/*
* Copyright (C) 2006 Jakub Jermar
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* - The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/**
* @file backend_elf.c
* @brief Backend for address space areas backed by an ELF image.
*/
#include <elf.h>
#include <debug.h>
#include <arch/types.h>
#include <typedefs.h>
#include <mm/as.h>
#include <mm/frame.h>
#include <mm/slab.h>
#include <mm/page.h>
#include <genarch/mm/page_pt.h>
#include <genarch/mm/page_ht.h>
#include <align.h>
#include <memstr.h>
#include <macros.h>
#include <arch.h>
static int elf_page_fault(as_area_t *area, __address addr, pf_access_t access);
static void elf_frame_free(as_area_t *area, __address page, __address frame);
static void elf_share(as_area_t *area);
mem_backend_t elf_backend = {
.page_fault = elf_page_fault,
.frame_free = elf_frame_free,
.share = elf_share
};
/** Service a page fault in the ELF backend address space area.
*
* The address space area and page tables must be already locked.
*
* @param area Pointer to the address space area.
* @param addr Faulting virtual address.
* @param access Access mode that caused the fault (i.e. read/write/exec).
*
* @return AS_PF_FAULT on failure (i.e. page fault) or AS_PF_OK on success (i.e. serviced).
*/
int elf_page_fault(as_area_t *area, __address addr, pf_access_t access)
{
elf_header_t *elf = area->backend_data.elf;
elf_segment_header_t *entry = area->backend_data.segment;
btree_node_t *leaf;
__address base, frame;
index_t i;
if (!as_area_check_access(area, access))
return AS_PF_FAULT;
ASSERT((addr >= entry->p_vaddr) && (addr < entry->p_vaddr + entry->p_memsz));
i = (addr - entry->p_vaddr) >> PAGE_WIDTH;
base = (__address) (((void *) elf) + entry->p_offset);
ASSERT(ALIGN_UP(base, FRAME_SIZE) == base);
if (area->sh_info) {
bool found = false;
/*
* The address space area is shared.
*/
mutex_lock(&area->sh_info->lock);
frame = (__address) btree_search(&area->sh_info->pagemap,
ALIGN_DOWN(addr, PAGE_SIZE) - area->base, &leaf);
if (!frame) {
int i;
/*
* Workaround for valid NULL address.
*/
for (i = 0; i < leaf->keys; i++) {
if (leaf->key[i] == ALIGN_DOWN(addr, PAGE_SIZE)) {
found = true;
break;
}
}
}
if (frame || found) {
frame_reference_add(ADDR2PFN(frame));
page_mapping_insert(AS, addr, frame, as_area_get_flags(area));
frame_reference_add(ADDR2PFN(PTE_GET_FRAME(pte)));
if (!used_space_insert(area, ALIGN_DOWN(addr, PAGE_SIZE), 1))
panic("Could not insert used space.\n");
mutex_unlock(&area->sh_info->lock);
return AS_PF_OK;
}
}
/*
* The area is either not shared or the pagemap does not contain the mapping.
*/
if (ALIGN_DOWN(addr, PAGE_SIZE) + PAGE_SIZE < entry->p_vaddr + entry->p_filesz) {
/*
* Initialized portion of the segment. The memory is backed
* directly by the content of the ELF image. Pages are
* only copied if the segment is writable so that there
* can be more instantions of the same memory ELF image
* used at a time. Note that this could be later done
* as COW.
*/
if (entry->p_flags & PF_W) {
frame = PFN2ADDR(frame_alloc(ONE_FRAME, 0));
memcpy((void *) PA2KA
(frame
), (void *) (base
+ i
*FRAME_SIZE
), FRAME_SIZE
);
if (area->sh_info) {
frame_reference_add(ADDR2PFN(frame));
btree_insert(&area->sh_info->pagemap, ALIGN_DOWN(addr, PAGE_SIZE) - area->base,
(void *) frame, leaf);
}
} else {
frame = KA2PA(base + i*FRAME_SIZE);
}
} else if (ALIGN_DOWN(addr, PAGE_SIZE) >= ALIGN_UP(entry->p_vaddr + entry->p_filesz, PAGE_SIZE)) {
/*
* This is the uninitialized portion of the segment.
* It is not physically present in the ELF image.
* To resolve the situation, a frame must be allocated
* and cleared.
*/
frame = PFN2ADDR(frame_alloc(ONE_FRAME, 0));
memsetb(PA2KA(frame), FRAME_SIZE, 0);
if (area->sh_info) {
frame_reference_add(ADDR2PFN(frame));
btree_insert(&area->sh_info->pagemap, ALIGN_DOWN(addr, PAGE_SIZE) - area->base,
(void *) frame, leaf);
}
} else {
size_t size;
/*
* The mixed case.
