Revision 44e1e9f8e70506728b02a18e6d03599a6485d67f authored by Shuah Khan on 29 May 2012, 22:07:30 UTC, committed by Linus Torvalds on 29 May 2012, 23:22:32 UTC
The leds timer trigger does not currently have an interface to activate a one shot timer. The current support allows for setting two timers, one for specifying how long a state to be on, and the second for how long the state to be off. The delay_on value specifies the time period an LED should stay in on state, followed by a delay_off value that specifies how long the LED should stay in off state. The on and off cycle repeats until the trigger gets deactivated. There is no provision for one time activation to implement features that require an on or off state to be held just once and then stay in the original state forever. Without one shot timer interface, user space can still use timer trigger to set a timer to hold a state, however when user space application crashes or goes away without deactivating the timer, the hardware will be left in that state permanently. As a specific example of this use-case, let's look at vibrate feature on phones. Vibrate function on phones is implemented using PWM pins on SoC or PMIC. There is a need to activate one shot timer to control the vibrate feature, to prevent user space crashes leaving the phone in vibrate mode permanently causing the battery to drain. This trigger exports three properties, activate, state, and duration When transient trigger is activated these properties are set to default values. - duration allows setting timer value in msecs. The initial value is 0. - activate allows activating and deactivating the timer specified by duration as needed. The initial and default value is 0. This will allow duration to be set after trigger activation. - state allows user to specify a transient state to be held for the specified duration. Signed-off-by: Shuah Khan <shuahkhan@gmail.com> Cc: Jonas Bonn <jonas@southpole.se> Cc: Richard Purdie <rpurdie@rpsys.net> Cc: NeilBrown <neilb@suse.de> Cc: Bryan Wu <bryan.wu@canonical.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent 49dca5a
process_vm_access.c
/*
* linux/mm/process_vm_access.c
*
* 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/uio.h>
#include <linux/sched.h>
#include <linux/highmem.h>
#include <linux/ptrace.h>
#include <linux/slab.h>
#include <linux/syscalls.h>
#ifdef CONFIG_COMPAT
#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
* @process_pages: struct pages area that can store at least
* nr_pages_to_copy struct page pointers
* @pa: address of page in task to start copying from/to
* @start_offset: offset in page to start copying from/to
* @len: number of bytes to copy
* @lvec: iovec array specifying where to copy to/from
* @lvec_cnt: number of elements in iovec array
* @lvec_current: index in iovec array we are up to
* @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 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 pgs_copied = 0;
int j;
int ret;
ssize_t bytes_to_copy;
ssize_t rc = 0;
*bytes_copied = 0;
/* Get the pages we're interested in */
down_read(&mm->mmap_sem);
pages_pinned = get_user_pages(task, mm, pa,
nr_pages_to_copy,
vm_write, 0, process_pages, NULL);
up_read(&mm->mmap_sem);
if (pages_pinned != nr_pages_to_copy) {
rc = -EFAULT;
goto end;
}
/* Do the copy for each page */
for (pgs_copied = 0;
(pgs_copied < nr_pages_to_copy) && (*lvec_current < lvec_cnt);
pgs_copied++) {
/* Make sure we have a non zero length iovec */
while (*lvec_current < lvec_cnt
&& lvec[*lvec_current].iov_len == 0)
(*lvec_current)++;
if (*lvec_current == lvec_cnt)
break;
/*
* Will copy smallest of:
* - bytes remaining in page
* - bytes remaining in destination iovec
*/
bytes_to_copy = min_t(ssize_t, PAGE_SIZE - start_offset,
len - *bytes_copied);
bytes_to_copy = min_t(ssize_t, bytes_to_copy,
lvec[*lvec_current].iov_len
- *lvec_offset);
target_kaddr = kmap(process_pages[pgs_copied]) + start_offset;
if (vm_write)
ret = copy_from_user(target_kaddr,
lvec[*lvec_current].iov_base
+ *lvec_offset,
bytes_to_copy);
else
ret = copy_to_user(lvec[*lvec_current].iov_base
+ *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;
*lvec_offset += bytes_to_copy;
if (*lvec_offset == lvec[*lvec_current].iov_len) {
/*
* Need to copy remaining part of page into the
* next iovec if there are any bytes left in page
*/
(*lvec_current)++;
*lvec_offset = 0;
start_offset = (start_offset + bytes_to_copy)
% PAGE_SIZE;
if (start_offset)
pgs_copied--;
} else {
start_offset = 0;
}
}
end:
if (vm_write) {
for (j = 0; j < pages_pinned; j++) {
if (j < pgs_copied)
set_page_dirty_lock(process_pages[j]);
put_page(process_pages[j]);
}
} else {
for (j = 0; j < pages_pinned; j++)
put_page(process_pages[j]);
}
return rc;
}
/* 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
* @lvec: iovec array specifying where to copy to/from locally
* @lvec_cnt: number of elements in iovec array
* @lvec_current: index in iovec array we are up to
* @lvec_offset: offset in bytes from current iovec iov_base we are up to
