mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-23 17:30:02 +00:00
![Linus Torvalds](/assets/img/avatar_default.png)
Pull x32 support for x86-64 from Ingo Molnar: "This tree introduces the X32 binary format and execution mode for x86: 32-bit data space binaries using 64-bit instructions and 64-bit kernel syscalls. This allows applications whose working set fits into a 32 bits address space to make use of 64-bit instructions while using a 32-bit address space with shorter pointers, more compressed data structures, etc." Fix up trivial context conflicts in arch/x86/{Kconfig,vdso/vma.c} * 'x86-x32-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (71 commits) x32: Fix alignment fail in struct compat_siginfo x32: Fix stupid ia32/x32 inversion in the siginfo format x32: Add ptrace for x32 x32: Switch to a 64-bit clock_t x32: Provide separate is_ia32_task() and is_x32_task() predicates x86, mtrr: Use explicit sizing and padding for the 64-bit ioctls x86/x32: Fix the binutils auto-detect x32: Warn and disable rather than error if binutils too old x32: Only clear TIF_X32 flag once x32: Make sure TS_COMPAT is cleared for x32 tasks fs: Remove missed ->fds_bits from cessation use of fd_set structs internally fs: Fix close_on_exec pointer in alloc_fdtable x32: Drop non-__vdso weak symbols from the x32 VDSO x32: Fix coding style violations in the x32 VDSO code x32: Add x32 VDSO support x32: Allow x32 to be configured x32: If configured, add x32 system calls to system call tables x32: Handle process creation x32: Signal-related system calls x86: Add #ifdef CONFIG_COMPAT to <asm/sys_ia32.h> ...
484 lines
12 KiB
C
484 lines
12 KiB
C
/*
|
|
* linux/fs/file.c
|
|
*
|
|
* Copyright (C) 1998-1999, Stephen Tweedie and Bill Hawes
|
|
*
|
|
* Manage the dynamic fd arrays in the process files_struct.
|
|
*/
|
|
|
|
#include <linux/export.h>
|
|
#include <linux/fs.h>
|
|
#include <linux/mm.h>
|
|
#include <linux/mmzone.h>
|
|
#include <linux/time.h>
|
|
#include <linux/sched.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/vmalloc.h>
|
|
#include <linux/file.h>
|
|
#include <linux/fdtable.h>
|
|
#include <linux/bitops.h>
|
|
#include <linux/interrupt.h>
|
|
#include <linux/spinlock.h>
|
|
#include <linux/rcupdate.h>
|
|
#include <linux/workqueue.h>
|
|
|
|
struct fdtable_defer {
|
|
spinlock_t lock;
|
|
struct work_struct wq;
|
|
struct fdtable *next;
|
|
};
|
|
|
|
int sysctl_nr_open __read_mostly = 1024*1024;
|
|
int sysctl_nr_open_min = BITS_PER_LONG;
|
|
int sysctl_nr_open_max = 1024 * 1024; /* raised later */
|
|
|
|
/*
|
|
* We use this list to defer free fdtables that have vmalloced
|
|
* sets/arrays. By keeping a per-cpu list, we avoid having to embed
|
|
* the work_struct in fdtable itself which avoids a 64 byte (i386) increase in
|
|
* this per-task structure.
|
|
*/
|
|
static DEFINE_PER_CPU(struct fdtable_defer, fdtable_defer_list);
|
|
|
|
static void *alloc_fdmem(size_t size)
|
|
{
|
|
/*
|
|
* Very large allocations can stress page reclaim, so fall back to
|
|
* vmalloc() if the allocation size will be considered "large" by the VM.
