| |
| /*--------------------------------------------------------------------*/ |
| /*--- Implementation of POSIX signals. ---*/ |
| /*--- vg_signals.c ---*/ |
| /*--------------------------------------------------------------------*/ |
| |
| /* |
| This file is part of Valgrind, an x86 protected-mode emulator |
| designed for debugging and profiling binaries on x86-Unixes. |
| |
| Copyright (C) 2000-2002 Julian Seward |
| jseward@acm.org |
| Julian_Seward@muraroa.demon.co.uk |
| |
| 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, write to the Free Software |
| Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA |
| 02111-1307, USA. |
| |
| The GNU General Public License is contained in the file LICENSE. |
| */ |
| |
| |
| #include "vg_include.h" |
| #include "vg_constants.h" |
| #include "vg_unsafe.h" |
| #include "valgrind.h" /* for VALGRIND_MAGIC_SEQUENCE */ |
| |
| /* --------------------------------------------------------------------- |
| Signal state for this process. |
| ------------------------------------------------------------------ */ |
| |
| /* For each signal, the current action. Is NULL if the client hasn't |
| asked to handle the signal. Consequently, we expect never to |
| receive a signal for which the corresponding handler is NULL. */ |
| void* VG_(sighandler)[VKI_KNSIG]; |
| |
| |
| /* For each signal, either: |
| -- VG_SIGIDLE if not pending and not running |
| -- Handler address if pending |
| -- VG_SIGRUNNING if the handler is running and hasn't (returned or |
| unblocked the signal using sigprocmask following a longjmp out |
| of the handler). |
| */ |
| #define VG_SIGIDLE ((void*)0) |
| #define VG_SIGRUNNING ((void*)1) |
| |
| void* VG_(sigpending)[VKI_KNSIG]; |
| |
| |
| /* For each signal that we have a handler for (ie, for those for which |
| the VG_(sighandler) entry is non-NULL), record whether or not the |
| client asked for syscalls to be restartable (SA_RESTART) if |
| interrupted by this signal. We need to consult this when a signal |
| returns, if it should happen that the signal which we delivered has |
| interrupted a system call. */ |
| Bool vg_sig_sarestart[VKI_KNSIG]; |
| |
| |
| /* --------------------------------------------------------------------- |
| Handy utilities to block/restore all host signals. |
| ------------------------------------------------------------------ */ |
| |
| /* Block all host signals, dumping the old mask in *saved_mask. */ |
| void VG_(block_all_host_signals) ( /* OUT */ vki_ksigset_t* saved_mask ) |
| { |
| Int ret; |
| vki_ksigset_t block_procmask; |
| VG_(ksigfillset)(&block_procmask); |
| ret = VG_(ksigprocmask) |
| (VKI_SIG_SETMASK, &block_procmask, saved_mask); |
| vg_assert(ret == 0); |
| } |
| |
| /* Restore the blocking mask using the supplied saved one. */ |
| void VG_(restore_host_signals) ( /* IN */ vki_ksigset_t* saved_mask ) |
| { |
| Int ret; |
| ret = VG_(ksigprocmask)(VKI_SIG_SETMASK, saved_mask, NULL); |
| vg_assert(ret == 0); |
| } |
| |
| |
| /* --------------------------------------------------------------------- |
| The signal simulation proper. A simplified version of what the |
| Linux kernel does. |
| ------------------------------------------------------------------ */ |
