| /* |
| * Emulation of Linux signals |
| * |
| * Copyright (c) 2003 Fabrice Bellard |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License as published by |
| * the Free Software Foundation; either version 2 of the License, or |
| * (at your option) any later version. |
| * |
| * This program is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| * GNU General Public License for more details. |
| * |
| * You should have received a copy of the GNU General Public License |
| * along with this program; if not, see <http://www.gnu.org/licenses/>. |
| */ |
| #include "qemu/osdep.h" |
| #include "qemu/bitops.h" |
| #include "exec/gdbstub.h" |
| |
| #include <sys/ucontext.h> |
| #include <sys/resource.h> |
| |
| #include "qemu.h" |
| #include "user-internals.h" |
| #include "strace.h" |
| #include "loader.h" |
| #include "trace.h" |
| #include "signal-common.h" |
| |
| static struct target_sigaction sigact_table[TARGET_NSIG]; |
| |
| static void host_signal_handler(int host_signum, siginfo_t *info, |
| void *puc); |
| |
| /* Fallback addresses into sigtramp page. */ |
| abi_ulong default_sigreturn; |
| abi_ulong default_rt_sigreturn; |
| |
| /* |
| * System includes define _NSIG as SIGRTMAX + 1, |
| * but qemu (like the kernel) defines TARGET_NSIG as TARGET_SIGRTMAX |
| * and the first signal is SIGHUP defined as 1 |
| * Signal number 0 is reserved for use as kill(pid, 0), to test whether |
| * a process exists without sending it a signal. |
| */ |
| #ifdef __SIGRTMAX |
| QEMU_BUILD_BUG_ON(__SIGRTMAX + 1 != _NSIG); |
| #endif |
| static uint8_t host_to_target_signal_table[_NSIG] = { |
| [SIGHUP] = TARGET_SIGHUP, |
| [SIGINT] = TARGET_SIGINT, |
| [SIGQUIT] = TARGET_SIGQUIT, |
| [SIGILL] = TARGET_SIGILL, |
| [SIGTRAP] = TARGET_SIGTRAP, |
| [SIGABRT] = TARGET_SIGABRT, |
| /* [SIGIOT] = TARGET_SIGIOT,*/ |
| [SIGBUS] = TARGET_SIGBUS, |
| [SIGFPE] = TARGET_SIGFPE, |
| [SIGKILL] = TARGET_SIGKILL, |
| [SIGUSR1] = TARGET_SIGUSR1, |
| [SIGSEGV] = TARGET_SIGSEGV, |
| [SIGUSR2] = TARGET_SIGUSR2, |
| [SIGPIPE] = TARGET_SIGPIPE, |
| [SIGALRM] = TARGET_SIGALRM, |
| [SIGTERM] = TARGET_SIGTERM, |
| #ifdef SIGSTKFLT |
| [SIGSTKFLT] = TARGET_SIGSTKFLT, |
| #endif |
| [SIGCHLD] = TARGET_SIGCHLD, |
| [SIGCONT] = TARGET_SIGCONT, |
| [SIGSTOP] = TARGET_SIGSTOP, |
| [SIGTSTP] = TARGET_SIGTSTP, |
| [SIGTTIN] = TARGET_SIGTTIN, |
| [SIGTTOU] = TARGET_SIGTTOU, |
| [SIGURG] = TARGET_SIGURG, |
| [SIGXCPU] = TARGET_SIGXCPU, |
| [SIGXFSZ] = TARGET_SIGXFSZ, |
| [SIGVTALRM] = TARGET_SIGVTALRM, |
| [SIGPROF] = TARGET_SIGPROF, |
| [SIGWINCH] = TARGET_SIGWINCH, |
| [SIGIO] = TARGET_SIGIO, |
| [SIGPWR] = TARGET_SIGPWR, |
| [SIGSYS] = TARGET_SIGSYS, |
| /* next signals stay the same */ |
| }; |
| |
| static uint8_t target_to_host_signal_table[TARGET_NSIG + 1]; |
| |
| /* valid sig is between 1 and _NSIG - 1 */ |
| int host_to_target_signal(int sig) |
| { |
| if (sig < 1 || sig >= _NSIG) { |
| return sig; |
| } |
| return host_to_target_signal_table[sig]; |
| } |
| |
| /* valid sig is between 1 and TARGET_NSIG */ |
| int target_to_host_signal(int sig) |
| { |
| if (sig < 1 || sig > TARGET_NSIG) { |
| return sig; |
| } |
| return target_to_host_signal_table[sig]; |
| } |
| |
| static inline void target_sigaddset(target_sigset_t *set, int signum) |
| { |
| signum--; |
| abi_ulong mask = (abi_ulong)1 << (signum % TARGET_NSIG_BPW); |
| set->sig[signum / TARGET_NSIG_BPW] |= mask; |
| } |
| |
| static inline int target_sigismember(const target_sigset_t *set, int signum) |
| { |
| signum--; |
| abi_ulong mask = (abi_ulong)1 << (signum % TARGET_NSIG_BPW); |
| return ((set->sig[signum / TARGET_NSIG_BPW] & mask) != 0); |
| } |
| |
| void host_to_target_sigset_internal(target_sigset_t *d, |
| const sigset_t *s) |
| { |
| int host_sig, target_sig; |
| target_sigemptyset(d); |
| for (host_sig = 1; host_sig < _NSIG; host_sig++) { |
| target_sig = host_to_target_signal(host_sig); |
| if (target_sig < 1 || target_sig > TARGET_NSIG) { |
| continue; |
| } |
| if (sigismember(s, host_sig)) { |
| target_sigaddset(d, target_sig); |
| } |
| } |
| } |
| |
| void host_to_target_sigset(target_sigset_t *d, const sigset_t *s) |
| { |
| target_sigset_t d1; |
| int i; |
| |
| host_to_target_sigset_internal(&d1, s); |
