[mirror_spl-debian.git] / module / spl / spl-generic.c

/*****************************************************************************\
 *  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://github.com/behlendorf/spl/>.
 *
 *  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/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/utsname.h>
#include <sys/file.h>
#include <linux/kmod.h>
#include <linux/proc_compat.h>
#include <spl-debug.h>

#ifdef SS_DEBUG_SUBSYS
#undef SS_DEBUG_SUBSYS
#endif

#define SS_DEBUG_SUBSYS SS_GENERIC

char spl_version[32] = "SPL v" SPL_META_VERSION "-" SPL_META_RELEASE;
EXPORT_SYMBOL(spl_version);

unsigned long spl_hostid = HW_INVALID_HOSTID;
EXPORT_SYMBOL(spl_hostid);
module_param(spl_hostid, ulong, 0644);
MODULE_PARM_DESC(spl_hostid, "The system hostid.");

char hw_serial[HW_HOSTID_LEN] = "<none>";
EXPORT_SYMBOL(hw_serial);

proc_t p0 = { 0 };
EXPORT_SYMBOL(p0);

#ifndef HAVE_KALLSYMS_LOOKUP_NAME
DECLARE_WAIT_QUEUE_HEAD(spl_kallsyms_lookup_name_waitq);
kallsyms_lookup_name_t spl_kallsyms_lookup_name_fn = SYMBOL_POISON;
#endif

int
highbit(unsigned long i)
{
        register int h = 1;
        SENTRY;

        if (i == 0)
                SRETURN(0);
#if BITS_PER_LONG == 64
        if (i & 0xffffffff00000000ul) {
                h += 32; i >>= 32;
        }
#endif
        if (i & 0xffff0000) {
                h += 16; i >>= 16;
        }
        if (i & 0xff00) {
                h += 8; i >>= 8;
        }
        if (i & 0xf0) {
                h += 4; i >>= 4;
        }
        if (i & 0xc) {
                h += 2; i >>= 2;
        }
        if (i & 0x2) {
                h += 1;
        }
        SRETURN(h);
}
EXPORT_SYMBOL(highbit);

#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 */

struct new_utsname *__utsname(void)
{
#ifdef HAVE_INIT_UTSNAME
        return init_utsname();
#else
        return &system_utsname;
#endif
}
EXPORT_SYMBOL(__utsname);


/*
 * 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;
        unsigned long 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;
}

#define GET_HOSTID_CMD \
        "exec 0</dev/null " \
        "     1>/proc/sys/kernel/spl/hostid " \
        "     2>/dev/null; " \
        "hostid"

static int
hostid_exec(void)
{
        char *argv[] = { "/bin/sh",
                         "-c",
                         GET_HOSTID_CMD,
                         NULL };
        char *envp[] = { "HOME=/",
                         "TERM=linux",
                         "PATH=/sbin:/usr/sbin:/bin:/usr/bin",
                         NULL };
        int rc;

        /* Doing address resolution in the kernel is tricky and just
         * not a good idea in general.  So to set the proper 'hw_serial'
         * use the usermodehelper support to ask '/bin/sh' to run
         * '/usr/bin/hostid' and redirect the result to /proc/sys/spl/hostid
         * for us to use.  It's a horrific solution but it will do for now.
         */
        rc = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_PROC);
        if (rc)
                printk("SPL: Failed user helper '%s %s %s', rc = %d\n",
                       argv[0], argv[1], argv[2], rc);

        return rc;
}

uint32_t
zone_get_hostid(void *zone)
{
        static int first = 1;
        unsigned long hostid;
        int rc;

        /* Only the global zone is supported */
        ASSERT(zone == NULL);

        if (first) {
                first = 0;

                /*
                 * Get the hostid if it was not passed as a module parameter.
                 * Try reading the /etc/hostid file directly, and then fall
                 * back to calling the /usr/bin/hostid utility.
                 */
                if ((spl_hostid == HW_INVALID_HOSTID) &&
                    (rc = hostid_read()) && (rc = hostid_exec()))
                        return HW_INVALID_HOSTID;

                printk(KERN_NOTICE "SPL: using hostid 0x%08x\n",
                        (unsigned int) spl_hostid);
        }

        if (ddi_strtoul(hw_serial, NULL, HW_HOSTID_LEN-1, &hostid) != 0)
                return HW_INVALID_HOSTID;

        return (uint32_t)hostid;
}
EXPORT_SYMBOL(zone_get_hostid);

#ifndef HAVE_KALLSYMS_LOOKUP_NAME
/*
 * The kallsyms_lookup_name() kernel function is not an exported symbol in
 * Linux 2.6.19 through 2.6.32 inclusive.
 *
 * This function replaces the functionality by performing an upcall to user
 * space where /proc/kallsyms is consulted for the requested address.
 *
 */

