v4.19.13 snapshot.
diff --git a/fs/select.c b/fs/select.c
new file mode 100644
index 0000000..4a6b6e4
--- /dev/null
+++ b/fs/select.c
@@ -0,0 +1,1424 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * This file contains the procedures for the handling of select and poll
+ *
+ * Created for Linux based loosely upon Mathius Lattner's minix
+ * patches by Peter MacDonald. Heavily edited by Linus.
+ *
+ * 4 February 1994
+ * COFF/ELF binary emulation. If the process has the STICKY_TIMEOUTS
+ * flag set in its personality we do *not* modify the given timeout
+ * parameter to reflect time remaining.
+ *
+ * 24 January 2000
+ * Changed sys_poll()/do_poll() to use PAGE_SIZE chunk-based allocation
+ * of fds to overcome nfds < 16390 descriptors limit (Tigran Aivazian).
+ */
+
+#include <linux/kernel.h>
+#include <linux/sched/signal.h>
+#include <linux/sched/rt.h>
+#include <linux/syscalls.h>
+#include <linux/export.h>
+#include <linux/slab.h>
+#include <linux/poll.h>
+#include <linux/personality.h> /* for STICKY_TIMEOUTS */
+#include <linux/file.h>
+#include <linux/fdtable.h>
+#include <linux/fs.h>
+#include <linux/rcupdate.h>
+#include <linux/hrtimer.h>
+#include <linux/freezer.h>
+#include <net/busy_poll.h>
+#include <linux/vmalloc.h>
+
+#include <linux/uaccess.h>
+
+
+/*
+ * Estimate expected accuracy in ns from a timeval.
+ *
+ * After quite a bit of churning around, we've settled on
+ * a simple thing of taking 0.1% of the timeout as the
+ * slack, with a cap of 100 msec.
+ * "nice" tasks get a 0.5% slack instead.
+ *
+ * Consider this comment an open invitation to come up with even
+ * better solutions..
+ */
+
+#define MAX_SLACK (100 * NSEC_PER_MSEC)
+
+static long __estimate_accuracy(struct timespec64 *tv)
+{
+ long slack;
+ int divfactor = 1000;
+
+ if (tv->tv_sec < 0)
+ return 0;
+
+ if (task_nice(current) > 0)
+ divfactor = divfactor / 5;
+
+ if (tv->tv_sec > MAX_SLACK / (NSEC_PER_SEC/divfactor))
+ return MAX_SLACK;
+
+ slack = tv->tv_nsec / divfactor;
+ slack += tv->tv_sec * (NSEC_PER_SEC/divfactor);
+
+ if (slack > MAX_SLACK)
+ return MAX_SLACK;
+
+ return slack;
+}
+
+u64 select_estimate_accuracy(struct timespec64 *tv)
+{
+ u64 ret;
+ struct timespec64 now;
+
+ /*
+ * Realtime tasks get a slack of 0 for obvious reasons.
+ */
+
+ if (rt_task(current))
+ return 0;
+
+ ktime_get_ts64(&now);
+ now = timespec64_sub(*tv, now);
+ ret = __estimate_accuracy(&now);
+ if (ret < current->timer_slack_ns)
+ return current->timer_slack_ns;
+ return ret;
+}
+
+
+
+struct poll_table_page {
+ struct poll_table_page * next;
+ struct poll_table_entry * entry;
+ struct poll_table_entry entries[0];
+};
+
+#define POLL_TABLE_FULL(table) \
+ ((unsigned long)((table)->entry+1) > PAGE_SIZE + (unsigned long)(table))
+
+/*
+ * Ok, Peter made a complicated, but straightforward multiple_wait() function.
+ * I have rewritten this, taking some shortcuts: This code may not be easy to
+ * follow, but it should be free of race-conditions, and it's practical. If you
+ * understand what I'm doing here, then you understand how the linux
+ * sleep/wakeup mechanism works.
+ *
+ * Two very simple procedures, poll_wait() and poll_freewait() make all the
+ * work. poll_wait() is an inline-function defined in <linux/poll.h>,
+ * as all select/poll functions have to call it to add an entry to the
+ * poll table.
+ */
+static void __pollwait(struct file *filp, wait_queue_head_t *wait_address,
+ poll_table *p);
+
+void poll_initwait(struct poll_wqueues *pwq)
+{
+ init_poll_funcptr(&pwq->pt, __pollwait);
+ pwq->polling_task = current;
+ pwq->triggered = 0;
+ pwq->error = 0;
+ pwq->table = NULL;
+ pwq->inline_index = 0;
+}
+EXPORT_SYMBOL(poll_initwait);
+
+static void free_poll_entry(struct poll_table_entry *entry)
+{
+ remove_wait_queue(entry->wait_address, &entry->wait);
+ fput(entry->filp);
+}
+
+void poll_freewait(struct poll_wqueues *pwq)
+{
+ struct poll_table_page * p = pwq->table;
+ int i;
+ for (i = 0; i < pwq->inline_index; i++)
+ free_poll_entry(pwq->inline_entries + i);
+ while (p) {
+ struct poll_table_entry * entry;
+ struct poll_table_page *old;
+
+ entry = p->entry;
+ do {
+ entry--;
+ free_poll_entry(entry);
+ } while (entry > p->entries);
+ old = p;
+ p = p->next;
+ free_page((unsigned long) old);
+ }
+}
+EXPORT_SYMBOL(poll_freewait);
+
+static struct poll_table_entry *poll_get_entry(struct poll_wqueues *p)
+{
+ struct poll_table_page *table = p->table;
+
+ if (p->inline_index < N_INLINE_POLL_ENTRIES)
+ return p->inline_entries + p->inline_index++;
+
+ if (!table || POLL_TABLE_FULL(table)) {
+ struct poll_table_page *new_table;
+
+ new_table = (struct poll_table_page *) __get_free_page(GFP_KERNEL);
+ if (!new_table) {
+ p->error = -ENOMEM;
+ return NULL;
+ }
+ new_table->entry = new_table->entries;
+ new_table->next = table;
+ p->table = new_table;
+ table = new_table;
+ }
+
+ return table->entry++;
+}
+
+static int __pollwake(wait_queue_entry_t *wait, unsigned mode, int sync, void *key)
+{
+ struct poll_wqueues *pwq = wait->private;
+ DECLARE_WAITQUEUE(dummy_wait, pwq->polling_task);
+
+ /*
+ * Although this function is called under waitqueue lock, LOCK
+ * doesn't imply write barrier and the users expect write
+ * barrier semantics on wakeup functions. The following
+ * smp_wmb() is equivalent to smp_wmb() in try_to_wake_up()
+ * and is paired with smp_store_mb() in poll_schedule_timeout.
