Subversion Repositories HelenOS

Rev

Rev 1425 | Go to most recent revision | Details | Last modification | View Log | RSS feed

Rev Author Line No. Line
1424 jermar 1 
/*
2 
 * Copyright (C) 2006 Jakub Jermar
3 
 * All rights reserved.
4 
 *
5 
 * Redistribution and use in source and binary forms, with or without
6 
 * modification, are permitted provided that the following conditions
7 
 * are met:
8 
 *
9 
 * - Redistributions of source code must retain the above copyright
10 
 *   notice, this list of conditions and the following disclaimer.
11 
 * - Redistributions in binary form must reproduce the above copyright
12 
 *   notice, this list of conditions and the following disclaimer in the
13 
 *   documentation and/or other materials provided with the distribution.
14 
 * - The name of the author may not be used to endorse or promote products
15 
 *   derived from this software without specific prior written permission.
16 
 *
17 
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18 
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21 
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 
 */
28 
 
29 
/**
30 
 * @file    backend_elf.c
31 
 * @brief   Backend for address space areas backed by an ELF image.
32 
 */
33 
 
34 
#include <elf.h>
35 
#include <debug.h>
36 
#include <arch/types.h>
37 
#include <typedefs.h>
38 
#include <mm/as.h>
39 
#include <mm/frame.h>
40 
#include <mm/slab.h>
41 
#include <align.h>
42 
#include <memstr.h>
43 
#include <macros.h>
44 
#include <arch.h>
45 
 
46 
static int elf_page_fault(as_area_t *area, __address addr, pf_access_t access);
47 
static void elf_frame_free(as_area_t *area, __address page, __address frame);
48 
 
49 
mem_backend_t elf_backend = {
50 
    .page_fault = elf_page_fault,
51 
    .frame_free = elf_frame_free,
52 
    .share = NULL
53 
};
54 
 
55 
/** Service a page fault in the ELF backend address space area.
56 
 *
57 
 * The address space area and page tables must be already locked.
58 
 *
59 
 * @param area Pointer to the address space area.
60 
 * @param addr Faulting virtual address.
61 
 * @param access Access mode that caused the fault (i.e. read/write/exec).
62 
 *
63 
 * @return AS_PF_FAULT on failure (i.e. page fault) or AS_PF_OK on success (i.e. serviced).
64 
 */
65 
int elf_page_fault(as_area_t *area, __address addr, pf_access_t access)
66 
{
67 
    elf_header_t *elf = (elf_header_t *) area->backend_data.d1;
68 
    elf_segment_header_t *entry = (elf_segment_header_t *) area->backend_data.d2;
69 
    __address base, frame;
70 
    index_t i;
71 
 
72 
    if (!as_area_check_access(area, access))
73 
        return AS_PF_FAULT;
74 
 
75 
    ASSERT((addr >= entry->p_vaddr) && (addr < entry->p_vaddr + entry->p_memsz));
76 
    i = (addr - entry->p_vaddr) >> PAGE_WIDTH;
77 
    base = (__address) (((void *) elf) + entry->p_offset);
78 
    ASSERT(ALIGN_UP(base, FRAME_SIZE) == base);
79 
 
80 
    if (ALIGN_DOWN(addr, PAGE_SIZE) + PAGE_SIZE < entry->p_vaddr + entry->p_filesz) {
81 
        /*
82 
         * Initialized portion of the segment. The memory is backed
83 
         * directly by the content of the ELF image. Pages are
84 
         * only copied if the segment is writable so that there
85 
         * can be more instantions of the same memory ELF image
86 
         * used at a time. Note that this could be later done
87 
         * as COW.
88 
         */
89 
        if (entry->p_flags & PF_W) {
90 
            frame = PFN2ADDR(frame_alloc(ONE_FRAME, 0));
91 
            memcpy((void *) PA2KA(frame), (void *) (base + i*FRAME_SIZE), FRAME_SIZE);
92 
        } else {
93 
            frame = KA2PA(base + i*FRAME_SIZE);
94 
        }  
95 
    } else if (ALIGN_DOWN(addr, PAGE_SIZE) >= ALIGN_UP(entry->p_vaddr + entry->p_filesz, PAGE_SIZE)) {
96 
        /*
97 
         * This is the uninitialized portion of the segment.
98 
         * It is not physically present in the ELF image.
99 
         * To resolve the situation, a frame must be allocated
100 
         * and cleared.
101 
         */
102 
        frame = PFN2ADDR(frame_alloc(ONE_FRAME, 0));
103 
        memsetb(PA2KA(frame), FRAME_SIZE, 0);
104 
    } else {
105 
        size_t size;
106 
        /*
107 
         * The mixed case.
108 
         * The lower part is backed by the ELF image and
109 
         * the upper part is anonymous memory.
110 
         */
111 
        size = entry->p_filesz - (i<<PAGE_WIDTH);
112 
        frame = PFN2ADDR(frame_alloc(ONE_FRAME, 0));
113 
        memsetb(PA2KA(frame) + size, FRAME_SIZE - size, 0);
114 
        memcpy((void *) PA2KA(frame), (void *) (base + i*FRAME_SIZE), size);
115 
    }
116 
 
117 
    page_mapping_insert(AS, addr, frame, as_area_get_flags(area));
118 
        if (!used_space_insert(area, ALIGN_DOWN(addr, PAGE_SIZE), 1))
119 
                panic("Could not insert used space.\n");
120 
 
121 
    return AS_PF_OK;
122 
}
123 
 
124 
/** Free a frame that is backed by the ELF backend.
125 
 *
126 
 * The address space area and page tables must be already locked.
127 
 *
128 
 * @param area Pointer to the address space area.
129 
 * @param page Page that is mapped to frame. Must be aligned to PAGE_SIZE.
130 
 * @param frame Frame to be released.
131 
 *
132 
 */
133 
void elf_frame_free(as_area_t *area, __address page, __address frame)
134 
{
135 
    elf_header_t *elf = (elf_header_t *) area->backend_data.d1;
136 
    elf_segment_header_t *entry = (elf_segment_header_t *) area->backend_data.d2;
137 
    __address base;
138 
    index_t i;
139 
 
140 
    ASSERT((page >= entry->p_vaddr) && (page < entry->p_vaddr + entry->p_memsz));
141 
    i = (page - entry->p_vaddr) >> PAGE_WIDTH;
142 
    base = (__address) (((void *) elf) + entry->p_offset);
143 
    ASSERT(ALIGN_UP(base, FRAME_SIZE) == base);
144 
 
145 
    if (page + PAGE_SIZE < ALIGN_UP(entry->p_vaddr + entry->p_filesz, PAGE_SIZE)) {
146 
        if (entry->p_flags & PF_W) {
147 
            /*
148 
             * Free the frame with the copy of writable segment data.
149 
             */
150 
            frame_free(ADDR2PFN(frame));
151 
        }
152 
    } else {
153 
        /*
154 
         * The frame is either anonymous memory or the mixed case (i.e. lower
155 
         * part is backed by the ELF image and the upper is anonymous).
156 
         * In any case, a frame needs to be freed.
157 
         */
158 
        frame_free(ADDR2PFN(frame));
159 
    }
160 
}