xnu-2050.18.24.tar.gz

[apple/xnu.git] / osfmk / i386 / copyio.c

/*
 * Copyright (c) 2009 Apple Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 * 
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 * 
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */
#include <mach_assert.h>
#include <sys/errno.h>
#include <i386/param.h>
#include <i386/misc_protos.h>
#include <i386/cpu_data.h>
#include <i386/machine_routines.h>
#include <vm/pmap.h>
#include <vm/vm_map.h>
#include <vm/vm_kern.h>
#include <vm/vm_fault.h>

#include <sys/kdebug.h>

/*
 * the copy engine has the following characteristics
 *   - copyio handles copies to/from user or kernel space
 *   - copypv deals with physical or virtual addresses
 *
 * implementation details as follows
 *   - a cache of up to NCOPY_WINDOWS is maintained per thread for
 *     access of user virutal space
 *   - the window size is determined by the amount of virtual space
 *     that can be mapped by a single page table
 *   - the mapping is done by copying the page table pointer from
 *     the user's directory entry corresponding to the window's
 *     address in user space to the directory entry corresponding
 *     to the window slot in the kernel's address space
 *   - the set of mappings is preserved across context switches,
 *     so the copy can run with pre-emption enabled
 *   - there is a gdt entry set up to anchor the kernel window on
 *     each processor
 *   - the copies are done using the selector corresponding to the
 *     gdt entry
 *   - the addresses corresponding to the user virtual address are
 *     relative to the beginning of the window being used to map
 *     that region... thus the thread can be pre-empted and switched
 *     to a different processor while in the midst of a copy
 *   - the window caches must be invalidated if the pmap changes out
 *     from under the thread... this can happen during vfork/exec...
 *     inval_copy_windows is the invalidation routine to be used
 *   - the copyio engine has 4 different states associated with it
 *     that allows for lazy tlb flushes and the ability to avoid
 *     a flush all together if we've just come from user space
 *     the 4 states are as follows...
 *
 *      WINDOWS_OPENED - set by copyio to indicate to the context
 *        switch code that it is necessary to do a tlbflush after
 *        switching the windows since we're in the middle of a copy
 *
 *      WINDOWS_CLOSED - set by copyio to indicate that it's done
 *        using the windows, so that the context switch code need
 *        not do the tlbflush... instead it will set the state to...
 *
 *      WINDOWS_DIRTY - set by the context switch code to indicate
 *        to the copy engine that it is responsible for doing a 
 *        tlbflush before using the windows again... it's also
 *        set by the inval_copy_windows routine to indicate the
 *        same responsibility.
 *
 *      WINDOWS_CLEAN - set by the return to user path to indicate
 *        that a tlbflush has happened and that there is no need
 *        for copyio to do another when it is entered next...
 *
 *   - a window for mapping single physical pages is provided for copypv
 *   - this window is maintained across context switches and has the
 *     same characteristics as the user space windows w/r to pre-emption
 */

extern int copyout_user(const char *, vm_offset_t, vm_size_t);
extern int copyout_kern(const char *, vm_offset_t, vm_size_t);
extern int copyin_user(const vm_offset_t, char *, vm_size_t);
extern int copyin_kern(const vm_offset_t, char *, vm_size_t);
extern int copyoutphys_user(const char *, vm_offset_t, vm_size_t);
extern int copyoutphys_kern(const char *, vm_offset_t, vm_size_t);
extern int copyinphys_user(const vm_offset_t, char *, vm_size_t);
extern int copyinphys_kern(const vm_offset_t, char *, vm_size_t);
extern int copyinstr_user(const vm_offset_t, char *, vm_size_t, vm_size_t *);
extern int copyinstr_kern(const vm_offset_t, char *, vm_size_t, vm_size_t *);

static int copyio(int, user_addr_t, char *, vm_size_t, vm_size_t *, int);
static int copyio_phys(addr64_t, addr64_t, vm_size_t, int);


#define COPYIN          0
#define COPYOUT         1
#define COPYINSTR       2
#define COPYINPHYS      3
#define COPYOUTPHYS     4

void inval_copy_windows(thread_t thread)
{
        int     i;

        for (i = 0; i < NCOPY_WINDOWS; i++) {
                thread->machine.copy_window[i].user_base = -1;
        }
        thread->machine.nxt_window = 0;
        thread->machine.copyio_state = WINDOWS_DIRTY;

