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runtime: Catch signals on altstack, disable splitstack signal blocking. 

From-SVN: r182607
This commit is contained in:
Ian Lance Taylor 2011-12-21 22:24:47 +00:00
parent e0d2f03016
commit a6dcb7d465
6 changed files with 349 additions and 142 deletions
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8
libgo/runtime/go-panic.c
View File

@ -24,13 +24,13 @@ __printpanics (struct __go_panic_stack *p)
if (p->__next != NULL)
{
__printpanics (p->__next);
printf ("\t");
fprintf (stderr, "\t");
}
printf ("panic: ");
fprintf (stderr, "panic: ");
printany (p->__arg);
if (p->__was_recovered)
printf (" [recovered]");
putchar ('\n');
fprintf (stderr, " [recovered]");
fputc ('\n', stderr);
}
/* This implements __go_panic which is used for the panic

433
libgo/runtime/go-signal.c
View File

@ -17,109 +17,133 @@
#define SA_RESTART 0
#endif
/* What to do for a signal. */
#ifdef USING_SPLIT_STACK
struct sigtab
{
/* Signal number. */
int sig;
/* Nonzero if the signal should be caught. */
_Bool catch;
/* Nonzero if the signal should be queued. */
_Bool queue;
/* Nonzero if the signal should be ignored. */
_Bool ignore;
/* Nonzero if we should restart system calls. */
_Bool restart;
};
extern void __splitstack_getcontext(void *context[10]);
/* What to do for signals. */
extern void __splitstack_setcontext(void *context[10]);
static struct sigtab signals[] =
{
{ SIGHUP, 0, 1, 0, 1 },
{ SIGINT, 0, 1, 0, 1 },
{ SIGQUIT, 0, 1, 0, 1 },
{ SIGALRM, 0, 1, 1, 1 },
{ SIGTERM, 0, 1, 0, 1 },
#endif
#define C SigCatch
#define I SigIgnore
#define R SigRestart
#define Q SigQueue
#define P SigPanic
/* Signal actions. This collects the sigtab tables for several
different targets from the master library. SIGKILL, SIGCONT, and
SIGSTOP are not listed, as we don't want to set signal handlers for
them. */
SigTab runtime_sigtab[] = {
#ifdef SIGHUP
{ SIGHUP, Q + R },
#endif
#ifdef SIGINT
{ SIGINT, Q + R },
#endif
#ifdef SIGQUIT
{ SIGQUIT, C },
#endif
#ifdef SIGILL
{ SIGILL, 1, 0, 0, 0 },
{ SIGILL, C },
#endif
#ifdef SIGTRAP
{ SIGTRAP, 1, 0, 0, 0 },
{ SIGTRAP, C },
#endif
#ifdef SIGABRT
{ SIGABRT, 1, 0, 0, 0 },
{ SIGABRT, C },
#endif
#ifdef SIGBUS
{ SIGBUS, 1, 0, 0, 0 },
{ SIGBUS, C + P },
#endif
#ifdef SIGFPE
{ SIGFPE, 1, 0, 0, 0 },
{ SIGFPE, C + P },
#endif
#ifdef SIGUSR1
{ SIGUSR1, 0, 1, 1, 1 },
{ SIGUSR1, Q + I + R },
#endif
#ifdef SIGSEGV
{ SIGSEGV, 1, 0, 0, 0 },
{ SIGSEGV, C + P },
#endif
#ifdef SIGUSR2
{ SIGUSR2, 0, 1, 1, 1 },
{ SIGUSR2, Q + I + R },
#endif
#ifdef SIGPIPE
{ SIGPIPE, 0, 0, 1, 0 },
{ SIGPIPE, I },
#endif
#ifdef SIGALRM
{ SIGALRM, Q + I + R },
#endif
#ifdef SIGTERM
{ SIGTERM, Q + R },
#endif
#ifdef SIGSTKFLT
{ SIGSTKFLT, 1, 0, 0, 0 },
{ SIGSTKFLT, C },
#endif
#ifdef SIGCHLD
{ SIGCHLD, 0, 1, 1, 1 },
{ SIGCHLD, Q + I + R },
#endif
#ifdef SIGTSTP
{ SIGTSTP, 0, 1, 1, 1 },
{ SIGTSTP, Q + I + R },
#endif
#ifdef SIGTTIN
{ SIGTTIN, 0, 1, 1, 1 },
{ SIGTTIN, Q + I + R },
#endif
#ifdef SIGTTOU
{ SIGTTOU, 0, 1, 1, 1 },
{ SIGTTOU, Q + I + R },
#endif
#ifdef SIGURG
