diff options
Diffstat (limited to 'linux-user/signal.c')
| -rw-r--r-- | linux-user/signal.c | 459 |
1 files changed, 303 insertions, 156 deletions
diff --git a/linux-user/signal.c b/linux-user/signal.c index a67ab47d30..3b8efec89f 100644 --- a/linux-user/signal.c +++ b/linux-user/signal.c @@ -32,6 +32,7 @@ #include "signal-common.h" #include "host-signal.h" #include "user/safe-syscall.h" +#include "tcg/tcg.h" static struct target_sigaction sigact_table[TARGET_NSIG]; @@ -43,9 +44,8 @@ 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 + * System includes define _NSIG as SIGRTMAX + 1, but qemu (like the kernel) + * defines TARGET_NSIG as TARGET_SIGRTMAX and the first signal is 1. * Signal number 0 is reserved for use as kill(pid, 0), to test whether * a process exists without sending it a signal. */ @@ -56,7 +56,6 @@ static uint8_t host_to_target_signal_table[_NSIG] = { #define MAKE_SIG_ENTRY(sig) [sig] = TARGET_##sig, MAKE_SIGNAL_LIST #undef MAKE_SIG_ENTRY - /* next signals stay the same */ }; static uint8_t target_to_host_signal_table[TARGET_NSIG + 1]; @@ -64,18 +63,24 @@ 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) { + if (sig < 1) { return sig; } + if (sig >= _NSIG) { + return TARGET_NSIG + 1; + } 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) { + if (sig < 1) { return sig; } + if (sig > TARGET_NSIG) { + return _NSIG; + } return target_to_host_signal_table[sig]; } @@ -487,26 +492,6 @@ void target_to_host_siginfo(siginfo_t *info, const target_siginfo_t *tinfo) 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) { @@ -526,57 +511,69 @@ static int core_dump_signal(int sig) static void signal_table_init(void) { - int host_sig, target_sig, count; + int hsig, tsig, 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. + * until we run out of host realtime signals. Glibc uses the lower 2 + * RT signals and (hopefully) nobody uses the upper ones. + * This is why SIGRTMIN (34) is generally greater than __SIGRTMIN (32). + * To fix this properly we would need to do manual signal delivery + * multiplexed over a single host signal. * Attempts for configure "missing" signals via sigaction will be * silently ignored. + * + * Remap the target SIGABRT, so that we can distinguish host abort + * from guest abort. When the guest registers a signal handler or + * calls raise(SIGABRT), the host will raise SIG_RTn. If the guest + * arrives at dump_core_and_abort(), we will map back to host SIGABRT + * so that the parent (native or emulated) sees the correct signal. + * Finally, also map host to guest SIGABRT so that the emulated + * parent sees the correct mapping from wait status. */ - 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; + + hsig = SIGRTMIN; + host_to_target_signal_table[SIGABRT] = 0; + host_to_target_signal_table[hsig++] = TARGET_SIGABRT; + + for (; hsig <= SIGRTMAX; hsig++) { + tsig = hsig - SIGRTMIN + TARGET_SIGRTMIN; + if (tsig <= TARGET_NSIG) { + host_to_target_signal_table[hsig] = tsig; } } - /* 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; + /* Invert the mapping that has already been assigned. */ + for (hsig = 1; hsig < _NSIG; hsig++) { + tsig = host_to_target_signal_table[hsig]; + if (tsig) { + assert(target_to_host_signal_table[tsig] == 0); + target_to_host_signal_table[tsig] = hsig; } } - 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++; - } + host_to_target_signal_table[SIGABRT] = TARGET_SIGABRT; + + /* Map