+ */
+ smp_wmb();
+ pwq->triggered = 1;
+
+ /*
+ * Perform the default wake up operation using a dummy
+ * waitqueue.
+ *
+ * TODO: This is hacky but there currently is no interface to
+ * pass in @sync. @sync is scheduled to be removed and once
+ * that happens, wake_up_process() can be used directly.
+ */
+ return default_wake_function(&dummy_wait, mode, sync, key);
+}
+
+static int pollwake(wait_queue_entry_t *wait, unsigned mode, int sync, void *key)
+{
+ struct poll_table_entry *entry;
+
+ entry = container_of(wait, struct poll_table_entry, wait);
+ if (key && !(key_to_poll(key) & entry->key))
+ return 0;
+ return __pollwake(wait, mode, sync, key);
+}
+
+/* Add a new entry */
+static void __pollwait(struct file *filp, wait_queue_head_t *wait_address,
+ poll_table *p)
+{
+ struct poll_wqueues *pwq = container_of(p, struct poll_wqueues, pt);
+ struct poll_table_entry *entry = poll_get_entry(pwq);
+ if (!entry)
+ return;
+ entry->filp = get_file(filp);
+ entry->wait_address = wait_address;
+ entry->key = p->_key;
+ init_waitqueue_func_entry(&entry->wait, pollwake);
+ entry->wait.private = pwq;
+ add_wait_queue(wait_address, &entry->wait);
+}
+
+static int poll_schedule_timeout(struct poll_wqueues *pwq, int state,
+ ktime_t *expires, unsigned long slack)
+{
+ int rc = -EINTR;
+
+ set_current_state(state);
+ if (!pwq->triggered)
+ rc = schedule_hrtimeout_range(expires, slack, HRTIMER_MODE_ABS);
+ __set_current_state(TASK_RUNNING);
+
+ /*
+ * Prepare for the next iteration.
+ *
+ * The following smp_store_mb() serves two purposes. First, it's
+ * the counterpart rmb of the wmb in pollwake() such that data
+ * written before wake up is always visible after wake up.
+ * Second, the full barrier guarantees that triggered clearing
+ * doesn't pass event check of the next iteration. Note that
+ * this problem doesn't exist for the first iteration as
+ * add_wait_queue() has full barrier semantics.
+ */
+ smp_store_mb(pwq->triggered, 0);
+
+ return rc;
+}
+
+/**
+ * poll_select_set_timeout - helper function to setup the timeout value
+ * @to: pointer to timespec64 variable for the final timeout
+ * @sec: seconds (from user space)
+ * @nsec: nanoseconds (from user space)
+ *
+ * Note, we do not use a timespec for the user space value here, That
+ * way we can use the function for timeval and compat interfaces as well.
+ *
+ * Returns -EINVAL if sec/nsec are not normalized. Otherwise 0.
+ */
+int poll_select_set_timeout(struct timespec64 *to, time64_t sec, long nsec)
+{
+ struct timespec64 ts = {.tv_sec = sec, .tv_nsec = nsec};
+
+ if (!timespec64_valid(&ts))
+ return -EINVAL;
+
+ /* Optimize for the zero timeout value here */
+ if (!sec && !nsec) {
+ to->tv_sec = to->tv_nsec = 0;
+ } else {
+ ktime_get_ts64(to);
+ *to = timespec64_add_safe(*to, ts);
+ }
+ return 0;
+}
+
+static int poll_select_copy_remaining(struct timespec64 *end_time,
+ void __user *p,
+ int timeval, int ret)
+{
+ struct timespec64 rts;
+ struct timeval rtv;
+
+ if (!p)
+ return ret;
+
+ if (current->personality & STICKY_TIMEOUTS)
+ goto sticky;
+
+ /* No update for zero timeout */
+ if (!end_time->tv_sec && !end_time->tv_nsec)
+ return ret;
+
+ ktime_get_ts64(&rts);
+ rts = timespec64_sub(*end_time, rts);
+ if (rts.tv_sec < 0)
+ rts.tv_sec = rts.tv_nsec = 0;
+
+
+ if (timeval) {
+ if (sizeof(rtv) > sizeof(rtv.tv_sec) + sizeof(rtv.tv_usec))
+ memset(&rtv, 0, sizeof(rtv));
+ rtv.tv_sec = rts.tv_sec;
+ rtv.tv_usec = rts.tv_nsec / NSEC_PER_USEC;
+
+ if (!copy_to_user(p, &rtv, sizeof(rtv)))
+ return ret;
+
+ } else if (!put_timespec64(&rts, p))
+ return ret;
+
+ /*
+ * If an application puts its timeval in read-only memory, we
+ * don't want the Linux-specific update to the timeval to
+ * cause a fault after the select has completed
+ * successfully. However, because we're not updating the
+ * timeval, we can't restart the system call.
+ */
+
+sticky:
+ if (ret == -ERESTARTNOHAND)
+ ret = -EINTR;
+ return ret;
+}
+
+/*
+ * Scalable version of the fd_set.
+ */
+
+typedef struct {
+ unsigned long *in, *out, *ex;
+ unsigned long *res_in, *res_out, *res_ex;
+} fd_set_bits;
+
+/*
+ * How many longwords for "nr" bits?
+ */
+#define FDS_BITPERLONG (8*sizeof(long))
+#define FDS_LONGS(nr) (((nr)+FDS_BITPERLONG-1)/FDS_BITPERLONG)
+#define FDS_BYTES(nr) (FDS_LONGS(nr)*sizeof(long))
+
+/*
+ * We do a VERIFY_WRITE here even though we are only reading this time:
+ * we'll write to it eventually..