| for(i = 0;i < TARGET_NSIG_WORDS; i++) |
| d->sig[i] = tswapal(d1.sig[i]); |
| } |
| |
| void target_to_host_sigset_internal(sigset_t *d, |
| const target_sigset_t *s) |
| { |
| int host_sig, target_sig; |
| sigemptyset(d); |
| for (target_sig = 1; target_sig <= TARGET_NSIG; target_sig++) { |
| host_sig = target_to_host_signal(target_sig); |
| if (host_sig < 1 || host_sig >= _NSIG) { |
| continue; |
| } |
| if (target_sigismember(s, target_sig)) { |
| sigaddset(d, host_sig); |
| } |
| } |
| } |
| |
| void target_to_host_sigset(sigset_t *d, const target_sigset_t *s) |
| { |
| target_sigset_t s1; |
| int i; |
| |
| for(i = 0;i < TARGET_NSIG_WORDS; i++) |
| s1.sig[i] = tswapal(s->sig[i]); |
| target_to_host_sigset_internal(d, &s1); |
| } |
| |
| void host_to_target_old_sigset(abi_ulong *old_sigset, |
| const sigset_t *sigset) |
| { |
| target_sigset_t d; |
| host_to_target_sigset(&d, sigset); |
| *old_sigset = d.sig[0]; |
| } |
| |
| void target_to_host_old_sigset(sigset_t *sigset, |
| const abi_ulong *old_sigset) |
| { |
| target_sigset_t d; |
| int i; |
| |
| d.sig[0] = *old_sigset; |
| for(i = 1;i < TARGET_NSIG_WORDS; i++) |
| d.sig[i] = 0; |
| target_to_host_sigset(sigset, &d); |
| } |
| |
| int block_signals(void) |
| { |
| TaskState *ts = (TaskState *)thread_cpu->opaque; |
| sigset_t set; |
| |
| /* It's OK to block everything including SIGSEGV, because we won't |
| * run any further guest code before unblocking signals in |
| * process_pending_signals(). |
| */ |
| sigfillset(&set); |
| sigprocmask(SIG_SETMASK, &set, 0); |
| |
| return qatomic_xchg(&ts->signal_pending, 1); |
| } |
| |
| /* Wrapper for sigprocmask function |
| * Emulates a sigprocmask in a safe way for the guest. Note that set and oldset |
| * are host signal set, not guest ones. Returns -TARGET_ERESTARTSYS if |
| * a signal was already pending and the syscall must be restarted, or |
| * 0 on success. |
| * If set is NULL, this is guaranteed not to fail. |
| */ |
| int do_sigprocmask(int how, const sigset_t *set, sigset_t *oldset) |
| { |
| TaskState *ts = (TaskState *)thread_cpu->opaque; |
| |
| if (oldset) { |
| *oldset = ts->signal_mask; |
| } |
| |
| if (set) { |
| int i; |
| |
| if (block_signals()) { |
| return -TARGET_ERESTARTSYS; |
| } |
| |
| switch (how) { |
| case SIG_BLOCK: |
| sigorset(&ts->signal_mask, &ts->signal_mask, set); |
| break; |
| case SIG_UNBLOCK: |
| for (i = 1; i <= NSIG; ++i) { |
| if (sigismember(set, i)) { |
| sigdelset(&ts->signal_mask, i); |
| } |
| } |
| break; |
| case SIG_SETMASK: |
| ts->signal_mask = *set; |
| break; |
| default: |
| g_assert_not_reached(); |
| } |
| |
| /* Silently ignore attempts to change blocking status of KILL or STOP */ |
| sigdelset(&ts->signal_mask, SIGKILL); |
| sigdelset(&ts->signal_mask, SIGSTOP); |
| } |
| return 0; |
| } |
| |
| #if !defined(TARGET_NIOS2) |
| /* Just set the guest's signal mask to the specified value; the |
| * caller is assumed to have called block_signals() already. |
| */ |
| void set_sigmask(const sigset_t *set) |
| { |
| TaskState *ts = (TaskState *)thread_cpu->opaque; |
| |
| ts->signal_mask = *set; |
| } |
| #endif |
| |
| /* sigaltstack management */ |
| |
| int on_sig_stack(unsigned long sp) |
| { |
| TaskState *ts = (TaskState *)thread_cpu->opaque; |
| |
| return (sp - ts->sigaltstack_used.ss_sp |
| < ts->sigaltstack_used.ss_size); |
| } |
| |
| int sas_ss_flags(unsigned long sp) |
| { |
| TaskState *ts = (TaskState *)thread_cpu->opaque; |
| |
| return (ts->sigaltstack_used.ss_size == 0 ? SS_DISABLE |
| : on_sig_stack(sp) ? SS_ONSTACK : 0); |
| } |
| |
| abi_ulong target_sigsp(abi_ulong sp, struct target_sigaction *ka) |
| { |
| /* |
| * This is the X/Open sanctioned signal stack switching. |
| */ |
| TaskState *ts = (TaskState *)thread_cpu->opaque; |
| |
| if ((ka->sa_flags & TARGET_SA_ONSTACK) && !sas_ss_flags(sp)) { |
| return ts->sigaltstack_used.ss_sp + ts->sigaltstack_used.ss_size; |
| } |
| return sp; |
| } |
| |
| void target_save_altstack(target_stack_t *uss, CPUArchState *env) |
| { |
| TaskState *ts = (TaskState *)thread_cpu->opaque; |
| |
| __put_user(ts->sigaltstack_used.ss_sp, &uss->ss_sp); |
| __put_user(sas_ss_flags(get_sp_from_cpustate(env)), &uss->ss_flags); |
| __put_user(ts->sigaltstack_used.ss_size, &uss->ss_size); |