        KERNEL_DEBUG(0xeff70058 | DBG_FUNC_NONE, (uintptr_t)thread_tid(thread), (int)thread->map, 0, 0, 0);
}


static int
copyio(int copy_type, user_addr_t user_addr, char *kernel_addr,
       vm_size_t nbytes, vm_size_t *lencopied, int use_kernel_map)
{
        thread_t        thread;
        pmap_t          pmap;
        pt_entry_t      *updp;
        pt_entry_t      *kpdp;
        user_addr_t     user_base;
        vm_offset_t     user_offset;
        vm_offset_t     kern_vaddr;
        vm_size_t       cnt;
        vm_size_t       bytes_copied;
        int             error = 0;
        int             window_index;
        int             copyio_state;
        boolean_t       istate;
#if KDEBUG
        int             debug_type = 0xeff70010;
        debug_type += (copy_type << 2);
#endif

        thread = current_thread();

        KERNEL_DEBUG(debug_type | DBG_FUNC_START, (int)(user_addr >> 32), (int)user_addr,
                     (int)nbytes, thread->machine.copyio_state, 0);

        if (nbytes == 0) {
                KERNEL_DEBUG(debug_type | DBG_FUNC_END, (unsigned)user_addr,
                             (unsigned)kernel_addr, (unsigned)nbytes, 0, 0);
                return (0);
        }
        pmap = thread->map->pmap;

        if (pmap == kernel_pmap || use_kernel_map) {

                kern_vaddr = (vm_offset_t)user_addr;
          
                switch (copy_type) {

                case COPYIN:
                        error = copyin_kern(kern_vaddr, kernel_addr, nbytes);
                        break;

                case COPYOUT:
                        error = copyout_kern(kernel_addr, kern_vaddr, nbytes);
                        break;

                case COPYINSTR:
                        error = copyinstr_kern(kern_vaddr, kernel_addr, nbytes, lencopied);
                        break;

                case COPYINPHYS:
                        error = copyinphys_kern(kern_vaddr, kernel_addr, nbytes);
                        break;

                case COPYOUTPHYS:
                        error = copyoutphys_kern(kernel_addr, kern_vaddr, nbytes);
                        break;
                }
                KERNEL_DEBUG(debug_type | DBG_FUNC_END, (unsigned)kern_vaddr,
                             (unsigned)kernel_addr, (unsigned)nbytes,
                             error | 0x80000000, 0);
                return (error);
        }
        
#if CONFIG_DTRACE
        thread->machine.specFlags |= CopyIOActive;
#endif /* CONFIG_DTRACE */
        
        if ((nbytes && (user_addr + nbytes <= user_addr)) ||
            (user_addr          < vm_map_min(thread->map)) ||
            (user_addr + nbytes > vm_map_max(thread->map))) {
                error = EFAULT;
                goto done;
        }

        user_base = user_addr & ~((user_addr_t)(NBPDE - 1));
        user_offset = (vm_offset_t)(user_addr & (NBPDE - 1));

        KERNEL_DEBUG(debug_type | DBG_FUNC_NONE, (int)(user_base >> 32), (int)user_base,
                     (int)user_offset, 0, 0);

        cnt = NBPDE - user_offset;

        if (cnt > nbytes)
                cnt = nbytes;

        istate = ml_set_interrupts_enabled(FALSE);

        copyio_state = thread->machine.copyio_state;
        thread->machine.copyio_state = WINDOWS_OPENED;

        (void) ml_set_interrupts_enabled(istate);


        for (;;) {

                for (window_index = 0; window_index < NCOPY_WINDOWS; window_index++) {
                        if (thread->machine.copy_window[window_index].user_base == user_base)
                                        break;
                }
                if (window_index >= NCOPY_WINDOWS) {

                        window_index = thread->machine.nxt_window;
                        thread->machine.nxt_window++;

                        if (thread->machine.nxt_window >= NCOPY_WINDOWS)
                                thread->machine.nxt_window = 0;

                        /*
                         * it's necessary to disable pre-emption
                         * since I have to compute the kernel descriptor pointer
                         * for the new window
                         */
                        istate = ml_set_interrupts_enabled(FALSE);

                        thread->machine.copy_window[window_index].user_base = user_base;

                        updp = pmap_pde(pmap, user_base);

                        kpdp = current_cpu_datap()->cpu_copywindow_pdp;
                        kpdp += window_index;

                        pmap_store_pte(kpdp, updp ? *updp : 0);

                        (void) ml_set_interrupts_enabled(istate);

                        copyio_state = WINDOWS_DIRTY;