|
|
*/
|
|
if (size <= (PAGE_SIZE << PAGE_ALLOC_COSTLY_ORDER)) {
|
|
void *data = kmalloc(size, GFP_KERNEL|__GFP_NOWARN);
|
|
if (data != NULL)
|
|
return data;
|
|
}
|
|
return vmalloc(size);
|
|
}
|
|
|
|
static void free_fdmem(void *ptr)
|
|
{
|
|
is_vmalloc_addr(ptr) ? vfree(ptr) : kfree(ptr);
|
|
}
|
|
|
|
static void __free_fdtable(struct fdtable *fdt)
|
|
{
|
|
free_fdmem(fdt->fd);
|
|
free_fdmem(fdt->open_fds);
|
|
kfree(fdt);
|
|
}
|
|
|
|
static void free_fdtable_work(struct work_struct *work)
|
|
{
|
|
struct fdtable_defer *f =
|
|
container_of(work, struct fdtable_defer, wq);
|
|
struct fdtable *fdt;
|
|
|
|
spin_lock_bh(&f->lock);
|
|
fdt = f->next;
|
|
f->next = NULL;
|
|
spin_unlock_bh(&f->lock);
|
|
while(fdt) {
|
|
struct fdtable *next = fdt->next;
|
|
|
|
__free_fdtable(fdt);
|
|
fdt = next;
|
|
}
|
|
}
|
|
|
|
void free_fdtable_rcu(struct rcu_head *rcu)
|
|
{
|
|
struct fdtable *fdt = container_of(rcu, struct fdtable, rcu);
|
|
struct fdtable_defer *fddef;
|
|
|
|
BUG_ON(!fdt);
|
|
|
|
if (fdt->max_fds <= NR_OPEN_DEFAULT) {
|
|
/*
|
|
* This fdtable is embedded in the files structure and that
|
|
* structure itself is getting destroyed.
|
|
*/
|
|
kmem_cache_free(files_cachep,
|
|
container_of(fdt, struct files_struct, fdtab));
|
|
return;
|
|
}
|
|
if (!is_vmalloc_addr(fdt->fd) && !is_vmalloc_addr(fdt->open_fds)) {
|
|
kfree(fdt->fd);
|
|
kfree(fdt->open_fds);
|
|
kfree(fdt);
|
|
} else {
|
|
fddef = &get_cpu_var(fdtable_defer_list);
|
|
spin_lock(&fddef->lock);
|
|
fdt->next = fddef->next;
|
|
fddef->next = fdt;
|
|
/* vmallocs are handled from the workqueue context */
|
|
schedule_work(&fddef->wq);
|
|
spin_unlock(&fddef->lock);
|
|
put_cpu_var(fdtable_defer_list);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Expand the fdset in the files_struct. Called with the files spinlock
|
|
* held for write.
|
|
*/
|
|
static void copy_fdtable(struct fdtable *nfdt, struct fdtable *ofdt)
|
|
{
|
|
unsigned int cpy, set;
|
|
|
|
BUG_ON(nfdt->max_fds < ofdt->max_fds);
|
|
|
|
cpy = ofdt->max_fds * sizeof(struct file *);
|
|
set = (nfdt->max_fds - ofdt->max_fds) * sizeof(struct file *);
|
|
memcpy(nfdt->fd, ofdt->fd, cpy);
|
|
memset((char *)(nfdt->fd) + cpy, 0, set);
|
|
|
|
cpy = ofdt->max_fds / BITS_PER_BYTE;
|
|
set = (nfdt->max_fds - ofdt->max_fds) / BITS_PER_BYTE;
|
|
memcpy(nfdt->open_fds, ofdt->open_fds, cpy);
|
|
memset((char *)(nfdt->open_fds) + cpy, 0, set);
|
|
memcpy(nfdt->close_on_exec, ofdt->close_on_exec, cpy);
|
|
memset((char *)(nfdt->close_on_exec) + cpy, 0, set);
|
|
}
|
|
|
|
static struct fdtable * alloc_fdtable(unsigned int nr)
|
|
{
|
|
struct fdtable *fdt;
|
|
void *data;
|
|
|
|
/*
|
|
* Figure out how many fds we actually want to support in this fdtable.
|
|
* Allocation steps are keyed to the size of the fdarray, since it
|
|
* grows far faster than any of the other dynamic data. We try to fit
|
|
* the fdarray into comfortable page-tuned chunks: starting at 1024B
|
|
* and growing in powers of two from there on.
|
|
*/
|
|
nr /= (1024 / sizeof(struct file *));
|
|
nr = roundup_pow_of_two(nr + 1);
|
|
nr *= (1024 / sizeof(struct file *));
|
|
/*
|
|
* Note that this can drive nr *below* what we had passed if sysctl_nr_open
|
|
* had been set lower between the check in expand_files() and here. Deal
|
|
* with that in caller, it's cheaper that way.