| } |
| |
| abi_long target_restore_altstack(target_stack_t *uss, CPUArchState *env) |
| { |
| TaskState *ts = (TaskState *)thread_cpu->opaque; |
| size_t minstacksize = TARGET_MINSIGSTKSZ; |
| target_stack_t ss; |
| |
| #if defined(TARGET_PPC64) |
| /* ELF V2 for PPC64 has a 4K minimum stack size for signal handlers */ |
| struct image_info *image = ts->info; |
| if (get_ppc64_abi(image) > 1) { |
| minstacksize = 4096; |
| } |
| #endif |
| |
| __get_user(ss.ss_sp, &uss->ss_sp); |
| __get_user(ss.ss_size, &uss->ss_size); |
| __get_user(ss.ss_flags, &uss->ss_flags); |
| |
| if (on_sig_stack(get_sp_from_cpustate(env))) { |
| return -TARGET_EPERM; |
| } |
| |
| switch (ss.ss_flags) { |
| default: |
| return -TARGET_EINVAL; |
| |
| case TARGET_SS_DISABLE: |
| ss.ss_size = 0; |
| ss.ss_sp = 0; |
| break; |
| |
| case TARGET_SS_ONSTACK: |
| case 0: |
| if (ss.ss_size < minstacksize) { |
| return -TARGET_ENOMEM; |
| } |
| break; |
| } |
| |
| ts->sigaltstack_used.ss_sp = ss.ss_sp; |
| ts->sigaltstack_used.ss_size = ss.ss_size; |
| return 0; |
| } |
| |
| /* siginfo conversion */ |
| |
| static inline void host_to_target_siginfo_noswap(target_siginfo_t *tinfo, |
| const siginfo_t *info) |
| { |
| int sig = host_to_target_signal(info->si_signo); |
| int si_code = info->si_code; |
| int si_type; |
| tinfo->si_signo = sig; |
| tinfo->si_errno = 0; |
| tinfo->si_code = info->si_code; |
| |
| /* This memset serves two purposes: |
| * (1) ensure we don't leak random junk to the guest later |
| * (2) placate false positives from gcc about fields |
| * being used uninitialized if it chooses to inline both this |
| * function and tswap_siginfo() into host_to_target_siginfo(). |
| */ |
| memset(tinfo->_sifields._pad, 0, sizeof(tinfo->_sifields._pad)); |
| |
| /* This is awkward, because we have to use a combination of |
| * the si_code and si_signo to figure out which of the union's |
| * members are valid. (Within the host kernel it is always possible |
| * to tell, but the kernel carefully avoids giving userspace the |
| * high 16 bits of si_code, so we don't have the information to |
| * do this the easy way...) We therefore make our best guess, |
| * bearing in mind that a guest can spoof most of the si_codes |
| * via rt_sigqueueinfo() if it likes. |
| * |
| * Once we have made our guess, we record it in the top 16 bits of |
| * the si_code, so that tswap_siginfo() later can use it. |
| * tswap_siginfo() will strip these top bits out before writing |
| * si_code to the guest (sign-extending the lower bits). |
| */ |
| |
| switch (si_code) { |
| case SI_USER: |
| case SI_TKILL: |
| case SI_KERNEL: |
| /* Sent via kill(), tkill() or tgkill(), or direct from the kernel. |
| * These are the only unspoofable si_code values. |
| */ |
| tinfo->_sifields._kill._pid = info->si_pid; |
| tinfo->_sifields._kill._uid = info->si_uid; |
| si_type = QEMU_SI_KILL; |
| break; |
| default: |
| /* Everything else is spoofable. Make best guess based on signal */ |
| switch (sig) { |
| case TARGET_SIGCHLD: |
| tinfo->_sifields._sigchld._pid = info->si_pid; |
| tinfo->_sifields._sigchld._uid = info->si_uid; |
| tinfo->_sifields._sigchld._status = info->si_status; |
| tinfo->_sifields._sigchld._utime = info->si_utime; |
| tinfo->_sifields._sigchld._stime = info->si_stime; |
| si_type = QEMU_SI_CHLD; |
| break; |
| case TARGET_SIGIO: |
| tinfo->_sifields._sigpoll._band = info->si_band; |
| tinfo->_sifields._sigpoll._fd = info->si_fd; |
| si_type = QEMU_SI_POLL; |
| break; |
| default: |
| /* Assume a sigqueue()/mq_notify()/rt_sigqueueinfo() source. */ |
| tinfo->_sifields._rt._pid = info->si_pid; |
| tinfo->_sifields._rt._uid = info->si_uid; |
| /* XXX: potential problem if 64 bit */ |
| tinfo->_sifields._rt._sigval.sival_ptr |
| = (abi_ulong)(unsigned long)info->si_value.sival_ptr; |
| si_type = QEMU_SI_RT; |
| break; |
| } |
| break; |
| } |
| |
| tinfo->si_code = deposit32(si_code, 16, 16, si_type); |
| } |
| |
| void tswap_siginfo(target_siginfo_t *tinfo, |
| const target_siginfo_t *info) |
| { |
| int si_type = extract32(info->si_code, 16, 16); |
| int si_code = sextract32(info->si_code, 0, 16); |
| |
| __put_user(info->si_signo, &tinfo->si_signo); |
| __put_user(info->si_errno, &tinfo->si_errno); |