| |
| /* A structure in which to save the application's registers |
| during the execution of signal handlers. */ |
| |
| typedef |
| struct { |
| /* These are parameters to the signal handler. */ |
| UInt retaddr; /* Sig handler's (bogus) return address */ |
| Int sigNo; /* The arg to the sig handler. */ |
| Addr psigInfo; /* ptr to siginfo_t; NULL for now. */ |
| Addr puContext; /* ptr to ucontext; NULL for now. */ |
| /* Sanity check word. */ |
| UInt magicPI; |
| /* Saved processor state. */ |
| UInt fpustate[VG_SIZE_OF_FPUSTATE_W]; |
| UInt eax; |
| UInt ecx; |
| UInt edx; |
| UInt ebx; |
| UInt ebp; |
| UInt esp; |
| UInt esi; |
| UInt edi; |
| Addr eip; |
| UInt eflags; |
| /* Scheduler-private stuff: what was the thread's status prior to |
| delivering this signal? */ |
| ThreadStatus status; |
| /* Sanity check word. Is the highest-addressed word; do not |
| move!*/ |
| UInt magicE; |
| } |
| VgSigFrame; |
| |
| |
| |
| /* Set up a stack frame (VgSigContext) for the client's signal |
| handler. This includes the signal number and a bogus return |
| address. */ |
| static |
| void vg_push_signal_frame ( ThreadId tid, int sigNo ) |
| { |
| Int i; |
| Addr esp; |
| VgSigFrame* frame; |
| ThreadState* tst; |
| |
| tst = VG_(get_thread_state)(tid); |
| esp = tst->m_esp; |
| |
| esp -= sizeof(VgSigFrame); |
| frame = (VgSigFrame*)esp; |
| /* Assert that the frame is placed correctly. */ |
| vg_assert( (sizeof(VgSigFrame) & 0x3) == 0 ); |
| vg_assert( ((Char*)(&frame->magicE)) + sizeof(UInt) |
| == ((Char*)(tst->m_esp)) ); |
| |
| frame->retaddr = (UInt)(&VG_(signalreturn_bogusRA)); |
| frame->sigNo = sigNo; |
| frame->psigInfo = (Addr)NULL; |
| frame->puContext = (Addr)NULL; |
| frame->magicPI = 0x31415927; |
| |
| for (i = 0; i < VG_SIZE_OF_FPUSTATE_W; i++) |
| frame->fpustate[i] = tst->m_fpu[i]; |
| |
| frame->eax = tst->m_eax; |
| frame->ecx = tst->m_ecx; |
| frame->edx = tst->m_edx; |
| frame->ebx = tst->m_ebx; |
| frame->ebp = tst->m_ebp; |
| frame->esp = tst->m_esp; |
| frame->esi = tst->m_esi; |
| frame->edi = tst->m_edi; |
| frame->eip = tst->m_eip; |
| frame->eflags = tst->m_eflags; |
| |
| frame->status = tst->status; |
| |
| frame->magicE = 0x27182818; |
| |
| /* Set the thread so it will next run the handler. */ |
| tst->m_esp = esp; |
| tst->m_eip = (Addr)VG_(sigpending)[sigNo]; |
| /* This thread needs to be marked runnable, but we leave that the |
| caller to do. */ |
| |
| /* Make sigNo and retaddr fields readable -- at 0(%ESP) and 4(%ESP) */ |
| if (VG_(clo_instrument)) { |
| VGM_(make_readable) ( ((Addr)esp)+0 ,4 ); |
| VGM_(make_readable) ( ((Addr)esp)+4 ,4 ); |
| } |
| |
| /* |
| VG_(printf)("pushed signal frame; %%ESP now = %p, next %%EBP = %p\n", |
| esp, tst->m_eip); |
| */ |
| } |
| |
| |
| /* Clear the signal frame created by vg_push_signal_frame, restore the |
| simulated machine state, and return the signal number that the |
| frame was for. */ |
| static |
| Int vg_pop_signal_frame ( ThreadId tid ) |
| { |
| Addr esp; |
| Int sigNo, i; |
| VgSigFrame* frame; |
| ThreadState* tst; |
| |
| tst = VG_(get_thread_state)(tid); |
| |
| /* Correctly reestablish the frame base address. */ |
| esp = tst->m_esp; |
| frame = (VgSigFrame*) |
