/*
* The eip contains the *virtual* address of the Guest's instruction:
* we copy the instruction here so the Launcher doesn't have to walk
* the page tables to decode it. We handle the case (eg. in a kernel
* module) where the instruction is over two pages, and the pages are
* virtually but not physically contiguous.
*
* The longest possible x86 instruction is 15 bytes, but we don't handle
* anything that strange.
*/
static void copy_from_guest(struct lg_cpu *cpu,
void *dst, unsigned long vaddr, size_t len)
{
size_t to_page_end = PAGE_SIZE - (vaddr % PAGE_SIZE);
unsigned long paddr;
BUG_ON(len > PAGE_SIZE);
/* If it goes over a page, copy in two parts. */
if (len > to_page_end) {
/* But make sure the next page is mapped! */
if (__guest_pa(cpu, vaddr + to_page_end, &paddr))
copy_from_guest(cpu, dst + to_page_end,
vaddr + to_page_end,
len - to_page_end);
else
/* Otherwise fill with zeroes. */
memset(dst + to_page_end, 0, len - to_page_end);
len = to_page_end;
}
/* This will kill the guest if it isn't mapped, but that
* shouldn't happen. */
__lgread(cpu, dst, guest_pa(cpu, vaddr), len);
}
/*
* This is the version we normally use: kills the Guest if it uses a
* bad address
*/
unsigned long guest_pa(struct lg_cpu *cpu, unsigned long vaddr)
{
unsigned long paddr;
if (!__guest_pa(cpu, vaddr, &paddr))
kill_guest(cpu, "Bad address %#lx", vaddr);
return paddr;
}