![WANG Cong](/assets/img/avatar_default.png)
This patch contains varied fixes and improvements for some files under arch/um/os-Linux/, such as a typo fix in a perror message, a missing argument fix for a printf, some constifying for pointers and so on. [ jdike - made sigprocmask failure return -errno instead of -1 ] Signed-off-by: WANG Cong <xiyou.wangcong@gmail.com> Signed-off-by: Jeff Dike <jdike@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
283 lines
6.2 KiB
C
283 lines
6.2 KiB
C
/*
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* Copyright (C) 2004 PathScale, Inc
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* Copyright (C) 2004 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
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* Licensed under the GPL
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*/
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#include <stdlib.h>
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#include <stdarg.h>
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#include <errno.h>
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#include <signal.h>
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#include <strings.h>
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#include "os.h"
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#include "sysdep/barrier.h"
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#include "sysdep/sigcontext.h"
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#include "user.h"
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/*
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* These are the asynchronous signals. SIGPROF is excluded because we want to
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* be able to profile all of UML, not just the non-critical sections. If
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* profiling is not thread-safe, then that is not my problem. We can disable
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* profiling when SMP is enabled in that case.
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*/
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#define SIGIO_BIT 0
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#define SIGIO_MASK (1 << SIGIO_BIT)
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#define SIGVTALRM_BIT 1
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#define SIGVTALRM_MASK (1 << SIGVTALRM_BIT)
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/*
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* These are used by both the signal handlers and
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* block/unblock_signals. I don't want modifications cached in a
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* register - they must go straight to memory.
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*/
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static volatile int signals_enabled = 1;
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static volatile int pending = 0;
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void sig_handler(int sig, struct sigcontext *sc)
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{
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int enabled;
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enabled = signals_enabled;
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if (!enabled && (sig == SIGIO)) {
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pending |= SIGIO_MASK;
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return;
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}
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block_signals();
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sig_handler_common_skas(sig, sc);
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set_signals(enabled);
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}
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static void real_alarm_handler(struct sigcontext *sc)
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{
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struct uml_pt_regs regs;
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if (sc != NULL)
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copy_sc(®s, sc);
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regs.is_user = 0;
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unblock_signals();
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timer_handler(SIGVTALRM, ®s);
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}
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void alarm_handler(int sig, struct sigcontext *sc)
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{
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int enabled;
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enabled = signals_enabled;
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if (!signals_enabled) {
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pending |= SIGVTALRM_MASK;
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return;
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}
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block_signals();
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real_alarm_handler(sc);
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set_signals(enabled);
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}
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void timer_init(void)
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{
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set_handler(SIGVTALRM, (__sighandler_t) alarm_handler,
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SA_ONSTACK | SA_RESTART, SIGUSR1, SIGIO, SIGWINCH, -1);
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}
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void set_sigstack(void *sig_stack, int size)
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{
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stack_t stack = ((stack_t) { .ss_flags = 0,
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.ss_sp = (__ptr_t) sig_stack,
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.ss_size = size - sizeof(void *) });
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if (sigaltstack(&stack, NULL) != 0)
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panic("enabling signal stack failed, errno = %d\n", errno);
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}
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void remove_sigstack(void)
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{
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stack_t stack = ((stack_t) { .ss_flags = SS_DISABLE,
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.ss_sp = NULL,
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.ss_size = 0 });
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if (sigaltstack(&stack, NULL) != 0)
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panic("disabling signal stack failed, errno = %d\n", errno);
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}
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void (*handlers[_NSIG])(int sig, struct sigcontext *sc);
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void handle_signal(int sig, struct sigcontext *sc)
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{
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unsigned long pending = 1UL << sig;
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do {
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int nested, bail;
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/*
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* pending comes back with one bit set for each
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* interrupt that arrived while setting up the stack,
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* plus a bit for this interrupt, plus the zero bit is
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* set if this is a nested interrupt.