+ *
+ * Use "unsigned long" accesses to let user-mode fd_set's be long-aligned.
+ */
+static inline
+int get_fd_set(unsigned long nr, void __user *ufdset, unsigned long *fdset)
+{
+ nr = FDS_BYTES(nr);
+ if (ufdset)
+ return copy_from_user(fdset, ufdset, nr) ? -EFAULT : 0;
+
+ memset(fdset, 0, nr);
+ return 0;
+}
+
+static inline unsigned long __must_check
+set_fd_set(unsigned long nr, void __user *ufdset, unsigned long *fdset)
+{
+ if (ufdset)
+ return __copy_to_user(ufdset, fdset, FDS_BYTES(nr));
+ return 0;
+}
+
+static inline
+void zero_fd_set(unsigned long nr, unsigned long *fdset)
+{
+ memset(fdset, 0, FDS_BYTES(nr));
+}
+
+#define FDS_IN(fds, n) (fds->in + n)
+#define FDS_OUT(fds, n) (fds->out + n)
+#define FDS_EX(fds, n) (fds->ex + n)
+
+#define BITS(fds, n) (*FDS_IN(fds, n)|*FDS_OUT(fds, n)|*FDS_EX(fds, n))
+
+static int max_select_fd(unsigned long n, fd_set_bits *fds)
+{
+ unsigned long *open_fds;
+ unsigned long set;
+ int max;
+ struct fdtable *fdt;
+
+ /* handle last in-complete long-word first */
+ set = ~(~0UL << (n & (BITS_PER_LONG-1)));
+ n /= BITS_PER_LONG;
+ fdt = files_fdtable(current->files);
+ open_fds = fdt->open_fds + n;
+ max = 0;
+ if (set) {
+ set &= BITS(fds, n);
+ if (set) {
+ if (!(set & ~*open_fds))
+ goto get_max;
+ return -EBADF;
+ }
+ }
+ while (n) {
+ open_fds--;
+ n--;
+ set = BITS(fds, n);
+ if (!set)
+ continue;
+ if (set & ~*open_fds)
+ return -EBADF;
+ if (max)
+ continue;
+get_max:
+ do {
+ max++;
+ set >>= 1;
+ } while (set);
+ max += n * BITS_PER_LONG;
+ }
+
+ return max;
+}
+
+#define POLLIN_SET (EPOLLRDNORM | EPOLLRDBAND | EPOLLIN | EPOLLHUP | EPOLLERR)
+#define POLLOUT_SET (EPOLLWRBAND | EPOLLWRNORM | EPOLLOUT | EPOLLERR)
+#define POLLEX_SET (EPOLLPRI)
+
+static inline void wait_key_set(poll_table *wait, unsigned long in,
+ unsigned long out, unsigned long bit,
+ __poll_t ll_flag)
+{
+ wait->_key = POLLEX_SET | ll_flag;
+ if (in & bit)
+ wait->_key |= POLLIN_SET;
+ if (out & bit)
+ wait->_key |= POLLOUT_SET;
+}
+
+static int do_select(int n, fd_set_bits *fds, struct timespec64 *end_time)
+{
+ ktime_t expire, *to = NULL;
+ struct poll_wqueues table;
+ poll_table *wait;
+ int retval, i, timed_out = 0;
+ u64 slack = 0;
+ __poll_t busy_flag = net_busy_loop_on() ? POLL_BUSY_LOOP : 0;
+ unsigned long busy_start = 0;
+
+ rcu_read_lock();
+ retval = max_select_fd(n, fds);
+ rcu_read_unlock();
+
+ if (retval < 0)
+ return retval;
+ n = retval;
+
+ poll_initwait(&table);
+ wait = &table.pt;
+ if (end_time && !end_time->tv_sec && !end_time->tv_nsec) {
+ wait->_qproc = NULL;
+ timed_out = 1;
+ }
+
+ if (end_time && !timed_out)
+ slack = select_estimate_accuracy(end_time);
+
+ retval = 0;
+ for (;;) {
+ unsigned long *rinp, *routp, *rexp, *inp, *outp, *exp;
+ bool can_busy_loop = false;
+
+ inp = fds->in; outp = fds->out; exp = fds->ex;
+ rinp = fds->res_in; routp = fds->res_out; rexp = fds->res_ex;
+
+ for (i = 0; i < n; ++rinp, ++routp, ++rexp) {
+ unsigned long in, out, ex, all_bits, bit = 1, j;
+ unsigned long res_in = 0, res_out = 0, res_ex = 0;
+ __poll_t mask;
+
+ in = *inp++; out = *outp++; ex = *exp++;
+ all_bits = in | out | ex;
+ if (all_bits == 0) {
+ i += BITS_PER_LONG;
+ continue;
+ }
+
+ for (j = 0; j < BITS_PER_LONG; ++j, ++i, bit <<= 1) {
+ struct fd f;
+ if (i >= n)
+ break;
+ if (!(bit & all_bits))
+ continue;
+ f = fdget(i);
+ if (f.file) {
+ wait_key_set(wait, in, out, bit,
+ busy_flag);
+ mask = vfs_poll(f.file, wait);
+
+ fdput(f);
+ if ((mask & POLLIN_SET) && (in & bit)) {
+ res_in |= bit;
+ retval++;
+ wait->_qproc = NULL;
+ }
+ if ((mask & POLLOUT_SET) && (out & bit)) {
+ res_out |= bit;
+ retval++;
+ wait->_qproc = NULL;
+ }
+ if ((mask & POLLEX_SET) && (ex & bit)) {
+ res_ex |= bit;
+ retval++;
+ wait->_qproc = NULL;
+ }
+ /* got something, stop busy polling */
+ if (retval) {
+ can_busy_loop = false;
+ busy_flag = 0;
+
+ /*
+ * only remember a returned
+ * POLL_BUSY_LOOP if we asked for it
+ */
+ } else if (busy_flag & mask)
+ can_busy_loop = true;
+
+ }
+ }
+ if (res_in)
+ *rinp = res_in;
+ if (res_out)
+ *routp = res_out;
+ if (res_ex)
+ *rexp = res_ex;
+ cond_resched();
+ }
+ wait->_qproc = NULL;
+ if (retval || timed_out || signal_pending(current))
+ break;
+ if (table.error) {
+ retval = table.error;
+ break;
+ }
+
+ /* only if found POLL_BUSY_LOOP sockets && not out of time */
+ if (can_busy_loop && !need_resched()) {
+ if (!busy_start) {
+ busy_start = busy_loop_current_time();
+ continue;
+ }
+ if (!busy_loop_timeout(busy_start))
+ continue;
+ }
+ busy_flag = 0;
+
+ /*
+ * If this is the first loop and we have a timeout
+ * given, then we convert to ktime_t and set the to
+ * pointer to the expiry value.
