blob: acec0af6034c6bf39bf1d83bafb2064ef39f7b1c [file] [log] [blame]
/*
* Copyright (c) 2015 Hauke Mehrtens <hauke@hauke-m.de>
*
* Backport functionality introduced in Linux 4.0.
*
* 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/mm.h>
#include <linux/sched.h>
#include <linux/ctype.h>
#include <linux/printk.h>
#include <linux/export.h>
#include <asm/unaligned.h>
static __always_inline long __get_user_pages_locked(struct task_struct *tsk,
struct mm_struct *mm,
unsigned long start,
unsigned long nr_pages,
int write, int force,
struct page **pages,
struct vm_area_struct **vmas,
int *locked, bool notify_drop,
unsigned int flags)
{
long ret, pages_done;
bool lock_dropped;
if (locked) {
/* if VM_FAULT_RETRY can be returned, vmas become invalid */
BUG_ON(vmas);
/* check caller initialized locked */
BUG_ON(*locked != 1);
}
if (pages)
flags |= FOLL_GET;
if (write)
flags |= FOLL_WRITE;
if (force)
flags |= FOLL_FORCE;
pages_done = 0;
lock_dropped = false;
for (;;) {
ret = __get_user_pages(tsk, mm, start, nr_pages, flags, pages,
vmas, locked);
if (!locked)
/* VM_FAULT_RETRY couldn't trigger, bypass */
return ret;
/* VM_FAULT_RETRY cannot return errors */
if (!*locked) {
BUG_ON(ret < 0);
BUG_ON(ret >= nr_pages);
}
if (!pages)
/* If it's a prefault don't insist harder */
return ret;
if (ret > 0) {
nr_pages -= ret;
pages_done += ret;
if (!nr_pages)
break;
}
if (*locked) {
/* VM_FAULT_RETRY didn't trigger */
if (!pages_done)
pages_done = ret;
break;
}
/* VM_FAULT_RETRY triggered, so seek to the faulting offset */
pages += ret;
start += ret << PAGE_SHIFT;
/*
* Repeat on the address that fired VM_FAULT_RETRY
* without FAULT_FLAG_ALLOW_RETRY but with
* FAULT_FLAG_TRIED.
*/
*locked = 1;
lock_dropped = true;
down_read(&mm->mmap_sem);
ret = __get_user_pages(tsk, mm, start, 1, flags | FOLL_TRIED,
pages, NULL, NULL);
if (ret != 1) {
BUG_ON(ret > 1);
if (!pages_done)
pages_done = ret;
break;
}
nr_pages--;
pages_done++;
if (!nr_pages)
break;
pages++;
start += PAGE_SIZE;
}
if (notify_drop && lock_dropped && *locked) {
/*
* We must let the caller know we temporarily dropped the lock
* and so the critical section protected by it was lost.
*/
up_read(&mm->mmap_sem);
*locked = 0;
}
return pages_done;
}
/*
* We can leverage the VM_FAULT_RETRY functionality in the page fault
* paths better by using either get_user_pages_locked() or
* get_user_pages_unlocked().
*
* get_user_pages_locked() is suitable to replace the form:
*
* down_read(&mm->mmap_sem);
* do_something()
* get_user_pages(tsk, mm, ..., pages, NULL);
* up_read(&mm->mmap_sem);
*
* to:
*
* int locked = 1;
* down_read(&mm->mmap_sem);
* do_something()
* get_user_pages_locked(tsk, mm, ..., pages, &locked);
* if (locked)
* up_read(&mm->mmap_sem);
*/
long get_user_pages_locked(struct task_struct *tsk, struct mm_struct *mm,
unsigned long start, unsigned long nr_pages,
int write, int force, struct page **pages,
int *locked)
{
return __get_user_pages_locked(tsk, mm, start, nr_pages, write, force,
pages, NULL, locked, true, FOLL_TOUCH);
}
EXPORT_SYMBOL_GPL(get_user_pages_locked);
/*
* Same as get_user_pages_unlocked(...., FOLL_TOUCH) but it allows to
* pass additional gup_flags as last parameter (like FOLL_HWPOISON).
*
* NOTE: here FOLL_TOUCH is not set implicitly and must be set by the
* caller if required (just like with __get_user_pages). "FOLL_GET",
* "FOLL_WRITE" and "FOLL_FORCE" are set implicitly as needed
* according to the parameters "pages", "write", "force"
* respectively.
*/
__always_inline long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
unsigned long start, unsigned long nr_pages,
int write, int force, struct page **pages,
unsigned int gup_flags)
{
long ret;
int locked = 1;
down_read(&mm->mmap_sem);
ret = __get_user_pages_locked(tsk, mm, start, nr_pages, write, force,
pages, NULL, &locked, false, gup_flags);
if (locked)
up_read(&mm->mmap_sem);
return ret;
}
EXPORT_SYMBOL_GPL(__get_user_pages_unlocked);
/*
* get_user_pages_unlocked() is suitable to replace the form:
*
* down_read(&mm->mmap_sem);
* get_user_pages(tsk, mm, ..., pages, NULL);
* up_read(&mm->mmap_sem);
*
* with:
*
* get_user_pages_unlocked(tsk, mm, ..., pages);
*
* It is functionally equivalent to get_user_pages_fast so
* get_user_pages_fast should be used instead, if the two parameters
* "tsk" and "mm" are respectively equal to current and current->mm,
* or if "force" shall be set to 1 (get_user_pages_fast misses the
* "force" parameter).