                        KERNEL_DEBUG(0xeff70040 | DBG_FUNC_NONE, window_index,
                                     (unsigned)user_base, (unsigned)updp,
                                     (unsigned)kpdp, 0);

                }
#if JOE_DEBUG
                else {
                        istate = ml_set_interrupts_enabled(FALSE);

                        updp = pmap_pde(pmap, user_base);

                        kpdp = current_cpu_datap()->cpu_copywindow_pdp;

                        kpdp += window_index;

                        if ((*kpdp & PG_FRAME) != (*updp & PG_FRAME)) {
                                panic("copyio: user pdp mismatch - kpdp = 0x%qx,  updp = 0x%qx\n", *kpdp, *updp);
                        }
                        (void) ml_set_interrupts_enabled(istate);
                }
#endif
                if (copyio_state == WINDOWS_DIRTY) {
                        flush_tlb();

                        copyio_state = WINDOWS_CLEAN;

                        KERNEL_DEBUG(0xeff70054 | DBG_FUNC_NONE, window_index, 0, 0, 0, 0);
                }
                user_offset += (window_index * NBPDE);

                KERNEL_DEBUG(0xeff70044 | DBG_FUNC_NONE, (unsigned)user_offset,
                             (unsigned)kernel_addr, cnt, 0, 0);

                switch (copy_type) {

                case COPYIN:
                        error = copyin_user(user_offset, kernel_addr, cnt);
                        break;
                        
                case COPYOUT:
                        error = copyout_user(kernel_addr, user_offset, cnt);
                        break;

                case COPYINPHYS:
                        error = copyinphys_user(user_offset, kernel_addr, cnt);
                        break;
                        
                case COPYOUTPHYS:
                        error = copyoutphys_user(kernel_addr, user_offset, cnt);
                        break;

                case COPYINSTR:
                        error = copyinstr_user(user_offset, kernel_addr, cnt, &bytes_copied);

                        /*
                         * lencopied should be updated on success
                         * or ENAMETOOLONG...  but not EFAULT
                         */
                        if (error != EFAULT)
                                *lencopied += bytes_copied;

                        /*
                         * if we still have room, then the ENAMETOOLONG
                         * is just an artifact of the buffer straddling
                         * a window boundary and we should continue
                         */
                        if (error == ENAMETOOLONG && nbytes > cnt)
                                error = 0;

                        if (error) {
#if KDEBUG
                                nbytes = *lencopied;
#endif
                                break;
                        }
                        if (*(kernel_addr + bytes_copied - 1) == 0) {
                                /*
                                 * we found a NULL terminator... we're done
                                 */
#if KDEBUG
                                nbytes = *lencopied;
#endif
                                goto done;
                        }
                        if (cnt == nbytes) {
                                /*
                                 * no more room in the buffer and we haven't
                                 * yet come across a NULL terminator
                                 */
#if KDEBUG
                                nbytes = *lencopied;
#endif
                                error = ENAMETOOLONG;
                                break;
                        }
                        assert(cnt == bytes_copied);

                        break;
                }
                if (error)
                        break;
                if ((nbytes -= cnt) == 0)
                        break;

                kernel_addr += cnt;
                user_base += NBPDE;
                user_offset = 0;

                if (nbytes > NBPDE)
                        cnt = NBPDE;
                else
                        cnt = nbytes;
        }
done:
        thread->machine.copyio_state = WINDOWS_CLOSED;

        KERNEL_DEBUG(debug_type | DBG_FUNC_END, (unsigned)user_addr,
                     (unsigned)kernel_addr, (unsigned)nbytes, error, 0);

#if CONFIG_DTRACE
        thread->machine.specFlags &= ~CopyIOActive;
#endif /* CONFIG_DTRACE */

        return (error);
}

static int
copyio_phys(addr64_t source, addr64_t sink, vm_size_t csize, int which)
{
        pmap_paddr_t paddr;
        user_addr_t vaddr;
        char        *window_offset;
        pt_entry_t  pentry;
        int         ctype;
        int         retval;
        boolean_t   istate;


        if (which & cppvPsnk) {
                paddr  = (pmap_paddr_t)sink;
                vaddr  = (user_addr_t)source;
                ctype  = COPYINPHYS;
                pentry = (pt_entry_t)(INTEL_PTE_VALID | (paddr & PG_FRAME) | INTEL_PTE_RW);
        } else {
                paddr  = (pmap_paddr_t)source;
                vaddr  = (user_addr_t)sink;
                ctype  = COPYOUTPHYS;
                pentry = (pt_entry_t)(INTEL_PTE_VALID | (paddr & PG_FRAME));
        }
        /* Fold in cache attributes for this physical page */
        pentry |= pmap_get_cache_attributes(i386_btop(paddr));
        window_offset = (char *)(uintptr_t)((uint32_t)paddr & (PAGE_SIZE - 1));

        assert(!((current_thread()->machine.specFlags & CopyIOActive) && ((which & cppvKmap) == 0)));

        if (current_thread()->machine.physwindow_busy) {
                pt_entry_t      old_pentry;

