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page fault handler maps on demand pages for the BSS section

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This commit is contained in:
Stefan Lankes 2016-01-01 17:48:31 +01:00
parent f33f4e1047
commit 750fff5230
1 changed files with 28 additions and 3 deletions
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31
hermit/arch/x86/mm/page.c
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@ -47,7 +47,7 @@
/* Note that linker symbols are not variables, they have no memory
* allocated for maintaining a value, rather their address is their value. */
extern const void kernel_start;
//extern const void kernel_end;
extern const void kernel_end;
/// This page is reserved for copying
#define PAGE_TMP (PAGE_FLOOR((size_t) &kernel_start) - PAGE_SIZE)
@ -288,8 +288,33 @@ void page_fault_handler(struct state *s)
size_t viraddr = read_cr2();
task_t* task = per_core(current_task);
// on demand userspace heap mapping
if ((task->heap) && (viraddr >= task->heap->start) && (viraddr < task->heap->end)) {
// do we got a pagefault within the kernel? => BSS is not initialized
if ((viraddr >= (size_t) &kernel_start) && (viraddr < (size_t) &kernel_end))
{
kprintf("Pagefault within the kernel: 0x%llx\n", viraddr);
viraddr &= PAGE_MASK;
size_t phyaddr = get_page();
if (BUILTIN_EXPECT(!phyaddr, 0)) {
kprintf("out of memory: task = %u\n", task->id);
goto default_handler;
}
int ret = page_map(viraddr, phyaddr, 1, PG_RW);
if (BUILTIN_EXPECT(ret, 0)) {
kprintf("map_region: could not map %#lx to %#lx, task = %u\n", phyaddr, viraddr, task->id);
put_page(phyaddr);
goto default_handler;
}
memset((void*) viraddr, 0x00, PAGE_SIZE); // fill with zeros
return;
} else if ((task->heap) && (viraddr >= task->heap->start) && (viraddr < task->heap->end)) {
// on demand userspace heap mapping
viraddr &= PAGE_MASK;
size_t phyaddr = get_page();