "SPL v" SPL_META_VERSION "-" SPL_META_RELEASE;
EXPORT_SYMBOL(spl_version);
unsigned long spl_hostid = 0;
EXPORT_SYMBOL(spl_hostid);
module_param(spl_hostid, ulong, 0644);
MODULE_PARM_DESC(spl_hostid, "The system hostid.");
proc_t p0;
EXPORT_SYMBOL(p0);
/*
* Xorshift Pseudo Random Number Generator based on work by Sebastiano Vigna
*
* "Further scramblings of Marsaglia's xorshift generators"
* http://vigna.di.unimi.it/ftp/papers/xorshiftplus.pdf
*
* random_get_pseudo_bytes() is an API function on Illumos whose sole purpose
* is to provide bytes containing random numbers. It is mapped to /dev/urandom
* on Illumos, which uses a "FIPS 186-2 algorithm". No user of the SPL's
* random_get_pseudo_bytes() needs bytes that are of cryptographic quality, so
* we can implement it using a fast PRNG that we seed using Linux' actual
* equivalent to random_get_pseudo_bytes(). We do this by providing each CPU
* with an independent seed so that all calls to random_get_pseudo_bytes() are
* free of atomic instructions.
*
* A consequence of using a fast PRNG is that using random_get_pseudo_bytes()
* to generate words larger than 128 bits will paradoxically be limited to
* `2^128 - 1` possibilities. This is because we have a sequence of `2^128 - 1`
* 128-bit words and selecting the first will implicitly select the second. If
* a caller finds this behavior undesireable, random_get_bytes() should be used
* instead.
*
* XXX: Linux interrupt handlers that trigger within the critical section
* formed by `s[1] = xp[1];` and `xp[0] = s[0];` and call this function will
* see the same numbers. Nothing in the code currently calls this in an
* interrupt handler, so this is considered to be okay. If that becomes a
* problem, we could create a set of per-cpu variables for interrupt handlers
* and use them when in_interrupt() from linux/preempt_mask.h evaluates to
* true.
*/
static DEFINE_PER_CPU(uint64_t[2], spl_pseudo_entropy);
/*
* spl_rand_next()/spl_rand_jump() are copied from the following CC-0 licensed
* file:
*
* http://xorshift.di.unimi.it/xorshift128plus.c
*/
static inline uint64_t
spl_rand_next(uint64_t *s) {
uint64_t s1 = s[0];
const uint64_t s0 = s[1];
s[0] = s0;
s1 ^= s1 << 23; // a
s[1] = s1 ^ s0 ^ (s1 >> 18) ^ (s0 >> 5); // b, c
return (s[1] + s0);
}
static inline void
spl_rand_jump(uint64_t *s) {
static const uint64_t JUMP[] = { 0x8a5cd789635d2dff, 0x121fd2155c472f96 };
uint64_t s0 = 0;
uint64_t s1 = 0;
int i, b;
for(i = 0; i < sizeof JUMP / sizeof *JUMP; i++)
for(b = 0; b < 64; b++) {
if (JUMP[i] & 1ULL << b) {
s0 ^= s[0];
s1 ^= s[1];
}
(void) spl_rand_next(s);
}
s[0] = s0;
s[1] = s1;
}
int
random_get_pseudo_bytes(uint8_t *ptr, size_t len)
{
uint64_t *xp, s[2];
ASSERT(ptr);
xp = get_cpu_var(spl_pseudo_entropy);
s[0] = xp[0];
s[1] = xp[1];
while (len) {
union {
uint64_t ui64;
uint8_t byte[sizeof (uint64_t)];
}entropy;
int i = MIN(len, sizeof (uint64_t));
len -= i;
entropy.ui64 = spl_rand_next(s);
while (i--)
*ptr++ = entropy.byte[i];
}
xp[0] = s[0];
xp[1] = s[1];
put_cpu_var(spl_pseudo_entropy);
return (0);
}
EXPORT_SYMBOL(random_get_pseudo_bytes);
#if BITS_PER_LONG == 32
/*
* Support 64/64 => 64 division on a 32-bit platform. While the kernel
* provides a div64_u64() function for this we do not use it because the
* implementation is flawed. There are cases which return incorrect
* results as late as linux-2.6.35. Until this is fixed upstream the
* spl must provide its own implementation.