everything else out-of-bounds. */ + for (hsig = 1; hsig < _NSIG; hsig++) { + if (host_to_target_signal_table[hsig] == 0) { + host_to_target_signal_table[hsig] = TARGET_NSIG + 1; } - trace_signal_table_init(count); } + for (count = 0, tsig = 1; tsig <= TARGET_NSIG; tsig++) { + if (target_to_host_signal_table[tsig] == 0) { + target_to_host_signal_table[tsig] = _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; + struct sigaction act, oact; /* initialize signal conversion tables */ signal_table_init(); @@ -587,22 +584,36 @@ void signal_init(void) sigfillset(&act.sa_mask); act.sa_flags = SA_SIGINFO; act.sa_sigaction = host_signal_handler; - for(i = 1; i <= TARGET_NSIG; i++) { - 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; + + /* + * A parent process may configure ignored signals, but all other + * signals are default. For any target signals that have no host + * mapping, set to ignore. For all core_dump_signal, install our + * host signal handler so that we may invoke dump_core_and_abort. + * This includes SIGSEGV and SIGBUS, which are also need our signal + * handler for paging and exceptions. + */ + for (int tsig = 1; tsig <= TARGET_NSIG; tsig++) { + int hsig = target_to_host_signal(tsig); + abi_ptr thand = TARGET_SIG_IGN; + + if (hsig >= _NSIG) { + continue; } - /* 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); + + /* As we force remap SIGABRT, cannot probe and install in one step. */ + if (tsig == TARGET_SIGABRT) { + sigaction(SIGABRT, NULL, &oact); + sigaction(hsig, &act, NULL); + } else { + struct sigaction *iact = core_dump_signal(tsig) ? &act : NULL; + sigaction(hsig, iact, &oact); + } + + if (oact.sa_sigaction != (void *)SIG_IGN) { + thand = TARGET_SIG_DFL; + } + sigact_table[tsig - 1]._sa_handler = thand; } } @@ -690,14 +701,45 @@ void cpu_loop_exit_sigbus(CPUState *cpu, target_ulong addr, /* abort execution with signal */ static G_NORETURN +void die_with_signal(int host_sig) +{ + struct sigaction act = { + .sa_handler = SIG_DFL, + }; + + /* + * 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 + * the signal and we wait for it to arrive. + */ + sigfillset(&act.sa_mask); + sigaction(host_sig, &act, NULL); + + kill(getpid(), host_sig); + + /* Make sure the signal isn't masked (reusing the mask inside of act). */ + sigdelset(&act.sa_mask, host_sig); + sigsuspend(&act.sa_mask); + + /* unreachable */ + _exit(EXIT_FAILURE); +} + +static G_NORETURN void dump_core_and_abort(CPUArchState *env, int target_sig) { CPUState *cpu = env_cpu(env); TaskState *ts = (TaskState *)cpu->opaque; int host_sig, core_dumped = 0; - struct sigaction act; - host_sig = target_to_host_signal(target_sig); + /* On exit, undo the remapping of SIGABRT. */ + if (target_sig == TARGET_SIGABRT) { + host_sig = SIGABRT; + } else { + host_sig = target_to_host_signal(target_sig); + } trace_user_dump_core_and_abort(env, target_sig, host_sig); gdb_signalled(env, target_sig); @@ -719,29 +761,7 @@ void dump_core_and_abort(CPUArchState *env, int target_sig) } preexit_cleanup(env, 128 + target_sig); - - /* 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(); + die_with_signal(host_sig); } /* queue a signal so that it will be send to the virtual CPU as soon @@ -775,6 +795,161 @@ static inline void rewind_if_in_safe_syscall(void *puc) } } +static G_NORETURN +void die_from_signal(siginfo_t *info) +{ + char sigbuf[4], codebuf[12]; + const char *sig, *code = NULL; + + switch (info->si_signo) { + case SIGSEGV: + sig = "SEGV"; + switch (info->si_code) { + case SEGV_MAPERR: + code = "MAPERR"; + break; + case SEGV_ACCERR: + code = "ACCERR"; + break; + } + break; + case SIGBUS: + sig = "BUS"; + switch (info->si_code) { + case BUS_ADRALN: + code = "ADRALN"; + break; + case BUS_ADRERR: + code = "ADRERR"; + break; + } + break; + case SIGILL: + sig = "ILL"; + switch (info->si_code) { + case ILL_ILLOPC: + code = "ILLOPC"; + break; + case ILL_ILLOPN: + code = "ILLOPN"; + break; + case ILL_ILLADR: + code = "ILLADR"; + break; + case ILL_PRVOPC: + code = "PRVOPC"; + break; + case ILL_PRVREG: + code = "PRVREG"; + break; + case ILL_COPROC: + code = "COPROC"; + break; + } + break; + case SIGFPE: + sig = "FPE"; + switch (info->si_code) { + case FPE_INTDIV: + code = "INTDIV"; + break; + case FPE_INTOVF: + code = "INTOVF"; + break; + } + break; + case SIGTRAP: + sig = "TRAP"; + break; + default: + snprintf(sigbuf, sizeof(sigbuf), "%d", info->si_signo); + sig = sigbuf; + break; + } + if (code == NULL) { + snprintf(codebuf, sizeof(sigbuf), "%d", info->si_code); + code = codebuf; + } + + error_report("QEMU internal SIG%s {code=%s, addr=%p}", + sig, code, info->si_addr); + die_with_signal(info->si_signo); +} + +static void host_sigsegv_handler(CPUState *cpu, siginfo_t *info, + host_sigcontext *uc) +{ + uintptr_t host_addr = (uintptr_t)info->si_addr; + /* + * Convert forcefully to guest address space: addresses outside + * reserved_va are still valid to report via SEGV_MAPERR. + */ + bool is_valid = h2g_valid(host_addr); + abi_ptr guest_addr = h2g_nocheck(host_addr); + uintptr_t pc = host_signal_pc(uc); + bool is_write = host_signal_write(info, uc); + MMUAccessType access_type = adjust_signal_pc(&pc, is_write); + bool maperr; + + /* If this was a write to a TB protected page, restart. */ + if (is_write + && is_valid + && info->si_code == SEGV_ACCERR + && handle_sigsegv_accerr_write(cpu, host_signal_mask(uc), + pc, guest_addr)) { + return; + } + + /* + * If the access was not on behalf of the guest, within the executable + * mapping of the generated code buffer, then it is a host bug. + */ + if (access_type != MMU_INST_FETCH + && !in_code_gen_buffer((void *)(pc - tcg_splitwx_diff))) { + die_from_signal(info); + } + + maperr = true; + if (is_valid && info->si_code == SEGV_ACCERR) { + /* + * With reserved_va, the whole address space is PROT_NONE, + * which means that we may get ACCERR when we want MAPERR. + */ + if (page_get_flags(guest_addr) & PAGE_VALID) { + maperr = false; + } else { + info->si_code = SEGV_MAPERR; + } + } + + sigprocmask(SIG_SETMASK, host_signal_mask(uc), NULL); + cpu_loop_exit_sigsegv(cpu, guest_addr, access_type, maperr, pc); +} + +static void host_sigbus_handler(CPUState *cpu, siginfo_t *info, + host_sigcontext *uc) +{ + uintptr_t pc = host_signal_pc(uc); + bool is_write = host_signal_write(info, uc); + MMUAccessType access_type = adjust_signal_pc(&pc, is_write); + + /* + * If the access was not on behalf of the guest, within the executable + * mapping of the generated code buffer, then it is a host bug. + */ + if (!in_code_gen_buffer((void *)(pc - tcg_splitwx_diff))) { + die_from_signal(info); + } + + if (info->si_code == BUS_ADRALN) { + uintptr_t host_addr = (uintptr_t)info->si_addr; + abi_ptr guest_addr = h2g_nocheck(host_addr); + + sigprocmask(SIG_SETMASK, host_signal_mask(uc), NULL); + cpu_loop_exit_sigbus(cpu, guest_addr, access_type, pc); + } +} + static