| (esp -4 /* because the handler's RET pops the RA */ |
| +20 /* because signalreturn_bogusRA pushes 5 words */); |
| |
| vg_assert(frame->magicPI == 0x31415927); |
| vg_assert(frame->magicE == 0x27182818); |
| if (VG_(clo_trace_signals)) |
| VG_(message)(Vg_DebugMsg, "vg_pop_signal_frame: valid magic"); |
| |
| /* restore machine state */ |
| for (i = 0; i < VG_SIZE_OF_FPUSTATE_W; i++) |
| tst->m_fpu[i] = frame->fpustate[i]; |
| |
| /* Mark the frame structure as nonaccessible. Has to happen |
| _before_ vg_m_state.m_esp is given a new value. |
| handle_esp_assignment reads %ESP from baseBlock, so we park it |
| there first. Re-place the junk there afterwards. */ |
| if (VG_(clo_instrument)) { |
| vg_assert(VG_(baseBlock)[VGOFF_(m_esp)] == 0xDEADBEEF); |
| VG_(baseBlock)[VGOFF_(m_esp)] = tst->m_esp; |
| VGM_(handle_esp_assignment) ( frame->esp ); |
| VG_(baseBlock)[VGOFF_(m_esp)] = 0xDEADBEEF; |
| } |
| |
| /* Restore machine state from the saved context. */ |
| tst->m_eax = frame->eax; |
| tst->m_ecx = frame->ecx; |
| tst->m_edx = frame->edx; |
| tst->m_ebx = frame->ebx; |
| tst->m_ebp = frame->ebp; |
| tst->m_esp = frame->esp; |
| tst->m_esi = frame->esi; |
| tst->m_edi = frame->edi; |
| tst->m_eflags = frame->eflags; |
| tst->m_eip = frame->eip; |
| sigNo = frame->sigNo; |
| |
| /* And restore the thread's status to what it was before the signal |
| was delivered. */ |
| tst->status = frame->status; |
| |
| return sigNo; |
| } |
| |
| |
| /* A handler is returning. Restore the machine state from the stacked |
| VgSigContext and continue with whatever was going on before the |
| handler ran. Returns the SA_RESTART syscall-restartability-status |
| of the delivered signal. */ |
| |
| Bool VG_(signal_returns) ( ThreadId tid ) |
| { |
| Int sigNo; |
| vki_ksigset_t saved_procmask; |
| |
| /* Block host signals ... */ |
| VG_(block_all_host_signals)( &saved_procmask ); |
| |
| /* Pop the signal frame and restore tid's status to what it was |
| before the signal was delivered. */ |
| sigNo = vg_pop_signal_frame(tid); |
| |
| /* You would have thought that the following assertion made sense |
| here: |
| |
| vg_assert(vg_sigpending[sigNo] == VG_SIGRUNNING); |
| |
| Alas, you would be wrong. If a sigprocmask has been intercepted |
| and it unblocks this signal, then vg_sigpending[sigNo] will |
| either be VG_SIGIDLE, or (worse) another instance of it will |
| already have arrived, so that the stored value is that of the |
| handler. |
| |
| Note that these anomalies can only occur when a signal handler |
| unblocks its own signal inside itself AND THEN RETURNS anyway |
| (which seems a bizarre thing to do). |
| |
| Ho Hum. This seems like a race condition which surely isn't |
| handled correctly. */ |
| |
| vg_assert(sigNo >= 1 && sigNo < VKI_KNSIG); |
| VG_(sigpending)[sigNo] = VG_SIGIDLE; |
| |
| /* Unlock and return. */ |
| VG_(restore_host_signals)( &saved_procmask ); |
| |
| /* Scheduler now can resume this thread, or perhaps some other. |
| Tell the scheduler whether or not any syscall interrupted by |
| this signal should be restarted, if possible, or no. */ |
| return vg_sig_sarestart[sigNo]; |
| } |
| |
| |
| /* Deliver all pending signals, by building stack frames for their |