*
* This implementation is a slightly modified version of the algorithm
* proposed by the book 'Hacker's Delight'. The original source can be
* found here and is available for use without restriction.
*
* http://www.hackersdelight.org/HDcode/newCode/divDouble.c
*/
/*
* Calculate number of leading of zeros for a 64-bit value.
*/
static int
nlz64(uint64_t x) {
register int n = 0;
if (x == 0)
return 64;
if (x <= 0x00000000FFFFFFFFULL) {n = n + 32; x = x << 32;}
if (x <= 0x0000FFFFFFFFFFFFULL) {n = n + 16; x = x << 16;}
if (x <= 0x00FFFFFFFFFFFFFFULL) {n = n + 8; x = x << 8;}
if (x <= 0x0FFFFFFFFFFFFFFFULL) {n = n + 4; x = x << 4;}
if (x <= 0x3FFFFFFFFFFFFFFFULL) {n = n + 2; x = x << 2;}
if (x <= 0x7FFFFFFFFFFFFFFFULL) {n = n + 1;}
return n;
}
/*
* Newer kernels have a div_u64() function but we define our own
* to simplify portibility between kernel versions.
*/
static inline uint64_t
__div_u64(uint64_t u, uint32_t v)
{
(void) do_div(u, v);
return u;
}
/*
* Implementation of 64-bit unsigned division for 32-bit machines.
*
* First the procedure takes care of the case in which the divisor is a
* 32-bit quantity. There are two subcases: (1) If the left half of the
* dividend is less than the divisor, one execution of do_div() is all that
* is required (overflow is not possible). (2) Otherwise it does two
* divisions, using the grade school method.
*/
uint64_t
__udivdi3(uint64_t u, uint64_t v)
{
uint64_t u0, u1, v1, q0, q1, k;
int n;
if (v >> 32 == 0) { // If v < 2**32:
if (u >> 32 < v) { // If u/v cannot overflow,
return __div_u64(u, v); // just do one division.
} else { // If u/v would overflow:
u1 = u >> 32; // Break u into two halves.
u0 = u & 0xFFFFFFFF;
q1 = __div_u64(u1, v); // First quotient digit.
k = u1 - q1 * v; // First remainder, < v.
u0 += (k << 32);
q0 = __div_u64(u0, v); // Seconds quotient digit.
return (q1 << 32) + q0;
}
} else { // If v >= 2**32:
n = nlz64(v); // 0 <= n <= 31.
v1 = (v << n) >> 32; // Normalize divisor, MSB is 1.
u1 = u >> 1; // To ensure no overflow.
q1 = __div_u64(u1, v1); // Get quotient from
q0 = (q1 << n) >> 31; // Undo normalization and
// division of u by 2.
if (q0 != 0) // Make q0 correct or
q0 = q0 - 1; // too small by 1.
if ((u - q0 * v) >= v)
q0 = q0 + 1; // Now q0 is correct.
return q0;
}
}
EXPORT_SYMBOL(__udivdi3);
/*
* Implementation of 64-bit signed division for 32-bit machines.
*/
int64_t
__divdi3(int64_t u, int64_t v)
{
int64_t q, t;
q = __udivdi3(abs64(u), abs64(v));
t = (u ^ v) >> 63; // If u, v have different
return (q ^ t) - t; // signs, negate q.
}
EXPORT_SYMBOL(__divdi3);
/*
* Implementation of 64-bit unsigned modulo for 32-bit machines.
*/
uint64_t
__umoddi3(uint64_t dividend, uint64_t divisor)
{
return (dividend - (divisor * __udivdi3(dividend, divisor)));
}
EXPORT_SYMBOL(__umoddi3);
#if defined(__arm) || defined(__arm__)
/*
* Implementation of 64-bit (un)signed division for 32-bit arm machines.
