/*
- * linux/mm/process_vm_access.c
+ * linux/mm/process_vm_access.c
*
- * Copyright (C) 2010-2011 Christopher Yeoh <cyeoh@au1.ibm.com>, IBM Corp.
+ * Copyright (C) 2010-2011 Christopher Yeoh <cyeoh@au1.ibm.com>, IBM Corp.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
*/
#include <linux/mm.h>
#include <linux/compat.h>
#endif
-/*
+/**
* process_vm_rw_pages - read/write pages from task specified
* @task: task to read/write from
* @mm: mm for task
* @lvec_offset: offset in bytes from current iovec iov_base we are up to
* @vm_write: 0 means copy from, 1 means copy to
* @nr_pages_to_copy: number of pages to copy
+ * @bytes_copied: returns number of bytes successfully copied
+ * Returns 0 on success, error code otherwise
*/
-static ssize_t process_vm_rw_pages(struct task_struct *task,
- struct mm_struct *mm,
- struct page **process_pages,
- unsigned long pa,
- unsigned long start_offset,
- unsigned long len,
- const struct iovec *lvec,
- unsigned long lvec_cnt,
- unsigned long *lvec_current,
- size_t *lvec_offset,
- int vm_write,
- unsigned int nr_pages_to_copy)
+static int process_vm_rw_pages(struct task_struct *task,
+ struct mm_struct *mm,
+ struct page **process_pages,
+ unsigned long pa,
+ unsigned long start_offset,
+ unsigned long len,
+ const struct iovec *lvec,
+ unsigned long lvec_cnt,
+ unsigned long *lvec_current,
+ size_t *lvec_offset,
+ int vm_write,
+ unsigned int nr_pages_to_copy,
+ ssize_t *bytes_copied)
{
int pages_pinned;
void *target_kaddr;
int j;
int ret;
ssize_t bytes_to_copy;
- ssize_t bytes_copied = 0;
- ssize_t rc = -EFAULT;
+ ssize_t rc = 0;
+
+ *bytes_copied = 0;
/* Get the pages we're interested in */
down_read(&mm->mmap_sem);
vm_write, 0, process_pages, NULL);
up_read(&mm->mmap_sem);
- if (pages_pinned != nr_pages_to_copy)
+ if (pages_pinned != nr_pages_to_copy) {
+ rc = -EFAULT;
goto end;
+ }
/* Do the copy for each page */
for (pgs_copied = 0;
* - bytes remaining in destination iovec
*/
bytes_to_copy = min_t(ssize_t, PAGE_SIZE - start_offset,
- len - bytes_copied);
+ len - *bytes_copied);
bytes_to_copy = min_t(ssize_t, bytes_to_copy,
lvec[*lvec_current].iov_len
- *lvec_offset);
target_kaddr, bytes_to_copy);
kunmap(process_pages[pgs_copied]);
if (ret) {
+ *bytes_copied += bytes_to_copy - ret;
pgs_copied++;
+ rc = -EFAULT;
goto end;
}
- bytes_copied += bytes_to_copy;
+ *bytes_copied += bytes_to_copy;
*lvec_offset += bytes_to_copy;
if (*lvec_offset == lvec[*lvec_current].iov_len) {
/*
}
}
- rc = bytes_copied;
-
end:
if (vm_write) {
for (j = 0; j < pages_pinned; j++) {
/* Maximum number of pages kmalloc'd to hold struct page's during copy */
#define PVM_MAX_KMALLOC_PAGES (PAGE_SIZE * 2)
-/*
+/**
* process_vm_rw_single_vec - read/write pages from task specified
* @addr: start memory address of target process
* @len: size of area to copy to/from
* @mm: mm for task
* @task: task to read/write from
* @vm_write: 0 means copy from, 1 means copy to
+ * @bytes_copied: returns number of bytes successfully copied
+ * Returns 0 on success or on failure error code
*/
-static ssize_t process_vm_rw_single_vec(unsigned long addr,
- unsigned long len,
- const struct iovec *lvec,
- unsigned long lvec_cnt,
- unsigned long *lvec_current,
- size_t *lvec_offset,
- struct page **process_pages,
- struct mm_struct *mm,
- struct task_struct *task,
- int vm_write)
+static int process_vm_rw_single_vec(unsigned long addr,
+ unsigned long len,
+ const struct iovec *lvec,
+ unsigned long lvec_cnt,
+ unsigned long *lvec_current,
+ size_t *lvec_offset,
+ struct page **process_pages,
+ struct mm_struct *mm,
+ struct task_struct *task,
+ int vm_write,
+ ssize_t *bytes_copied)
{
unsigned long pa = addr & PAGE_MASK;
unsigned long start_offset = addr - pa;
unsigned long nr_pages;
- ssize_t bytes_copied = 0;
- ssize_t rc;
+ ssize_t bytes_copied_loop;
