static void handler(enum exception_type type, int subtype, void *vaddr,
arch_registers_state_t *regs, arch_registers_fpu_state_t *fpuregs)
{
debug_printf("got exception %d(%d) on %p\n", type, subtype, vaddr);
assert(type == EXCEPT_PAGEFAULT);
assert(subtype == PAGEFLT_WRITE);
uintptr_t addr = (uintptr_t) vaddr;
uintptr_t faddr = addr & ~BASE_PAGE_MASK;
uintptr_t base = (uintptr_t) cow_vbuf;
if (addr < base || addr >= base + BUFSIZE) {
debug_printf("unexpected write pagefault on %p\n", vaddr);
exit(1);
}
assert(cow_frame_count);
debug_printf("got expected write pagefault on %p, creating copy of page\n", vaddr);
// get and map copy of page
size_t frame_id = (addr - base) / BASE_PAGE_SIZE;
debug_printf("remapping frame %zu\n", frame_id);
struct memobj *m = vregion_get_memobj(cow_vregion);
assert(m);
errval_t err;
struct capref retframe;
struct capref f = (struct capref) { .cnode = cow_frames, .slot = frame_id };
size_t retoff;
struct vregion *vr;
void *buf;
// copy data from faulting page to new page
err = vspace_map_one_frame(&buf, BASE_PAGE_SIZE, f, NULL, &vr);
assert(err_is_ok(err));
memcpy(buf, (void *)faddr, BASE_PAGE_SIZE);
vregion_destroy(vr);
err = m->f.unfill(m, frame_id * BASE_PAGE_SIZE, &retframe, &retoff);
assert(err_is_ok(err));
err = m->f.fill(m, frame_id * BASE_PAGE_SIZE, f, BASE_PAGE_SIZE);
assert(err_is_ok(err));
err = m->f.pagefault(m, cow_vregion, frame_id * BASE_PAGE_SIZE, 0);
assert(err_is_ok(err));
err = m->f.protect(m, cow_vregion, frame_id * BASE_PAGE_SIZE,
BASE_PAGE_SIZE, VREGION_FLAGS_READ_WRITE);
assert(err_is_ok(err));
}
/**
* \brief Destroy the given region
*
* \return SYS_ERR_OK on success, error code on failure
*
* \bug This only works if the memobj type is memobj_one_frame.
*/
errval_t vregion_destroy(struct vregion *vregion)
{
errval_t err;
struct vspace *vspace = vregion_get_vspace(vregion);
if (vspace != NULL) {
err = vspace_remove_vregion(vspace, vregion);
if (err_is_fail(err)) {
return err_push(err, LIB_ERR_VSPACE_REMOVE_REGION);
}
}
struct memobj *memobj = vregion_get_memobj(vregion);
if (memobj != NULL) {
err = memobj->f.unmap_region(memobj, vregion);
if (err_is_fail(err)) {
return err_push(err, LIB_ERR_MEMOBJ_UNMAP_REGION);
}
}
return SYS_ERR_OK;
}
