From 9f72949f679df06021c9e43886c9191494fdb007 Mon Sep 17 00:00:00 2001 From: David Woodhouse Date: Wed, 18 Jan 2006 17:44:05 -0800 Subject: [PATCH] Add pselect/ppoll system call implementation The following implementation of ppoll() and pselect() system calls depends on the architecture providing a TIF_RESTORE_SIGMASK flag in the thread_info. These system calls have to change the signal mask during their operation, and signal handlers must be invoked using the new, temporary signal mask. The old signal mask must be restored either upon successful exit from the system call, or upon returning from the invoked signal handler if the system call is interrupted. We can't simply restore the original signal mask and return to userspace, since the restored signal mask may actually block the signal which interrupted the system call. The TIF_RESTORE_SIGMASK flag deals with this by causing the syscall exit path to trap into do_signal() just as TIF_SIGPENDING does, and by causing do_signal() to use the saved signal mask instead of the current signal mask when setting up the stack frame for the signal handler -- or by causing do_signal() to simply restore the saved signal mask in the case where there is no handler to be invoked. The first patch implements the sys_pselect() and sys_ppoll() system calls, which are present only if TIF_RESTORE_SIGMASK is defined. That #ifdef should go away in time when all architectures have implemented it. The second patch implements TIF_RESTORE_SIGMASK for the PowerPC kernel (in the -mm tree), and the third patch then removes the arch-specific implementations of sys_rt_sigsuspend() and replaces them with generic versions using the same trick. The fourth and fifth patches, provided by David Howells, implement TIF_RESTORE_SIGMASK for FR-V and i386 respectively, and the sixth patch adds the syscalls to the i386 syscall table. This patch: Add the pselect() and ppoll() system calls, providing core routines usable by the original select() and poll() system calls and also the new calls (with their semantics w.r.t timeouts). Signed-off-by: David Woodhouse Cc: Michael Kerrisk Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/compat.c | 260 +++++++++++++++++++++++++++++++++++++++++++++++++++--------- 1 file changed, 223 insertions(+), 37 deletions(-) (limited to 'fs/compat.c') diff --git a/fs/compat.c b/fs/compat.c index c6ba9deabad..18b21b4c9e3 100644 --- a/fs/compat.c +++ b/fs/compat.c @@ -53,6 +53,8 @@ #include #include +extern void sigset_from_compat(sigset_t *set, compat_sigset_t *compat); + /* * Not all architectures have sys_utime, so implement this in terms * of sys_utimes. @@ -1657,36 +1659,14 @@ static void select_bits_free(void *bits, int size) #define MAX_SELECT_SECONDS \ ((unsigned long) (MAX_SCHEDULE_TIMEOUT / HZ)-1) -asmlinkage long -compat_sys_select(int n, compat_ulong_t __user *inp, compat_ulong_t __user *outp, - compat_ulong_t __user *exp, struct compat_timeval __user *tvp) +int compat_core_sys_select(int n, compat_ulong_t __user *inp, + compat_ulong_t __user *outp, compat_ulong_t __user *exp, s64 *timeout) { fd_set_bits fds; char *bits; - long timeout; int size, max_fdset, ret = -EINVAL; struct fdtable *fdt; - timeout = MAX_SCHEDULE_TIMEOUT; - if (tvp) { - time_t sec, usec; - - if (!access_ok(VERIFY_READ, tvp, sizeof(*tvp)) - || __get_user(sec, &tvp->tv_sec) - || __get_user(usec, &tvp->tv_usec)) { - ret = -EFAULT; - goto out_nofds; - } - - if (sec < 0 || usec < 0) - goto out_nofds; - - if ((unsigned long) sec < MAX_SELECT_SECONDS) { - timeout = ROUND_UP(usec, 1000000/HZ); - timeout += sec * (unsigned long) HZ; - } - } - if (n < 0) goto out_nofds; @@ -1723,19 +1703,7 @@ compat_sys_select(int n, compat_ulong_t __user *inp, compat_ulong_t __user *outp zero_fd_set(n, fds.res_out); zero_fd_set(n, fds.res_ex); - ret = do_select(n, &fds, &timeout); - - if (tvp && !