|
|
*
|
|
* We make sure that nr remains a multiple of BITS_PER_LONG - otherwise
|
|
* bitmaps handling below becomes unpleasant, to put it mildly...
|
|
*/
|
|
if (unlikely(nr > sysctl_nr_open))
|
|
nr = ((sysctl_nr_open - 1) | (BITS_PER_LONG - 1)) + 1;
|
|
|
|
fdt = kmalloc(sizeof(struct fdtable), GFP_KERNEL);
|
|
if (!fdt)
|
|
goto out;
|
|
fdt->max_fds = nr;
|
|
data = alloc_fdmem(nr * sizeof(struct file *));
|
|
if (!data)
|
|
goto out_fdt;
|
|
fdt->fd = data;
|
|
|
|
data = alloc_fdmem(max_t(size_t,
|
|
2 * nr / BITS_PER_BYTE, L1_CACHE_BYTES));
|
|
if (!data)
|
|
goto out_arr;
|
|
fdt->open_fds = data;
|
|
data += nr / BITS_PER_BYTE;
|
|
fdt->close_on_exec = data;
|
|
fdt->next = NULL;
|
|
|
|
return fdt;
|
|
|
|
out_arr:
|
|
free_fdmem(fdt->fd);
|
|
out_fdt:
|
|
kfree(fdt);
|
|
out:
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* Expand the file descriptor table.
|
|
* This function will allocate a new fdtable and both fd array and fdset, of
|
|
* the given size.
|
|
* Return <0 error code on error; 1 on successful completion.
|
|
* The files->file_lock should be held on entry, and will be held on exit.
|
|
*/
|
|
static int expand_fdtable(struct files_struct *files, int nr)
|
|
__releases(files->file_lock)
|
|
__acquires(files->file_lock)
|
|
{
|
|
struct fdtable *new_fdt, *cur_fdt;
|
|
|
|
spin_unlock(&files->file_lock);
|
|
new_fdt = alloc_fdtable(nr);
|
|
spin_lock(&files->file_lock);
|
|
if (!new_fdt)
|
|
return -ENOMEM;
|
|
/*
|
|
* extremely unlikely race - sysctl_nr_open decreased between the check in
|
|
* caller and alloc_fdtable(). Cheaper to catch it here...
|
|
*/
|
|
if (unlikely(new_fdt->max_fds <= nr)) {
|
|
__free_fdtable(new_fdt);
|
|
return -EMFILE;
|
|
}
|
|
/*
|
|
* Check again since another task may have expanded the fd table while
|
|
* we dropped the lock
|
|
*/
|
|
cur_fdt = files_fdtable(files);
|
|
if (nr >= cur_fdt->max_fds) {
|
|
/* Continue as planned */
|
|
copy_fdtable(new_fdt, cur_fdt);
|
|
rcu_assign_pointer(files->fdt, new_fdt);
|
|
if (cur_fdt->max_fds > NR_OPEN_DEFAULT)
|
|
free_fdtable(cur_fdt);
|
|
} else {
|
|
/* Somebody else expanded, so undo our attempt */
|
|
__free_fdtable(new_fdt);
|
|
}
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* Expand files.
|
|
* This function will expand the file structures, if the requested size exceeds
|
|
* the current capacity and there is room for expansion.
|
|
* Return <0 error code on error; 0 when nothing done; 1 when files were
|
|
* expanded and execution may have blocked.
|
|
* The files->file_lock should be held on entry, and will be held on exit.
|
|
*/
|
|
int expand_files(struct files_struct *files, int nr)
|
|
{
|
|
struct fdtable *fdt;
|
|
|
|
fdt = files_fdtable(files);
|
|
|
|
/*
|
|
* N.B. For clone tasks sharing a files structure, this test
|
|
* will limit the total number of files that can be opened.
