/*
 * Handling of different ABIs (personalities).
 *
 * We group personalities into execution domains which have their
 * own handlers for kernel entry points, signal mapping, etc...
 *
 * 2001-05-06   Complete rewrite,  Christoph Hellwig (hch@infradead.org)
 */

#include <linux/config.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/kmod.h>
#include <linux/module.h>
#include <linux/personality.h>
#include <linux/sched.h>
#include <linux/sysctl.h>
#include <linux/types.h>


static void default_handler(int, struct pt_regs *);

static struct exec_domain *exec_domains = &default_exec_domain;
static rwlock_t exec_domains_lock = RW_LOCK_UNLOCKED;


static u_long ident_map[32] = {
        0,      1,      2,      3,      4,      5,      6,      7,
        8,      9,      10,     11,     12,     13,     14,     15,
        16,     17,     18,     19,     20,     21,     22,     23,
        24,     25,     26,     27,     28,     29,     30,     31
};

struct exec_domain default_exec_domain = {
        "Linux",                /* name */
        default_handler,        /* lcall7 causes a seg fault. */
        0, 0,                   /* PER_LINUX personality. */
        ident_map,              /* Identity map signals. */
        ident_map,              /*  - both ways. */
};


static void
default_handler(int segment, struct pt_regs *regp)
{
        u_long                  pers = 0;

        /*
         * This may have been a static linked SVr4 binary, so we would
         * have the personality set incorrectly. Or it might have been
         * a Solaris/x86 binary. We can tell which because the former
         * uses lcall7, while the latter used lcall 0x27.
         * Try to find or load the appropriate personality, and fall back
         * to just forcing a SEGV.
         *
         * XXX: this is IA32-specific and should be moved to the MD-tree.
         */
        switch (segment) {
#ifdef __i386__
        case 0x07:
                pers = abi_defhandler_lcall7;
                break;
        case 0x27:
                pers = PER_SOLARIS;
                break;
#endif
        }
        set_personality(pers);

        if (current->exec_domain->handler != default_handler)
                current->exec_domain->handler(segment, regp);
        else
                send_sig(SIGSEGV, current, 1);
}

static struct exec_domain *
lookup_exec_domain(u_long personality)
{
        struct exec_domain *    ep;
        u_long                  pers = personality(personality);
                
        read_lock(&exec_domains_lock);
        for (ep = exec_domains; ep; ep = ep->next) {
                if (pers >= ep->pers_low && pers <= ep->pers_high)
                        if (try_inc_mod_count(ep->module))
                                goto out;
        }

#ifdef CONFIG_KMOD
        read_unlock(&exec_domains_lock);
        {
                char buffer[30];
                sprintf(buffer, "personality-%ld", pers);
                request_module(buffer);
        }
        read_lock(&exec_domains_lock);

        for (ep = exec_domains; ep; ep = ep->next) {
                if (pers >= ep->pers_low && pers <= ep->pers_high)
                        if (try_inc_mod_count(ep->module))
                                goto out;
        }
#endif

        ep = &default_exec_domain;
out:
        read_unlock(&exec_domains_lock);
        return (ep);
}

int
register_exec_domain(struct exec_domain *ep)
{
        struct exec_domain      *tmp;
        int                     err = -EBUSY;

        if (ep == NULL)
                return -EINVAL;

        if (ep->next != NULL)
                return -EBUSY;

        write_lock(&exec_domains_lock);
        for (tmp = exec_domains; tmp; tmp = tmp->next) {
                if (tmp == ep)
                        goto out;
        }

        ep->next = exec_domains;
        exec_domains = ep;
        err = 0;

out:
        write_unlock(&exec_domains_lock);
        return (err);
}

int
unregister_exec_domain(struct exec_domain *ep)
{
        struct exec_domain      **epp;

        epp = &exec_domains;
        write_lock(&exec_domains_lock);
        for (epp = &exec_domains; *epp; epp = &(*epp)->next) {
                if (ep == *epp)
                        goto unregister;
        }
        write_unlock(&exec_domains_lock);
        return -EINVAL;

unregister:
        *epp = ep->next;
        ep->next = NULL;
        write_unlock(&exec_domains_lock);
        return 0;
}