* The lower part is backed by the ELF image and
* the upper part is anonymous memory.
*/
size = entry->p_filesz - (i<<PAGE_WIDTH);
frame = PFN2ADDR(frame_alloc(ONE_FRAME, 0));
memsetb(PA2KA(frame) + size, FRAME_SIZE - size, 0);
memcpy((void *) PA2KA
(frame
), (void *) (base
+ i
*FRAME_SIZE
), size
);
if (area->sh_info) {
frame_reference_add(ADDR2PFN(frame));
btree_insert(&area->sh_info->pagemap, ALIGN_DOWN(addr, PAGE_SIZE) - area->base,
(void *) frame, leaf);
}
}
if (area->sh_info)
mutex_unlock(&area->sh_info->lock);
page_mapping_insert(AS, addr, frame, as_area_get_flags(area));
if (!used_space_insert(area, ALIGN_DOWN(addr, PAGE_SIZE), 1))
panic("Could not insert used space.\n");
return AS_PF_OK;
}
/** Free a frame that is backed by the ELF backend.
*
* The address space area and page tables must be already locked.
*
* @param area Pointer to the address space area.
* @param page Page that is mapped to frame. Must be aligned to PAGE_SIZE.
* @param frame Frame to be released.
*
*/
void elf_frame_free(as_area_t *area, __address page, __address frame)
{
elf_header_t *elf = area->backend_data.elf;
elf_segment_header_t *entry = area->backend_data.segment;
__address base;
index_t i;
ASSERT((page >= entry->p_vaddr) && (page < entry->p_vaddr + entry->p_memsz));
i = (page - entry->p_vaddr) >> PAGE_WIDTH;
base = (__address) (((void *) elf) + entry->p_offset);
ASSERT(ALIGN_UP(base, FRAME_SIZE) == base);
if (page + PAGE_SIZE < ALIGN_UP(entry->p_vaddr + entry->p_filesz, PAGE_SIZE)) {
if (entry->p_flags & PF_W) {
/*
* Free the frame with the copy of writable segment data.
*/
frame_free(ADDR2PFN(frame));
}
} else {
/*
* The frame is either anonymous memory or the mixed case (i.e. lower
* part is backed by the ELF image and the upper is anonymous).
* In any case, a frame needs to be freed.
*/
frame_free(ADDR2PFN(frame));
}
}
/** Share ELF image backed address space area.
*
* If the area is writable, then all mapped pages are duplicated in the pagemap.
* Otherwise only portions of the area that are not backed by the ELF image
* are put into the pagemap.
*
* The address space and address space area must be locked prior to the call.
*
* @param area Address space area.
*/
void elf_share(as_area_t *area)
{
elf_segment_header_t *entry = area->backend_data.segment;
link_t *cur;
btree_node_t *leaf, *node;
__address start_anon = entry->p_vaddr + entry->p_filesz;
/*
* Find the node in which to start linear search.
*/
if (area->flags & AS_AREA_WRITE) {
node = list_get_instance(area->used_space.leaf_head.next, btree_node_t, leaf_link);
} else {
(void) btree_search(&area->sh_info->pagemap, start_anon, &leaf);
node = btree_leaf_node_left_neighbour(&area->sh_info->pagemap, leaf);
if (!node)
node = leaf;
}
/*
* Copy used anonymous portions of the area to sh_info's page map.
*/
mutex_lock(&area->sh_info->lock);
for (cur = &node->leaf_link; cur != &area->used_space.leaf_head; cur = cur->next) {
int i;
node = list_get_instance(cur, btree_node_t, leaf_link);
for (i = 0; i < node->keys; i++) {
__address base = node->key[i];
count_t count = (count_t) node->value[i];
int j;
/*
* Skip read-only areas of used space that are backed
* by the ELF image.
*/
if (!(area->flags & AS_AREA_WRITE))
if (base + count*PAGE_SIZE <= start_anon)
continue;
for (j = 0; j < count; j++) {
pte_t *pte;
/*
* Skip read-only pages that are backed by the ELF image.
*/
if (!(area->flags & AS_AREA_WRITE))
if (base + (j + 1)*PAGE_SIZE <= start_anon)
continue;
page_table_lock(area->as, false);
pte = page_mapping_find(area->as, base + j*PAGE_SIZE);
ASSERT(pte && PTE_VALID(pte) && PTE_PRESENT(pte));
btree_insert(&area->sh_info->pagemap, (base + j*PAGE_SIZE) - area->base,
(void *) PTE_GET_FRAME(pte), NULL);
page_table_unlock(area->as, false);
frame_reference_add(ADDR2PFN(PTE_GET_FRAME(pte)));
}
}
}
mutex_unlock(&area->sh_info->lock);
}