|
|
*/
|
|
if (nr >= rlimit(RLIMIT_NOFILE))
|
|
return -EMFILE;
|
|
|
|
/* Do we need to expand? */
|
|
if (nr < fdt->max_fds)
|
|
return 0;
|
|
|
|
/* Can we expand? */
|
|
if (nr >= sysctl_nr_open)
|
|
return -EMFILE;
|
|
|
|
/* All good, so we try */
|
|
return expand_fdtable(files, nr);
|
|
}
|
|
|
|
static int count_open_files(struct fdtable *fdt)
|
|
{
|
|
int size = fdt->max_fds;
|
|
int i;
|
|
|
|
/* Find the last open fd */
|
|
for (i = size / BITS_PER_LONG; i > 0; ) {
|
|
if (fdt->open_fds[--i])
|
|
break;
|
|
}
|
|
i = (i + 1) * BITS_PER_LONG;
|
|
return i;
|
|
}
|
|
|
|
/*
|
|
* Allocate a new files structure and copy contents from the
|
|
* passed in files structure.
|
|
* errorp will be valid only when the returned files_struct is NULL.
|
|
*/
|
|
struct files_struct *dup_fd(struct files_struct *oldf, int *errorp)
|
|
{
|
|
struct files_struct *newf;
|
|
struct file **old_fds, **new_fds;
|
|
int open_files, size, i;
|
|
struct fdtable *old_fdt, *new_fdt;
|
|
|
|
*errorp = -ENOMEM;
|
|
newf = kmem_cache_alloc(files_cachep, GFP_KERNEL);
|
|
if (!newf)
|
|
goto out;
|
|
|
|
atomic_set(&newf->count, 1);
|
|
|
|
spin_lock_init(&newf->file_lock);
|
|
newf->next_fd = 0;
|
|
new_fdt = &newf->fdtab;
|
|
new_fdt->max_fds = NR_OPEN_DEFAULT;
|
|
new_fdt->close_on_exec = newf->close_on_exec_init;
|
|
new_fdt->open_fds = newf->open_fds_init;
|
|
new_fdt->fd = &newf->fd_array[0];
|
|
new_fdt->next = NULL;
|
|
|
|
spin_lock(&oldf->file_lock);
|
|
old_fdt = files_fdtable(oldf);
|
|
open_files = count_open_files(old_fdt);
|
|
|
|
/*
|
|
* Check whether we need to allocate a larger fd array and fd set.
|
|
*/
|
|
while (unlikely(open_files > new_fdt->max_fds)) {
|
|
spin_unlock(&oldf->file_lock);
|
|
|
|
if (new_fdt != &newf->fdtab)
|
|
__free_fdtable(new_fdt);
|
|
|
|
new_fdt = alloc_fdtable(open_files - 1);
|
|
if (!new_fdt) {
|
|
*errorp = -ENOMEM;
|
|
goto out_release;
|
|
}
|
|
|
|
/* beyond sysctl_nr_open; nothing to do */
|
|
if (unlikely(new_fdt->max_fds < open_files)) {
|
|
__free_fdtable(new_fdt);
|
|
*errorp = -EMFILE;
|
|
goto out_release;
|
|
}
|
|
|
|
/*
|
|
* Reacquire the oldf lock and a pointer to its fd table
|
|
* who knows it may have a new bigger fd table. We need
|
|
* the latest pointer.
|
|
*/
|
|
spin_lock(&oldf->file_lock);
|
|
old_fdt = files_fdtable(oldf);
|
|
open_files = count_open_files(old_fdt);
|
|
}
|
|
|
|
old_fds = old_fdt->fd;
|
|
new_fds = new_fdt->fd;
|
|
|
|
memcpy(new_fdt->open_fds, old_fdt->open_fds, open_files / 8);
|
|
memcpy(new_fdt->close_on_exec, old_fdt->close_on_exec, open_files / 8);
|
|
|
|
for (i = open_files; i != 0; i--) {
|
|
struct file *f = *old_fds++;
|
|
if (f) {
|
|
get_file(f);
|
|
} else {
|
|
/*
|
|
* The fd may be claimed in the fd bitmap but not yet
|
|
* instantiated in the files array if a sibling thread
|
|
* is partway through open(). So make sure that this
|
|
* fd is available to the new process.