| __put_user(si_code, &tinfo->si_code); |
| |
| /* We can use our internal marker of which fields in the structure |
| * are valid, rather than duplicating the guesswork of |
| * host_to_target_siginfo_noswap() here. |
| */ |
| switch (si_type) { |
| case QEMU_SI_KILL: |
| __put_user(info->_sifields._kill._pid, &tinfo->_sifields._kill._pid); |
| __put_user(info->_sifields._kill._uid, &tinfo->_sifields._kill._uid); |
| break; |
| case QEMU_SI_TIMER: |
| __put_user(info->_sifields._timer._timer1, |
| &tinfo->_sifields._timer._timer1); |
| __put_user(info->_sifields._timer._timer2, |
| &tinfo->_sifields._timer._timer2); |
| break; |
| case QEMU_SI_POLL: |
| __put_user(info->_sifields._sigpoll._band, |
| &tinfo->_sifields._sigpoll._band); |
| __put_user(info->_sifields._sigpoll._fd, |
| &tinfo->_sifields._sigpoll._fd); |
| break; |
| case QEMU_SI_FAULT: |
| __put_user(info->_sifields._sigfault._addr, |
| &tinfo->_sifields._sigfault._addr); |
| break; |
| case QEMU_SI_CHLD: |
| __put_user(info->_sifields._sigchld._pid, |
| &tinfo->_sifields._sigchld._pid); |
| __put_user(info->_sifields._sigchld._uid, |
| &tinfo->_sifields._sigchld._uid); |
| __put_user(info->_sifields._sigchld._status, |
| &tinfo->_sifields._sigchld._status); |
| __put_user(info->_sifields._sigchld._utime, |
| &tinfo->_sifields._sigchld._utime); |
| __put_user(info->_sifields._sigchld._stime, |
| &tinfo->_sifields._sigchld._stime); |
| break; |
| case QEMU_SI_RT: |
| __put_user(info->_sifields._rt._pid, &tinfo->_sifields._rt._pid); |
| __put_user(info->_sifields._rt._uid, &tinfo->_sifields._rt._uid); |
| __put_user(info->_sifields._rt._sigval.sival_ptr, |
| &tinfo->_sifields._rt._sigval.sival_ptr); |
| break; |
| default: |
| g_assert_not_reached(); |
| } |
| } |
| |
| void host_to_target_siginfo(target_siginfo_t *tinfo, const siginfo_t *info) |
| { |
| target_siginfo_t tgt_tmp; |
| host_to_target_siginfo_noswap(&tgt_tmp, info); |
| tswap_siginfo(tinfo, &tgt_tmp); |
| } |
| |
| /* XXX: we support only POSIX RT signals are used. */ |
| /* XXX: find a solution for 64 bit (additional malloced data is needed) */ |
| void target_to_host_siginfo(siginfo_t *info, const target_siginfo_t *tinfo) |
| { |
| /* This conversion is used only for the rt_sigqueueinfo syscall, |
| * and so we know that the _rt fields are the valid ones. |
| */ |
| abi_ulong sival_ptr; |
| |
| __get_user(info->si_signo, &tinfo->si_signo); |
| __get_user(info->si_errno, &tinfo->si_errno); |
| __get_user(info->si_code, &tinfo->si_code); |
| __get_user(info->si_pid, &tinfo->_sifields._rt._pid); |
| __get_user(info->si_uid, &tinfo->_sifields._rt._uid); |
| __get_user(sival_ptr, &tinfo->_sifields._rt._sigval.sival_ptr); |
| info->si_value.sival_ptr = (void *)(long)sival_ptr; |
| } |
| |
| static int fatal_signal (int sig) |
| { |
| switch (sig) { |
| case TARGET_SIGCHLD: |
| case TARGET_SIGURG: |
| case TARGET_SIGWINCH: |
| /* Ignored by default. */ |
| return 0; |
| case TARGET_SIGCONT: |
| case TARGET_SIGSTOP: |
| case TARGET_SIGTSTP: |
| case TARGET_SIGTTIN: |
| case TARGET_SIGTTOU: |
| /* Job control signals. */ |
| return 0; |
| default: |
| return 1; |
| } |
| } |
| |
| /* returns 1 if given signal should dump core if not handled */ |
| static int core_dump_signal(int sig) |
| { |
| switch (sig) { |
| case TARGET_SIGABRT: |
| case TARGET_SIGFPE: |
| case TARGET_SIGILL: |
| case TARGET_SIGQUIT: |
| case TARGET_SIGSEGV: |
| case TARGET_SIGTRAP: |
| case TARGET_SIGBUS: |
| return (1); |
| default: |
| return (0); |
| } |
| } |
| |
| static void signal_table_init(void) |
| { |
| int host_sig, target_sig, count; |
| |
| /* |
| * Signals are supported starting from TARGET_SIGRTMIN and going up |
| * until we run out of host realtime signals. |
| * glibc at least uses only the lower 2 rt signals and probably |
| * nobody's using the upper ones. |
| * it's why SIGRTMIN (34) is generally greater than __SIGRTMIN (32) |
| * To fix this properly we need to do manual signal delivery multiplexed |
| * over a single host signal. |
| * Attempts for configure "missing" signals via sigaction will be |
| * silently ignored. |
| */ |
| for (host_sig = SIGRTMIN; host_sig <= SIGRTMAX; host_sig++) { |
| target_sig = host_sig - SIGRTMIN + TARGET_SIGRTMIN; |
