diff options
Diffstat (limited to 'kernel/arch/um/os-Linux/signal.c')
| -rw-r--r-- | kernel/arch/um/os-Linux/signal.c | 314 |
1 files changed, 314 insertions, 0 deletions
diff --git a/kernel/arch/um/os-Linux/signal.c b/kernel/arch/um/os-Linux/signal.c new file mode 100644 index 000000000..7b605e4df --- /dev/null +++ b/kernel/arch/um/os-Linux/signal.c @@ -0,0 +1,314 @@ +/* + * Copyright (C) 2004 PathScale, Inc + * Copyright (C) 2004 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com) + * Licensed under the GPL + */ + +#include <stdlib.h> +#include <stdarg.h> +#include <errno.h> +#include <signal.h> +#include <strings.h> +#include <as-layout.h> +#include <kern_util.h> +#include <os.h> +#include <sysdep/mcontext.h> +#include "internal.h" + +void (*sig_info[NSIG])(int, struct siginfo *, struct uml_pt_regs *) = { + [SIGTRAP] = relay_signal, + [SIGFPE] = relay_signal, + [SIGILL] = relay_signal, + [SIGWINCH] = winch, + [SIGBUS] = bus_handler, + [SIGSEGV] = segv_handler, + [SIGIO] = sigio_handler, + [SIGVTALRM] = timer_handler }; + +static void sig_handler_common(int sig, struct siginfo *si, mcontext_t *mc) +{ + struct uml_pt_regs r; + int save_errno = errno; + + r.is_user = 0; + if (sig == SIGSEGV) { + /* For segfaults, we want the data from the sigcontext. */ + get_regs_from_mc(&r, mc); + GET_FAULTINFO_FROM_MC(r.faultinfo, mc); + } + + /* enable signals if sig isn't IRQ signal */ + if ((sig != SIGIO) && (sig != SIGWINCH) && (sig != SIGVTALRM)) + unblock_signals(); + + (*sig_info[sig])(sig, si, &r); + + errno = save_errno; +} + +/* + * These are the asynchronous signals. SIGPROF is excluded because we want to + * be able to profile all of UML, not just the non-critical sections. If + * profiling is not thread-safe, then that is not my problem. We can disable + * profiling when SMP is enabled in that case. + */ +#define SIGIO_BIT 0 +#define SIGIO_MASK (1 << SIGIO_BIT) + +#define SIGVTALRM_BIT 1 +#define SIGVTALRM_MASK (1 << SIGVTALRM_BIT) + +static int signals_enabled; +static unsigned int signals_pending; + +void sig_handler(int sig, struct siginfo *si, mcontext_t *mc) +{ + int enabled; + + enabled = signals_enabled; + if (!enabled && (sig == SIGIO)) { + signals_pending |= SIGIO_MASK; + return; + } + + block_signals(); + + sig_handler_common(sig, si, mc); + + set_signals(enabled); +} + +static void real_alarm_handler(mcontext_t *mc) +{ + struct uml_pt_regs regs; + + if (mc != NULL) + get_regs_from_mc(®s, mc); + regs.is_user = 0; + unblock_signals(); + timer_handler(SIGVTALRM, NULL, ®s); +} + +void alarm_handler(int sig, struct siginfo *unused_si, mcontext_t *mc) +{ + int enabled; + + enabled = signals_enabled; + if (!signals_enabled) { + signals_pending |= SIGVTALRM_MASK; + return; + } + + block_signals(); + + real_alarm_handler(mc); + set_signals(enabled); +} + +void timer_init(void) +{ + set_handler(SIGVTALRM); +} + +void set_sigstack(void *sig_stack, int size) +{ + stack_t stack = ((stack_t) { .ss_flags = 0, + .ss_sp = (__ptr_t) sig_stack, + .ss_size = size - sizeof(void *) }); + + if (sigaltstack(&stack, NULL) != 0) + panic("enabling signal stack failed, errno = %d\n", errno); +} + +static void (*handlers[_NSIG])(int sig, struct siginfo *si, mcontext_t *mc) = { + [SIGSEGV] = sig_handler, + [SIGBUS] = sig_handler, + [SIGILL] = sig_handler, + [SIGFPE] = sig_handler, + [SIGTRAP] = sig_handler, + + [SIGIO] = sig_handler, + [SIGWINCH] = sig_handler, + [SIGVTALRM] = alarm_handler +}; + + +static void hard_handler(int sig, siginfo_t *si, void *p) +{ + struct ucontext *uc = p; + mcontext_t *mc = &uc->uc_mcontext; + unsigned long pending = 1UL << sig; + + do { + int nested, bail; + + /* + * pending comes back with one bit set for each + * interrupt that arrived