| handlers. */ |
| void VG_(deliver_signals) ( ThreadId tid ) |
| { |
| vki_ksigset_t saved_procmask; |
| Int sigNo; |
| Bool found; |
| |
| /* A cheap check. We don't need to have exclusive access |
| to the queue, because in the worst case, vg_oursignalhandler |
| will add signals, causing us to return, thinking there |
| are no signals to deliver, when in fact there are some. |
| A subsequent call here will handle the signal(s) we missed. |
| */ |
| found = False; |
| for (sigNo = 1; sigNo < VKI_KNSIG; sigNo++) |
| if (VG_(sigpending)[sigNo] != VG_SIGIDLE && |
| VG_(sigpending)[sigNo] != VG_SIGRUNNING) found = True; |
| |
| if (!found) return; |
| |
| /* Now we have to do it properly. Get exclusive access by |
| blocking all the host's signals. That means vg_oursignalhandler |
| can't run whilst we are messing with stuff. |
| */ |
| VG_(block_all_host_signals)( &saved_procmask ); |
| |
| /* Look for signals to deliver ... */ |
| for (sigNo = 1; sigNo < VKI_KNSIG; sigNo++) { |
| if (VG_(sigpending)[sigNo] == VG_SIGIDLE || |
| VG_(sigpending)[sigNo] == VG_SIGRUNNING) continue; |
| |
| if (VG_(clo_trace_signals)) |
| VG_(message)(Vg_DebugMsg,"delivering signal %d", sigNo ); |
| |
| /* Create a signal delivery frame, and set the client's %ESP and |
| %EIP so that when execution continues, we will enter the |
| signal handler with the frame on top of the client's stack, |
| as it expects. */ |
| vg_push_signal_frame ( tid, sigNo ); |
| VG_(get_thread_state)(tid)->status = VgTs_Runnable; |
| |
| /* Signify that the signal has been delivered. */ |
| VG_(sigpending)[sigNo] = VG_SIGRUNNING; |
| } |
| |
| /* Unlock and return. */ |
| VG_(restore_host_signals)( &saved_procmask ); |
| return; |
| } |
| |
| |
| /* Receive a signal from the host, and either discard it or park it in |
| the queue of pending signals. All other signals will be blocked |
| when this handler runs. Runs with all host signals blocked, so as |
| to have mutual exclusion when adding stuff to the queue. */ |
| |
| static void VG_(oursignalhandler) ( Int sigNo ) |
| { |
| Int dummy_local; |
| vki_ksigset_t saved_procmask; |
| |
| if (VG_(clo_trace_signals)) { |
| VG_(start_msg)(Vg_DebugMsg); |
| VG_(add_to_msg)("signal %d arrived ... ", sigNo ); |
| } |
| vg_assert(sigNo >= 1 && sigNo < VKI_KNSIG); |
| |
| /* Sanity check. Ensure we're really running on the signal stack |
| we asked for. */ |
| if ( !( |
| ((Char*)(&(VG_(sigstack)[0])) <= (Char*)(&dummy_local)) |
| && |
| ((Char*)(&dummy_local) < (Char*)(&(VG_(sigstack)[10000]))) |
| ) |
| ) { |
| VG_(message)(Vg_DebugMsg, |
| "FATAL: signal delivered on the wrong stack?!"); |
| VG_(message)(Vg_DebugMsg, |
| "A possible workaround follows. Please tell me"); |
| VG_(message)(Vg_DebugMsg, |
| "(jseward@acm.org) if the suggested workaround doesn't help."); |
| VG_(unimplemented) |
| ("support for progs compiled with -p/-pg; " |
| "rebuild your prog without -p/-pg"); |
| } |
| |
| vg_assert((Char*)(&(VG_(sigstack)[0])) <= (Char*)(&dummy_local)); |
| vg_assert((Char*)(&dummy_local) < (Char*)(&(VG_(sigstack)[10000]))); |
| |
| if (sigNo == VKI_SIGABRT && VG_(sighandler)[sigNo] == NULL) { |
| /* We get here if SIGABRT is delivered and the client hasn't |