| if (target_sig <= TARGET_NSIG) { |
| host_to_target_signal_table[host_sig] = target_sig; |
| } |
| } |
| |
| /* generate signal conversion tables */ |
| for (target_sig = 1; target_sig <= TARGET_NSIG; target_sig++) { |
| target_to_host_signal_table[target_sig] = _NSIG; /* poison */ |
| } |
| for (host_sig = 1; host_sig < _NSIG; host_sig++) { |
| if (host_to_target_signal_table[host_sig] == 0) { |
| host_to_target_signal_table[host_sig] = host_sig; |
| } |
| target_sig = host_to_target_signal_table[host_sig]; |
| if (target_sig <= TARGET_NSIG) { |
| target_to_host_signal_table[target_sig] = host_sig; |
| } |
| } |
| |
| if (trace_event_get_state_backends(TRACE_SIGNAL_TABLE_INIT)) { |
| for (target_sig = 1, count = 0; target_sig <= TARGET_NSIG; target_sig++) { |
| if (target_to_host_signal_table[target_sig] == _NSIG) { |
| count++; |
| } |
| } |
| trace_signal_table_init(count); |
| } |
| } |
| |
| void signal_init(void) |
| { |
| TaskState *ts = (TaskState *)thread_cpu->opaque; |
| struct sigaction act; |
| struct sigaction oact; |
| int i; |
| int host_sig; |
| |
| /* initialize signal conversion tables */ |
| signal_table_init(); |
| |
| /* Set the signal mask from the host mask. */ |
| sigprocmask(0, 0, &ts->signal_mask); |
| |
| sigfillset(&act.sa_mask); |
| act.sa_flags = SA_SIGINFO; |
| act.sa_sigaction = host_signal_handler; |
| for(i = 1; i <= TARGET_NSIG; i++) { |
| #ifdef CONFIG_GPROF |
| if (i == TARGET_SIGPROF) { |
| continue; |
| } |
| #endif |
| host_sig = target_to_host_signal(i); |
| sigaction(host_sig, NULL, &oact); |
| if (oact.sa_sigaction == (void *)SIG_IGN) { |
| sigact_table[i - 1]._sa_handler = TARGET_SIG_IGN; |
| } else if (oact.sa_sigaction == (void *)SIG_DFL) { |
| sigact_table[i - 1]._sa_handler = TARGET_SIG_DFL; |
| } |
| /* If there's already a handler installed then something has |
| gone horribly wrong, so don't even try to handle that case. */ |
| /* Install some handlers for our own use. We need at least |
| SIGSEGV and SIGBUS, to detect exceptions. We can not just |
| trap all signals because it affects syscall interrupt |
| behavior. But do trap all default-fatal signals. */ |
| if (fatal_signal (i)) |
| sigaction(host_sig, &act, NULL); |
| } |
| } |
| |
| /* Force a synchronously taken signal. The kernel force_sig() function |
| * also forces the signal to "not blocked, not ignored", but for QEMU |
| * that work is done in process_pending_signals(). |
| */ |
| void force_sig(int sig) |
| { |
| CPUState *cpu = thread_cpu; |
| CPUArchState *env = cpu->env_ptr; |
| target_siginfo_t info = {}; |
| |
| info.si_signo = sig; |
| info.si_errno = 0; |
| info.si_code = TARGET_SI_KERNEL; |
| info._sifields._kill._pid = 0; |
| info._sifields._kill._uid = 0; |
| queue_signal(env, info.si_signo, QEMU_SI_KILL, &info); |
| } |
| |
| /* |
| * Force a synchronously taken QEMU_SI_FAULT signal. For QEMU the |
| * 'force' part is handled in process_pending_signals(). |
| */ |
| void force_sig_fault(int sig, int code, abi_ulong addr) |
| { |
| CPUState *cpu = thread_cpu; |
| CPUArchState *env = cpu->env_ptr; |
| target_siginfo_t info = {}; |
| |
| info.si_signo = sig; |
| info.si_errno = 0; |
| info.si_code = code; |
| info._sifields._sigfault._addr = addr; |
| queue_signal(env, sig, QEMU_SI_FAULT, &info); |
| } |
| |
| /* Force a SIGSEGV if we couldn't write to memory trying to set |
| * up the signal frame. oldsig is the signal we were trying to handle |
| * at the point of failure. |
| */ |
| #if !defined(TARGET_RISCV) |
| void force_sigsegv(int oldsig) |
| { |
| if (oldsig == SIGSEGV) { |
| /* Make sure we don't try to deliver the signal again; this will |
| * end up with handle_pending_signal() calling dump_core_and_abort(). |
| */ |
| sigact_table[oldsig - 1]._sa_handler = TARGET_SIG_DFL; |
| } |
| force_sig(TARGET_SIGSEGV); |
| } |
| |
| #endif |
| |
| /* abort execution with signal */ |
| static void QEMU_NORETURN dump_core_and_abort(int target_sig) |
| { |
| CPUState *cpu = thread_cpu; |
| CPUArchState *env = cpu->env_ptr; |
| TaskState *ts = (TaskState *)cpu->opaque; |
| int host_sig, core_dumped = 0; |
| struct sigaction act; |
| |
| host_sig = target_to_host_signal(target_sig); |
| trace_user_force_sig(env, target_sig, host_sig); |
