sigact_table stores the signal handlers for the given process. Once we support CLONE_VM, two tasks using the same virtual memory may need different signal handler tables (e.g., if CLONE_SIGHAND is not provided). Here we make sigact_table part of the TaskState, so it can be duplicated as needed when cloning children.
Signed-off-by: Josh Kunz <j...@google.com> --- linux-user/qemu.h | 8 ++++++++ linux-user/signal.c | 35 +++++++++++++++++++++++++++-------- linux-user/syscall.c | 17 +++++++++++++++++ 3 files changed, 52 insertions(+), 8 deletions(-) diff --git a/linux-user/qemu.h b/linux-user/qemu.h index 989e01ad8d..54bf4f47be 100644 --- a/linux-user/qemu.h +++ b/linux-user/qemu.h @@ -177,6 +177,12 @@ typedef struct TaskState { * the table itself should be guarded. */ struct fd_trans_table *fd_trans_tbl; + + /* + * A table containing signal actions for the target. It should have at + * least TARGET_NSIG entries + */ + struct target_sigaction *sigact_tbl; } __attribute__((aligned(16))) TaskState; extern char *exec_path; @@ -419,7 +425,9 @@ void print_syscall_ret(int num, abi_long arg1); */ void print_taken_signal(int target_signum, const target_siginfo_t *tinfo); + /* signal.c */ +struct target_sigaction *sigact_table_clone(struct target_sigaction *orig); void process_pending_signals(CPUArchState *cpu_env); void signal_init(void); int queue_signal(CPUArchState *env, int sig, int si_type, diff --git a/linux-user/signal.c b/linux-user/signal.c index 8cf51ffecd..dc98def6d1 100644 --- a/linux-user/signal.c +++ b/linux-user/signal.c @@ -25,7 +25,13 @@ #include "trace.h" #include "signal-common.h" -static struct target_sigaction sigact_table[TARGET_NSIG]; +struct target_sigaltstack target_sigaltstack_used = { + .ss_sp = 0, + .ss_size = 0, + .ss_flags = TARGET_SS_DISABLE, +}; + +typedef struct target_sigaction sigact_table[TARGET_NSIG]; static void host_signal_handler(int host_signum, siginfo_t *info, void *puc); @@ -542,6 +548,11 @@ static void signal_table_init(void) } } +struct target_sigaction *sigact_table_clone(struct target_sigaction *orig) +{ + return memcpy(g_new(sigact_table, 1), orig, sizeof(sigact_table)); +} + void signal_init(void) { TaskState *ts = (TaskState *)thread_cpu->opaque; @@ -556,6 +567,12 @@ void signal_init(void) /* Set the signal mask from the host mask. */ sigprocmask(0, 0, &ts->signal_mask); + /* + * Set all host signal handlers. ALL signals are blocked during + * the handlers to serialize them. + */ + ts->sigact_tbl = (struct target_sigaction *) g_new0(sigact_table, 1); + sigfillset(&act.sa_mask); act.sa_flags = SA_SIGINFO; act.sa_sigaction = host_signal_handler; @@ -568,9 +585,9 @@ void signal_init(void) 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; + ts->sigact_tbl[i - 1]._sa_handler = TARGET_SIG_IGN; } else if (oact.sa_sigaction == (void *)SIG_DFL) { - sigact_table[i - 1]._sa_handler = TARGET_SIG_DFL; + ts->sigact_tbl[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. */ @@ -608,11 +625,12 @@ void force_sig(int sig) #if !defined(TARGET_RISCV) void force_sigsegv(int oldsig) { + TaskState *ts = (TaskState *)thread_cpu->opaque; 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; + ts->sigact_tbl[oldsig - 1]._sa_handler = TARGET_SIG_DFL; } force_sig(TARGET_SIGSEGV); } @@ -837,6 +855,7 @@ int do_sigaction(int sig, const struct target_sigaction *act, struct sigaction act1; int host_sig; int ret = 0; + TaskState* ts = (TaskState *)thread_cpu->opaque; trace_signal_do_sigaction_guest(sig, TARGET_NSIG); @@ -848,7 +867,7 @@ int do_sigaction(int sig, const struct target_sigaction *act, return -TARGET_ERESTARTSYS; } - k = &sigact_table[sig - 1]; + k = &ts->sigact_tbl[sig - 1]; if (oact) { __put_user(k->_sa_handler, &oact->_sa_handler); __put_user(k->sa_flags, &oact->sa_flags); @@ -930,7 +949,7 @@ static void handle_pending_signal(CPUArchState *cpu_env, int sig, sa = NULL; handler = TARGET_SIG_IGN; } else { - sa = &sigact_table[sig - 1]; + sa = &ts->sigact_tbl[sig - 1]; handler = sa->_sa_handler; } @@ -1022,9 +1041,9 @@ void process_pending_signals(CPUArchState *cpu_env) * 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) { + || ts->sigact_tbl[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; + ts->sigact_tbl[sig - 1]._sa_handler = TARGET_SIG_DFL; } handle_pending_signal(cpu_env, sig, &ts->sync_signal); diff --git a/linux-user/syscall.c b/linux-user/syscall.c index ff1d07871f..838caf9c98 100644 --- a/linux-user/syscall.c +++ b/linux-user/syscall.c @@ -5989,6 +5989,17 @@ static int do_fork(CPUArchState *env, unsigned int flags, abi_ulong newsp, return -TARGET_EINVAL; } + if ((flags & CLONE_SIGHAND) && !(flags & CLONE_VM)) { + /* + * Like CLONE_FILES, this flag combination is unsupported. If + * CLONE_SIGHAND is specified without CLONE_VM, then we need to keep + * the sigact table in-sync across virtual memory boundaries, which is + * substantially more complicated. + */ + qemu_log_mask(LOG_UNIMP, "CLONE_SIGHAND only supported with CLONE_VM"); + return -TARGET_EINVAL; + } + pthread_mutex_init(&info.mutex, NULL); pthread_mutex_lock(&info.mutex); pthread_cond_init(&info.cond, NULL); @@ -6025,6 +6036,12 @@ static int do_fork(CPUArchState *env, unsigned int flags, abi_ulong newsp, ts->fd_trans_tbl = fd_trans_table_clone(parent_ts->fd_trans_tbl); } + if (flags & CLONE_SIGHAND) { + ts->sigact_tbl = parent_ts->sigact_tbl; + } else { + ts->sigact_tbl = sigact_table_clone(parent_ts->sigact_tbl); + } + if (flags & CLONE_CHILD_CLEARTID) { ts->child_tidptr = child_tidptr; } -- 2.27.0.290.gba653c62da-goog