                KERNEL_DEBUG(0xeff70048 | DBG_FUNC_NONE, paddr, csize, 0, -1, 0);
                /*
                 * we had better be targeting wired memory at this point
                 * we will not be able to handle a fault with interrupts
                 * disabled... we disable them because we can't tolerate
                 * being preempted during this nested use of the window
                 */
                istate = ml_set_interrupts_enabled(FALSE);

                old_pentry = *(current_cpu_datap()->cpu_physwindow_ptep);
                pmap_store_pte((current_cpu_datap()->cpu_physwindow_ptep), pentry);

                invlpg((uintptr_t)current_cpu_datap()->cpu_physwindow_base);

                retval = copyio(ctype, vaddr, window_offset, csize, NULL, which & cppvKmap);

                pmap_store_pte((current_cpu_datap()->cpu_physwindow_ptep), old_pentry);

                invlpg((uintptr_t)current_cpu_datap()->cpu_physwindow_base);

                (void) ml_set_interrupts_enabled(istate);
        } else {
                /*
                 * mark the window as in use... if an interrupt hits while we're
                 * busy, or we trigger another coyppv from the fault path into
                 * the driver on a user address space page fault due to a copyin/out
                 * then we need to save and restore the current window state instead
                 * of caching the window preserving it across context switches
                 */
                current_thread()->machine.physwindow_busy = 1;

                if (current_thread()->machine.physwindow_pte != pentry) {
                        KERNEL_DEBUG(0xeff70048 | DBG_FUNC_NONE, paddr, csize, 0, 0, 0);

                        current_thread()->machine.physwindow_pte = pentry;
                        
                        /*
                         * preemption at this point would be bad since we
                         * could end up on the other processor after we grabbed the
                         * pointer to the current cpu data area, but before we finished
                         * using it to stuff the page table entry since we would
                         * be modifying a window that no longer belonged to us
                         * the invlpg can be done unprotected since it only flushes
                         * this page address from the tlb... if it flushes the wrong
                         * one, no harm is done, and the context switch that moved us
                         * to the other processor will have already take care of 
                         * flushing the tlb after it reloaded the page table from machine.physwindow_pte
                         */
                        istate = ml_set_interrupts_enabled(FALSE);

                        pmap_store_pte((current_cpu_datap()->cpu_physwindow_ptep), pentry);
                        (void) ml_set_interrupts_enabled(istate);

                        invlpg((uintptr_t)current_cpu_datap()->cpu_physwindow_base);
                }
#if JOE_DEBUG
                else {
                        if (pentry !=
                            (*(current_cpu_datap()->cpu_physwindow_ptep) & (INTEL_PTE_VALID | PG_FRAME | INTEL_PTE_RW)))
                                panic("copyio_phys: pentry != *physwindow_ptep");
                }
#endif
                retval = copyio(ctype, vaddr, window_offset, csize, NULL, which & cppvKmap);

                current_thread()->machine.physwindow_busy = 0;
        }
        return (retval);
}

int
copyinmsg(const user_addr_t user_addr, char *kernel_addr, mach_msg_size_t nbytes)
{
        return (copyio(COPYIN, user_addr, kernel_addr, nbytes, NULL, 0));
}    

int
copyin(const user_addr_t user_addr, char *kernel_addr, vm_size_t nbytes)
{
        return (copyio(COPYIN, user_addr, kernel_addr, nbytes, NULL, 0));
}

int
copyinstr(const user_addr_t user_addr,  char *kernel_addr, vm_size_t nbytes, vm_size_t *lencopied)
{
        *lencopied = 0;

        return (copyio(COPYINSTR, user_addr, kernel_addr, nbytes, lencopied, 0));
}

int
copyoutmsg(const char *kernel_addr, user_addr_t user_addr, mach_msg_size_t nbytes)
{
        return (copyio(COPYOUT, user_addr, (char *)(uintptr_t)kernel_addr, nbytes, NULL, 0));
}

int
copyout(const void *kernel_addr, user_addr_t user_addr, vm_size_t nbytes)
{
        return (copyio(COPYOUT, user_addr, (char *)(uintptr_t)kernel_addr, nbytes, NULL, 0));
}


kern_return_t
copypv(addr64_t src64, addr64_t snk64, unsigned int size, int which)
{
        unsigned int lop, csize;
        int bothphys = 0;
        