void host_signal_handler(int host_sig, siginfo_t *info, void *puc) { CPUState *cpu = thread_cpu; @@ -786,61 +961,28 @@ static void host_signal_handler(int host_sig, siginfo_t *info, void *puc) int guest_sig; uintptr_t pc = 0; bool sync_sig = false; - void *sigmask = host_signal_mask(uc); + void *sigmask; /* * Non-spoofed SIGSEGV and SIGBUS are synchronous, and need special - * handling wrt signal blocking and unwinding. + * handling wrt signal blocking and unwinding. Non-spoofed SIGILL, + * SIGFPE, SIGTRAP are always host bugs. */ - if ((host_sig == SIGSEGV || host_sig == SIGBUS) && info->si_code > 0) { - MMUAccessType access_type; - uintptr_t host_addr; - abi_ptr guest_addr; - bool is_write; - - host_addr = (uintptr_t)info->si_addr; - - /* - * Convert forcefully to guest address space: addresses outside - * reserved_va are still valid to report via SEGV_MAPERR. - */ - guest_addr = h2g_nocheck(host_addr); - - pc = host_signal_pc(uc); - is_write = host_signal_write(info, uc); - access_type = adjust_signal_pc(&pc, is_write); - - if (host_sig == SIGSEGV) { - bool maperr = true; - - if (info->si_code == SEGV_ACCERR && h2g_valid(host_addr)) { - /* If this was a write to a TB protected page, restart. */ - if (is_write && - handle_sigsegv_accerr_write(cpu, sigmask, pc, guest_addr)) { - return; - } - - /* - * With reserved_va, the whole address space is PROT_NONE, - * which means that we may get ACCERR when we want MAPERR. - */ - if (page_get_flags(guest_addr) & PAGE_VALID) { - maperr = false; - } else { - info->si_code = SEGV_MAPERR; - } - } - - sigprocmask(SIG_SETMASK, sigmask, NULL); - cpu_loop_exit_sigsegv(cpu, guest_addr, access_type, maperr, pc); - } else { - sigprocmask(SIG_SETMASK, sigmask, NULL); - if (info->si_code == BUS_ADRALN) { - cpu_loop_exit_sigbus(cpu, guest_addr, access_type, pc); - } + if (info->si_code > 0) { + switch (host_sig) { + case SIGSEGV: + /* Only returns on handle_sigsegv_accerr_write success. */ + host_sigsegv_handler(cpu, info, uc); + return; + case SIGBUS: + host_sigbus_handler(cpu, info, uc); + sync_sig = true; + break; + case SIGILL: + case SIGFPE: + case SIGTRAP: + die_from_signal(info); } - - sync_sig = true; } /* get target signal number */ @@ -881,6 +1023,7 @@ static void host_signal_handler(int host_sig, siginfo_t *info, void *puc) * would write 0xff bytes off the end of the structure and trash * data on the struct. */ + sigmask = host_signal_mask(uc); memset(sigmask, 0xff, SIGSET_T_SIZE); sigdelset(sigmask, SIGSEGV); sigdelset(sigmask, SIGBUS); @@ -936,7 +1079,6 @@ 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; @@ -996,22 +1138,27 @@ int do_sigaction(int sig, const struct target_sigaction *act, return 0; } if (host_sig != SIGSEGV && host_sig != SIGBUS) { + struct sigaction act1; + 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) { + /* + * It is important to update the host kernel signal ignore + * state to avoid getting unexpected interrupted syscalls. + */ act1.sa_sigaction = (void *)SIG_IGN; } else if (k->_sa_handler == TARGET_SIG_DFL) { - if (fatal_signal (sig)) + if (core_dump_signal(sig)) { act1.sa_sigaction = host_signal_handler; - else + } else { act1.sa_sigaction = (void *)SIG_DFL; + } } else { act1.sa_sigaction = host_signal_handler; + if (k->sa_flags & TARGET_SA_RESTART) { + act1.sa_flags |= SA_RESTART; + } } ret = sigaction(host_sig, &act1, NULL); } |