*
* Run-time ABI for the ARM Architecture (page 20). A pair of (unsigned)
* long longs is returned in {{r0, r1}, {r2,r3}}, the quotient in {r0, r1},
* and the remainder in {r2, r3}. The return type is specifically left
* set to 'void' to ensure the compiler does not overwrite these registers
* during the return. All results are in registers as per ABI
*/
void
__aeabi_uldivmod(uint64_t u, uint64_t v)
{
uint64_t res;
uint64_t mod;
res = __udivdi3(u, v);
mod = __umoddi3(u, v);
{
register uint32_t r0 asm("r0") = (res & 0xFFFFFFFF);
register uint32_t r1 asm("r1") = (res >> 32);
register uint32_t r2 asm("r2") = (mod & 0xFFFFFFFF);
register uint32_t r3 asm("r3") = (mod >> 32);
asm volatile(""
: "+r"(r0), "+r"(r1), "+r"(r2),"+r"(r3) /* output */
: "r"(r0), "r"(r1), "r"(r2), "r"(r3)); /* input */
return; /* r0; */
}
}
EXPORT_SYMBOL(__aeabi_uldivmod);
void
__aeabi_ldivmod(int64_t u, int64_t v)
{
int64_t res;
uint64_t mod;
res = __divdi3(u, v);
mod = __umoddi3(u, v);
{
register uint32_t r0 asm("r0") = (res & 0xFFFFFFFF);
register uint32_t r1 asm("r1") = (res >> 32);
register uint32_t r2 asm("r2") = (mod & 0xFFFFFFFF);
register uint32_t r3 asm("r3") = (mod >> 32);
asm volatile(""
: "+r"(r0), "+r"(r1), "+r"(r2),"+r"(r3) /* output */
: "r"(r0), "r"(r1), "r"(r2), "r"(r3)); /* input */
return; /* r0; */
}
}
EXPORT_SYMBOL(__aeabi_ldivmod);
#endif /* __arm || __arm__ */
#endif /* BITS_PER_LONG */
/* NOTE: The strtoxx behavior is solely based on my reading of the Solaris
* ddi_strtol(9F) man page. I have not verified the behavior of these
* functions against their Solaris counterparts. It is possible that I
* may have misinterpreted the man page or the man page is incorrect.
*/
int ddi_strtoul(const char *, char **, int, unsigned long *);
int ddi_strtol(const char *, char **, int, long *);
int ddi_strtoull(const char *, char **, int, unsigned long long *);
int ddi_strtoll(const char *, char **, int, long long *);
#define define_ddi_strtoux(type, valtype) \
int ddi_strtou##type(const char *str, char **endptr, \
int base, valtype *result) \
{ \
valtype last_value, value = 0; \
char *ptr = (char *)str; \
int flag = 1, digit; \
\
if (strlen(ptr) == 0) \
return EINVAL; \
\
/* Auto-detect base based on prefix */ \
if (!base) { \
if (str[0] == '0') { \
if (tolower(str[1])=='x' && isxdigit(str[2])) { \
base = 16; /* hex */ \
ptr += 2; \
} else if (str[1] >= '0' && str[1] < 8) { \
base = 8; /* octal */ \
ptr += 1; \
} else { \
return EINVAL; \
} \
} else { \
base = 10; /* decimal */ \
} \
} \
\
while (1) { \
if (isdigit(*ptr)) \
digit = *ptr - '0'; \
else if (isalpha(*ptr)) \
digit = tolower(*ptr) - 'a' + 10; \
else \
break; \
\
if (digit >= base) \
break; \
\
last_value = value; \
value = value * base + digit; \
if (last_value > value) /* Overflow */ \
return ERANGE; \
\
flag = 1; \
ptr++; \
} \
\
if (flag) \
*result = value; \
\
if (endptr) \
*endptr = (char *)(flag ? ptr : str); \
\
return 0; \
} \
#define define_ddi_strtox(type, valtype) \
int ddi_strto##type(const char *str, char **endptr, \
int base, valtype *result) \
{ \
int rc; \
\
if (*str == '-') { \
rc = ddi_strtou##type(str + 1, endptr, base, result); \
if (!rc) { \
if (*endptr == str + 1) \
*endptr = (char *)str; \
else \
*result = -*result; \
} \
} else { \
rc = ddi_strtou##type(str, endptr, base, result); \
} \
\
return rc; \
}
define_ddi_strtoux(l, unsigned long)
define_ddi_strtox(l, long)
define_ddi_strtoux(ll, unsigned long long)
define_ddi_strtox(ll, long long)
EXPORT_SYMBOL(ddi_strtoul);
EXPORT_SYMBOL(ddi_strtol);
EXPORT_SYMBOL(ddi_strtoll);
EXPORT_SYMBOL(ddi_strtoull);
int
ddi_copyin(const void *from, void *to, size_t len, int flags)
{
/* Fake ioctl() issued by kernel, 'from' is a kernel address */
if (flags & FKIOCTL) {
memcpy(to, from, len);
return 0;
}
return copyin(from, to, len);
}
EXPORT_SYMBOL(ddi_copyin);
int
ddi_copyout(const void *from, void *to, size_t len, int flags)
{
/* Fake ioctl() issued by kernel, 'from' is a kernel address */
if (flags & FKIOCTL) {
memcpy(to, from, len);
return 0;
}
return copyout(from, to, len);
}
EXPORT_SYMBOL(ddi_copyout);
#ifndef HAVE_PUT_TASK_STRUCT
/*
* This is only a stub function which should never be used. The SPL should
* never be putting away the last reference on a task structure so this will
* not be called. However, we still need to define it so the module does not
* have undefined symbol at load time. That all said if this impossible
* thing does somehow happen PANIC immediately so we know about it.