+ ssize_t rc = 0;
unsigned long nr_pages_copied = 0;
unsigned long nr_pages_to_copy;
unsigned long max_pages_per_loop = PVM_MAX_KMALLOC_PAGES
/ sizeof(struct pages *);
+ *bytes_copied = 0;
/* Work out address and page range required */
if (len == 0)
return 0;
nr_pages = (addr + len - 1) / PAGE_SIZE - addr / PAGE_SIZE + 1;
-
while ((nr_pages_copied < nr_pages) && (*lvec_current < lvec_cnt)) {
nr_pages_to_copy = min(nr_pages - nr_pages_copied,
max_pages_per_loop);
start_offset, len,
lvec, lvec_cnt,
lvec_current, lvec_offset,
- vm_write, nr_pages_to_copy);
+ vm_write, nr_pages_to_copy,
+ &bytes_copied_loop);
start_offset = 0;
+ *bytes_copied += bytes_copied_loop;
- if (rc < 0)
+ if (rc < 0) {
return rc;
- else {
- bytes_copied += rc;
- len -= rc;
+ } else {
+ len -= bytes_copied_loop;
nr_pages_copied += nr_pages_to_copy;
pa += nr_pages_to_copy * PAGE_SIZE;
}
}
- rc = bytes_copied;
return rc;
}
-static ssize_t process_vm_rw(pid_t pid, const struct iovec *lvec,
- unsigned long liovcnt,
- const struct iovec *rvec,
- unsigned long riovcnt,
- unsigned long flags, int vm_write)
+/**
+ * process_vm_rw_core - core of reading/writing pages from task specified
+ * @pid: PID of process to read/write from/to
+ * @lvec: iovec array specifying where to copy to/from locally
+ * @liovcnt: size of lvec array
+ * @rvec: iovec array specifying where to copy to/from in the other process
+ * @riovcnt: size of rvec array
+ * @flags: currently unused
+ * @vm_write: 0 if reading from other process, 1 if writing to other process
+ * Returns the number of bytes read/written or error code. May
+ * return less bytes than expected if an error occurs during the copying
+ * process.
+ */
+static ssize_t process_vm_rw_core(pid_t pid, const struct iovec *lvec,
+ unsigned long liovcnt,
+ const struct iovec *rvec,
+ unsigned long riovcnt,
+ unsigned long flags, int vm_write)
{
struct task_struct *task;
struct page **process_pages = NULL;
struct mm_struct *mm;
unsigned long i;
- ssize_t rc;
- ssize_t bytes_copied;
+ ssize_t rc = 0;
+ ssize_t bytes_copied_loop;
+ ssize_t bytes_copied = 0;
unsigned long nr_pages = 0;
unsigned long nr_pages_iov;
unsigned long iov_l_curr_idx = 0;
atomic_inc(&mm->mm_users);
task_unlock(task);
- rc = 0;
for (i = 0; i < riovcnt && iov_l_curr_idx < liovcnt; i++) {
- bytes_copied = process_vm_rw_single_vec(
+ rc = process_vm_rw_single_vec(
(unsigned long)rvec[i].iov_base, rvec[i].iov_len,
lvec, liovcnt, &iov_l_curr_idx, &iov_l_curr_offset,
- process_pages, mm, task, vm_write);
- if (bytes_copied < 0) {
- rc = bytes_copied;
+ process_pages, mm, task, vm_write, &bytes_copied_loop);
+ bytes_copied += bytes_copied_loop;
+ if (rc != 0) {
+ /* If we have managed to copy any data at all then
+ we return the number of bytes copied. Otherwise
+ we return the error code */
+ if (bytes_copied)
+ rc = bytes_copied;
goto put_mm;
- } else {
- rc += bytes_copied;
}
}
+ rc = bytes_copied;
put_mm:
mmput(mm);
put_task_struct:
put_task_struct(task);
-
free_proc_pages:
kfree(process_pages);
return rc;
}
-static ssize_t process_vm_rw_check_iovecs(pid_t pid,
- const struct iovec __user *lvec,
- unsigned long liovcnt,
- const struct iovec __user *rvec,
- unsigned long riovcnt,
- unsigned long flags, int vm_write)
+/**
+ * process_vm_rw - check iovecs before calling core routine
+ * @pid: PID of process to read/write from/to
+ * @lvec: iovec array specifying where to copy to/from locally
+ * @liovcnt: size of lvec array
+ * @rvec: iovec array specifying where to copy to/from in the other process
+ * @riovcnt: size of rvec array
+ * @flags: currently unused
+ * @vm_write: 0 if reading from other process, 1 if writing to other process
+ * Returns the number of bytes read/written or error code. May
+ * return less bytes than expected if an error occurs during the copying
+ * process.