| asked to catch it. The aim is to exit in a controlled |
| manner. */ |
| if (VG_(clo_trace_signals)) { |
| VG_(add_to_msg)("catching SIGABRT"); |
| VG_(end_msg)(); |
| } |
| VG_(ksignal)(VKI_SIGABRT, VKI_SIG_DFL); |
| VG_(longjmpd_on_signal) = VKI_SIGABRT; |
| __builtin_longjmp(VG_(scheduler_jmpbuf),1); |
| } |
| |
| VG_(block_all_host_signals)( &saved_procmask ); |
| |
| if (VG_(sighandler)[sigNo] == NULL) { |
| if (VG_(clo_trace_signals)) { |
| VG_(add_to_msg)("unexpected!"); |
| VG_(end_msg)(); |
| } |
| /* Note: we panic with all signals blocked here. Don't think |
| that matters. */ |
| VG_(panic)("vg_oursignalhandler: unexpected signal"); |
| } |
| |
| /* Decide what to do with it. */ |
| if (VG_(sigpending)[sigNo] == VG_SIGRUNNING) { |
| /* Already running; ignore it. */ |
| if (VG_(clo_trace_signals)) { |
| VG_(add_to_msg)("already running; discarded" ); |
| VG_(end_msg)(); |
| } |
| } |
| else |
| if (VG_(sigpending)[sigNo] != VG_SIGRUNNING && |
| VG_(sigpending)[sigNo] != VG_SIGIDLE) { |
| /* Not running and not idle == pending; ignore it. */ |
| if (VG_(clo_trace_signals)) { |
| VG_(add_to_msg)("already pending; discarded" ); |
| VG_(end_msg)(); |
| } |
| } |
| else { |
| /* Ok, we'd better deliver it to the client. */ |
| vg_assert(VG_(sigpending)[sigNo] == VG_SIGIDLE); |
| /* Queue it up for delivery at some point in the future. */ |
| VG_(sigpending)[sigNo] = VG_(sighandler)[sigNo]; |
| if (VG_(clo_trace_signals)) { |
| VG_(add_to_msg)("queued" ); |
| VG_(end_msg)(); |
| } |
| } |
| |
| /* We've finished messing with the queue, so re-enable host |
| signals. */ |
| VG_(restore_host_signals)( &saved_procmask ); |
| |
| if (sigNo == VKI_SIGSEGV || sigNo == VKI_SIGBUS |
| || sigNo == VKI_SIGFPE || sigNo == VKI_SIGILL) { |
| /* Can't continue; must longjmp back to the scheduler and thus |
| enter the sighandler immediately. */ |
| VG_(longjmpd_on_signal) = sigNo; |
| __builtin_longjmp(VG_(scheduler_jmpbuf),1); |
| } |
| } |
| |
| |
| /* The outer insn loop calls here to reenable a host signal if |
| vg_oursighandler longjmp'd. |
| */ |
| void VG_(unblock_host_signal) ( Int sigNo ) |
| { |
| Int ret; |
| vki_ksigset_t set; |
| VG_(ksigemptyset)(&set); |
| ret = VG_(ksigaddset)(&set,sigNo); |
| vg_assert(ret == 0); |
| ret = VG_(ksigprocmask)(VKI_SIG_UNBLOCK,&set,NULL); |
| vg_assert(ret == 0); |
| } |
| |
| |
| static __attribute((unused)) |
| void pp_vg_ksigaction ( vki_ksigaction* sa ) |
| { |
| Int i; |
| VG_(printf)("vg_ksigaction: handler %p, flags 0x%x, restorer %p\n", |
| sa->ksa_handler, (UInt)sa->ksa_flags, sa->ksa_restorer); |
| VG_(printf)("vg_ksigaction: { "); |
| for (i = 1; i < VKI_KNSIG; i++) |
| if (VG_(ksigismember(&(sa->ksa_mask),i))) |
| VG_(printf)("%d ", i); |
| VG_(printf)("}\n"); |
| } |
| |
| |
| /* Copy the process' real signal state to the sim state. Whilst |
| doing this, block all real signals. |
| */ |
| void VG_(sigstartup_actions) ( void ) |
| { |
| Int i, ret; |
| |
| vki_ksigset_t saved_procmask; |
| vki_kstack_t altstack_info; |
| vki_ksigaction sa; |
| |
| /* VG_(printf)("SIGSTARTUP\n"); */ |
| /* Block all signals. |
| saved_procmask remembers the previous mask. */ |
| VG_(block_all_host_signals)( &saved_procmask ); |