+ */
+ if (end_time && !to) {
+ expire = timespec64_to_ktime(*end_time);
+ to = &expire;
+ }
+
+ if (!poll_schedule_timeout(&table, TASK_INTERRUPTIBLE,
+ to, slack))
+ timed_out = 1;
+ }
+
+ poll_freewait(&table);
+
+ return retval;
+}
+
+/*
+ * We can actually return ERESTARTSYS instead of EINTR, but I'd
+ * like to be certain this leads to no problems. So I return
+ * EINTR just for safety.
+ *
+ * Update: ERESTARTSYS breaks at least the xview clock binary, so
+ * I'm trying ERESTARTNOHAND which restart only when you want to.
+ */
+int core_sys_select(int n, fd_set __user *inp, fd_set __user *outp,
+ fd_set __user *exp, struct timespec64 *end_time)
+{
+ fd_set_bits fds;
+ void *bits;
+ int ret, max_fds;
+ size_t size, alloc_size;
+ struct fdtable *fdt;
+ /* Allocate small arguments on the stack to save memory and be faster */
+ long stack_fds[SELECT_STACK_ALLOC/sizeof(long)];
+
+ ret = -EINVAL;
+ if (n < 0)
+ goto out_nofds;
+
+ /* max_fds can increase, so grab it once to avoid race */
+ rcu_read_lock();
+ fdt = files_fdtable(current->files);
+ max_fds = fdt->max_fds;
+ rcu_read_unlock();
+ if (n > max_fds)
+ n = max_fds;
+
+ /*
+ * We need 6 bitmaps (in/out/ex for both incoming and outgoing),
+ * since we used fdset we need to allocate memory in units of
+ * long-words.
+ */
+ size = FDS_BYTES(n);
+ bits = stack_fds;
+ if (size > sizeof(stack_fds) / 6) {
+ /* Not enough space in on-stack array; must use kmalloc */
+ ret = -ENOMEM;
+ if (size > (SIZE_MAX / 6))
+ goto out_nofds;
+
+ alloc_size = 6 * size;
+ bits = kvmalloc(alloc_size, GFP_KERNEL);
+ if (!bits)
+ goto out_nofds;
+ }
+ fds.in = bits;
+ fds.out = bits + size;
+ fds.ex = bits + 2*size;
+ fds.res_in = bits + 3*size;
+ fds.res_out = bits + 4*size;
+ fds.res_ex = bits + 5*size;
+
+ if ((ret = get_fd_set(n, inp, fds.in)) ||
+ (ret = get_fd_set(n, outp, fds.out)) ||
+ (ret = get_fd_set(n, exp, fds.ex)))
+ goto out;
+ zero_fd_set(n, fds.res_in);
+ zero_fd_set(n, fds.res_out);
+ zero_fd_set(n, fds.res_ex);
+
+ ret = do_select(n, &fds, end_time);
+
+ if (ret < 0)
+ goto out;
+ if (!ret) {
+ ret = -ERESTARTNOHAND;
+ if (signal_pending(current))
+ goto out;
+ ret = 0;
+ }
+
+ if (set_fd_set(n, inp, fds.res_in) ||
+ set_fd_set(n, outp, fds.res_out) ||
+ set_fd_set(n, exp, fds.res_ex))
+ ret = -EFAULT;
+
+out:
+ if (bits != stack_fds)
+ kvfree(bits);
+out_nofds:
+ return ret;
+}
+
+static int kern_select(int n, fd_set __user *inp, fd_set __user *outp,
+ fd_set __user *exp, struct timeval __user *tvp)
+{
+ struct timespec64 end_time, *to = NULL;
+ struct timeval tv;
+ int ret;
+
+ if (tvp) {
+ if (copy_from_user(&tv, tvp, sizeof(tv)))
+ return -EFAULT;
+
+ to = &end_time;
+ if (poll_select_set_timeout(to,
+ tv.tv_sec + (tv.tv_usec / USEC_PER_SEC),
+ (tv.tv_usec % USEC_PER_SEC) * NSEC_PER_USEC))
+ return -EINVAL;
+ }
+
+ ret = core_sys_select(n, inp, outp, exp, to);
+ ret = poll_select_copy_remaining(&end_time, tvp, 1, ret);
+
+ return ret;
+}
+
+SYSCALL_DEFINE5(select, int, n, fd_set __user *, inp, fd_set __user *, outp,
+ fd_set __user *, exp, struct timeval __user *, tvp)
+{
+ return kern_select(n, inp, outp, exp, tvp);
+}
+
+static long do_pselect(int n, fd_set __user *inp, fd_set __user *outp,
+ fd_set __user *exp, struct timespec __user *tsp,
+ const sigset_t __user *sigmask, size_t sigsetsize)
+{
+ sigset_t ksigmask, sigsaved;
+ struct timespec64 ts, end_time, *to = NULL;
+ int ret;
+
+ if (tsp) {
+ if (get_timespec64(&ts, tsp))
+ return -EFAULT;
+
+ to = &end_time;
+ if (poll_select_set_timeout(to, ts.tv_sec, ts.tv_nsec))
+ return -EINVAL;
+ }
+
+ if (sigmask) {
+ /* XXX: Don't preclude handling different sized sigset_t's. */
+ if (sigsetsize != sizeof(sigset_t))
+ return -EINVAL;
+ if (copy_from_user(&ksigmask, sigmask, sizeof(ksigmask)))
+ return -EFAULT;
+
+ sigdelsetmask(&ksigmask, sigmask(SIGKILL)|sigmask(SIGSTOP));
+ sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved);
+ }
+
+ ret = core_sys_select(n, inp, outp, exp, to);
+ ret = poll_select_copy_remaining(&end_time, tsp, 0, ret);
+
+ if (ret == -ERESTARTNOHAND) {
+ /*
+ * Don't restore the signal mask yet. Let do_signal() deliver
+ * the signal on the way back to userspace, before the signal
+ * mask is restored.