|
|
*/
|
|
__clear_open_fd(open_files - i, new_fdt);
|
|
}
|
|
rcu_assign_pointer(*new_fds++, f);
|
|
}
|
|
spin_unlock(&oldf->file_lock);
|
|
|
|
/* compute the remainder to be cleared */
|
|
size = (new_fdt->max_fds - open_files) * sizeof(struct file *);
|
|
|
|
/* This is long word aligned thus could use a optimized version */
|
|
memset(new_fds, 0, size);
|
|
|
|
if (new_fdt->max_fds > open_files) {
|
|
int left = (new_fdt->max_fds - open_files) / 8;
|
|
int start = open_files / BITS_PER_LONG;
|
|
|
|
memset(&new_fdt->open_fds[start], 0, left);
|
|
memset(&new_fdt->close_on_exec[start], 0, left);
|
|
}
|
|
|
|
rcu_assign_pointer(newf->fdt, new_fdt);
|
|
|
|
return newf;
|
|
|
|
out_release:
|
|
kmem_cache_free(files_cachep, newf);
|
|
out:
|
|
return NULL;
|
|
}
|
|
|
|
static void __devinit fdtable_defer_list_init(int cpu)
|
|
{
|
|
struct fdtable_defer *fddef = &per_cpu(fdtable_defer_list, cpu);
|
|
spin_lock_init(&fddef->lock);
|
|
INIT_WORK(&fddef->wq, free_fdtable_work);
|
|
fddef->next = NULL;
|
|
}
|
|
|
|
void __init files_defer_init(void)
|
|
{
|
|
int i;
|
|
for_each_possible_cpu(i)
|
|
fdtable_defer_list_init(i);
|
|
sysctl_nr_open_max = min((size_t)INT_MAX, ~(size_t)0/sizeof(void *)) &
|
|
-BITS_PER_LONG;
|
|
}
|
|
|
|
struct files_struct init_files = {
|
|
.count = ATOMIC_INIT(1),
|
|
.fdt = &init_files.fdtab,
|
|
.fdtab = {
|
|
.max_fds = NR_OPEN_DEFAULT,
|
|
.fd = &init_files.fd_array[0],
|
|
.close_on_exec = init_files.close_on_exec_init,
|
|
.open_fds = init_files.open_fds_init,
|
|
},
|
|
.file_lock = __SPIN_LOCK_UNLOCKED(init_task.file_lock),
|
|
};
|
|
|
|
/*
|
|
* allocate a file descriptor, mark it busy.
|
|
*/
|
|
int alloc_fd(unsigned start, unsigned flags)
|
|
{
|
|
struct files_struct *files = current->files;
|
|
unsigned int fd;
|
|
int error;
|
|
struct fdtable *fdt;
|
|
|
|
spin_lock(&files->file_lock);
|
|
repeat:
|
|
fdt = files_fdtable(files);
|
|
fd = start;
|
|
if (fd < files->next_fd)
|
|
fd = files->next_fd;
|
|
|
|
if (fd < fdt->max_fds)
|
|
fd = find_next_zero_bit(fdt->open_fds, fdt->max_fds, fd);
|
|
|
|
error = expand_files(files, fd);
|
|
if (error < 0)
|
|
goto out;
|
|
|
|
/*
|
|
* If we needed to expand the fs array we
|
|
* might have blocked - try again.
|
|
*/
|
|
if (error)
|
|
goto repeat;
|
|
|
|
if (start <= files->next_fd)
|
|
files->next_fd = fd + 1;
|
|
|
|
__set_open_fd(fd, fdt);
|
|
if (flags & O_CLOEXEC)
|
|
__set_close_on_exec(fd, fdt);
|
|
else
|
|
__clear_close_on_exec(fd, fdt);
|
|
error = fd;
|
|
#if 1
|
|
/* Sanity check */
|
|
if (rcu_dereference_raw(fdt->fd[fd]) != NULL) {
|
|
printk(KERN_WARNING "alloc_fd: slot %d not NULL!\n", fd);
|
|
rcu_assign_pointer(fdt->fd[fd], NULL);
|
|
}
|
|
#endif
|
|
|
|
out:
|
|
spin_unlock(&files->file_lock);
|
|
return error;
|
|
}
|
|
|
|
int get_unused_fd(void)
|
|
{
|
|
return alloc_fd(0, 0);
|
|
}
|
|
EXPORT_SYMBOL(get_unused_fd);
|