| |
| /* Register an alternative stack for our own signal handler to run |
| on. */ |
| altstack_info.ss_sp = &(VG_(sigstack)[0]); |
| altstack_info.ss_size = 10000 * sizeof(UInt); |
| altstack_info.ss_flags = 0; |
| ret = VG_(ksigaltstack)(&altstack_info, NULL); |
| if (ret != 0) { |
| VG_(panic)( |
| "vg_sigstartup_actions: couldn't install alternative sigstack"); |
| } |
| if (VG_(clo_trace_signals)) { |
| VG_(message)(Vg_DebugExtraMsg, |
| "vg_sigstartup_actions: sigstack installed ok"); |
| } |
| |
| /* Set initial state for the signal simulation. */ |
| for (i = 1; i < VKI_KNSIG; i++) { |
| VG_(sighandler)[i] = NULL; |
| VG_(sigpending)[i] = NULL; |
| vg_sig_sarestart[i] = True; /* An easy default */ |
| } |
| |
| for (i = 1; i < VKI_KNSIG; i++) { |
| |
| /* Get the old host action */ |
| ret = VG_(ksigaction)(i, NULL, &sa); |
| vg_assert(ret == 0); |
| |
| /* If there's already a handler set, record it, then route the |
| signal through to our handler. */ |
| if (sa.ksa_handler != VKI_SIG_IGN && sa.ksa_handler != VKI_SIG_DFL) { |
| if (VG_(clo_trace_signals)) |
| VG_(printf)("snaffling handler 0x%x for signal %d\n", |
| (Addr)(sa.ksa_handler), i ); |
| if ((sa.ksa_flags & VKI_SA_ONSTACK) != 0) |
| VG_(unimplemented) |
| ("signals on an alternative stack (SA_ONSTACK)"); |
| |
| VG_(sighandler)[i] = sa.ksa_handler; |
| sa.ksa_handler = &VG_(oursignalhandler); |
| /* Save the restart status, then set it to restartable. */ |
| vg_sig_sarestart[i] |
| = (sa.ksa_flags & VKI_SA_RESTART) ? True : False; |
| sa.ksa_flags |= VKI_SA_RESTART; |
| |
| ret = VG_(ksigaction)(i, &sa, NULL); |
| vg_assert(ret == 0); |
| } |
| } |
| |
| VG_(ksignal)(VKI_SIGABRT, &VG_(oursignalhandler)); |
| |
| /* Finally, restore the blocking mask. */ |
| VG_(restore_host_signals)( &saved_procmask ); |
| } |
| |
| |
| /* Copy the process' sim signal state to the real state, |
| for when we transfer from the simulated to real CPU. |
| PROBLEM: what if we're running a signal handler when we |
| get here? Hmm. |
| I guess we wind up in vg_signalreturn_bogusRA, *or* the |
| handler has done/will do a longjmp, in which case we're ok. |
| |
| It is important (see vg_startup.S) that this proc does not |
| change the state of the real FPU, since it is called when |
| running the program on the real CPU. |
| */ |
| void VG_(sigshutdown_actions) ( void ) |
| { |
| Int i, ret; |
| |
| vki_ksigset_t saved_procmask; |
| vki_ksigaction sa; |
| |
| VG_(block_all_host_signals)( &saved_procmask ); |
| |
| /* copy the sim signal actions to the real ones. */ |
| /* Hmm, this isn't accurate. Doesn't properly restore the |
| SA_RESTART flag nor SA_ONSTACK. */ |
| for (i = 1; i < VKI_KNSIG; i++) { |
| if (i == VKI_SIGKILL || i == VKI_SIGSTOP) continue; |
| if (VG_(sighandler)[i] == NULL) continue; |
| ret = VG_(ksigaction)(i, NULL, &sa); |
| vg_assert(ret == 0); |
| sa.ksa_handler = VG_(sighandler)[i]; |
| ret = VG_(ksigaction)(i, &sa, NULL); |
| } |
| |
| VG_(restore_host_signals)( &saved_procmask ); |
| } |
| |
| |
| /* --------------------------------------------------------------------- |
| Handle signal-related syscalls from the simulatee. |
| ------------------------------------------------------------------ */ |