int
__set_personality(u_long personality)
{
        struct exec_domain      *ep, *oep;

        ep = lookup_exec_domain(personality);
        if (ep == current->exec_domain) {
                current->personality = personality;
                return 0;
        }

        if (atomic_read(&current->fs->count) != 1) {
                struct fs_struct *fsp, *ofsp;

                fsp = copy_fs_struct(current->fs);
                if (fsp == NULL) {
                        put_exec_domain(ep);
                        return -ENOMEM;;
                }

                task_lock(current);
                ofsp = current->fs;
                current->fs = fsp;
                task_unlock(current);

                put_fs_struct(ofsp);
        }

        /*
         * At that point we are guaranteed to be the sole owner of
         * current->fs.
         */

        current->personality = personality;
        oep = current->exec_domain;
        current->exec_domain = ep;
        set_fs_altroot();

        put_exec_domain(oep);

        return 0;
}

int
get_exec_domain_list(char *page)
{
        struct exec_domain      *ep;
        int                     len = 0;

        read_lock(&exec_domains_lock);
        for (ep = exec_domains; ep && len < PAGE_SIZE - 80; ep = ep->next)
                len += sprintf(page + len, "%d-%d\t%-16s\t[%s]\n",
                        ep->pers_low, ep->pers_high, ep->name,
                        ep->module ? ep->module->name : "kernel");
        read_unlock(&exec_domains_lock);
        return (len);
}

asmlinkage long
sys_personality(u_long personality)
{
        u_long old = current->personality;;

        if (personality != 0xffffffff) {
                set_personality(personality);
                if (current->personality != personality)
                        return -EINVAL;
        }

        return (long)old;
}


EXPORT_SYMBOL(register_exec_domain);
EXPORT_SYMBOL(unregister_exec_domain);
EXPORT_SYMBOL(__set_personality);

/*
 * We have to have all sysctl handling for the Linux-ABI
 * in one place as the dynamic registration of sysctls is
 * horribly crufty in Linux <= 2.4.
 *
 * I hope the new sysctl schemes discussed for future versions
 * will obsolete this.
 *
 *                              --hch
 */

u_long abi_defhandler_coff = PER_SCOSVR3;
u_long abi_defhandler_elf = PER_LINUX;
u_long abi_defhandler_lcall7 = PER_SVR4;
u_long abi_defhandler_libcso = PER_SVR4;
u_int abi_traceflg;
int abi_fake_utsname;

static struct ctl_table abi_table[] = {
        {ABI_DEFHANDLER_COFF, "defhandler_coff", &abi_defhandler_coff,
                sizeof(int), 0644, NULL, &proc_doulongvec_minmax},
        {ABI_DEFHANDLER_ELF, "defhandler_elf", &abi_defhandler_elf,
                sizeof(int), 0644, NULL, &proc_doulongvec_minmax},
        {ABI_DEFHANDLER_LCALL7, "defhandler_lcall7", &abi_defhandler_lcall7,
                sizeof(int), 0644, NULL, &proc_doulongvec_minmax},
        {ABI_DEFHANDLER_LIBCSO, "defhandler_libcso", &abi_defhandler_libcso,
                sizeof(int), 0644, NULL, &proc_doulongvec_minmax},
        {ABI_TRACE, "trace", &abi_traceflg,
                sizeof(u_int), 0644, NULL, &proc_dointvec},
        {ABI_FAKE_UTSNAME, "fake_utsname", &abi_fake_utsname,
                sizeof(int), 0644, NULL, &proc_dointvec},
        {0}
};

static struct ctl_table abi_root_table[] = {
        {CTL_ABI, "abi", NULL, 0, 0555, abi_table},
        {0}
};

static int __init
abi_register_sysctl(void)
{
        register_sysctl_table(abi_root_table, 1);
        return 0;
}

__initcall(abi_register_sysctl);


EXPORT_SYMBOL(abi_defhandler_coff);
EXPORT_SYMBOL(abi_defhandler_elf);
EXPORT_SYMBOL(abi_defhandler_lcall7);
EXPORT_SYMBOL(abi_defhandler_libcso);
EXPORT_SYMBOL(abi_traceflg);
EXPORT_SYMBOL(abi_fake_utsname);