common/os/brand.c

	brand.c revision 9a5d73e03cd3312ddb571a748c40a63c58bd66e5
/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#include <sys/kmem.h>
#include <sys/errno.h>
#include <sys/systm.h>
#include <sys/cmn_err.h>
#include <sys/brand.h>
#include <sys/machbrand.h>
#include <sys/modctl.h>
#include <sys/rwlock.h>
#include <sys/zone.h>

#define SUPPORTED_BRAND_VERSION BRAND_VER_1

#if defined(__sparcv9)
/* sparcv9 uses system wide brand interposition hooks */
static void brand_plat_interposition_enable(void);
static void brand_plat_interposition_disable(void);

struct brand_mach_ops native_mach_ops  = {
        NULL, NULL
};
#else /* !__sparcv9 */
struct brand_mach_ops native_mach_ops  = {
        NULL, NULL, NULL, NULL, NULL, NULL
};
#endif /* !__sparcv9 */

brand_t native_brand = {
        BRAND_VER_1,
        "native",
        NULL,
        &native_mach_ops
};

/*
 * Used to maintain a list of all the brands currently loaded into the
 * kernel.
 */
struct brand_list {
    int         bl_refcnt;
    struct brand_list   *bl_next;
    brand_t         *bl_brand;
};

static struct brand_list *brand_list = NULL;

/*
 * This lock protects the integrity of the brand list.
 */
static kmutex_t brand_list_lock;

void
brand_init()
{
    mutex_init(&brand_list_lock, NULL, MUTEX_DEFAULT, NULL);
    p0.p_brand = &native_brand;
}

int
brand_register(brand_t *brand)
{
    struct brand_list *list, *scan;

    if (brand == NULL)
        return (EINVAL);

    if (brand->b_version != SUPPORTED_BRAND_VERSION) {
        if (brand->b_version < SUPPORTED_BRAND_VERSION) {
            cmn_err(CE_WARN,
                "brand '%s' was built to run on older versions "
                "of Solaris.",
                brand->b_name);
        } else {
            cmn_err(CE_WARN,
                "brand '%s' was built to run on a newer version "
                "of Solaris.",
                brand->b_name);
        }
        return (EINVAL);
    }

    /* Sanity checks */
    if (brand->b_name == NULL || brand->b_ops == NULL ||
        brand->b_ops->b_brandsys == NULL) {
        cmn_err(CE_WARN, "Malformed brand");
        return (EINVAL);
    }

    list = kmem_alloc(sizeof (struct brand_list), KM_SLEEP);

    /* Add the brand to the list of loaded brands. */
    mutex_enter(&brand_list_lock);

    /*
     * Check to be sure we haven't already registered this brand.
     */
    for (scan = brand_list; scan != NULL; scan = scan->bl_next) {
        if (strcmp(brand->b_name, scan->bl_brand->b_name) == 0) {
            cmn_err(CE_WARN,
                "Invalid attempt to load a second instance of "
                "brand %s", brand->b_name);
            mutex_exit(&brand_list_lock);
            kmem_free(list, sizeof (struct brand_list));
            return (EINVAL);
        }
    }

#if defined(__sparcv9)
    /* sparcv9 uses system wide brand interposition hooks */
    if (brand_list == NULL)
        brand_plat_interposition_enable();
#endif /* __sparcv9 */

    list->bl_brand = brand;
    list->bl_refcnt = 0;
    list->bl_next = brand_list;
    brand_list = list;

    mutex_exit(&brand_list_lock);

    return (0);
}

/*
 * The kernel module implementing this brand is being unloaded, so remove
 * it from the list of active brands.
 */
int
brand_unregister(brand_t *brand)
{
    struct brand_list *list, *prev;

