The patch titled
cross-memory-attach-update
has been added to the -mm tree. Its filename is
cross-memory-attach-update.patch
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*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find
out what to do about this
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: cross-memory-attach-update
From: Christopher Yeoh <cyeoh@xxxxxxxxxxx>
- Add x86_64 specific wire up
- Change behaviour so process_vm_readv and process_vm_writev return
the number of bytes successfully read or written even if an error
occurs
- Add more kernel doc interface comments
- rename some internal functions (process_vm_rw_check_iovecs,
process_vm_rw) so they make more sense.
- Add licence message
- Fix kernel-doc comment format
Still need to do benchmarking to see if the optimisation for small copies
using a local on-stack array in process_vm_rw_core is worth it.
Signed-off-by: Chris Yeoh <cyeoh@xxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Randy Dunlap <rdunlap@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/x86/ia32/ia32entry.S | 2
arch/x86/include/asm/unistd_64.h | 4
kernel/sys_ni.c | 4
mm/process_vm_access.c | 203 +++++++++++++++++------------
4 files changed, 132 insertions(+), 81 deletions(-)
diff -puN arch/x86/ia32/ia32entry.S~cross-memory-attach-update arch/x86/ia32/ia32entry.S
--- a/arch/x86/ia32/ia32entry.S~cross-memory-attach-update
+++ a/arch/x86/ia32/ia32entry.S
@@ -850,4 +850,6 @@ ia32_sys_call_table:
.quad sys_syncfs
.quad compat_sys_sendmmsg /* 345 */
.quad sys_setns
+ .quad compat_sys_process_vm_readv
+ .quad compat_sys_process_vm_writev
ia32_syscall_end:
diff -puN arch/x86/include/asm/unistd_64.h~cross-memory-attach-update arch/x86/include/asm/unistd_64.h
--- a/arch/x86/include/asm/unistd_64.h~cross-memory-attach-update
+++ a/arch/x86/include/asm/unistd_64.h
@@ -681,6 +681,10 @@ __SYSCALL(__NR_syncfs, sys_syncfs)
__SYSCALL(__NR_sendmmsg, sys_sendmmsg)
#define __NR_setns 308
__SYSCALL(__NR_setns, sys_setns)
+#define __NR_process_vm_readv 309
+__SYSCALL(__NR_process_vm_readv, sys_process_vm_readv)
+#define __NR_process_vm_writev 310
+__SYSCALL(__NR_process_vm_writev, sys_process_vm_writev)
#ifndef __NO_STUBS
#define __ARCH_WANT_OLD_READDIR
diff -puN kernel/sys_ni.c~cross-memory-attach-update kernel/sys_ni.c
--- a/kernel/sys_ni.c~cross-memory-attach-update
+++ a/kernel/sys_ni.c
@@ -146,6 +146,10 @@ cond_syscall(sys_io_submit);
cond_syscall(sys_io_cancel);
cond_syscall(sys_io_getevents);
cond_syscall(sys_syslog);
+cond_syscall(sys_process_vm_readv);
+cond_syscall(sys_process_vm_writev);
+cond_syscall(compat_sys_process_vm_readv);
+cond_syscall(compat_sys_process_vm_writev);
/* arch-specific weak syscall entries */
cond_syscall(sys_pciconfig_read);
diff -puN mm/process_vm_access.c~cross-memory-attach-update mm/process_vm_access.c
--- a/mm/process_vm_access.c~cross-memory-attach-update
+++ a/mm/process_vm_access.c
@@ -1,7 +1,12 @@
/*
- * linux/mm/process_vm_access.c
+ * linux/mm/process_vm_access.c
*
- * Copyright (C) 2010-2011 Christopher Yeoh <cyeoh@xxxxxxxxxxx>, IBM Corp.
+ * Copyright (C) 2010-2011 Christopher Yeoh <cyeoh@xxxxxxxxxxx>, 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>
@@ -16,7 +21,7 @@
#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
@@ -31,19 +36,22 @@
* @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;
@@ -51,8 +59,9 @@ static ssize_t process_vm_rw_pages(struc
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);
@@ -61,8 +70,10 @@ static ssize_t process_vm_rw_pages(struc
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;
@@ -81,7 +92,7 @@ static ssize_t process_vm_rw_pages(struc
* - 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);
@@ -99,10 +110,12 @@ static ssize_t process_vm_rw_pages(struc
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) {
/*
@@ -120,8 +133,6 @@ static ssize_t process_vm_rw_pages(struc
}
}
- rc = bytes_copied;
-
end:
if (vm_write) {
for (j = 0; j < pages_pinned; j++) {
@@ -140,7 +151,7 @@ end:
/* 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
@@ -153,35 +164,38 @@ end:
* @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);
@@ -190,35 +204,49 @@ static ssize_t process_vm_rw_single_vec(
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;
@@ -279,38 +307,53 @@ static ssize_t process_vm_rw(pid_t pid,
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];
@@ -336,8 +379,8 @@ static ssize_t process_vm_rw_check_iovec
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)
@@ -352,8 +395,7 @@ SYSCALL_DEFINE6(process_vm_readv, pid_t,
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,
@@ -361,19 +403,18 @@ SYSCALL_DEFINE6(process_vm_writev, pid_t
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];
@@ -406,8 +447,8 @@ compat_process_vm_rw_check_iovecs(compat
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)
@@ -427,8 +468,8 @@ compat_sys_process_vm_readv(compat_pid_t
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
@@ -439,8 +480,8 @@ compat_sys_process_vm_writev(compat_pid_
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
_
Patches currently in -mm which might be from cyeoh@xxxxxxxxxxx are
cross-memory-attach-v3.patch
cross-memory-attach-update.patch
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