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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 "xdp_umem.h"
#define XDP_UMEM_MIN_CHUNK_SIZE 2048
static void xdp_umem_unpin_pages(struct xdp_umem *umem)
{
unsigned int i;
for (i = 0; i < umem->npgs; i++) {
struct page *page = umem->pgs[i];
set_page_dirty_lock(page);
put_page(page);
}
kfree(umem->pgs);
umem->pgs = NULL;
}
static void xdp_umem_unaccount_pages(struct xdp_umem *umem)
{
atomic_long_sub(umem->npgs, &umem->user->locked_vm);
free_uid(umem->user);
}
static void xdp_umem_release(struct xdp_umem *umem)
{
struct task_struct *task;
struct mm_struct *mm;
if (umem->fq) {
xskq_destroy(umem->fq);
umem->fq = NULL;
}
if (umem->cq) {
xskq_destroy(umem->cq);
umem->cq = NULL;
}
xdp_umem_unpin_pages(umem);
task = get_pid_task(umem->pid, PIDTYPE_PID);
put_pid(umem->pid);
if (!task)
goto out;
mm = get_task_mm(task);
put_task_struct(task);
if (!mm)
goto out;
mmput(mm);
xdp_umem_unaccount_pages(umem);
out:
kfree(umem);
}
static void xdp_umem_release_deferred(struct work_struct *work)
{
struct xdp_umem *umem = container_of(work, struct xdp_umem, work);
xdp_umem_release(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)) {
INIT_WORK(&umem->work, xdp_umem_release_deferred);
schedule_work(&umem->work);
}
}
static int xdp_umem_pin_pages(struct xdp_umem *umem)
{
unsigned int gup_flags = FOLL_WRITE;
long npgs;
int err;
umem->pgs = kcalloc(umem->npgs, sizeof(*umem->pgs), GFP_KERNEL);
if (!umem->pgs)
return -ENOMEM;
down_write(¤t->mm->mmap_sem);
npgs = get_user_pages(umem->address, umem->npgs,
gup_flags, &umem->pgs[0], NULL);
up_write(¤t->mm->mmap_sem);
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 chunk_size = mr->chunk_size, headroom = mr->headroom;
unsigned int chunks, chunks_per_page;
u64 addr = mr->addr, size = mr->len;
int size_chk, 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 (!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;
chunks = (unsigned int)div_u64(size, chunk_size);
if (chunks == 0)
return -EINVAL;
chunks_per_page = PAGE_SIZE / chunk_size;
if (chunks < chunks_per_page || chunks % chunks_per_page)
return -EINVAL;
headroom = ALIGN(headroom, 64);
size_chk = chunk_size - headroom - XDP_PACKET_HEADROOM;
if (size_chk < 0)
return -EINVAL;
umem->pid = get_task_pid(current, PIDTYPE_PID);
umem->address = (unsigned long)addr;
umem->props.chunk_mask = ~((u64)chunk_size - 1);
umem->props.size = size;
umem->headroom = headroom;
umem->chunk_size_nohr = chunk_size - headroom;
umem->npgs = size / PAGE_SIZE;
umem->pgs = NULL;
umem->user = NULL;
refcount_set(&umem->users, 1);
err = xdp_umem_account_pages(umem);
if (err)
goto out;
err = xdp_umem_pin_pages(umem);
if (err)
goto out_account;
return 0;
out_account:
xdp_umem_unaccount_pages(umem);
out:
put_pid(umem->pid);
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 = xdp_umem_reg(umem, mr);
if (err) {
kfree(umem);
return ERR_PTR(err);
}
return umem;
}
bool xdp_umem_validate_queues(struct xdp_umem *umem)
{
return umem->fq && umem->cq;
}
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