| gdb_signalled(env, target_sig); |
| |
| /* dump core if supported by target binary format */ |
| if (core_dump_signal(target_sig) && (ts->bprm->core_dump != NULL)) { |
| stop_all_tasks(); |
| core_dumped = |
| ((*ts->bprm->core_dump)(target_sig, env) == 0); |
| } |
| if (core_dumped) { |
| /* we already dumped the core of target process, we don't want |
| * a coredump of qemu itself */ |
| struct rlimit nodump; |
| getrlimit(RLIMIT_CORE, &nodump); |
| nodump.rlim_cur=0; |
| setrlimit(RLIMIT_CORE, &nodump); |
| (void) fprintf(stderr, "qemu: uncaught target signal %d (%s) - %s\n", |
| target_sig, strsignal(host_sig), "core dumped" ); |
| } |
| |
| /* The proper exit code for dying from an uncaught signal is |
| * -<signal>. The kernel doesn't allow exit() or _exit() to pass |
| * a negative value. To get the proper exit code we need to |
| * actually die from an uncaught signal. Here the default signal |
| * handler is installed, we send ourself a signal and we wait for |
| * it to arrive. */ |
| sigfillset(&act.sa_mask); |
| act.sa_handler = SIG_DFL; |
| act.sa_flags = 0; |
| sigaction(host_sig, &act, NULL); |
| |
| /* For some reason raise(host_sig) doesn't send the signal when |
| * statically linked on x86-64. */ |
| kill(getpid(), host_sig); |
| |
| /* Make sure the signal isn't masked (just reuse the mask inside |
| of act) */ |
| sigdelset(&act.sa_mask, host_sig); |
| sigsuspend(&act.sa_mask); |
| |
| /* unreachable */ |
| abort(); |
| } |
| |
| /* queue a signal so that it will be send to the virtual CPU as soon |
| as possible */ |
| int queue_signal(CPUArchState *env, int sig, int si_type, |
| target_siginfo_t *info) |
| { |
| CPUState *cpu = env_cpu(env); |
| TaskState *ts = cpu->opaque; |
| |
| trace_user_queue_signal(env, sig); |
| |
| info->si_code = deposit32(info->si_code, 16, 16, si_type); |
| |
| ts->sync_signal.info = *info; |
| ts->sync_signal.pending = sig; |
| /* signal that a new signal is pending */ |
| qatomic_set(&ts->signal_pending, 1); |
| return 1; /* indicates that the signal was queued */ |
| } |
| |
| #ifndef HAVE_SAFE_SYSCALL |
| static inline void rewind_if_in_safe_syscall(void *puc) |
| { |
| /* Default version: never rewind */ |
| } |
| #endif |
| |
| static void host_signal_handler(int host_signum, siginfo_t *info, |
| void *puc) |
| { |
| CPUArchState *env = thread_cpu->env_ptr; |
| CPUState *cpu = env_cpu(env); |
| TaskState *ts = cpu->opaque; |
| |
| int sig; |
| target_siginfo_t tinfo; |
| ucontext_t *uc = puc; |
| struct emulated_sigtable *k; |
| |
| /* the CPU emulator uses some host signals to detect exceptions, |
| we forward to it some signals */ |
| if ((host_signum == SIGSEGV || host_signum == SIGBUS) |
| && info->si_code > 0) { |
| if (cpu_signal_handler(host_signum, info, puc)) |
| return; |
| } |
| |
| /* get target signal number */ |
| sig = host_to_target_signal(host_signum); |
| if (sig < 1 || sig > TARGET_NSIG) |
| return; |
| trace_user_host_signal(env, host_signum, sig); |
| |
| rewind_if_in_safe_syscall(puc); |
| |
| host_to_target_siginfo_noswap(&tinfo, info); |
| k = &ts->sigtab[sig - 1]; |
| k->info = tinfo; |
| k->pending = sig; |
| ts->signal_pending = 1; |
| |
| /* Block host signals until target signal handler entered. We |
| * can't block SIGSEGV or SIGBUS while we're executing guest |
| * code in case the guest code provokes one in the window between |
| * now and it getting out to the main loop. Signals will be |
| * unblocked again in process_pending_signals(). |
| * |
| * WARNING: we cannot use sigfillset() here because the uc_sigmask |
| * field is a kernel sigset_t, which is much smaller than the |
| * libc sigset_t which sigfillset() operates on. Using sigfillset() |
| * would write 0xff bytes off the end of the structure and trash |
| * data on the struct. |
| * We can't use sizeof(uc->uc_sigmask) either, because the libc |
| * headers define the struct field with the wrong (too large) type. |
| */ |
| memset(&uc->uc_sigmask, 0xff, SIGSET_T_SIZE); |
| sigdelset(&uc->uc_sigmask, SIGSEGV); |
| sigdelset(&uc->uc_sigmask, SIGBUS); |
| |
| /* interrupt the virtual CPU as soon as possible */ |
| cpu_exit(thread_cpu); |
| } |
| |
| /* do_sigaltstack() returns target values and errnos. */ |