while setting up the stack, + * plus a bit for this interrupt, plus the zero bit is + * set if this is a nested interrupt. + * If bail is true, then we interrupted another + * handler setting up the stack. In this case, we + * have to return, and the upper handler will deal + * with this interrupt. + */ + bail = to_irq_stack(&pending); + if (bail) + return; + + nested = pending & 1; + pending &= ~1; + + while ((sig = ffs(pending)) != 0){ + sig--; + pending &= ~(1 << sig); + (*handlers[sig])(sig, (struct siginfo *)si, mc); + } + + /* + * Again, pending comes back with a mask of signals + * that arrived while tearing down the stack. If this + * is non-zero, we just go back, set up the stack + * again, and handle the new interrupts. + */ + if (!nested) + pending = from_irq_stack(nested); + } while (pending); +} + +void set_handler(int sig) +{ + struct sigaction action; + int flags = SA_SIGINFO | SA_ONSTACK; + sigset_t sig_mask; + + action.sa_sigaction = hard_handler; + + /* block irq ones */ + sigemptyset(&action.sa_mask); + sigaddset(&action.sa_mask, SIGVTALRM); + sigaddset(&action.sa_mask, SIGIO); + sigaddset(&action.sa_mask, SIGWINCH); + + if (sig == SIGSEGV) + flags |= SA_NODEFER; + + if (sigismember(&action.sa_mask, sig)) + flags |= SA_RESTART; /* if it's an irq signal */ + + action.sa_flags = flags; + action.sa_restorer = NULL; + if (sigaction(sig, &action, NULL) < 0) + panic("sigaction failed - errno = %d\n", errno); + + sigemptyset(&sig_mask); + sigaddset(&sig_mask, sig); + if (sigprocmask(SIG_UNBLOCK, &sig_mask, NULL) < 0) + panic("sigprocmask failed - errno = %d\n", errno); +} + +int change_sig(int signal, int on) +{ + sigset_t sigset; + + sigemptyset(&sigset); + sigaddset(&sigset, signal); + if (sigprocmask(on ? SIG_UNBLOCK : SIG_BLOCK, &sigset, NULL) < 0) + return -errno; + + return 0; +} + +void block_signals(void) +{ + signals_enabled = 0; + /* + * This must return with signals disabled, so this barrier + * ensures that writes are flushed out before the return. + * This might matter if gcc figures out how to inline this and + * decides to shuffle this code into the caller. + */ + barrier(); +} + +void unblock_signals(void) +{ + int save_pending; + + if (signals_enabled == 1) + return; + + /* + * We loop because the IRQ handler returns with interrupts off. So, + * interrupts may have arrived and we need to re-enable them and + * recheck signals_pending. + */ + while (1) { + /* + * Save and reset save_pending after enabling signals. This + * way, signals_pending won't be changed while we're reading it. + */ + signals_enabled = 1; + + /* + * Setting signals_enabled and reading signals_pending must + * happen in this order. + */ + barrier(); + + save_pending = signals_pending; + if (save_pending == 0) + return; + + signals_pending = 0; + + /* + * We have pending interrupts, so disable signals, as the + * handlers expect them off when they are called. They will + * be enabled again above. + */ + + signals_enabled = 0; + + /* + * Deal with SIGIO first because the alarm handler might + * schedule, leaving the pending SIGIO stranded until we come + * back here. + * + * SIGIO's handler doesn't use siginfo or mcontext, + * so they can be NULL. + */ + if (save_pending & SIGIO_MASK) + sig_handler_common(SIGIO, NULL, NULL); + + if (save_pending & SIGVTALRM_MASK) + real_alarm_handler(NULL); + } +} + +int get_signals(void) +{ + return signals_enabled; +} + +int set_signals(int enable) +{ + int ret; + if (signals_enabled == enable) + return enable; + + ret = signals_enabled; + if (enable) + unblock_signals(); + else block_signals(); + + return ret; +} + +int os_is_signal_stack(void) +{ + stack_t ss; + sigaltstack(NULL, &ss); + + return ss.ss_flags & SS_ONSTACK; +} |