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* If bail is true, then we interrupted another
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* handler setting up the stack. In this case, we
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* have to return, and the upper handler will deal
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* with this interrupt.
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*/
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bail = to_irq_stack(&pending);
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if (bail)
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return;
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nested = pending & 1;
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pending &= ~1;
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while ((sig = ffs(pending)) != 0){
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sig--;
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pending &= ~(1 << sig);
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(*handlers[sig])(sig, sc);
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}
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/*
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* Again, pending comes back with a mask of signals
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* that arrived while tearing down the stack. If this
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* is non-zero, we just go back, set up the stack
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* again, and handle the new interrupts.
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*/
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if (!nested)
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pending = from_irq_stack(nested);
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} while (pending);
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}
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extern void hard_handler(int sig);
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void set_handler(int sig, void (*handler)(int), int flags, ...)
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{
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struct sigaction action;
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va_list ap;
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sigset_t sig_mask;
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int mask;
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handlers[sig] = (void (*)(int, struct sigcontext *)) handler;
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action.sa_handler = hard_handler;
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sigemptyset(&action.sa_mask);
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va_start(ap, flags);
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while ((mask = va_arg(ap, int)) != -1)
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sigaddset(&action.sa_mask, mask);
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va_end(ap);
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action.sa_flags = flags;
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action.sa_restorer = NULL;
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if (sigaction(sig, &action, NULL) < 0)
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panic("sigaction failed - errno = %d\n", errno);
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sigemptyset(&sig_mask);
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sigaddset(&sig_mask, sig);
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if (sigprocmask(SIG_UNBLOCK, &sig_mask, NULL) < 0)
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panic("sigprocmask failed - errno = %d\n", errno);
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}
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int change_sig(int signal, int on)
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{
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sigset_t sigset, old;
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sigemptyset(&sigset);
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sigaddset(&sigset, signal);
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if (sigprocmask(on ? SIG_UNBLOCK : SIG_BLOCK, &sigset, &old) < 0)
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return -errno;
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return !sigismember(&old, signal);
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}
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void block_signals(void)
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{
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signals_enabled = 0;
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/*
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* This must return with signals disabled, so this barrier
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* ensures that writes are flushed out before the return.
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* This might matter if gcc figures out how to inline this and
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* decides to shuffle this code into the caller.
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*/
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mb();
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}
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void unblock_signals(void)
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{
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int save_pending;
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if (signals_enabled == 1)
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return;
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/*
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* We loop because the IRQ handler returns with interrupts off. So,
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* interrupts may have arrived and we need to re-enable them and
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* recheck pending.
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*/
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while(1) {
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/*
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* Save and reset save_pending after enabling signals. This
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* way, pending won't be changed while we're reading it.
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*/
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signals_enabled = 1;
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/*
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* Setting signals_enabled and reading pending must
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* happen in this order.
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*/
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mb();
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save_pending = pending;
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if (save_pending == 0) {
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/*
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* This must return with signals enabled, so
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* this barrier ensures that writes are
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* flushed out before the return. This might
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* matter if gcc figures out how to inline
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* this (unlikely, given its size) and decides
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* to shuffle this code into the caller.
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*/
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mb();
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return;
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}
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pending = 0;
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/*
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* We have pending interrupts, so disable signals, as the
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* handlers expect them off when they are called. They will
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* be enabled again above.
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*/
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signals_enabled = 0;
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/*
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* Deal with SIGIO first because the alarm handler might
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* schedule, leaving the pending SIGIO stranded until we come
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* back here.
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*/
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if (save_pending & SIGIO_MASK)
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sig_handler_common_skas(SIGIO, NULL);
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if (save_pending & SIGVTALRM_MASK)
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real_alarm_handler(NULL);
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}
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}
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int get_signals(void)
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{
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return signals_enabled;
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}
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int set_signals(int enable)
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{
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int ret;
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if (signals_enabled == enable)
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return enable;
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ret = signals_enabled;
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if (enable)
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unblock_signals();
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else block_signals();
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return ret;
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}
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