| /* compare linux/kernel/signal.c:do_sigaltstack() */ |
| abi_long do_sigaltstack(abi_ulong uss_addr, abi_ulong uoss_addr, |
| CPUArchState *env) |
| { |
| target_stack_t oss, *uoss = NULL; |
| abi_long ret = -TARGET_EFAULT; |
| |
| if (uoss_addr) { |
| /* Verify writability now, but do not alter user memory yet. */ |
| if (!lock_user_struct(VERIFY_WRITE, uoss, uoss_addr, 0)) { |
| goto out; |
| } |
| target_save_altstack(&oss, env); |
| } |
| |
| if (uss_addr) { |
| target_stack_t *uss; |
| |
| if (!lock_user_struct(VERIFY_READ, uss, uss_addr, 1)) { |
| goto out; |
| } |
| ret = target_restore_altstack(uss, env); |
| if (ret) { |
| goto out; |
| } |
| } |
| |
| if (uoss_addr) { |
| memcpy(uoss, &oss, sizeof(oss)); |
| unlock_user_struct(uoss, uoss_addr, 1); |
| uoss = NULL; |
| } |
| ret = 0; |
| |
| out: |
| if (uoss) { |
| unlock_user_struct(uoss, uoss_addr, 0); |
| } |
| return ret; |
| } |
| |
| /* do_sigaction() return target values and host errnos */ |
| int do_sigaction(int sig, const struct target_sigaction *act, |
| struct target_sigaction *oact, abi_ulong ka_restorer) |
| { |
| struct target_sigaction *k; |
| struct sigaction act1; |
| int host_sig; |
| int ret = 0; |
| |
| trace_signal_do_sigaction_guest(sig, TARGET_NSIG); |
| |
| if (sig < 1 || sig > TARGET_NSIG) { |
| return -TARGET_EINVAL; |
| } |
| |
| if (act && (sig == TARGET_SIGKILL || sig == TARGET_SIGSTOP)) { |
| return -TARGET_EINVAL; |
| } |
| |
| if (block_signals()) { |
| return -TARGET_ERESTARTSYS; |
| } |
| |
| k = &sigact_table[sig - 1]; |
| if (oact) { |
| __put_user(k->_sa_handler, &oact->_sa_handler); |
| __put_user(k->sa_flags, &oact->sa_flags); |
| #ifdef TARGET_ARCH_HAS_SA_RESTORER |
| __put_user(k->sa_restorer, &oact->sa_restorer); |
| #endif |
| /* Not swapped. */ |
| oact->sa_mask = k->sa_mask; |
| } |
| if (act) { |
| /* FIXME: This is not threadsafe. */ |
| __get_user(k->_sa_handler, &act->_sa_handler); |
| __get_user(k->sa_flags, &act->sa_flags); |
| #ifdef TARGET_ARCH_HAS_SA_RESTORER |
| __get_user(k->sa_restorer, &act->sa_restorer); |
| #endif |
| #ifdef TARGET_ARCH_HAS_KA_RESTORER |
| k->ka_restorer = ka_restorer; |
| #endif |
| /* To be swapped in target_to_host_sigset. */ |
| k->sa_mask = act->sa_mask; |
| |
| /* we update the host linux signal state */ |
| host_sig = target_to_host_signal(sig); |
| trace_signal_do_sigaction_host(host_sig, TARGET_NSIG); |
| if (host_sig > SIGRTMAX) { |
| /* we don't have enough host signals to map all target signals */ |
| qemu_log_mask(LOG_UNIMP, "Unsupported target signal #%d, ignored\n", |
| sig); |
| /* |
| * we don't return an error here because some programs try to |
| * register an handler for all possible rt signals even if they |
| * don't need it. |
| * An error here can abort them whereas there can be no problem |
| * to not have the signal available later. |
| * This is the case for golang, |
| * See https://github.com/golang/go/issues/33746 |
| * So we silently ignore the error. |
| */ |
| return 0; |
| } |
| if (host_sig != SIGSEGV && host_sig != SIGBUS) { |
| sigfillset(&act1.sa_mask); |
| act1.sa_flags = SA_SIGINFO; |
| if (k->sa_flags & TARGET_SA_RESTART) |
| act1.sa_flags |= SA_RESTART; |
| /* NOTE: it is important to update the host kernel signal |
| ignore state to avoid getting unexpected interrupted |
| syscalls */ |
| if (k->_sa_handler == TARGET_SIG_IGN) { |
| act1.sa_sigaction = (void *)SIG_IGN; |
| } else if (k->_sa_handler == TARGET_SIG_DFL) { |
| if (fatal_signal (sig)) |
| act1.sa_sigaction = host_signal_handler; |
| else |
| act1.sa_sigaction = (void *)SIG_DFL; |
| } else { |
| act1.sa_sigaction = host_signal_handler; |
| } |
| ret = sigaction(host_sig, &act1, NULL); |
| } |
| } |
| return ret; |
| } |
| |
| static void handle_pending_signal(CPUArchState *cpu_env, int sig, |
| struct emulated_sigtable *k) |
| { |
| CPUState *cpu = env_cpu(cpu_env); |
| abi_ulong handler; |
| sigset_t set; |
| target_sigset_t target_old_set; |
| struct target_sigaction *sa; |
| TaskState *ts = cpu->opaque; |
| |
| trace_user_handle_signal(cpu_env, sig); |
| /* dequeue signal */ |
| k->pending = 0; |
| |
| sig = gdb_handlesig(cpu, sig); |
| if (!sig) { |
| sa = NULL; |
| handler = TARGET_SIG_IGN; |
| } else { |
| sa = &sigact_table[sig - 1]; |