*/
void
__put_task_struct(struct task_struct *t)
{
PANIC("Unexpectly put last reference on task %d\n", (int)t->pid);
}
EXPORT_SYMBOL(__put_task_struct);
#endif /* HAVE_PUT_TASK_STRUCT */
/*
* Read the unique system identifier from the /etc/hostid file.
*
* The behavior of /usr/bin/hostid on Linux systems with the
* regular eglibc and coreutils is:
*
* 1. Generate the value if the /etc/hostid file does not exist
* or if the /etc/hostid file is less than four bytes in size.
*
* 2. If the /etc/hostid file is at least 4 bytes, then return
* the first four bytes [0..3] in native endian order.
*
* 3. Always ignore bytes [4..] if they exist in the file.
*
* Only the first four bytes are significant, even on systems that
* have a 64-bit word size.
*
* See:
*
* eglibc: sysdeps/unix/sysv/linux/gethostid.c
* coreutils: src/hostid.c
*
* Notes:
*
* The /etc/hostid file on Solaris is a text file that often reads:
*
* # DO NOT EDIT
* "0123456789"
*
* Directly copying this file to Linux results in a constant
* hostid of 4f442023 because the default comment constitutes
* the first four bytes of the file.
*
*/
char *spl_hostid_path = HW_HOSTID_PATH;
module_param(spl_hostid_path, charp, 0444);
MODULE_PARM_DESC(spl_hostid_path, "The system hostid file (/etc/hostid)");
static int
hostid_read(void)
{
int result;
uint64_t size;
struct _buf *file;
uint32_t hostid = 0;
file = kobj_open_file(spl_hostid_path);
if (file == (struct _buf *)-1)
return -1;
result = kobj_get_filesize(file, &size);
if (result != 0) {
printk(KERN_WARNING
"SPL: kobj_get_filesize returned %i on %s\n",
result, spl_hostid_path);
kobj_close_file(file);
return -2;
}
if (size < sizeof(HW_HOSTID_MASK)) {
printk(KERN_WARNING
"SPL: Ignoring the %s file because it is %llu bytes; "
"expecting %lu bytes instead.\n", spl_hostid_path,
size, (unsigned long)sizeof(HW_HOSTID_MASK));
kobj_close_file(file);
return -3;
}
/* Read directly into the variable like eglibc does. */
/* Short reads are okay; native behavior is preserved. */
result = kobj_read_file(file, (char *)&hostid, sizeof(hostid), 0);
if (result < 0) {
printk(KERN_WARNING
"SPL: kobj_read_file returned %i on %s\n",
result, spl_hostid_path);
kobj_close_file(file);
return -4;
}
/* Mask down to 32 bits like coreutils does. */
spl_hostid = hostid & HW_HOSTID_MASK;
kobj_close_file(file);
return 0;
}
uint32_t
zone_get_hostid(void *zone)
{
static int first = 1;
/* Only the global zone is supported */
ASSERT(zone == NULL);
if (first) {
first = 0;
spl_hostid &= HW_HOSTID_MASK;
/*
* Get the hostid if it was not passed as a module parameter.