{ SIGURG, 0, 1, 1, 1 },
{ SIGURG, Q + I + R },
#endif
#ifdef SIGXCPU
{ SIGXCPU, 0, 1, 1, 1 },
{ SIGXCPU, Q + I + R },
#endif
#ifdef SIGXFSZ
{ SIGXFSZ, 0, 1, 1, 1 },
{ SIGXFSZ, Q + I + R },
#endif
#ifdef SIGVTARLM
{ SIGVTALRM, 0, 1, 1, 1 },
#ifdef SIGVTALRM
{ SIGVTALRM, Q + I + R },
#endif
#ifdef SIGPROF
{ SIGPROF, 0, 1, 1, 1 },
{ SIGPROF, Q + I + R },
#endif
#ifdef SIGWINCH
{ SIGWINCH, 0, 1, 1, 1 },
{ SIGWINCH, Q + I + R },
#endif
#ifdef SIGIO
{ SIGIO, 0, 1, 1, 1 },
{ SIGIO, Q + I + R },
#endif
#ifdef SIGPWR
{ SIGPWR, 0, 1, 1, 1 },
{ SIGPWR, Q + I + R },
#endif
#ifdef SIGSYS
{ SIGSYS, 1, 0, 0, 0 },
{ SIGSYS, C },
#endif
{ -1, 0, 0, 0, 0 }
#ifdef SIGEMT
{ SIGEMT, C },
#endif
#ifdef SIGINFO
{ SIGINFO, Q + I + R },
#endif
#ifdef SIGTHR
{ SIGTHR, Q + I + R },
#endif
{ -1, 0 }
};
#undef C
#undef I
#undef R
#undef Q
#undef P
/* The Go signal handler. */
/* Handle a signal, for cases where we don't panic. We can split the
stack here. */
static void
sighandler (int sig)
sig_handler (int sig)
{
const char *msg;
int i;
#ifdef SIGPROF
@ -131,99 +155,223 @@ sighandler (int sig)
}
#endif
/* FIXME: Should check siginfo for more information when
available. */
msg = NULL;
for (i = 0; runtime_sigtab[i].sig != -1; ++i)
{
struct sigaction sa;
if (runtime_sigtab[i].sig != sig)
continue;
if ((runtime_sigtab[i].flags & SigQueue) != 0)
{
if (__go_sigsend (sig)
|| (runtime_sigtab[sig].flags & SigIgnore) != 0)
return;
runtime_exit (2); // SIGINT, SIGTERM, etc
}
if (runtime_panicking)
runtime_exit (2);
runtime_panicking = 1;
/* We should do a stack backtrace here. Until we can do that,
we reraise the signal in order to get a slightly better
report from the shell. */
memset (&sa, 0, sizeof sa);
sa.sa_handler = SIG_DFL;
i = sigemptyset (&sa.sa_mask);
__go_assert (i == 0);
if (sigaction (sig, &sa, NULL) != 0)
abort ();
raise (sig);
runtime_exit (2);
}
__builtin_unreachable ();
}
/* The start of handling a signal which panics. */
static void
sig_panic_leadin (int sig)
{
int i;
sigset_t clear;
if (runtime_m ()->mallocing)
{
runtime_printf ("caught signal while mallocing: %d\n", sig);
runtime_throw ("caught signal while mallocing");
}
/* The signal handler blocked signals; unblock them. */
i = sigfillset (&clear);
__go_assert (i == 0);
i = sigprocmask (SIG_UNBLOCK, &clear, NULL);
__go_assert (i == 0);
}
#ifdef SA_SIGINFO
/* Signal dispatch for signals which panic, on systems which support
SA_SIGINFO. This is called on the thread stack, and as such it is
permitted to split the stack. */
static void
sig_panic_info_handler (int sig, siginfo_t *info,
void *context __attribute__ ((unused)))
{
if (runtime_g () == NULL)
{
sig_handler (sig);
return;
}
sig_panic_leadin (sig);
switch (sig)
{
#ifdef SIGILL
case SIGILL:
msg = "illegal instruction";
break;
#endif
#ifdef SIGBUS
case SIGBUS:
msg = "invalid memory address or nil pointer dereference";
break;
#endif
#ifdef SIGFPE
case SIGFPE:
msg = "integer divide by zero or floating point error";
break;
if (info->si_code == BUS_ADRERR && (uintptr_t) info->si_addr < 0x1000)