| handler = sa->_sa_handler; |
| } |
| |
| if (unlikely(qemu_loglevel_mask(LOG_STRACE))) { |
| print_taken_signal(sig, &k->info); |
| } |
| |
| if (handler == TARGET_SIG_DFL) { |
| /* default handler : ignore some signal. The other are job control or fatal */ |
| if (sig == TARGET_SIGTSTP || sig == TARGET_SIGTTIN || sig == TARGET_SIGTTOU) { |
| kill(getpid(),SIGSTOP); |
| } else if (sig != TARGET_SIGCHLD && |
| sig != TARGET_SIGURG && |
| sig != TARGET_SIGWINCH && |
| sig != TARGET_SIGCONT) { |
| dump_core_and_abort(sig); |
| } |
| } else if (handler == TARGET_SIG_IGN) { |
| /* ignore sig */ |
| } else if (handler == TARGET_SIG_ERR) { |
| dump_core_and_abort(sig); |
| } else { |
| /* compute the blocked signals during the handler execution */ |
| sigset_t *blocked_set; |
| |
| target_to_host_sigset(&set, &sa->sa_mask); |
| /* SA_NODEFER indicates that the current signal should not be |
| blocked during the handler */ |
| if (!(sa->sa_flags & TARGET_SA_NODEFER)) |
| sigaddset(&set, target_to_host_signal(sig)); |
| |
| /* save the previous blocked signal state to restore it at the |
| end of the signal execution (see do_sigreturn) */ |
| host_to_target_sigset_internal(&target_old_set, &ts->signal_mask); |
| |
| /* block signals in the handler */ |
| blocked_set = ts->in_sigsuspend ? |
| &ts->sigsuspend_mask : &ts->signal_mask; |
| sigorset(&ts->signal_mask, blocked_set, &set); |
| ts->in_sigsuspend = 0; |
| |
| /* if the CPU is in VM86 mode, we restore the 32 bit values */ |
| #if defined(TARGET_I386) && !defined(TARGET_X86_64) |
| { |
| CPUX86State *env = cpu_env; |
| if (env->eflags & VM_MASK) |
| save_v86_state(env); |
| } |
| #endif |
| /* prepare the stack frame of the virtual CPU */ |
| #if defined(TARGET_ARCH_HAS_SETUP_FRAME) |
| if (sa->sa_flags & TARGET_SA_SIGINFO) { |
| setup_rt_frame(sig, sa, &k->info, &target_old_set, cpu_env); |
| } else { |
| setup_frame(sig, sa, &target_old_set, cpu_env); |
| } |
| #else |
| /* These targets do not have traditional signals. */ |
| setup_rt_frame(sig, sa, &k->info, &target_old_set, cpu_env); |
| #endif |
| if (sa->sa_flags & TARGET_SA_RESETHAND) { |
| sa->_sa_handler = TARGET_SIG_DFL; |
| } |
| } |
| } |
| |
| void process_pending_signals(CPUArchState *cpu_env) |
| { |
| CPUState *cpu = env_cpu(cpu_env); |
| int sig; |
| TaskState *ts = cpu->opaque; |
| sigset_t set; |
| sigset_t *blocked_set; |
| |
| while (qatomic_read(&ts->signal_pending)) { |
| /* FIXME: This is not threadsafe. */ |
| sigfillset(&set); |
| sigprocmask(SIG_SETMASK, &set, 0); |
| |
| restart_scan: |
| sig = ts->sync_signal.pending; |
| if (sig) { |
| /* Synchronous signals are forced, |
| * see force_sig_info() and callers in Linux |
| * Note that not all of our queue_signal() calls in QEMU correspond |
| * to force_sig_info() calls in Linux (some are send_sig_info()). |
| * However it seems like a kernel bug to me to allow the process |
| * to block a synchronous signal since it could then just end up |
| * looping round and round indefinitely. |
| */ |
| if (sigismember(&ts->signal_mask, target_to_host_signal_table[sig]) |
| || sigact_table[sig - 1]._sa_handler == TARGET_SIG_IGN) { |
| sigdelset(&ts->signal_mask, target_to_host_signal_table[sig]); |
| sigact_table[sig - 1]._sa_handler = TARGET_SIG_DFL; |
| } |
| |
| handle_pending_signal(cpu_env, sig, &ts->sync_signal); |
| } |
| |
| for (sig = 1; sig <= TARGET_NSIG; sig++) { |
| blocked_set = ts->in_sigsuspend ? |
| &ts->sigsuspend_mask : &ts->signal_mask; |
| |
| if (ts->sigtab[sig - 1].pending && |
| (!sigismember(blocked_set, |
| target_to_host_signal_table[sig]))) { |
| handle_pending_signal(cpu_env, sig, &ts->sigtab[sig - 1]); |
| /* Restart scan from the beginning, as handle_pending_signal |
| * might have resulted in a new synchronous signal (eg SIGSEGV). |
| */ |
| goto restart_scan; |
| } |
| } |
| |
| /* if no signal is pending, unblock signals and recheck (the act |
| * of unblocking might cause us to take another host signal which |
| * will set signal_pending again). |
| */ |
| qatomic_set(&ts->signal_pending, 0); |
| ts->in_sigsuspend = 0; |
| set = ts->signal_mask; |
| sigdelset(&set, SIGSEGV); |
| sigdelset(&set, SIGBUS); |
| sigprocmask(SIG_SETMASK, &set, 0); |
| } |
| ts->in_sigsuspend = 0; |
| } |
