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FRET-qemu/linux-user/signal.c
Richard Henderson 1764ad70ce include/qemu: Add TCGCPUOps typedef to typedefs.h 
QEMU coding style recommends using structure typedefs.

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2024-01-29 21:04:10 +10:00

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/*
* 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 "gdbstub/user.h"
#include "hw/core/tcg-cpu-ops.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"
#include "host-signal.h"
#include "user/safe-syscall.h"
#include "tcg/tcg.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 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] = {
#define MAKE_SIG_ENTRY(sig) [sig] = TARGET_##sig,
MAKE_SIGNAL_LIST
#undef MAKE_SIG_ENTRY
};
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) {
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) {
return sig;
}
if (sig > TARGET_NSIG) {
return _NSIG;
}
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 -QEMU_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 -QEMU_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;
}
/* 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;
}
/* 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;
if (si_code == CLD_EXITED)
tinfo->_sifields._sigchld._status = info->si_status;
else
tinfo->_sifields._sigchld._status
= host_to_target_signal(info->si_status & 0x7f)
| (info->si_status & ~0x7f);
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;
}
/* 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 hsig, tsig, count;
/*
* Signals are supported starting from TARGET_SIGRTMIN and going up
* 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.
*/
hsig = SIGRTMIN;
host_to_target_signal_table[SIGABRT] = 0;
host_to_target_signal_table[hsig++] = TARGET_SIGABRT;
for (tsig = TARGET_SIGRTMIN;
hsig <= SIGRTMAX && tsig <= TARGET_NSIG;
hsig++, tsig++) {
host_to_target_signal_table[hsig] = tsig;
}
/* 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;
}
}
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;
}
}
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, oact;
/* 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;
/*
* 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;
}
/* 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;
}
}
/* 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(cpu);
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(cpu);
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
void cpu_loop_exit_sigsegv(CPUState *cpu, target_ulong addr,
MMUAccessType access_type, bool maperr, uintptr_t ra)
{
const TCGCPUOps *tcg_ops = CPU_GET_CLASS(cpu)->tcg_ops;
if (tcg_ops->record_sigsegv) {
tcg_ops->record_sigsegv(cpu, addr, access_type, maperr, ra);
}
force_sig_fault(TARGET_SIGSEGV,
maperr ? TARGET_SEGV_MAPERR : TARGET_SEGV_ACCERR,
addr);
cpu->exception_index = EXCP_INTERRUPT;
cpu_loop_exit_restore(cpu, ra);
}
void cpu_loop_exit_sigbus(CPUState *cpu, target_ulong addr,
MMUAccessType access_type, uintptr_t ra)
{
const TCGCPUOps *tcg_ops = CPU_GET_CLASS(cpu)->tcg_ops;
if (tcg_ops->record_sigbus) {
tcg_ops->record_sigbus(cpu, addr, access_type, ra);
}
force_sig_fault(TARGET_SIGBUS, TARGET_BUS_ADRALN, addr);
cpu->exception_index = EXCP_INTERRUPT;
cpu_loop_exit_restore(cpu, ra);
}
/* 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;
/* 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);
/* 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" );
}
preexit_cleanup(env, 128 + target_sig);
die_with_signal(host_sig);
}
/* queue a signal so that it will be send to the virtual CPU as soon
as possible */
void 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);
}
/* Adjust the signal context to rewind out of safe-syscall if we're in it */
static inline void rewind_if_in_safe_syscall(void *puc)
{
host_sigcontext *uc = (host_sigcontext *)puc;
uintptr_t pcreg = host_signal_pc(uc);
if (pcreg > (uintptr_t)safe_syscall_start
&& pcreg < (uintptr_t)safe_syscall_end) {
host_signal_set_pc(uc, (uintptr_t)safe_syscall_start);
}
}
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 uintptr_t 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);
}
return pc;
}
static void host_signal_handler(int host_sig, siginfo_t *info, void *puc)
{
CPUState *cpu = thread_cpu;
CPUArchState *env = cpu_env(cpu);
TaskState *ts = cpu->opaque;
target_siginfo_t tinfo;
host_sigcontext *uc = puc;
struct emulated_sigtable *k;
int guest_sig;
uintptr_t pc = 0;
bool sync_sig = false;
void *sigmask;
/*
* Non-spoofed SIGSEGV and SIGBUS are synchronous, and need special
* handling wrt signal blocking and unwinding. Non-spoofed SIGILL,
* SIGFPE, SIGTRAP are always host bugs.
*/
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:
pc = host_sigbus_handler(cpu, info, uc);
sync_sig = true;
break;
case SIGILL:
case SIGFPE:
case SIGTRAP:
die_from_signal(info);
}
}
/* get target signal number */
guest_sig = host_to_target_signal(host_sig);
if (guest_sig < 1 || guest_sig > TARGET_NSIG) {
return;
}
trace_user_host_signal(env, host_sig, guest_sig);
host_to_target_siginfo_noswap(&tinfo, info);
k = &ts->sigtab[guest_sig - 1];
k->info = tinfo;
k->pending = guest_sig;
ts->signal_pending = 1;
/*
* For synchronous signals, unwind the cpu state to the faulting
* insn and then exit back to the main loop so that the signal
* is delivered immediately.
*/
if (sync_sig) {
cpu->exception_index = EXCP_INTERRUPT;
cpu_loop_exit_restore(cpu, pc);
}
rewind_if_in_safe_syscall(puc);
/*
* 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 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.
*/
sigmask = host_signal_mask(uc);
memset(sigmask, 0xff, SIGSET_T_SIZE);
sigdelset(sigmask, SIGSEGV);
sigdelset(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;
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 -QEMU_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) {
__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) {
struct sigaction act1;
sigfillset(&act1.sa_mask);
act1.sa_flags = SA_SIGINFO;
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 (core_dump_signal(sig)) {
act1.sa_sigaction = host_signal_handler;
} 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);
}
}
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(cpu_env, sig);
}
} else if (handler == TARGET_SIG_IGN) {
/* ignore sig */
} else if (handler == TARGET_SIG_ERR) {
dump_core_and_abort(cpu_env, 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)) {
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;
}
int process_sigsuspend_mask(sigset_t **pset, target_ulong sigset,
target_ulong sigsize)
{
TaskState *ts = (TaskState *)thread_cpu->opaque;
sigset_t *host_set = &ts->sigsuspend_mask;
target_sigset_t *target_sigset;
if (sigsize != sizeof(*target_sigset)) {
/* Like the kernel, we enforce correct size sigsets */
return -TARGET_EINVAL;
}
target_sigset = lock_user(VERIFY_READ, sigset, sigsize, 1);
if (!target_sigset) {
return -TARGET_EFAULT;
}
target_to_host_sigset(host_set, target_sigset);
unlock_user(target_sigset, sigset, 0);
*pset = host_set;
return 0;
}
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