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// SPDX-License-Identifier: GPL-2.0
/* XDP user-space packet buffer
* Copyright(c) 2018 Intel Corporation.
*/
#include <linux/init.h>
#include <linux/sched/mm.h>
#include <linux/sched/signal.h>
#include <linux/sched/task.h>
#include <linux/uaccess.h>
#include <linux/slab.h>
#include <linux/bpf.h>
#include <linux/mm.h>
#include <linux/netdevice.h>
#include <linux/rtnetlink.h>
#include <linux/idr.h>
#include <linux/vmalloc.h>
#include "xdp_umem.h"
#include "xsk_queue.h"
#define XDP_UMEM_MIN_CHUNK_SIZE 2048
static DEFINE_IDA(umem_ida);
static void xdp_umem_unpin_pages(struct xdp_umem *umem)
{
unpin_user_pages_dirty_lock(umem->pgs, umem->npgs, true);
kfree(umem->pgs);
umem->pgs = NULL;
}
static void xdp_umem_unaccount_pages(struct xdp_umem *umem)
{
if (umem->user) {
atomic_long_sub(umem->npgs, &umem->user->locked_vm);
free_uid(umem->user);
}
}
static void xdp_umem_addr_unmap(struct xdp_umem *umem)
{
vunmap(umem->addrs);
umem->addrs = NULL;
}
static int xdp_umem_addr_map(struct xdp_umem *umem, struct page **pages,
u32 nr_pages)
{
umem->addrs = vmap(pages, nr_pages, VM_MAP, PAGE_KERNEL);
if (!umem->addrs)
return -ENOMEM;
return 0;
}
static void xdp_umem_release(struct xdp_umem *umem)
{
umem->zc = false;
ida_simple_remove(&umem_ida, umem->id);
xdp_umem_addr_unmap(umem);
xdp_umem_unpin_pages(umem);
xdp_umem_unaccount_pages(umem);
kfree(umem);
}
void xdp_get_umem(struct xdp_umem *umem)
{
refcount_inc(&umem->users);
}
void xdp_put_umem(struct xdp_umem *umem)
{
if (!umem)
return;
if (refcount_dec_and_test(&umem->users))
xdp_umem_release(umem);
}
static int xdp_umem_pin_pages(struct xdp_umem *umem, unsigned long address)
{
unsigned int gup_flags = FOLL_WRITE;
long npgs;
int err;
umem->pgs = kcalloc(umem->npgs, sizeof(*umem->pgs),
GFP_KERNEL | __GFP_NOWARN);
if (!umem->pgs)
return -ENOMEM;
mmap_read_lock(current->mm);
npgs = pin_user_pages(address, umem->npgs,
gup_flags | FOLL_LONGTERM, &umem->pgs[0], NULL);
mmap_read_unlock(current->mm);
if (npgs != umem->npgs) {
if (npgs >= 0) {
umem->npgs = npgs;
err = -ENOMEM;
goto out_pin;
}
err = npgs;
goto out_pgs;
}
return 0;
out_pin:
xdp_umem_unpin_pages(umem);
out_pgs:
kfree(umem->pgs);
umem->pgs = NULL;
return err;
}
static int xdp_umem_account_pages(struct xdp_umem *umem)
{
unsigned long lock_limit, new_npgs, old_npgs;
if (capable(CAP_IPC_LOCK))
return 0;
lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
umem->user = get_uid(current_user());
do {
old_npgs = atomic_long_read(&umem->user->locked_vm);
new_npgs = old_npgs + umem->npgs;
if (new_npgs > lock_limit) {
free_uid(umem->user);
umem->user = NULL;
return -ENOBUFS;
}
} while (atomic_long_cmpxchg(&umem->user->locked_vm, old_npgs,
new_npgs) != old_npgs);
return 0;
}
static int xdp_umem_reg(struct xdp_umem *umem, struct xdp_umem_reg *mr)
{
u32 npgs_rem, chunk_size = mr->chunk_size, headroom = mr->headroom;
bool unaligned_chunks = mr->flags & XDP_UMEM_UNALIGNED_CHUNK_FLAG;
u64 npgs, addr = mr->addr, size = mr->len;
unsigned int chunks, chunks_rem;
int err;
if (chunk_size < XDP_UMEM_MIN_CHUNK_SIZE || chunk_size > PAGE_SIZE) {
/* Strictly speaking we could support this, if:
* - huge pages, or*
* - using an IOMMU, or
* - making sure the memory area is consecutive
* but for now, we simply say "computer says no".
*/
return -EINVAL;
}
if (mr->flags & ~XDP_UMEM_UNALIGNED_CHUNK_FLAG)
return -EINVAL;
if (!unaligned_chunks && !is_power_of_2(chunk_size))
return -EINVAL;
if (!PAGE_ALIGNED(addr)) {
/* Memory area has to be page size aligned. For
* simplicity, this might change.
*/
return -EINVAL;
}
if ((addr + size) < addr)
return -EINVAL;
npgs = div_u64_rem(size, PAGE_SIZE, &npgs_rem);
if (npgs_rem)
npgs++;
if (npgs > U32_MAX)
return -EINVAL;
chunks = (unsigned int)div_u64_rem(size, chunk_size, &chunks_rem);
if (chunks == 0)
return -EINVAL;
if (!unaligned_chunks && chunks_rem)
return -EINVAL;
if (headroom >= chunk_size - XDP_PACKET_HEADROOM)
return -EINVAL;
umem->size = size;
umem->headroom = headroom;
umem->chunk_size = chunk_size;
umem->chunks = chunks;
umem->npgs = (u32)npgs;
umem->pgs = NULL;
umem->user = NULL;
umem->flags = mr->flags;
INIT_LIST_HEAD(&umem->xsk_dma_list);
refcount_set(&umem->users, 1);
err = xdp_umem_account_pages(umem);
if (err)
return err;
err = xdp_umem_pin_pages(umem, (unsigned long)addr);
if (err)
goto out_account;
err = xdp_umem_addr_map(umem, umem->pgs, umem->npgs);
if (err)
goto out_unpin;
return 0;
out_unpin:
xdp_umem_unpin_pages(umem);
out_account:
xdp_umem_unaccount_pages(umem);
return err;
}
struct xdp_umem *xdp_umem_create(struct xdp_umem_reg *mr)
{
struct xdp_umem *umem;
int err;
umem = kzalloc(sizeof(*umem), GFP_KERNEL);
if (!umem)
return ERR_PTR(-ENOMEM);
err = ida_simple_get(&umem_ida, 0, 0, GFP_KERNEL);
if (err < 0) {
kfree(umem);
return ERR_PTR(err);
}
umem->id = err;
err = xdp_umem_reg(umem, mr);
if (err) {
ida_simple_remove(&umem_ida, umem->id);
kfree(umem);
return ERR_PTR(err);
}
return umem;
}
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