/*
* 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.
*/
/** @addtogroup genericmm
* @{
*/
/**
* @file
* @brief Backend for address space areas backed by an ELF image.
*/
#include <lib/elf.h>
#include <debug.h>
#include <arch/types.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>
#ifdef CONFIG_VIRT_IDX_DCACHE
#include <arch/mm/cache.h>
#endif
static int elf_page_fault(as_area_t *area, uintptr_t addr, pf_access_t access);
static void elf_frame_free(as_area_t *area, uintptr_t page, uintptr_t 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, uintptr_t 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;
uintptr_t base, frame, page, start_anon;
index_t i;
bool dirty = false;
if (!as_area_check_access(area, access))
return AS_PF_FAULT;
ASSERT((addr >= ALIGN_DOWN(entry->p_vaddr, PAGE_SIZE)) &&
(addr < entry->p_vaddr + entry->p_memsz));
i = (addr - ALIGN_DOWN(entry->p_vaddr, PAGE_SIZE)) >> PAGE_WIDTH;
base = (uintptr_t)
(((void *) elf) + ALIGN_DOWN(entry->p_offset, PAGE_SIZE));
/* Virtual address of faulting page*/
page = ALIGN_DOWN(addr, PAGE_SIZE);
/* Virtual address of the end of initialized part of segment */
start_anon = entry->p_vaddr + entry->p_filesz;
if (area->sh_info) {
bool found = false;
/*
* The address space area is shared.
*/
mutex_lock(&area->sh_info->lock);
frame = (uintptr_t) btree_search(&area->sh_info->pagemap,
page - area->base, &leaf);
if (!frame) {
unsigned int i;
/*
* Workaround for valid NULL address.
*/
for (i = 0; i < leaf->keys; i++) {
if (leaf->key[i] == page) {
found = true;
break;
}
}
}
if (frame || found) {
frame_reference_add(ADDR2PFN(frame));
page_mapping_insert(AS, addr, frame,
as_area_get_flags(area));
if (!used_space_insert(area, page, 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 (page >= entry->p_vaddr && page + PAGE_SIZE <= start_anon) {
/*
* 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 = (uintptr_t)frame_alloc(ONE_FRAME, 0);
(void *) (base + i * FRAME_SIZE), FRAME_SIZE);
dirty = true;
} else {
frame = KA2PA(base + i * FRAME_SIZE);
}
} else if (page >= start_anon) {
/*
* 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 = (uintptr_t)frame_alloc(ONE_FRAME, 0);
memsetb(PA2KA(frame), FRAME_SIZE, 0);
dirty = true;
} else {
size_t pad_lo, pad_hi;
/*
* The mixed case.
*
* The middle part is backed by the ELF image and
* the lower and upper parts are anonymous memory.
* (The segment can be and often is shorter than 1 page).
*/
if (page < entry->p_vaddr)
pad_lo = entry->p_vaddr - page;
else
pad_lo = 0;
if (start_anon < page + PAGE_SIZE)
pad_hi = page + PAGE_SIZE - start_anon;
else
pad_hi = 0;
frame = (uintptr_t)frame_alloc(ONE_FRAME, 0);
memcpy((void *) (PA2KA
(frame
) + pad_lo
), (void *) (base + i * FRAME_SIZE + pad_lo),
FRAME_SIZE - pad_lo - pad_hi);
memsetb(PA2KA(frame), pad_lo, 0);
memsetb(PA2KA(frame) + FRAME_SIZE - pad_hi, pad_hi, 0);
dirty = true;
}
if (dirty && area->sh_info) {
frame_reference_add(ADDR2PFN(frame));
btree_insert(&area->sh_info->pagemap, page - 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, page, 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, uintptr_t page, uintptr_t frame)
{
elf_header_t *elf = area->backend_data.elf;
elf_segment_header_t *entry = area->backend_data.segment;
uintptr_t base, start_anon;
index_t i;
ASSERT((page >= ALIGN_DOWN(entry->p_vaddr, PAGE_SIZE)) &&
(page < entry->p_vaddr + entry->p_memsz));
i = (page - ALIGN_DOWN(entry->p_vaddr, PAGE_SIZE)) >> PAGE_WIDTH;
base = (uintptr_t) (((void *) elf) +
ALIGN_DOWN(entry->p_offset, FRAME_SIZE));
start_anon = entry->p_vaddr + entry->p_filesz;
if (page >= entry->p_vaddr && page + PAGE_SIZE <= start_anon) {
if (entry->p_flags & PF_W) {
/*
* Free the frame with the copy of writable segment
* data.
*/
frame_free(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(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;
uintptr_t 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) {
unsigned int i;
node = list_get_instance(cur, btree_node_t, leaf_link);
for (i = 0; i < node->keys; i++) {
uintptr_t base = node->key[i];
count_t count = (count_t) node->value[i];
unsigned int j;
/*
* Skip read-only areas of used space that are backed
* by the ELF image.
*/
if (!(area->flags & AS_AREA_WRITE))
if (base >= entry->p_vaddr &&
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 >= entry->p_vaddr &&
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);
pfn_t pfn = ADDR2PFN(PTE_GET_FRAME(pte));
frame_reference_add(pfn);
}
}
}
mutex_unlock(&area->sh_info->lock);
}
/** @}
*/