(current->personality & STICKY_TIMEOUTS)) { - time_t sec = 0, usec = 0; - if (timeout) { - sec = timeout / HZ; - usec = timeout % HZ; - usec *= (1000000/HZ); - } - if (put_user(sec, &tvp->tv_sec) || - put_user(usec, &tvp->tv_usec)) - ret = -EFAULT; - } + ret = do_select(n, &fds, timeout); if (ret < 0) goto out; @@ -1756,6 +1724,224 @@ out_nofds: return ret; } +asmlinkage long compat_sys_select(int n, compat_ulong_t __user *inp, + compat_ulong_t __user *outp, compat_ulong_t __user *exp, + struct compat_timeval __user *tvp) +{ + s64 timeout = -1; + struct compat_timeval tv; + int ret; + + if (tvp) { + if (copy_from_user(&tv, tvp, sizeof(tv))) + return -EFAULT; + + if (tv.tv_sec < 0 || tv.tv_usec < 0) + return -EINVAL; + + /* Cast to u64 to make GCC stop complaining */ + if ((u64)tv.tv_sec >= (u64)MAX_INT64_SECONDS) + timeout = -1; /* infinite */ + else { + timeout = ROUND_UP(tv.tv_sec, 1000000/HZ); + timeout += tv.tv_sec * HZ; + } + } + + ret = compat_core_sys_select(n, inp, outp, exp, &timeout); + + if (tvp) { + if (current->personality & STICKY_TIMEOUTS) + goto sticky; + tv.tv_usec = jiffies_to_usecs(do_div((*(u64*)&timeout), HZ)); + tv.tv_sec = timeout; + if (copy_to_user(tvp, &tv, sizeof(tv))) { +sticky: + /* + * 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. + */ + if (ret == -ERESTARTNOHAND) + ret = -EINTR; + } + } + + return ret; +} + +#ifdef TIF_RESTORE_SIGMASK +asmlinkage long compat_sys_pselect7(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) +{ + compat_sigset_t ss32; + sigset_t ksigmask, sigsaved; + long timeout = MAX_SCHEDULE_TIMEOUT; + struct compat_timespec ts; + int ret; + + if (tsp) { + if (copy_from_user(&ts, tsp, sizeof(ts))) + return -EFAULT; + + if (ts.tv_sec < 0 || ts.tv_nsec < 0) + return -EINVAL; + } + + if (sigmask) { + if (sigsetsize != sizeof(compat_sigset_t)) + return -EINVAL; + if (copy_from_user(&ss32, sigmask, sizeof(ss32))) + return -EFAULT; + sigset_from_compat(&ksigmask, &ss32); + + sigdelsetmask(&ksigmask, sigmask(SIGKILL)|sigmask(SIGSTOP)); + sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved); + } + + do { + if (tsp) { + if ((unsigned long)ts.tv_sec < MAX_SELECT_SECONDS) { + timeout = ROUND_UP(ts.tv_nsec, 1000000000/HZ); + timeout += ts.tv_sec * (unsigned long)HZ; + ts.tv_sec = 0; + ts.tv_nsec = 0; + } else { + ts.tv_sec -= MAX_SELECT_SECONDS; + timeout = MAX_SELECT_SECONDS * HZ; + } + } + + ret = compat_core_sys_select(n, inp, outp, exp, &timeout); + + } while (!ret && !timeout && tsp && (ts.tv_sec || ts.tv_nsec)); + + if (tsp && !(current->personality & STICKY_TIMEOUTS)) { + ts.tv_sec += timeout / HZ; + ts.tv_nsec += (timeout % HZ) * (1000000000/HZ); + if (ts.tv_nsec >= 1000000000) { + ts.tv_sec++; + ts.tv_nsec -= 1000000000; + } + (void)copy_to_user(tsp, &ts, sizeof(ts)); + } + + 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_thread_flag(TIF_RESTORE_SIGMASK); + } + } else if (sigmask) + sigprocmask(SIG_SETMASK, &sigsaved, NULL); + + return ret; +} + +asmlinkage long compat_sys_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 compat_sys_pselect7(n, inp, outp, exp, tsp, compat_ptr(up), + sigsetsize); +} + +asmlinkage long compat_sys_ppoll(struct pollfd __user *ufds, + unsigned int nfds, struct compat_timespec __user *tsp, + const compat_sigset_t __user *sigmask, compat_size_t sigsetsize) +{ + compat_sigset_t ss32; + sigset_t ksigmask, sigsaved; + struct compat_timespec ts; + s64 timeout = -1; + int ret; + + if (tsp) { + if (copy_from_user(&ts, tsp, sizeof(ts))) + return -EFAULT; + + /* We assume that ts.tv_sec is always lower than + the number of seconds that can be expressed in + an s64. Otherwise the compiler bitches at us */ + timeout = ROUND_UP(ts.tv_sec, 1000000000/HZ); + timeout += ts.tv_sec * HZ; + } + + if (sigmask) { + if (sigsetsize |= sizeof(compat_sigset_t)) + return -EINVAL; + if (copy_from_user(&ss32, sigmask, sizeof(ss32))) + return -EFAULT; + sigset_from_compat(&ksigmask, &ss32); + + sigdelsetmask(&ksigmask, sigmask(SIGKILL)|sigmask(SIGSTOP)); + sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved); + } + + ret = do_sys_poll(ufds, nfds, &timeout); + + /* 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_thread_flag(TIF_RESTORE_SIGMASK); + } + ret = -ERESTARTNOHAND; + } else if (sigmask) + sigprocmask(SIG_SETMASK, &sigsaved, NULL); + + if (tsp && timeout >= 0) { + if (current->personality & STICKY_TIMEOUTS) + goto sticky; + /* Yes, we know it's actually an s64, but it's also positive. */ + ts.tv_nsec = jiffies_to_usecs(do_div((*(u64*)&timeout), HZ)) * 1000; + ts.tv_sec = timeout; + if (copy_to_user(tsp, &ts, sizeof(ts))) { +sticky: + /* + * 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. + */ + if (ret == -ERESTARTNOHAND && timeout >= 0) + ret = -EINTR; + } + } + + return ret; +} +#endif /* TIF_RESTORE_SIGMASK */ + #if defined(CONFIG_NFSD) || defined(CONFIG_NFSD_MODULE) /* Stuff for NFS server syscalls... */ struct compat_nfsctl_svc { -- cgit v1.2.3