| |
| /* Do more error checking? */ |
| void VG_(do__NR_sigaction) ( ThreadId tid ) |
| { |
| UInt res; |
| void* our_old_handler; |
| vki_ksigaction* new_action; |
| vki_ksigaction* old_action; |
| ThreadState* tst = VG_(get_thread_state)( tid ); |
| UInt param1 = tst->m_ebx; /* int sigNo */ |
| UInt param2 = tst->m_ecx; /* k_sigaction* new_action */ |
| UInt param3 = tst->m_edx; /* k_sigaction* old_action */ |
| new_action = (vki_ksigaction*)param2; |
| old_action = (vki_ksigaction*)param3; |
| |
| if (VG_(clo_trace_signals)) |
| VG_(message)(Vg_DebugExtraMsg, |
| "__NR_sigaction: sigNo %d, " |
| "new 0x%x, old 0x%x, new flags 0x%x", |
| param1,(UInt)new_action,(UInt)old_action, |
| (UInt)(new_action ? new_action->ksa_flags : 0) ); |
| /* VG_(ppSigProcMask)(); */ |
| |
| /* Rule out various error conditions. The aim is to ensure that if |
| the call is passed to the kernel it will definitely succeed. */ |
| |
| /* Reject out-of-range signal numbers. */ |
| if (param1 < 1 || param1 >= VKI_KNSIG) goto bad_signo; |
| |
| /* Reject attempts to set a handler (or set ignore) for SIGKILL. */ |
| if ( (param1 == VKI_SIGKILL || param1 == VKI_SIGSTOP) |
| && new_action |
| && new_action->ksa_handler != VKI_SIG_DFL) |
| goto bad_sigkill; |
| |
| our_old_handler = VG_(sighandler)[param1]; |
| /* VG_(printf)("old handler = 0x%x\n", our_old_handler); */ |
| /* If a new handler has been specified, mess with its handler. */ |
| if (new_action) { |
| if (new_action->ksa_handler == VKI_SIG_IGN || |
| new_action->ksa_handler == VKI_SIG_DFL) { |
| VG_(sighandler)[param1] = NULL; |
| VG_(sigpending)[param1] = NULL; |
| /* Dangerous! Could lose signals like this. */ |
| } else { |
| /* VG_(printf)("new handler = 0x%x\n", new_action->ksa_handler); */ |
| /* The client isn't allowed to use an alternative signal |
| stack. We, however, must. */ |
| if ((new_action->ksa_flags & VKI_SA_ONSTACK) != 0) |
| VG_(unimplemented) |
| ("signals on an alternative stack (SA_ONSTACK)"); |
| new_action->ksa_flags |= VKI_SA_ONSTACK; |
| VG_(sighandler)[param1] = new_action->ksa_handler; |
| vg_sig_sarestart[param1] |
| = (new_action->ksa_flags & VKI_SA_RESTART) ? True : False; |
| new_action->ksa_flags |= VKI_SA_RESTART; |
| new_action->ksa_handler = &VG_(oursignalhandler); |
| } |
| } |
| |
| KERNEL_DO_SYSCALL(tid,res); |
| /* VG_(printf)("RES = %d\n", res); */ |
| |
| /* If the client asks for the old handler, maintain our fiction |
| by stuffing in the handler it thought it asked for ... */ |
| if (old_action) { |
| if (old_action->ksa_handler == VKI_SIG_IGN || |
| old_action->ksa_handler == VKI_SIG_DFL) { |
| /* No old action; we should have a NULL handler. */ |
| vg_assert(our_old_handler == NULL); |
| } else { |
| /* There's a handler. */ |
| if (param1 != VKI_SIGKILL && param1 != VKI_SIGABRT) { |
| vg_assert(old_action->ksa_handler == &VG_(oursignalhandler)); |
| vg_assert((old_action->ksa_flags & VKI_SA_ONSTACK) != 0); |
| } |
| old_action->ksa_handler = our_old_handler; |
| /* Since the client is not allowed to ask for an alternative |
| sig stack, unset the bit for anything we pass back to |
| it. */ |
| old_action->ksa_flags &= ~VKI_SA_ONSTACK; |