    /* Sanity checks */
    if (brand == NULL || brand->b_name == NULL) {
        cmn_err(CE_WARN, "Malformed brand");
        return (EINVAL);
    }

    prev = NULL;
    mutex_enter(&brand_list_lock);

    for (list = brand_list; list != NULL; list = list->bl_next) {
        if (list->bl_brand == brand)
            break;
        prev = list;
    }

    if (list == NULL) {
        cmn_err(CE_WARN, "Brand %s wasn't registered", brand->b_name);
        mutex_exit(&brand_list_lock);
        return (EINVAL);
    }

    if (list->bl_refcnt > 0) {
        cmn_err(CE_WARN, "Unregistering brand %s which is still in use",
            brand->b_name);
        mutex_exit(&brand_list_lock);
        return (EBUSY);
    }

    /* Remove brand from the list */
    if (prev != NULL)
        prev->bl_next = list->bl_next;
    else
        brand_list = list->bl_next;

#if defined(__sparcv9)
    /* sparcv9 uses system wide brand interposition hooks */
    if (brand_list == NULL)
        brand_plat_interposition_disable();
#endif /* __sparcv9 */

    mutex_exit(&brand_list_lock);

    kmem_free(list, sizeof (struct brand_list));

    return (0);
}

/*
 * Record that a zone of this brand has been instantiated.  If the kernel
 * module implementing this brand's functionality is not present, this
 * routine attempts to load the module as a side effect.
 */
brand_t *
brand_register_zone(struct brand_attr *attr)
{
    struct brand_list *l = NULL;
    ddi_modhandle_t hdl = NULL;
    char *modname;
    int err = 0;

    if (is_system_labeled()) {
        cmn_err(CE_WARN,
            "Branded zones are not allowed on labeled systems.");
        return (NULL);
    }

    /*
     * We make at most two passes through this loop.  The first time
     * through, we're looking to see if this is a new user of an
     * already loaded brand.  If the brand hasn't been loaded, we
     * call ddi_modopen() to force it to be loaded and then make a
     * second pass through the list of brands.  If we don't find the
     * brand the second time through it means that the modname
     * specified in the brand_attr structure doesn't provide the brand
     * specified in the brandname field.  This would suggest a bug in
     * the brand's config.xml file.  We close the module and return
     * 'NULL' to the caller.
     */
    for (;;) {
        /*
         * Search list of loaded brands
         */
        mutex_enter(&brand_list_lock);
        for (l = brand_list; l != NULL; l = l->bl_next)
            if (strcmp(attr->ba_brandname,
                l->bl_brand->b_name) == 0)
                break;
        if ((l != NULL) || (hdl != NULL))
            break;
        mutex_exit(&brand_list_lock);

        /*
         * We didn't find that the requested brand has been loaded
         * yet, so we trigger the load of the appropriate kernel
         * module and search the list again.
         */
        modname = kmem_alloc(MAXPATHLEN, KM_SLEEP);
        (void) strcpy(modname, "brand/");
        (void) strcat(modname, attr->ba_modname);
        hdl = ddi_modopen(modname, KRTLD_MODE_FIRST, &err);
        kmem_free(modname, MAXPATHLEN);

        if (err != 0)
            return (NULL);
    }

    /*
     * If we found the matching brand, bump its reference count.
     */
    if (l != NULL)
        l->bl_refcnt++;

    mutex_exit(&brand_list_lock);

    if (hdl != NULL)
        (void) ddi_modclose(hdl);

    return ((l != NULL) ? l->bl_brand : NULL);
}

/*
 * Return the number of zones currently using this brand.
 */
int
brand_zone_count(struct brand *bp)
{
    struct brand_list *l;
    int cnt = 0;

    mutex_enter(&brand_list_lock);
    for (l = brand_list; l != NULL; l = l->bl_next)
        if (l->bl_brand == bp) {
            cnt = l->bl_refcnt;
            break;
        }
    mutex_exit(&brand_list_lock);

    return (cnt);
}

void
brand_unregister_zone(struct brand *bp)
{
    struct brand_list *list;

    mutex_enter(&brand_list_lock);
    for (list = brand_list; list != NULL; list = list->bl_next) {
        if (list->bl_brand == bp) {
            ASSERT(list->bl_refcnt > 0);
            list->bl_refcnt--;
            break;
        }
    }
    mutex_exit(&brand_list_lock);
}

void
brand_setbrand(proc_t *p)
{
    brand_t *bp = p->p_zone->zone_brand;