+ */
+static ssize_t process_vm_rw(pid_t pid,
+ const struct iovec __user *lvec,
+ unsigned long liovcnt,
+ const struct iovec __user *rvec,
+ unsigned long riovcnt,
+ unsigned long flags, int vm_write)
{
struct iovec iovstack_l[UIO_FASTIOV];
struct iovec iovstack_r[UIO_FASTIOV];
if (rc <= 0)
goto free_iovecs;
- rc = process_vm_rw(pid, iov_l, liovcnt, iov_r, riovcnt, flags,
- vm_write);
+ rc = process_vm_rw_core(pid, iov_l, liovcnt, iov_r, riovcnt, flags,
+ vm_write);
free_iovecs:
if (iov_r != iovstack_r)
unsigned long, liovcnt, const struct iovec __user *, rvec,
unsigned long, riovcnt, unsigned long, flags)
{
- return process_vm_rw_check_iovecs(pid, lvec, liovcnt, rvec, riovcnt,
- flags, 0);
+ return process_vm_rw(pid, lvec, liovcnt, rvec, riovcnt, flags, 0);
}
SYSCALL_DEFINE6(process_vm_writev, pid_t, pid,
unsigned long, liovcnt, const struct iovec __user *, rvec,
unsigned long, riovcnt, unsigned long, flags)
{
- return process_vm_rw_check_iovecs(pid, lvec, liovcnt, rvec, riovcnt,
- flags, 1);
+ return process_vm_rw(pid, lvec, liovcnt, rvec, riovcnt, flags, 1);
}
#ifdef CONFIG_COMPAT
asmlinkage ssize_t
-compat_process_vm_rw_check_iovecs(compat_pid_t pid,
- const struct compat_iovec __user *lvec,
- unsigned long liovcnt,
- const struct compat_iovec __user *rvec,
- unsigned long riovcnt,
- unsigned long flags, int vm_write)
+compat_process_vm_rw(compat_pid_t pid,
+ const struct compat_iovec __user *lvec,
+ unsigned long liovcnt,
+ const struct compat_iovec __user *rvec,
+ unsigned long riovcnt,
+ unsigned long flags, int vm_write)
{
struct iovec iovstack_l[UIO_FASTIOV];
struct iovec iovstack_r[UIO_FASTIOV];
if (rc <= 0)
goto free_iovecs;
- rc = process_vm_rw(pid, iov_l, liovcnt, iov_r, riovcnt, flags,
- vm_write);
+ rc = process_vm_rw_core(pid, iov_l, liovcnt, iov_r, riovcnt, flags,
+ vm_write);
free_iovecs:
if (iov_r != iovstack_r)
unsigned long riovcnt,
unsigned long flags)
{
- return compat_process_vm_rw_check_iovecs(pid, lvec, liovcnt, rvec,
- riovcnt, flags, 0);
+ return compat_process_vm_rw(pid, lvec, liovcnt, rvec,
+ riovcnt, flags, 0);
}
asmlinkage ssize_t
unsigned long riovcnt,
unsigned long flags)
{
- return compat_process_vm_rw_check_iovecs(pid, lvec, liovcnt, rvec,
- riovcnt, flags, 1);
+ return compat_process_vm_rw(pid, lvec, liovcnt, rvec,
+ riovcnt, flags, 1);
}
#endif
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