mirror of https://gitee.com/openkylin/linux.git
285 lines
6.2 KiB
C
285 lines
6.2 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
|
|
/*
|
|
* linux/arch/arm/lib/uaccess_with_memcpy.c
|
|
*
|
|
* Written by: Lennert Buytenhek and Nicolas Pitre
|
|
* Copyright (C) 2009 Marvell Semiconductor
|
|
*/
|
|
|
|
#include <linux/kernel.h>
|
|
#include <linux/ctype.h>
|
|
#include <linux/uaccess.h>
|
|
#include <linux/rwsem.h>
|
|
#include <linux/mm.h>
|
|
#include <linux/sched.h>
|
|
#include <linux/hardirq.h> /* for in_atomic() */
|
|
#include <linux/gfp.h>
|
|
#include <linux/highmem.h>
|
|
#include <linux/hugetlb.h>
|
|
#include <asm/current.h>
|
|
#include <asm/page.h>
|
|
|
|
static int
|
|
pin_page_for_write(const void __user *_addr, pte_t **ptep, spinlock_t **ptlp)
|
|
{
|
|
unsigned long addr = (unsigned long)_addr;
|
|
pgd_t *pgd;
|
|
pmd_t *pmd;
|
|
pte_t *pte;
|
|
pud_t *pud;
|
|
spinlock_t *ptl;
|
|
|
|
pgd = pgd_offset(current->mm, addr);
|
|
if (unlikely(pgd_none(*pgd) || pgd_bad(*pgd)))
|
|
return 0;
|
|
|
|
pud = pud_offset(pgd, addr);
|
|
if (unlikely(pud_none(*pud) || pud_bad(*pud)))
|
|
return 0;
|
|
|
|
pmd = pmd_offset(pud, addr);
|
|
if (unlikely(pmd_none(*pmd)))
|
|
return 0;
|
|
|
|
/*
|
|
* A pmd can be bad if it refers to a HugeTLB or THP page.
|
|
*
|
|
* Both THP and HugeTLB pages have the same pmd layout
|
|
* and should not be manipulated by the pte functions.
|
|
*
|
|
* Lock the page table for the destination and check
|
|
* to see that it's still huge and whether or not we will
|
|
* need to fault on write.
|
|
*/
|
|
if (unlikely(pmd_thp_or_huge(*pmd))) {
|
|
ptl = ¤t->mm->page_table_lock;
|
|
spin_lock(ptl);
|
|
if (unlikely(!pmd_thp_or_huge(*pmd)
|
|
|| pmd_hugewillfault(*pmd))) {
|
|
spin_unlock(ptl);
|
|
return 0;
|
|
}
|
|
|
|
*ptep = NULL;
|
|
*ptlp = ptl;
|
|
return 1;
|
|
}
|
|
|
|
if (unlikely(pmd_bad(*pmd)))
|
|
return 0;
|
|
|
|
pte = pte_offset_map_lock(current->mm, pmd, addr, &ptl);
|
|
if (unlikely(!pte_present(*pte) || !pte_young(*pte) ||
|
|
!pte_write(*pte) || !pte_dirty(*pte))) {
|
|
pte_unmap_unlock(pte, ptl);
|
|
return 0;
|
|
}
|
|
|
|
*ptep = pte;
|
|
*ptlp = ptl;
|
|
|
|
return 1;
|
|
}
|
|
|
|
static unsigned long noinline
|
|
__copy_to_user_memcpy(void __user *to, const void *from, unsigned long n)
|
|
{
|
|
unsigned long ua_flags;
|
|
int atomic;
|
|
|
|
if (uaccess_kernel()) {
|
|
memcpy((void *)to, from, n);
|
|
return 0;
|
|
}
|
|
|
|
/* the mmap semaphore is taken only if not in an atomic context */
|
|
atomic = faulthandler_disabled();
|
|
|
|
if (!atomic)
|
|
down_read(¤t->mm->mmap_sem);
|
|
while (n) {
|
|
pte_t *pte;
|
|
spinlock_t *ptl;
|
|
int tocopy;
|
|
|
|
while (!pin_page_for_write(to, &pte, &ptl)) {
|
|
if (!atomic)
|
|
up_read(¤t->mm->mmap_sem);
|
|
if (__put_user(0, (char __user *)to))
|
|
goto out;
|
|
if (!atomic)
|
|
down_read(¤t->mm->mmap_sem);
|
|
}
|
|
|
|
tocopy = (~(unsigned long)to & ~PAGE_MASK) + 1;
|
|
if (tocopy > n)
|
|
tocopy = n;
|
|
|
|
ua_flags = uaccess_save_and_enable();
|
|
memcpy((void *)to, from, tocopy);
|
|
uaccess_restore(ua_flags);
|
|
to += tocopy;
|
|
from += tocopy;
|
|
n -= tocopy;
|
|
|
|
if (pte)
|
|
pte_unmap_unlock(pte, ptl);
|
|
else
|
|
spin_unlock(ptl);
|
|
}
|
|
if (!atomic)
|
|
up_read(¤t->mm->mmap_sem);
|
|
|
|
out:
|
|
return n;
|
|
}
|
|
|
|
unsigned long
|
|
arm_copy_to_user(void __user *to, const void *from, unsigned long n)
|
|
{
|
|
/*
|
|
* This test is stubbed out of the main function above to keep
|
|
* the overhead for small copies low by avoiding a large
|
|
* register dump on the stack just to reload them right away.
