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Annotation of tme/libtme/host/recode-mmap.c, revision 1.1

1.1     ! root        1: /* $Id: recode-mmap.c,v 1.2 2008/07/01 02:00:53 fredette Exp $ */
        !             2: 
        !             3: /* libtme/host/recode-mmap.c - recode code file for mmap() hosts: */
        !             4: 
        !             5: /*
        !             6:  * Copyright (c) 2008 Matt Fredette
        !             7:  * All rights reserved.
        !             8:  *
        !             9:  * Redistribution and use in source and binary forms, with or without
        !            10:  * modification, are permitted provided that the following conditions
        !            11:  * are met:
        !            12:  * 1. Redistributions of source code must retain the above copyright
        !            13:  *    notice, this list of conditions and the following disclaimer.
        !            14:  * 2. Redistributions in binary form must reproduce the above copyright
        !            15:  *    notice, this list of conditions and the following disclaimer in the
        !            16:  *    documentation and/or other materials provided with the distribution.
        !            17:  * 3. All advertising materials mentioning features or use of this software
        !            18:  *    must display the following acknowledgement:
        !            19:  *      This product includes software developed by Matt Fredette.
        !            20:  * 4. The name of the author may not be used to endorse or promote products
        !            21:  *    derived from this software without specific prior written permission.
        !            22:  *
        !            23:  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
        !            24:  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
        !            25:  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
        !            26:  * DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
        !            27:  * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
        !            28:  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
        !            29:  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
        !            30:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
        !            31:  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
        !            32:  * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
        !            33:  * POSSIBILITY OF SUCH DAMAGE.
        !            34:  */
        !            35: 
        !            36: #include <tme/common.h>
        !            37: _TME_RCSID("$Id: recode-mmap.c,v 1.2 2008/07/01 02:00:53 fredette Exp $");
        !            38: 
        !            39: #if TME_HAVE_RECODE
        !            40: 
        !            41: /* includes: */
        !            42: #include "recode-impl.h"
        !            43: #include <fcntl.h>
        !            44: #include <sys/types.h>
        !            45: #include <sys/mman.h>
        !            46: 
        !            47: /* this host function allocates memory for building and running thunks: */
        !            48: void
        !            49: tme_recode_host_thunks_alloc(struct tme_recode_ic *ic,
        !            50:                             tme_recode_thunk_off_t size_run)
        !            51: {
        !            52:   int size_page;
        !            53:   int fd;
        !            54:   tme_recode_host_insn_t *memory;
        !            55: 
        !            56:   /* get the page size: */
        !            57:   size_page = getpagesize();
        !            58:   assert ((size_page % sizeof(tme_recode_host_insn_t)) == 0);
        !            59: 
        !            60:   /* make sure the run memory size is at least the minimum thunk size,
        !            61:      and round the run memory size up to the page size: */
        !            62:   size_run = TME_MAX(size_run, TME_RECODE_HOST_THUNK_SIZE_MAX);
        !            63:   size_run += (size_page - 1);
        !            64:   size_run -= (size_run % size_page);
        !            65:   assert (size_run >= TME_MAX(size_page, TME_RECODE_HOST_THUNK_SIZE_MAX));
        !            66: 
        !            67:   /* if MAP_ANON isn't defined, assume that we have to mmap /dev/zero
        !            68:      to map anonymous memory: */
        !            69: #ifndef MAP_ANON
        !            70:   fd = open("/dev/zero", O_RDWR, 0);
        !            71:   if (fd < 0) {
        !            72:     abort();
        !            73:   }
        !            74: #else  /* MAP_ANON */
        !            75:   fd = -1;
        !            76: #endif /* MAP_ANON */
        !            77: 
        !            78:   /* mmap memory that is readable, writable and executable: */
        !            79:   memory
        !            80:     = ((tme_recode_host_insn_t *)
        !            81:        mmap((void *) 0,
        !            82:            size_run,
        !            83:            (PROT_READ
        !            84:             | PROT_WRITE
        !            85:             | PROT_EXEC),
        !            86:            (MAP_SHARED
        !            87: #ifdef MAP_ANON
        !            88:             | MAP_ANON
        !            89: #endif /* MAP_ANON */
        !            90:             ),
        !            91:            fd,
        !            92:            0));
        !            93:   if (memory == (tme_recode_host_insn_t *) MAP_FAILED) {
        !            94:     abort();
        !            95:   }
        !            96: 
        !            97:   /* return the memory: */
        !            98:   ic->tme_recode_mmap_ic_thunks_start = memory;
        !            99:   ic->tme_recode_ic_thunk_build_next = memory;
        !           100:   ic->tme_recode_ic_thunk_build_end = memory + (size_run / sizeof(tme_recode_host_insn_t));
        !           101: }
        !           102: 
        !           103: /* this host function starts building a new thunk.  it returns nonzero
        !           104:    if a thunk of TME_RECODE_HOST_THUNK_SIZE_MAX bytes can be built: */
        !           105: int
        !           106: tme_recode_host_thunk_start(struct tme_recode_ic *ic)
        !           107: {
        !           108:   return ((ic->tme_recode_ic_thunk_build_end
        !           109:           - ic->tme_recode_ic_thunk_build_next)
        !           110:          >= ((TME_RECODE_HOST_THUNK_SIZE_MAX
        !           111:               + sizeof(tme_recode_host_insn_t)
        !           112:               - 1)
        !           113:              / sizeof(tme_recode_host_insn_t)));
        !           114: }
        !           115: 
        !           116: /* this host function finishes building a new thunk: */
        !           117: void
        !           118: tme_recode_host_thunk_finish(struct tme_recode_ic *ic)
        !           119: {
        !           120: 
        !           121:   /* round the next build address up to the thunk alignment: */
        !           122:   ic->tme_recode_ic_thunk_build_next
        !           123:     = ((tme_recode_host_insn_t *)
        !           124:        ((((unsigned long) ic->tme_recode_ic_thunk_build_next)
        !           125:         + TME_RECODE_HOST_THUNK_ALIGN
        !           126:         - 1)
        !           127:        & (0 - (unsigned long) TME_RECODE_HOST_THUNK_ALIGN)));
        !           128: }
        !           129: 
        !           130: /* this host function invalidates all thunks starting from the given
        !           131:    thunk offset: */
        !           132: void
        !           133: tme_recode_host_thunk_invalidate_all(struct tme_recode_ic *ic,
        !           134:                                     tme_recode_thunk_off_t thunk_off)
        !           135: {
        !           136:   
        !           137:   /* reset the build address: */
        !           138:   ic->tme_recode_ic_thunk_build_next = ic->tme_recode_mmap_ic_thunks_start + thunk_off;
        !           139:   tme_recode_host_thunk_finish(ic);
        !           140: }
        !           141: 
        !           142: #endif /* TME_HAVE_RECODE */

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