| /* Restore the SA_RESTART flag to whatever we snaffled. */ |
| if (vg_sig_sarestart[param1]) |
| old_action->ksa_flags |= VKI_SA_RESTART; |
| else |
| old_action->ksa_flags &= ~VKI_SA_RESTART; |
| } |
| } |
| |
| VG_(ksignal)(VKI_SIGABRT, &VG_(oursignalhandler)); |
| goto good; |
| |
| good: |
| tst->m_eax = (UInt)0; |
| return; |
| |
| bad_signo: |
| VG_(message)(Vg_UserMsg, |
| "Warning: bad signal number %d in __NR_sigaction.", |
| param1); |
| VG_(baseBlock)[VGOFF_(m_eax)] = (UInt)(-VKI_EINVAL); |
| return; |
| |
| bad_sigkill: |
| VG_(message)(Vg_UserMsg, |
| "Warning: attempt to set SIGKILL handler in __NR_sigaction.", |
| param1); |
| VG_(baseBlock)[VGOFF_(m_eax)] = (UInt)(-VKI_EINVAL); |
| return; |
| } |
| |
| |
| /* The kernel handles sigprocmask in the usual way, but we also need |
| to inspect it, so as to spot requests to unblock signals. We then |
| inspect vg_sigpending, which records the current state of signal |
| delivery to the client. The problematic case is when a signal is |
| delivered to the client, in which case the relevant vg_sigpending |
| slot is set to VG_SIGRUNNING. This inhibits further signal |
| deliveries. This mechanism implements the POSIX requirement that a |
| signal is blocked in its own handler. |
| |
| If the handler returns normally, the slot is changed back to |
| VG_SIGIDLE, so that further instances of the signal can be |
| delivered. The problem occurs when the handler never returns, but |
| longjmps. POSIX mandates that you then have to do an explicit |
| setprocmask to re-enable the signal. That is what we try and spot |
| here. Although the call is passed to the kernel, we also need to |
| spot unblocked signals whose state is VG_SIGRUNNING, and change it |
| back to VG_SIGIDLE. |
| */ |
| void VG_(do__NR_sigprocmask) ( Int how, vki_ksigset_t* set ) |
| { |
| Int i; |
| if (VG_(clo_trace_signals)) |
| VG_(message)(Vg_DebugMsg, |
| "vg_do__NR_sigprocmask: how = %d (%s), set = %p", |
| how, |
| how==VKI_SIG_BLOCK ? "SIG_BLOCK" : ( |
| how==VKI_SIG_UNBLOCK ? "SIG_UNBLOCK" : ( |
| how==VKI_SIG_SETMASK ? "SIG_SETMASK" : "???")), |
| set |
| ); |
| |
| /* Sometimes this happens. I don't know what it signifies. */ |
| if (set == NULL) |
| return; |
| |
| /* Not interested in blocking of signals. */ |
| if (how == VKI_SIG_BLOCK) |
| return; |
| |
| /* Detect and ignore unknown action. */ |
| if (how != VKI_SIG_UNBLOCK && how != VKI_SIG_SETMASK) { |
| VG_(message)(Vg_DebugMsg, |
| "sigprocmask: unknown `how' field %d", how); |
| return; |
| } |
| |
| for (i = 1; i < VKI_KNSIG; i++) { |
| Bool unblock_me = False; |
| if (how == VKI_SIG_SETMASK) { |
| if (!VG_(ksigismember)(set,i)) |
| unblock_me = True; |
| } else { /* how == SIG_UNBLOCK */ |
| if (VG_(ksigismember)(set,i)) |
| unblock_me = True; |
| } |
| if (unblock_me && VG_(sigpending)[i] == VG_SIGRUNNING) { |
| VG_(sigpending)[i] = VG_SIGIDLE; |
| if (VG_(clo_verbosity) > 1) |
| VG_(message)(Vg_UserMsg, |
| "Warning: unblocking signal %d " |
| "due to sigprocmask", i ); |
| } |
| } |
| } |
| |
| |
| |
| /*--------------------------------------------------------------------*/ |
| /*--- end vg_signals.c ---*/ |
| /*--------------------------------------------------------------------*/ |