+ */
+ if (sigmask) {
+ memcpy(¤t->saved_sigmask, &sigsaved,
+ sizeof(sigsaved));
+ set_restore_sigmask();
+ }
+ } else if (sigmask)
+ sigprocmask(SIG_SETMASK, &sigsaved, NULL);
+
+ return ret;
+}
+
+/*
+ * Most architectures can't handle 7-argument syscalls. So we provide a
+ * 6-argument version where the sixth argument is a pointer to a structure
+ * which has a pointer to the sigset_t itself followed by a size_t containing
+ * the sigset size.
+ */
+SYSCALL_DEFINE6(pselect6, int, n, fd_set __user *, inp, fd_set __user *, outp,
+ fd_set __user *, exp, struct timespec __user *, tsp,
+ void __user *, sig)
+{
+ size_t sigsetsize = 0;
+ sigset_t __user *up = NULL;
+
+ if (sig) {
+ if (!access_ok(VERIFY_READ, sig, sizeof(void *)+sizeof(size_t))
+ || __get_user(up, (sigset_t __user * __user *)sig)
+ || __get_user(sigsetsize,
+ (size_t __user *)(sig+sizeof(void *))))
+ return -EFAULT;
+ }
+
+ return do_pselect(n, inp, outp, exp, tsp, up, sigsetsize);
+}
+
+#ifdef __ARCH_WANT_SYS_OLD_SELECT
+struct sel_arg_struct {
+ unsigned long n;
+ fd_set __user *inp, *outp, *exp;
+ struct timeval __user *tvp;
+};
+
+SYSCALL_DEFINE1(old_select, struct sel_arg_struct __user *, arg)
+{
+ struct sel_arg_struct a;
+
+ if (copy_from_user(&a, arg, sizeof(a)))
+ return -EFAULT;
+ return kern_select(a.n, a.inp, a.outp, a.exp, a.tvp);
+}
+#endif
+
+struct poll_list {
+ struct poll_list *next;
+ int len;
+ struct pollfd entries[0];
+};
+
+#define POLLFD_PER_PAGE ((PAGE_SIZE-sizeof(struct poll_list)) / sizeof(struct pollfd))
+
+/*
+ * Fish for pollable events on the pollfd->fd file descriptor. We're only
+ * interested in events matching the pollfd->events mask, and the result
+ * matching that mask is both recorded in pollfd->revents and returned. The
+ * pwait poll_table will be used by the fd-provided poll handler for waiting,
+ * if pwait->_qproc is non-NULL.
+ */
+static inline __poll_t do_pollfd(struct pollfd *pollfd, poll_table *pwait,
+ bool *can_busy_poll,
+ __poll_t busy_flag)
+{
+ int fd = pollfd->fd;
+ __poll_t mask = 0, filter;
+ struct fd f;
+
+ if (fd < 0)
+ goto out;
+ mask = EPOLLNVAL;
+ f = fdget(fd);
+ if (!f.file)
+ goto out;
+
+ /* userland u16 ->events contains POLL... bitmap */
+ filter = demangle_poll(pollfd->events) | EPOLLERR | EPOLLHUP;
+ pwait->_key = filter | busy_flag;
+ mask = vfs_poll(f.file, pwait);
+ if (mask & busy_flag)
+ *can_busy_poll = true;
+ mask &= filter; /* Mask out unneeded events. */
+ fdput(f);
+
+out:
+ /* ... and so does ->revents */
+ pollfd->revents = mangle_poll(mask);
+ return mask;
+}
+
+static int do_poll(struct poll_list *list, struct poll_wqueues *wait,
+ struct timespec64 *end_time)
+{
+ poll_table* pt = &wait->pt;
+ ktime_t expire, *to = NULL;
+ int timed_out = 0, count = 0;
+ u64 slack = 0;
+ __poll_t busy_flag = net_busy_loop_on() ? POLL_BUSY_LOOP : 0;
+ unsigned long busy_start = 0;
+
+ /* Optimise the no-wait case */
+ if (end_time && !end_time->tv_sec && !end_time->tv_nsec) {
+ pt->_qproc = NULL;
+ timed_out = 1;
+ }
+
+ if (end_time && !timed_out)
+ slack = select_estimate_accuracy(end_time);
+
+ for (;;) {
+ struct poll_list *walk;
+ bool can_busy_loop = false;
+
+ for (walk = list; walk != NULL; walk = walk->next) {
+ struct pollfd * pfd, * pfd_end;
+
+ pfd = walk->entries;
+ pfd_end = pfd + walk->len;
+ for (; pfd != pfd_end; pfd++) {
+ /*
+ * Fish for events. If we found one, record it
+ * and kill poll_table->_qproc, so we don't
+ * needlessly register any other waiters after
+ * this. They'll get immediately deregistered
+ * when we break out and return.
+ */
+ if (do_pollfd(pfd, pt, &can_busy_loop,
+ busy_flag)) {
+ count++;
+ pt->_qproc = NULL;
+ /* found something, stop busy polling */
+ busy_flag = 0;
+ can_busy_loop = false;
+ }
+ }
+ }
+ /*
+ * All waiters have already been registered, so don't provide
+ * a poll_table->_qproc to them on the next loop iteration.
+ */
+ pt->_qproc = NULL;
+ if (!count) {
+ count = wait->error;
+ if (signal_pending(current))
+ count = -EINTR;
+ }
+ if (count || timed_out)
+ break;
+
+ /* only if found POLL_BUSY_LOOP sockets && not out of time */
+ if (can_busy_loop && !need_resched()) {
+ if (!busy_start) {
+ busy_start = busy_loop_current_time();
+ continue;
+ }
+ if (!busy_loop_timeout(busy_start))
+ continue;
+ }
+ busy_flag = 0;
+
+ /*
+ * If this is the first loop and we have a timeout
+ * given, then we convert to ktime_t and set the to
+ * pointer to the expiry value.