* Try reading the /etc/hostid file directly.
*/
if (spl_hostid == 0 && hostid_read())
spl_hostid = 0;
printk(KERN_NOTICE "SPL: using hostid 0x%08x\n",
(unsigned int) spl_hostid);
}
return spl_hostid;
}
EXPORT_SYMBOL(zone_get_hostid);
static int
spl_kvmem_init(void)
{
int rc = 0;
rc = spl_kmem_init();
if (rc)
return (rc);
rc = spl_vmem_init();
if (rc) {
spl_kmem_fini();
return (rc);
}
return (rc);
}
/*
* We initialize the random number generator with 128 bits of entropy from the
* system random number generator. In the improbable case that we have a zero
* seed, we fallback to the system jiffies, unless it is also zero, in which
* situation we use a preprogrammed seed. We step forward by 2^64 iterations to
* initialize each of the per-cpu seeds so that the sequences generated on each
* CPU are guaranteed to never overlap in practice.
*/
static void __init
spl_random_init(void)
{
uint64_t s[2];
int i;
get_random_bytes(s, sizeof (s));
if (s[0] == 0 && s[1] == 0) {
if (jiffies != 0) {
s[0] = jiffies;
s[1] = ~0 - jiffies;
} else {
(void) memcpy(s, "improbable seed", sizeof (s));
}
printk("SPL: get_random_bytes() returned 0 "
"when generating random seed. Setting initial seed to "
"0x%016llx%016llx.", cpu_to_be64(s[0]), cpu_to_be64(s[1]));
}
for (i = 0; i < NR_CPUS; i++) {
uint64_t *wordp = per_cpu(spl_pseudo_entropy, i);
spl_rand_jump(s);
wordp[0] = s[0];
wordp[1] = s[1];
}
}
static void
spl_kvmem_fini(void)
{
spl_vmem_fini();
spl_kmem_fini();
}
static int __init
spl_init(void)
{
int rc = 0;
bzero(&p0, sizeof (proc_t));
spl_random_init();
if ((rc = spl_kvmem_init()))
goto out1;
if ((rc = spl_mutex_init()))
goto out2;
if ((rc = spl_rw_init()))
goto out3;
if ((rc = spl_tsd_init()))
goto out4;
if ((rc = spl_taskq_init()))
goto out5;
if ((rc = spl_kmem_cache_init()))
goto out6;
if ((rc = spl_vn_init()))
goto out7;
if ((rc = spl_proc_init()))
goto out8;
if ((rc = spl_kstat_init()))
goto out9;
if ((rc = spl_zlib_init()))
goto out10;
printk(KERN_NOTICE "SPL: Loaded module v%s-%s%s\n", SPL_META_VERSION,
SPL_META_RELEASE, SPL_DEBUG_STR);
return (rc);
out10:
spl_kstat_fini();
out9:
spl_proc_fini();
out8:
spl_vn_fini();
out7:
spl_kmem_cache_fini();
out6:
spl_taskq_fini();
out5:
spl_tsd_fini();
out4:
spl_rw_fini();
out3:
spl_mutex_fini();
out2:
spl_kvmem_fini();
out1:
printk(KERN_NOTICE "SPL: Failed to Load Solaris Porting Layer "
"v%s-%s%s, rc = %d\n", SPL_META_VERSION, SPL_META_RELEASE,
SPL_DEBUG_STR, rc);
return (rc);
}
static void __exit
spl_fini(void)
{
printk(KERN_NOTICE "SPL: Unloaded module v%s-%s%s\n",
SPL_META_VERSION, SPL_META_RELEASE, SPL_DEBUG_STR);
spl_zlib_fini();
spl_kstat_fini();
spl_proc_fini();
spl_vn_fini();
spl_kmem_cache_fini();
spl_taskq_fini();
spl_tsd_fini();
spl_rw_fini();
spl_mutex_fini();
spl_kvmem_fini();
}
module_init(spl_init);
module_exit(spl_fini);
MODULE_DESCRIPTION("Solaris Porting Layer");
MODULE_AUTHOR(SPL_META_AUTHOR);
MODULE_LICENSE(SPL_META_LICENSE);
MODULE_VERSION(SPL_META_VERSION "-" SPL_META_RELEASE);
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