* @process_pages: struct pages area that can store at least
* nr_pages_to_copy struct page pointers
* @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 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_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);
rc = process_vm_rw_pages(task, mm, process_pages, pa,
start_offset, len,
lvec, lvec_cnt,
lvec_current, lvec_offset,
vm_write, nr_pages_to_copy,
&bytes_copied_loop);
start_offset = 0;
*bytes_copied += bytes_copied_loop;
if (rc < 0) {
return rc;
} else {
len -= bytes_copied_loop;
nr_pages_copied += nr_pages_to_copy;
pa += nr_pages_to_copy * PAGE_SIZE;
}
}
return rc;
}
/* Maximum number of entries for process pages array
which lives on stack */
#define PVM_MAX_PP_ARRAY_COUNT 16
/**
* 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 *pp_stack[PVM_MAX_PP_ARRAY_COUNT];
struct page **process_pages = pp_stack;
struct mm_struct *mm;
unsigned long i;
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;
size_t iov_l_curr_offset = 0;
ssize_t iov_len;
/*
* Work out how many pages of struct pages we're going to need
* when eventually calling get_user_pages
*/
for (i = 0; i < riovcnt; i++) {
iov_len = rvec[i].iov_len;
if (iov_len > 0) {
nr_pages_iov = ((unsigned long)rvec[i].iov_base
+ iov_len)
/ PAGE_SIZE - (unsigned long)rvec[i].iov_base
/ PAGE_SIZE + 1;
nr_pages = max(nr_pages, nr_pages_iov);
}
}
if (nr_pages == 0)
return 0;
if (nr_pages > PVM_MAX_PP_ARRAY_COUNT) {
/* For reliability don't try to kmalloc more than
2 pages worth */
process_pages = kmalloc(min_t(size_t, PVM_MAX_KMALLOC_PAGES,
sizeof(struct pages *)*nr_pages),
GFP_KERNEL);
if (!process_pages)
return -ENOMEM;
}
/* Get process information */
rcu_read_lock();
task = find_task_by_vpid(pid);
if (task)
get_task_struct(task);
rcu_read_unlock();
if (!task) {
rc = -ESRCH;
goto free_proc_pages;
}
mm = mm_access(task, PTRACE_MODE_ATTACH);
if (!mm || IS_ERR(mm)) {
rc = IS_ERR(mm) ? PTR_ERR(mm) : -ESRCH;
/*
* Explicitly map EACCES to EPERM as EPERM is a more a
* appropriate error code for process_vw_readv/writev
*/
if (rc == -EACCES)
rc = -EPERM;
goto put_task_struct;
}
for (i = 0; i < riovcnt && iov_l_curr_idx < liovcnt; i++) {
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, &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;
}
}
rc = bytes_copied;
put_mm:
mmput(mm);
put_task_struct:
put_task_struct(task);
free_proc_pages:
if (process_pages != pp_stack)
kfree(process_pages);
return rc;
}
/**
* 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];
struct iovec *iov_l = iovstack_l;
struct iovec *iov_r = iovstack_r;
ssize_t rc;
if (flags != 0)
return -EINVAL;
/* Check iovecs */
if (vm_write)
rc = rw_copy_check_uvector(WRITE, lvec, liovcnt, UIO_FASTIOV,
iovstack_l, &iov_l, 1);
else
rc = rw_copy_check_uvector(READ, lvec, liovcnt, UIO_FASTIOV,
iovstack_l, &iov_l, 1);
if (rc <= 0)
goto free_iovecs;
rc = rw_copy_check_uvector(READ, rvec, riovcnt, UIO_FASTIOV,
iovstack_r, &iov_r, 0);
if (rc <= 0)
goto free_iovecs;
rc = process_vm_rw_core(pid, iov_l, liovcnt, iov_r, riovcnt, flags,
vm_write);
free_iovecs:
if (iov_r != iovstack_r)
kfree(iov_r);
if (iov_l != iovstack_l)
kfree(iov_l);
return rc;
}
SYSCALL_DEFINE6(process_vm_readv, pid_t, pid, const struct iovec __user *, lvec,
unsigned long, liovcnt, const struct iovec __user *, rvec,
unsigned long, riovcnt, unsigned long, flags)
{
return process_vm_rw(pid, lvec, liovcnt, rvec, riovcnt, flags, 0);
}
SYSCALL_DEFINE6(process_vm_writev, pid_t, pid,
const struct iovec __user *, lvec,
unsigned long, liovcnt, const struct iovec __user *, rvec,
unsigned long, riovcnt, unsigned long, flags)
{
return process_vm_rw(pid, lvec, liovcnt, rvec, riovcnt, flags, 1);
}
#ifdef CONFIG_COMPAT
asmlinkage ssize_t
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];
struct iovec *iov_l = iovstack_l;
struct iovec *iov_r = iovstack_r;
ssize_t rc = -EFAULT;
if (flags != 0)
return -EINVAL;
if (!access_ok(VERIFY_READ, lvec, liovcnt * sizeof(*lvec)))
goto out;
if (!access_ok(VERIFY_READ, rvec, riovcnt * sizeof(*rvec)))
goto out;
if (vm_write)
rc = compat_rw_copy_check_uvector(WRITE, lvec, liovcnt,
UIO_FASTIOV, iovstack_l,
&iov_l, 1);
else
rc = compat_rw_copy_check_uvector(READ, lvec, liovcnt,
UIO_FASTIOV, iovstack_l,
&iov_l, 1);
if (rc <= 0)
goto free_iovecs;
rc = compat_rw_copy_check_uvector(READ, rvec, riovcnt,
UIO_FASTIOV, iovstack_r,
&iov_r, 0);
if (rc <= 0)
goto free_iovecs;
rc = process_vm_rw_core(pid, iov_l, liovcnt, iov_r, riovcnt, flags,
vm_write);
free_iovecs:
if (iov_r != iovstack_r)
kfree(iov_r);
if (iov_l != iovstack_l)
kfree(iov_l);
out:
return rc;
}
asmlinkage ssize_t
compat_sys_process_vm_readv(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)
{
return compat_process_vm_rw(pid, lvec, liovcnt, rvec,
riovcnt, flags, 0);
}
asmlinkage ssize_t
compat_sys_process_vm_writev(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)
{
return compat_process_vm_rw(pid, lvec, liovcnt, rvec,
riovcnt, flags, 1);
}
#endif
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