+ */
+ if (end_time && !to) {
+ expire = timespec64_to_ktime(*end_time);
+ to = &expire;
+ }
+
+ if (!poll_schedule_timeout(wait, TASK_INTERRUPTIBLE, to, slack))
+ timed_out = 1;
+ }
+ return count;
+}
+
+#define N_STACK_PPS ((sizeof(stack_pps) - sizeof(struct poll_list)) / \
+ sizeof(struct pollfd))
+
+static int do_sys_poll(struct pollfd __user *ufds, unsigned int nfds,
+ struct timespec64 *end_time)
+{
+ struct poll_wqueues table;
+ int err = -EFAULT, fdcount, len, size;
+ /* Allocate small arguments on the stack to save memory and be
+ faster - use long to make sure the buffer is aligned properly
+ on 64 bit archs to avoid unaligned access */
+ long stack_pps[POLL_STACK_ALLOC/sizeof(long)];
+ struct poll_list *const head = (struct poll_list *)stack_pps;
+ struct poll_list *walk = head;
+ unsigned long todo = nfds;
+
+ if (nfds > rlimit(RLIMIT_NOFILE))
+ return -EINVAL;
+
+ len = min_t(unsigned int, nfds, N_STACK_PPS);
+ for (;;) {
+ walk->next = NULL;
+ walk->len = len;
+ if (!len)
+ break;
+
+ if (copy_from_user(walk->entries, ufds + nfds-todo,
+ sizeof(struct pollfd) * walk->len))
+ goto out_fds;
+
+ todo -= walk->len;
+ if (!todo)
+ break;
+
+ len = min(todo, POLLFD_PER_PAGE);
+ size = sizeof(struct poll_list) + sizeof(struct pollfd) * len;
+ walk = walk->next = kmalloc(size, GFP_KERNEL);
+ if (!walk) {
+ err = -ENOMEM;
+ goto out_fds;
+ }
+ }
+
+ poll_initwait(&table);
+ fdcount = do_poll(head, &table, end_time);
+ poll_freewait(&table);
+
+ for (walk = head; walk; walk = walk->next) {
+ struct pollfd *fds = walk->entries;
+ int j;
+
+ for (j = 0; j < walk->len; j++, ufds++)
+ if (__put_user(fds[j].revents, &ufds->revents))
+ goto out_fds;
+ }
+
+ err = fdcount;
+out_fds:
+ walk = head->next;
+ while (walk) {
+ struct poll_list *pos = walk;
+ walk = walk->next;
+ kfree(pos);
+ }
+
+ return err;
+}
+
+static long do_restart_poll(struct restart_block *restart_block)
+{
+ struct pollfd __user *ufds = restart_block->poll.ufds;
+ int nfds = restart_block->poll.nfds;
+ struct timespec64 *to = NULL, end_time;
+ int ret;
+
+ if (restart_block->poll.has_timeout) {
+ end_time.tv_sec = restart_block->poll.tv_sec;
+ end_time.tv_nsec = restart_block->poll.tv_nsec;
+ to = &end_time;
+ }
+
+ ret = do_sys_poll(ufds, nfds, to);
+
+ if (ret == -EINTR) {
+ restart_block->fn = do_restart_poll;
+ ret = -ERESTART_RESTARTBLOCK;
+ }
+ return ret;
+}
+
+SYSCALL_DEFINE3(poll, struct pollfd __user *, ufds, unsigned int, nfds,
+ int, timeout_msecs)
+{
+ struct timespec64 end_time, *to = NULL;
+ int ret;
+
+ if (timeout_msecs >= 0) {
+ to = &end_time;
+ poll_select_set_timeout(to, timeout_msecs / MSEC_PER_SEC,
+ NSEC_PER_MSEC * (timeout_msecs % MSEC_PER_SEC));
+ }
+
+ ret = do_sys_poll(ufds, nfds, to);
+
+ if (ret == -EINTR) {
+ struct restart_block *restart_block;
+
+ restart_block = ¤t->restart_block;
+ restart_block->fn = do_restart_poll;
+ restart_block->poll.ufds = ufds;
+ restart_block->poll.nfds = nfds;
+
+ if (timeout_msecs >= 0) {
+ restart_block->poll.tv_sec = end_time.tv_sec;
+ restart_block->poll.tv_nsec = end_time.tv_nsec;
+ restart_block->poll.has_timeout = 1;
+ } else
+ restart_block->poll.has_timeout = 0;
+
+ ret = -ERESTART_RESTARTBLOCK;
+ }
+ return ret;
+}
+
+SYSCALL_DEFINE5(ppoll, struct pollfd __user *, ufds, unsigned int, nfds,
+ struct timespec __user *, tsp, const sigset_t __user *, sigmask,
+ size_t, sigsetsize)
+{
+ sigset_t ksigmask, sigsaved;
+ struct timespec64 ts, end_time, *to = NULL;
+ int ret;
+
+ if (tsp) {
+ if (get_timespec64(&ts, tsp))
+ return -EFAULT;
+
+ to = &end_time;
+ if (poll_select_set_timeout(to, ts.tv_sec, ts.tv_nsec))
+ return -EINVAL;
+ }
+
+ if (sigmask) {
+ /* XXX: Don't preclude handling different sized sigset_t's. */
+ if (sigsetsize != sizeof(sigset_t))
+ return -EINVAL;
+ if (copy_from_user(&ksigmask, sigmask, sizeof(ksigmask)))
+ return -EFAULT;
+
+ sigdelsetmask(&ksigmask, sigmask(SIGKILL)|sigmask(SIGSTOP));
+ sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved);
+ }
+
+ ret = do_sys_poll(ufds, nfds, to);
+
+ /* We can restart this syscall, usually */
+ if (ret == -EINTR) {
+ /*
+ * Don't restore the signal mask yet. Let do_signal() deliver
+ * the signal on the way back to userspace, before the signal
+ * mask is restored.