    ASSERT(bp != NULL);
    ASSERT(p->p_brand == &native_brand);

    /*
     * We should only be called from exec(), when we know the process
     * is single-threaded.
     */
    ASSERT(p->p_tlist == p->p_tlist->t_forw);

    p->p_brand = bp;
    ASSERT(PROC_IS_BRANDED(p));
    BROP(p)->b_setbrand(p);
}

void
brand_clearbrand(proc_t *p)
{
    brand_t *bp = p->p_zone->zone_brand;
    ASSERT(bp != NULL);

    /*
     * We should only be called from exec_common() or proc_exit(),
     * when we know the process is single-threaded.
     */
    ASSERT(p->p_tlist == p->p_tlist->t_forw);

    ASSERT(PROC_IS_BRANDED(p));
    BROP(p)->b_proc_exit(p, p->p_tlist->t_lwp);
    p->p_brand = &native_brand;
}

#if defined(__sparcv9)
/*
 * Currently, only sparc has system level brand syscall interposition.
 * On x86 we're able to enable syscall interposition on a per-cpu basis
 * when a branded thread is scheduled to run on a cpu.
 */

/* Local variables needed for dynamic syscall interposition support */
static uint32_t syscall_trap_patch_instr_orig;
static uint32_t syscall_trap32_patch_instr_orig;

/* Trap Table syscall entry hot patch points */
extern void syscall_trap_patch_point(void);
extern void syscall_trap32_patch_point(void);

/* Alternate syscall entry handlers used when branded zones are running */
extern void syscall_wrapper(void);
extern void syscall_wrapper32(void);

/* Macros used to facilitate sparcv9 instruction generation */
#define BA_A_INSTR  0x30800000  /* ba,a addr */
#define DISP22(from, to) \
    ((((uintptr_t)(to) - (uintptr_t)(from)) >> 2) & 0x3fffff)

/*ARGSUSED*/
static void
brand_plat_interposition_enable(void)
{
    ASSERT(MUTEX_HELD(&brand_list_lock));

    /*
     * Before we hot patch the kernel save the current instructions
     * so that we can restore them later.
     */
    syscall_trap_patch_instr_orig =
        *(uint32_t *)syscall_trap_patch_point;
    syscall_trap32_patch_instr_orig =
        *(uint32_t *)syscall_trap32_patch_point;

    /*
     * Modify the trap table at the patch points.
     *
     * We basically replace the first instruction at the patch
     * point with a ba,a instruction that will transfer control
     * to syscall_wrapper or syscall_wrapper32 for 64-bit and
     * 32-bit syscalls respectively.  It's important to note that
     * the annul bit is set in the branch so we don't execute
     * the instruction directly following the one we're patching
     * during the branch's delay slot.
     *
     * It also doesn't matter that we're not atomically updating both
     * the 64 and 32 bit syscall paths at the same time since there's
     * no actual branded processes running on the system yet.
     */
    hot_patch_kernel_text((caddr_t)syscall_trap_patch_point,
        BA_A_INSTR | DISP22(syscall_trap_patch_point, syscall_wrapper),
        4);
    hot_patch_kernel_text((caddr_t)syscall_trap32_patch_point,
        BA_A_INSTR | DISP22(syscall_trap32_patch_point, syscall_wrapper32),
        4);
}

/*ARGSUSED*/
static void
brand_plat_interposition_disable(void)
{
    ASSERT(MUTEX_HELD(&brand_list_lock));

    /*
     * Restore the original instructions at the trap table syscall
     * patch points to disable the brand syscall interposition
     * mechanism.
     */
    hot_patch_kernel_text((caddr_t)syscall_trap_patch_point,
        syscall_trap_patch_instr_orig, 4);
    hot_patch_kernel_text((caddr_t)syscall_trap32_patch_point,
        syscall_trap32_patch_instr_orig, 4);
}
#endif /* __sparcv9 */