*/
long get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
unsigned long start, unsigned long nr_pages,
int write, int force, struct page **pages)
{
return __get_user_pages_unlocked(tsk, mm, start, nr_pages, write,
force, pages, FOLL_TOUCH);
}
EXPORT_SYMBOL_GPL(get_user_pages_unlocked);
/**
* hex_dump_to_buffer - convert a blob of data to "hex ASCII" in memory
* @buf: data blob to dump
* @len: number of bytes in the @buf
* @rowsize: number of bytes to print per line; must be 16 or 32
* @groupsize: number of bytes to print at a time (1, 2, 4, 8; default = 1)
* @linebuf: where to put the converted data
* @linebuflen: total size of @linebuf, including space for terminating NUL
* @ascii: include ASCII after the hex output
*
* hex_dump_to_buffer() works on one "line" of output at a time, i.e.,
* 16 or 32 bytes of input data converted to hex + ASCII output.
*
* Given a buffer of u8 data, hex_dump_to_buffer() converts the input data
* to a hex + ASCII dump at the supplied memory location.
* The converted output is always NUL-terminated.
*
* E.g.:
* hex_dump_to_buffer(frame->data, frame->len, 16, 1,
* linebuf, sizeof(linebuf), true);
*
* example output buffer:
* 40 41 42 43 44 45 46 47 48 49 4a 4b 4c 4d 4e 4f @ABCDEFGHIJKLMNO
*
* Return:
* The amount of bytes placed in the buffer without terminating NUL. If the
* output was truncated, then the return value is the number of bytes
* (excluding the terminating NUL) which would have been written to the final
* string if enough space had been available.
*/
int hex_dump_to_buffer(const void *buf, size_t len, int rowsize, int groupsize,
char *linebuf, size_t linebuflen, bool ascii)
{
const u8 *ptr = buf;
int ngroups;
u8 ch;
int j, lx = 0;
int ascii_column;
int ret;
if (rowsize != 16 && rowsize != 32)
rowsize = 16;
if (len > rowsize) /* limit to one line at a time */
len = rowsize;
if (!is_power_of_2(groupsize) || groupsize > 8)
groupsize = 1;
if ((len % groupsize) != 0) /* no mixed size output */
groupsize = 1;
ngroups = len / groupsize;
ascii_column = rowsize * 2 + rowsize / groupsize + 1;
if (!linebuflen)
goto overflow1;
if (!len)
goto nil;
if (groupsize == 8) {
const u64 *ptr8 = buf;
for (j = 0; j < ngroups; j++) {
ret = snprintf(linebuf + lx, linebuflen - lx,
"%s%16.16llx", j ? " " : "",
get_unaligned(ptr8 + j));
if (ret >= linebuflen - lx)
goto overflow1;
lx += ret;
}
} else if (groupsize == 4) {
const u32 *ptr4 = buf;
for (j = 0; j < ngroups; j++) {
ret = snprintf(linebuf + lx, linebuflen - lx,
"%s%8.8x", j ? " " : "",
get_unaligned(ptr4 + j));
if (ret >= linebuflen - lx)
goto overflow1;
lx += ret;
}
} else if (groupsize == 2) {
const u16 *ptr2 = buf;
for (j = 0; j < ngroups; j++) {
ret = snprintf(linebuf + lx, linebuflen - lx,
"%s%4.4x", j ? " " : "",
get_unaligned(ptr2 + j));
if (ret >= linebuflen - lx)
goto overflow1;
lx += ret;
}
} else {
for (j = 0; j < len; j++) {
if (linebuflen < lx + 3)
goto overflow2;
ch = ptr[j];
linebuf[lx++] = hex_asc_hi(ch);
linebuf[lx++] = hex_asc_lo(ch);
linebuf[lx++] = ' ';
}
if (j)
lx--;
}
if (!ascii)
goto nil;
while (lx < ascii_column) {
if (linebuflen < lx + 2)
goto overflow2;
linebuf[lx++] = ' ';
}
for (j = 0; j < len; j++) {
if (linebuflen < lx + 2)
goto overflow2;
ch = ptr[j];
linebuf[lx++] = (isascii(ch) && isprint(ch)) ? ch : '.';
}
nil:
linebuf[lx] = '\0';
return lx;
overflow2:
linebuf[lx++] = '\0';
overflow1:
return ascii ? ascii_column + len : (groupsize * 2 + 1) * ngroups - 1;
}
EXPORT_SYMBOL_GPL(hex_dump_to_buffer);