+ */
+ if (sigmask) {
+ memcpy(¤t->saved_sigmask, &sigsaved,
+ sizeof(sigsaved));
+ set_restore_sigmask();
+ }
+ ret = -ERESTARTNOHAND;
+ } else if (sigmask)
+ sigprocmask(SIG_SETMASK, &sigsaved, NULL);
+
+ ret = poll_select_copy_remaining(&end_time, tsp, 0, ret);
+
+ return ret;
+}
+
+#ifdef CONFIG_COMPAT
+#define __COMPAT_NFDBITS (8 * sizeof(compat_ulong_t))
+
+static
+int compat_poll_select_copy_remaining(struct timespec64 *end_time, void __user *p,
+ int timeval, int ret)
+{
+ struct timespec64 ts;
+
+ if (!p)
+ return ret;
+
+ if (current->personality & STICKY_TIMEOUTS)
+ goto sticky;
+
+ /* No update for zero timeout */
+ if (!end_time->tv_sec && !end_time->tv_nsec)
+ return ret;
+
+ ktime_get_ts64(&ts);
+ ts = timespec64_sub(*end_time, ts);
+ if (ts.tv_sec < 0)
+ ts.tv_sec = ts.tv_nsec = 0;
+
+ if (timeval) {
+ struct compat_timeval rtv;
+
+ rtv.tv_sec = ts.tv_sec;
+ rtv.tv_usec = ts.tv_nsec / NSEC_PER_USEC;
+
+ if (!copy_to_user(p, &rtv, sizeof(rtv)))
+ return ret;
+ } else {
+ if (!compat_put_timespec64(&ts, p))
+ return ret;
+ }
+ /*
+ * If an application puts its timeval in read-only memory, we
+ * don't want the Linux-specific update to the timeval to
+ * cause a fault after the select has completed
+ * successfully. However, because we're not updating the
+ * timeval, we can't restart the system call.
+ */
+
+sticky:
+ if (ret == -ERESTARTNOHAND)
+ ret = -EINTR;
+ return ret;
+}
+
+/*
+ * Ooo, nasty. We need here to frob 32-bit unsigned longs to
+ * 64-bit unsigned longs.
+ */
+static
+int compat_get_fd_set(unsigned long nr, compat_ulong_t __user *ufdset,
+ unsigned long *fdset)
+{
+ if (ufdset) {
+ return compat_get_bitmap(fdset, ufdset, nr);
+ } else {
+ zero_fd_set(nr, fdset);
+ return 0;
+ }
+}
+
+static
+int compat_set_fd_set(unsigned long nr, compat_ulong_t __user *ufdset,
+ unsigned long *fdset)
+{
+ if (!ufdset)
+ return 0;
+ return compat_put_bitmap(ufdset, fdset, nr);
+}
+
+
+/*
+ * This is a virtual copy of sys_select from fs/select.c and probably
+ * should be compared to it from time to time
+ */
+
+/*
+ * We can actually return ERESTARTSYS instead of EINTR, but I'd
+ * like to be certain this leads to no problems. So I return
+ * EINTR just for safety.
+ *
+ * Update: ERESTARTSYS breaks at least the xview clock binary, so
+ * I'm trying ERESTARTNOHAND which restart only when you want to.
+ */
+static int compat_core_sys_select(int n, compat_ulong_t __user *inp,
+ compat_ulong_t __user *outp, compat_ulong_t __user *exp,
+ struct timespec64 *end_time)
+{
+ fd_set_bits fds;
+ void *bits;
+ int size, max_fds, ret = -EINVAL;
+ struct fdtable *fdt;
+ long stack_fds[SELECT_STACK_ALLOC/sizeof(long)];
+
+ if (n < 0)
+ goto out_nofds;
+
+ /* max_fds can increase, so grab it once to avoid race */
+ rcu_read_lock();
+ fdt = files_fdtable(current->files);
+ max_fds = fdt->max_fds;
+ rcu_read_unlock();
+ if (n > max_fds)
+ n = max_fds;
+
+ /*
+ * We need 6 bitmaps (in/out/ex for both incoming and outgoing),
+ * since we used fdset we need to allocate memory in units of
+ * long-words.
+ */
+ size = FDS_BYTES(n);
+ bits = stack_fds;
+ if (size > sizeof(stack_fds) / 6) {
+ bits = kmalloc_array(6, size, GFP_KERNEL);
+ ret = -ENOMEM;
+ if (!bits)
+ goto out_nofds;
+ }
+ fds.in = (unsigned long *) bits;
+ fds.out = (unsigned long *) (bits + size);
+ fds.ex = (unsigned long *) (bits + 2*size);
+ fds.res_in = (unsigned long *) (bits + 3*size);
+ fds.res_out = (unsigned long *) (bits + 4*size);
+ fds.res_ex = (unsigned long *) (bits + 5*size);
+
+ if ((ret = compat_get_fd_set(n, inp, fds.in)) ||
+ (ret = compat_get_fd_set(n, outp, fds.out)) ||
+ (ret = compat_get_fd_set(n, exp, fds.ex)))
+ goto out;
+ zero_fd_set(n, fds.res_in);
+ zero_fd_set(n, fds.res_out);
+ zero_fd_set(n, fds.res_ex);
+
+ ret = do_select(n, &fds, end_time);
+
+ if (ret < 0)
+ goto out;
+ if (!ret) {
+ ret = -ERESTARTNOHAND;
+ if (signal_pending(current))
+ goto out;
+ ret = 0;
+ }
+
+ if (compat_set_fd_set(n, inp, fds.res_in) ||
+ compat_set_fd_set(n, outp, fds.res_out) ||
+ compat_set_fd_set(n, exp, fds.res_ex))
+ ret = -EFAULT;
+out:
+ if (bits != stack_fds)
+ kfree(bits);
+out_nofds:
+ return ret;
+}
+
+static int do_compat_select(int n, compat_ulong_t __user *inp,
+ compat_ulong_t __user *outp, compat_ulong_t __user *exp,
+ struct compat_timeval __user *tvp)