|
|
* With frame pointer disabled, tail call optimization kicks in
|
|
* as well making this test almost invisible.
|
|
*/
|
|
if (n < 64) {
|
|
unsigned long ua_flags = uaccess_save_and_enable();
|
|
n = __copy_to_user_std(to, from, n);
|
|
uaccess_restore(ua_flags);
|
|
} else {
|
|
n = __copy_to_user_memcpy(uaccess_mask_range_ptr(to, n),
|
|
from, n);
|
|
}
|
|
return n;
|
|
}
|
|
|
|
static unsigned long noinline
|
|
__clear_user_memset(void __user *addr, unsigned long n)
|
|
{
|
|
unsigned long ua_flags;
|
|
|
|
if (uaccess_kernel()) {
|
|
memset((void *)addr, 0, n);
|
|
return 0;
|
|
}
|
|
|
|
down_read(¤t->mm->mmap_sem);
|
|
while (n) {
|
|
pte_t *pte;
|
|
spinlock_t *ptl;
|
|
int tocopy;
|
|
|
|
while (!pin_page_for_write(addr, &pte, &ptl)) {
|
|
up_read(¤t->mm->mmap_sem);
|
|
if (__put_user(0, (char __user *)addr))
|
|
goto out;
|
|
down_read(¤t->mm->mmap_sem);
|
|
}
|
|
|
|
tocopy = (~(unsigned long)addr & ~PAGE_MASK) + 1;
|
|
if (tocopy > n)
|
|
tocopy = n;
|
|
|
|
ua_flags = uaccess_save_and_enable();
|
|
memset((void *)addr, 0, tocopy);
|
|
uaccess_restore(ua_flags);
|
|
addr += tocopy;
|
|
n -= tocopy;
|
|
|
|
if (pte)
|
|
pte_unmap_unlock(pte, ptl);
|
|
else
|
|
spin_unlock(ptl);
|
|
}
|
|
up_read(¤t->mm->mmap_sem);
|
|
|
|
out:
|
|
return n;
|
|
}
|
|
|
|
unsigned long arm_clear_user(void __user *addr, unsigned long n)
|
|
{
|
|
/* See rational for this in __copy_to_user() above. */
|
|
if (n < 64) {
|
|
unsigned long ua_flags = uaccess_save_and_enable();
|
|
n = __clear_user_std(addr, n);
|
|
uaccess_restore(ua_flags);
|
|
} else {
|
|
n = __clear_user_memset(addr, n);
|
|
}
|
|
return n;
|
|
}
|
|
|
|
#if 0
|
|
|
|
/*
|
|
* This code is disabled by default, but kept around in case the chosen
|
|
* thresholds need to be revalidated. Some overhead (small but still)
|
|
* would be implied by a runtime determined variable threshold, and
|
|
* so far the measurement on concerned targets didn't show a worthwhile
|
|
* variation.
|
|
*
|
|
* Note that a fairly precise sched_clock() implementation is needed
|
|
* for results to make some sense.
|
|
*/
|
|
|
|
#include <linux/vmalloc.h>
|
|
|
|
static int __init test_size_treshold(void)
|
|
{
|
|
struct page *src_page, *dst_page;
|
|
void *user_ptr, *kernel_ptr;
|
|
unsigned long long t0, t1, t2;
|
|
int size, ret;
|
|
|
|
ret = -ENOMEM;
|
|
src_page = alloc_page(GFP_KERNEL);
|
|
if (!src_page)
|
|
goto no_src;
|
|
dst_page = alloc_page(GFP_KERNEL);
|
|
if (!dst_page)
|
|
goto no_dst;
|
|
kernel_ptr = page_address(src_page);
|
|
user_ptr = vmap(&dst_page, 1, VM_IOREMAP, __pgprot(__P010));
|
|
if (!user_ptr)
|
|
goto no_vmap;
|
|
|
|
/* warm up the src page dcache */
|
|
ret = __copy_to_user_memcpy(user_ptr, kernel_ptr, PAGE_SIZE);
|
|
|
|
for (size = PAGE_SIZE; size >= 4; size /= 2) {
|
|
t0 = sched_clock();
|
|
ret |= __copy_to_user_memcpy(user_ptr, kernel_ptr, size);
|
|
t1 = sched_clock();
|
|
ret |= __copy_to_user_std(user_ptr, kernel_ptr, size);
|
|
t2 = sched_clock();
|
|
printk("copy_to_user: %d %llu %llu\n", size, t1 - t0, t2 - t1);
|
|
}
|
|
|
|
for (size = PAGE_SIZE; size >= 4; size /= 2) {
|
|
t0 = sched_clock();
|
|
ret |= __clear_user_memset(user_ptr, size);
|
|
t1 = sched_clock();
|
|
ret |= __clear_user_std(user_ptr, size);
|
|
t2 = sched_clock();
|
|
printk("clear_user: %d %llu %llu\n", size, t1 - t0, t2 - t1);
|
|
}
|
|
|
|
if (ret)
|
|
ret = -EFAULT;
|
|
|
|
vunmap(user_ptr);
|
|
no_vmap:
|
|
put_page(dst_page);
|
|
no_dst:
|
|
put_page(src_page);
|
|
no_src:
|
|
return ret;
|
|
}
|
|
|
|
subsys_initcall(test_size_treshold);
|
|
|
|
#endif
|