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/* Copies stuff between different pagedirs. Mostly a wrapper behind an old,
* bad interface. */
// TODO ensure the behaviour of kernel vs user fs on faults is the same
#include <kernel/arch/generic.h>
#include <kernel/mem/virt.h>
#include <kernel/panic.h>
#include <kernel/proc.h>
#include <kernel/util.h>
#include <shared/mem.h>
struct virt_iter {
void *frag;
size_t frag_len;
size_t prior; // sum of all prior frag_lens
bool error;
void __user *_virt;
size_t _remaining;
Pagedir *_pages;
bool _user;
bool _writeable;
};
struct virt_cpy_error { // unused
bool read_fail, write_fail;
};
/* if pages == NULL, creates an iterator over physical memory. */
static void virt_iter_new(
struct virt_iter *iter, void __user *virt, size_t length,
Pagedir *pages, bool user, bool writeable
);
static bool virt_iter_next(struct virt_iter *);
static size_t virt_cpy(
Pagedir *dest_pages, void __user *dest,
Pagedir *src_pages, const void __user *src,
size_t length, struct virt_cpy_error *err
);
static void
virt_iter_new(
struct virt_iter *iter, void __user *virt, size_t length,
Pagedir *pages, bool user, bool writeable
) {
iter->frag = NULL;
iter->frag_len = 0;
iter->prior = 0;
iter->error = false;
iter->_virt = virt;
iter->_remaining = length;
iter->_pages = pages;
iter->_user = user;
iter->_writeable = writeable;
}
static bool
virt_iter_next(struct virt_iter *iter)
{
/* note: While i'm pretty sure that this should always work, this
* was only tested in cases where the pages were consecutive both in
* virtual and physical memory, which might not always be the case.
* TODO test this */
size_t partial = iter->_remaining;
iter->prior += iter->frag_len;
if (partial <= 0) return false;
if (iter->_pages) { // if iterating over virtual memory
// don't cross page boundaries
size_t to_page = PAGE_SIZE - ((uintptr_t)iter->_virt & PAGE_MASK);
partial = min(partial, to_page);
iter->frag = pagedir_virt2phys(iter->_pages,
iter->_virt, iter->_user, iter->_writeable);
if (!iter->frag) {
iter->error = true;
return false;
}
} else {
// "iterate" over physical memory
// the double cast supresses the warning about changing address spaces
iter->frag = (void* __force)iter->_virt;
}
iter->frag_len = partial;
iter->_remaining -= partial;
iter->_virt += partial;
return true;
}
static size_t
virt_cpy(
Pagedir *dest_pages, void __user *dest,
Pagedir *src_pages, const void __user *src,
size_t length, struct virt_cpy_error *err
) {
struct virt_iter dest_iter, src_iter;
size_t total = 0, partial;
virt_iter_new(&dest_iter, dest, length, dest_pages, true, true);
virt_iter_new( &src_iter, (userptr_t)src, length, src_pages, true, false);
dest_iter.frag_len = 0;
src_iter.frag_len = 0;
for (;;) {
if (dest_iter.frag_len <= 0 && !virt_iter_next(&dest_iter)) break;
if ( src_iter.frag_len <= 0 && !virt_iter_next( &src_iter)) break;
partial = min(src_iter.frag_len, dest_iter.frag_len);
total += partial;
memcpy(dest_iter.frag, src_iter.frag, partial);
dest_iter.frag_len -= partial;
dest_iter.frag += partial;
src_iter.frag_len -= partial;
src_iter.frag += partial;
}
if (err) {
err->read_fail = src_iter.error;
err->write_fail = dest_iter.error;
}
if (src_iter.error || dest_iter.error)
assert(total != length);
else
assert(total == length);
return total;
}
size_t
pcpy_to(Proc *p, __user void *dst, const void *src, size_t len)
{
assert(p);
if (!p->pages) return 0;
return virt_cpy(p->pages, dst, NULL, (__user void*)src, len, NULL);
}
size_t
pcpy_from(Proc *p, void *dst, const __user void *src, size_t len)
{
assert(p);
if (!p->pages) return 0;
return virt_cpy(NULL, (__user void*)dst, p->pages, src, len, NULL);
}
size_t
pcpy_bi(
Proc *dstp, __user void *dst,
Proc *srcp, const __user void *src,
size_t len
) {
assert(dstp && srcp);
if (!dstp->pages) return 0;
if (!srcp->pages) return 0;
return virt_cpy(dstp->pages, dst, srcp->pages, src, len, NULL);
}
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