Commit 98797a24 authored by Russell King's avatar Russell King Committed by Russell King

Merge branch 'copy_user' of git://git.marvell.com/orion into devel

parents ca8cbc83 c626e3f5
......@@ -1091,6 +1091,22 @@ config ALIGNMENT_TRAP
correct operation of some network protocols. With an IP-only
configuration it is safe to say N, otherwise say Y.
config UACCESS_WITH_MEMCPY
bool "Use kernel mem{cpy,set}() for {copy_to,clear}_user() (EXPERIMENTAL)"
depends on MMU && EXPERIMENTAL
default y if CPU_FEROCEON
help
Implement faster copy_to_user and clear_user methods for CPU
cores where a 8-word STM instruction give significantly higher
memory write throughput than a sequence of individual 32bit stores.
A possible side effect is a slight increase in scheduling latency
between threads sharing the same address space if they invoke
such copy operations with large buffers.
However, if the CPU data cache is using a write-allocate mode,
this option is unlikely to provide any performance gain.
endmenu
menu "Boot options"
......
......@@ -386,7 +386,9 @@ do { \
#ifdef CONFIG_MMU
extern unsigned long __must_check __copy_from_user(void *to, const void __user *from, unsigned long n);
extern unsigned long __must_check __copy_to_user(void __user *to, const void *from, unsigned long n);
extern unsigned long __must_check __copy_to_user_std(void __user *to, const void *from, unsigned long n);
extern unsigned long __must_check __clear_user(void __user *addr, unsigned long n);
extern unsigned long __must_check __clear_user_std(void __user *addr, unsigned long n);
#else
#define __copy_from_user(to,from,n) (memcpy(to, (void __force *)from, n), 0)
#define __copy_to_user(to,from,n) (memcpy((void __force *)to, from, n), 0)
......
......@@ -29,6 +29,9 @@ else
endif
endif
# using lib_ here won't override already available weak symbols
obj-$(CONFIG_UACCESS_WITH_MEMCPY) += uaccess_with_memcpy.o
lib-$(CONFIG_MMU) += $(mmu-y)
ifeq ($(CONFIG_CPU_32v3),y)
......
......@@ -18,7 +18,8 @@
* : sz - number of bytes to clear
* Returns : number of bytes NOT cleared
*/
ENTRY(__clear_user)
ENTRY(__clear_user_std)
WEAK(__clear_user)
stmfd sp!, {r1, lr}
mov r2, #0
cmp r1, #4
......
......@@ -86,7 +86,8 @@
.text
ENTRY(__copy_to_user)
ENTRY(__copy_to_user_std)
WEAK(__copy_to_user)
#include "copy_template.S"
......
/*
* linux/arch/arm/lib/uaccess_with_memcpy.c
*
* Written by: Lennert Buytenhek and Nicolas Pitre
* Copyright (C) 2009 Marvell Semiconductor
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#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 <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;
spinlock_t *ptl;
pgd = pgd_offset(current->mm, addr);
if (unlikely(pgd_none(*pgd) || pgd_bad(*pgd)))
return 0;
pmd = pmd_offset(pgd, addr);
if (unlikely(pmd_none(*pmd) || 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)
{
int atomic;
if (unlikely(segment_eq(get_fs(), KERNEL_DS))) {
memcpy((void *)to, from, n);
return 0;
}
/* the mmap semaphore is taken only if not in an atomic context */
atomic = in_atomic();
if (!atomic)
down_read(&current->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(&current->mm->mmap_sem);
if (__put_user(0, (char __user *)to))
goto out;
if (!atomic)
down_read(&current->mm->mmap_sem);
}
tocopy = (~(unsigned long)to & ~PAGE_MASK) + 1;
if (tocopy > n)
tocopy = n;
memcpy((void *)to, from, tocopy);
to += tocopy;
from += tocopy;
n -= tocopy;
pte_unmap_unlock(pte, ptl);
}
if (!atomic)
up_read(&current->mm->mmap_sem);
out:
return n;
}
unsigned long
__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)
return __copy_to_user_std(to, from, n);
return __copy_to_user_memcpy(to, from, n);
}
static unsigned long noinline
__clear_user_memset(void __user *addr, unsigned long n)
{
if (unlikely(segment_eq(get_fs(), KERNEL_DS))) {
memset((void *)addr, 0, n);
return 0;
}
down_read(&current->mm->mmap_sem);
while (n) {
pte_t *pte;
spinlock_t *ptl;
int tocopy;
while (!pin_page_for_write(addr, &pte, &ptl)) {
up_read(&current->mm->mmap_sem);
if (__put_user(0, (char __user *)addr))
goto out;
down_read(&current->mm->mmap_sem);
}
tocopy = (~(unsigned long)addr & ~PAGE_MASK) + 1;
if (tocopy > n)
tocopy = n;
memset((void *)addr, 0, tocopy);
addr += tocopy;
n -= tocopy;
pte_unmap_unlock(pte, ptl);
}
up_read(&current->mm->mmap_sem);
out:
return n;
}
unsigned long __clear_user(void __user *addr, unsigned long n)
{
/* See rational for this in __copy_to_user() above. */
if (n < 64)
return __clear_user_std(addr, n);
return __clear_user_memset(addr, 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
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