#define GET_KALLSYMS_ADDR_CMD \
        "exec 0</dev/null " \
        "     1>/proc/sys/kernel/spl/kallsyms_lookup_name " \
        "     2>/dev/null; " \
        "awk  '{ if ( $3 == \"kallsyms_lookup_name\" ) { print $1 } }' " \
        "     /proc/kallsyms "

static int
set_kallsyms_lookup_name(void)
{
        char *argv[] = { "/bin/sh",
                         "-c",
                         GET_KALLSYMS_ADDR_CMD,
                         NULL };
        char *envp[] = { "HOME=/",
                         "TERM=linux",
                         "PATH=/sbin:/usr/sbin:/bin:/usr/bin",
                         NULL };
        int rc;

        rc = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_PROC);

        /*
         * Due to I/O buffering the helper may return successfully before
         * the proc handler has a chance to execute.  To catch this case
         * wait up to 1 second to verify spl_kallsyms_lookup_name_fn was
         * updated to a non SYMBOL_POISON value.
         */
        if (rc == 0) {
                rc = wait_event_timeout(spl_kallsyms_lookup_name_waitq,
                    spl_kallsyms_lookup_name_fn != SYMBOL_POISON, HZ);
                if (rc == 0)
                        rc = -ETIMEDOUT;
                else if (spl_kallsyms_lookup_name_fn == SYMBOL_POISON)
                        rc = -EFAULT;
                else
                        rc = 0;
        }

        if (rc)
                printk("SPL: Failed user helper '%s %s %s', rc = %d\n",
                       argv[0], argv[1], argv[2], rc);

        return rc;
}
#endif

static int
__init spl_init(void)
{
        int rc = 0;

        if ((rc = spl_debug_init()))
                return rc;

        if ((rc = spl_kmem_init()))
                SGOTO(out1, rc);

        if ((rc = spl_mutex_init()))
                SGOTO(out2, rc);

        if ((rc = spl_rw_init()))
                SGOTO(out3, rc);

        if ((rc = spl_taskq_init()))
                SGOTO(out4, rc);

        if ((rc = spl_vn_init()))
                SGOTO(out5, rc);

        if ((rc = spl_proc_init()))
                SGOTO(out6, rc);

        if ((rc = spl_kstat_init()))
                SGOTO(out7, rc);

        if ((rc = spl_tsd_init()))
                SGOTO(out8, rc);

        if ((rc = spl_zlib_init()))
                SGOTO(out9, rc);

#ifndef HAVE_KALLSYMS_LOOKUP_NAME
        if ((rc = set_kallsyms_lookup_name()))
                SGOTO(out10, rc = -EADDRNOTAVAIL);
#endif /* HAVE_KALLSYMS_LOOKUP_NAME */

        if ((rc = spl_kmem_init_kallsyms_lookup()))
                SGOTO(out10, rc);

        if ((rc = spl_vn_init_kallsyms_lookup()))
                SGOTO(out10, rc);

        printk(KERN_NOTICE "SPL: Loaded module v%s-%s%s\n", SPL_META_VERSION,
               SPL_META_RELEASE, SPL_DEBUG_STR);
        SRETURN(rc);
out10:
        spl_zlib_fini();
out9:
        spl_tsd_fini();
out8:
        spl_kstat_fini();
out7:
        spl_proc_fini();
out6:
        spl_vn_fini();
out5:
        spl_taskq_fini();
out4:
        spl_rw_fini();
out3:
        spl_mutex_fini();
out2:
        spl_kmem_fini();
out1:
        spl_debug_fini();

        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
spl_fini(void)
{
        SENTRY;

        printk(KERN_NOTICE "SPL: Unloaded module v%s-%s%s\n",
               SPL_META_VERSION, SPL_META_RELEASE, SPL_DEBUG_STR);
        spl_zlib_fini();
        spl_tsd_fini();
        spl_kstat_fini();
        spl_proc_fini();
        spl_vn_fini();
        spl_taskq_fini();
        spl_rw_fini();
        spl_mutex_fini();
        spl_kmem_fini();
        spl_debug_fini();
}

/* Called when a dependent module is loaded */
void
spl_setup(void)
{
        int rc;

        /*
         * At module load time the pwd is set to '/' on a Solaris system.
         * On a Linux system will be set to whatever directory the caller
         * was in when executing insmod/modprobe.
         */
        rc = vn_set_pwd("/");
        if (rc)
                printk("SPL: Warning unable to set pwd to '/': %d\n", rc);
}
EXPORT_SYMBOL(spl_setup);

/* Called when a dependent module is unloaded */
void
spl_cleanup(void)
{
}
EXPORT_SYMBOL(spl_cleanup);

module_init(spl_init);
module_exit(spl_fini);

MODULE_AUTHOR("Lawrence Livermore National Labs");
MODULE_DESCRIPTION("Solaris Porting Layer");
MODULE_LICENSE("GPL");