+{
+ struct timespec64 end_time, *to = NULL;
+ struct compat_timeval tv;
+ int ret;
+
+ if (tvp) {
+ if (copy_from_user(&tv, tvp, sizeof(tv)))
+ return -EFAULT;
+
+ to = &end_time;
+ if (poll_select_set_timeout(to,
+ tv.tv_sec + (tv.tv_usec / USEC_PER_SEC),
+ (tv.tv_usec % USEC_PER_SEC) * NSEC_PER_USEC))
+ return -EINVAL;
+ }
+
+ ret = compat_core_sys_select(n, inp, outp, exp, to);
+ ret = compat_poll_select_copy_remaining(&end_time, tvp, 1, ret);
+
+ return ret;
+}
+
+COMPAT_SYSCALL_DEFINE5(select, int, n, compat_ulong_t __user *, inp,
+ compat_ulong_t __user *, outp, compat_ulong_t __user *, exp,
+ struct compat_timeval __user *, tvp)
+{
+ return do_compat_select(n, inp, outp, exp, tvp);
+}
+
+struct compat_sel_arg_struct {
+ compat_ulong_t n;
+ compat_uptr_t inp;
+ compat_uptr_t outp;
+ compat_uptr_t exp;
+ compat_uptr_t tvp;
+};
+
+COMPAT_SYSCALL_DEFINE1(old_select, struct compat_sel_arg_struct __user *, arg)
+{
+ struct compat_sel_arg_struct a;
+
+ if (copy_from_user(&a, arg, sizeof(a)))
+ return -EFAULT;
+ return do_compat_select(a.n, compat_ptr(a.inp), compat_ptr(a.outp),
+ compat_ptr(a.exp), compat_ptr(a.tvp));
+}
+
+static long do_compat_pselect(int n, compat_ulong_t __user *inp,
+ compat_ulong_t __user *outp, compat_ulong_t __user *exp,
+ struct compat_timespec __user *tsp, compat_sigset_t __user *sigmask,
+ compat_size_t sigsetsize)
+{
+ sigset_t ksigmask, sigsaved;
+ struct timespec64 ts, end_time, *to = NULL;
+ int ret;
+
+ if (tsp) {
+ if (compat_get_timespec64(&ts, tsp))
+ return -EFAULT;
+
+ to = &end_time;
+ if (poll_select_set_timeout(to, ts.tv_sec, ts.tv_nsec))
+ return -EINVAL;
+ }
+
+ if (sigmask) {
+ if (sigsetsize != sizeof(compat_sigset_t))
+ return -EINVAL;
+ if (get_compat_sigset(&ksigmask, sigmask))
+ return -EFAULT;
+
+ sigdelsetmask(&ksigmask, sigmask(SIGKILL)|sigmask(SIGSTOP));
+ sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved);
+ }
+
+ ret = compat_core_sys_select(n, inp, outp, exp, to);
+ ret = compat_poll_select_copy_remaining(&end_time, tsp, 0, ret);
+
+ if (ret == -ERESTARTNOHAND) {
+ /*
+ * Don't restore the signal mask yet. Let do_signal() deliver
+ * the signal on the way back to userspace, before the signal
+ * mask is restored.
+ */
+ if (sigmask) {
+ memcpy(¤t->saved_sigmask, &sigsaved,
+ sizeof(sigsaved));
+ set_restore_sigmask();
+ }
+ } else if (sigmask)
+ sigprocmask(SIG_SETMASK, &sigsaved, NULL);
+
+ return ret;
+}
+
+COMPAT_SYSCALL_DEFINE6(pselect6, int, n, compat_ulong_t __user *, inp,
+ compat_ulong_t __user *, outp, compat_ulong_t __user *, exp,
+ struct compat_timespec __user *, tsp, void __user *, sig)
+{
+ compat_size_t sigsetsize = 0;
+ compat_uptr_t up = 0;
+
+ if (sig) {
+ if (!access_ok(VERIFY_READ, sig,
+ sizeof(compat_uptr_t)+sizeof(compat_size_t)) ||
+ __get_user(up, (compat_uptr_t __user *)sig) ||
+ __get_user(sigsetsize,
+ (compat_size_t __user *)(sig+sizeof(up))))
+ return -EFAULT;
+ }
+ return do_compat_pselect(n, inp, outp, exp, tsp, compat_ptr(up),
+ sigsetsize);
+}
+
+COMPAT_SYSCALL_DEFINE5(ppoll, struct pollfd __user *, ufds,
+ unsigned int, nfds, struct compat_timespec __user *, tsp,
+ const compat_sigset_t __user *, sigmask, compat_size_t, sigsetsize)
+{
+ sigset_t ksigmask, sigsaved;
+ struct timespec64 ts, end_time, *to = NULL;
+ int ret;
+
+ if (tsp) {
+ if (compat_get_timespec64(&ts, tsp))
+ return -EFAULT;
+
+ to = &end_time;
+ if (poll_select_set_timeout(to, ts.tv_sec, ts.tv_nsec))
+ return -EINVAL;
+ }
+
+ if (sigmask) {
+ if (sigsetsize != sizeof(compat_sigset_t))
+ return -EINVAL;
+ if (get_compat_sigset(&ksigmask, sigmask))
+ return -EFAULT;
+
+ sigdelsetmask(&ksigmask, sigmask(SIGKILL)|sigmask(SIGSTOP));
+ sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved);
+ }
+
+ ret = do_sys_poll(ufds, nfds, to);
+
+ /* We can restart this syscall, usually */
+ if (ret == -EINTR) {
+ /*
+ * Don't restore the signal mask yet. Let do_signal() deliver
+ * the signal on the way back to userspace, before the signal
+ * mask is restored.
+ */
+ if (sigmask) {
+ memcpy(¤t->saved_sigmask, &sigsaved,
+ sizeof(sigsaved));
+ set_restore_sigmask();
+ }
+ ret = -ERESTARTNOHAND;
+ } else if (sigmask)
+ sigprocmask(SIG_SETMASK, &sigsaved, NULL);
+
+ ret = compat_poll_select_copy_remaining(&end_time, tsp, 0, ret);
+
+ return ret;
+}
+#endif