        KERNEL_DEBUG(0xeff7004c | DBG_FUNC_START, (unsigned)src64,
                     (unsigned)snk64, size, which, 0);

        if ((which & (cppvPsrc | cppvPsnk)) == 0 )                              /* Make sure that only one is virtual */
                panic("copypv: no more than 1 parameter may be virtual\n");     /* Not allowed */

        if ((which & (cppvPsrc | cppvPsnk)) == (cppvPsrc | cppvPsnk))
                bothphys = 1;                                                   /* both are physical */

        while (size) {
          
                if (bothphys) {
                        lop = (unsigned int)(PAGE_SIZE - (snk64 & (PAGE_SIZE - 1)));            /* Assume sink smallest */

                        if (lop > (unsigned int)(PAGE_SIZE - (src64 & (PAGE_SIZE - 1))))
                                lop = (unsigned int)(PAGE_SIZE - (src64 & (PAGE_SIZE - 1)));    /* No, source is smaller */
                } else {
                        /*
                         * only need to compute the resid for the physical page
                         * address... we don't care about where we start/finish in
                         * the virtual since we just call the normal copyin/copyout
                         */
                        if (which & cppvPsrc)
                                lop = (unsigned int)(PAGE_SIZE - (src64 & (PAGE_SIZE - 1)));
                        else
                                lop = (unsigned int)(PAGE_SIZE - (snk64 & (PAGE_SIZE - 1)));
                }
                csize = size;                                           /* Assume we can copy it all */
                if (lop < size)
                        csize = lop;                                    /* Nope, we can't do it all */
#if 0           
                /*
                 * flush_dcache64 is currently a nop on the i386... 
                 * it's used when copying to non-system memory such
                 * as video capture cards... on PPC there was a need
                 * to flush due to how we mapped this memory... not
                 * sure if it's needed on i386.
                 */
                if (which & cppvFsrc)
                        flush_dcache64(src64, csize, 1);                /* If requested, flush source before move */
                if (which & cppvFsnk)
                        flush_dcache64(snk64, csize, 1);                /* If requested, flush sink before move */
#endif
                if (bothphys) {
                        bcopy_phys(src64, snk64, csize);                /* Do a physical copy, virtually */
                }
                else {
                        if (copyio_phys(src64, snk64, csize, which)) {
                                return (KERN_FAILURE);
                        }
                }
#if 0
                if (which & cppvFsrc)
                        flush_dcache64(src64, csize, 1);        /* If requested, flush source after move */
                if (which & cppvFsnk)
                        flush_dcache64(snk64, csize, 1);        /* If requested, flush sink after move */
#endif
                size   -= csize;                                        /* Calculate what is left */
                snk64 += csize;                                 /* Bump sink to next physical address */
                src64 += csize;                                 /* Bump source to next physical address */
        }
        KERNEL_DEBUG(0xeff7004c | DBG_FUNC_END, (unsigned)src64,
                     (unsigned)snk64, size, which, 0);

        return KERN_SUCCESS;
}
void
copy_window_fault(thread_t thread, vm_map_t map, int window)
{
        pt_entry_t      *updp;
        pt_entry_t      *kpdp;

        /*
         * in case there was no page table assigned
         * for the user base address and the pmap
         * got 'expanded' due to this fault, we'll
         * copy in the descriptor 
         *
         * we're either setting the page table descriptor
         * to the same value or it was 0... no need
         * for a TLB flush in either case
         */

        updp = pmap_pde(map->pmap, thread->machine.copy_window[window].user_base);
        assert(updp);
        if (0 == updp) panic("trap: updp 0"); /* XXX DEBUG */
        kpdp = current_cpu_datap()->cpu_copywindow_pdp;
        kpdp += window;

#if JOE_DEBUG
        if (*kpdp && (*kpdp & PG_FRAME) != (*updp & PG_FRAME))
                panic("kernel_fault: user pdp doesn't match - updp = 0x%qx, kpdp = 0x%qx\n", *updp, *kpdp);
#endif
        pmap_store_pte(kpdp, *updp);
}