runtime_panicstring ("invalid memory address or "
"nil pointer dereference");
runtime_printf ("unexpected fault address %p\n", info->si_addr);
runtime_throw ("fault");
#endif
#ifdef SIGSEGV
case SIGSEGV:
msg = "invalid memory address or nil pointer dereference";
break;
if ((info->si_code == 0
|| info->si_code == SEGV_MAPERR
|| info->si_code == SEGV_ACCERR)
&& (uintptr_t) info->si_addr < 0x1000)
runtime_panicstring ("invalid memory address or "
"nil pointer dereference");
runtime_printf ("unexpected fault address %p\n", info->si_addr);
runtime_throw ("fault");
#endif
default:
break;
}
if (msg != NULL)
{
sigset_t clear;
if (runtime_m()->mallocing)
#ifdef SIGFPE
case SIGFPE:
switch (info->si_code)
{
fprintf (stderr, "caught signal while mallocing: %s\n", msg);
__go_assert (0);
case FPE_INTDIV:
runtime_panicstring ("integer divide by zero");
case FPE_INTOVF:
runtime_panicstring ("integer overflow");
}
/* The signal handler blocked signals; unblock them. */
i = sigfillset (&clear);
__go_assert (i == 0);
i = sigprocmask (SIG_UNBLOCK, &clear, NULL);
__go_assert (i == 0);
runtime_panicstring (msg);
runtime_panicstring ("floating point error");
#endif
}
for (i = 0; signals[i].sig != -1; ++i)
{
if (signals[i].sig == sig)
{
struct sigaction sa;
if (signals[i].queue)
{
if (__go_sigsend (sig) || signals[i].ignore)
return;
runtime_exit (2); // SIGINT, SIGTERM, etc
}
if (runtime_panicking)
runtime_exit (2);
runtime_panicking = 1;
memset (&sa, 0, sizeof sa);
sa.sa_handler = SIG_DFL;
i = sigemptyset (&sa.sa_mask);
__go_assert (i == 0);
if (sigaction (sig, &sa, NULL) != 0)
abort ();
raise (sig);
exit (2);
}
}
abort ();
/* All signals with SigPanic should be in cases above, and this
handler should only be invoked for those signals. */
__builtin_unreachable ();
}
/* Ignore a signal. */
#else /* !defined (SA_SIGINFO) */
static void
sig_panic_handler (int sig)
{
if (runtime_g () == NULL)
{
sig_handler (sig);
return;
}
sig_panic_leadin (sig);
switch (sig)
{
#ifdef SIGBUS
case SIGBUS:
runtime_panicstring ("invalid memory address or "
"nil pointer dereference");
#endif
#ifdef SIGSEGV
case SIGSEGV:
runtime_panicstring ("invalid memory address or "
"nil pointer dereference");
#endif
#ifdef SIGFPE
case SIGFPE:
runtime_panicstring ("integer divide by zero or floating point error");
#endif
}
/* All signals with SigPanic should be in cases above, and this
handler should only be invoked for those signals. */
__builtin_unreachable ();
}
#endif /* !defined (SA_SIGINFO) */
/* Ignore a signal. This is called on the alternate signal stack so
it may not split the stack. */
static void sig_ignore (int) __attribute__ ((no_split_stack));
static void
sig_ignore (int sig __attribute__ ((unused)))
{
}
/* A signal handler used for signals which are not going to panic.
This is called on the alternate signal stack so it may not split
the stack. */
static void
sig_tramp (int) __attribute__ ((no_split_stack));
static void
sig_tramp (int sig)
{
G *gp;
M *mp;
/* We are now running on the stack registered via sigaltstack.
(Actually there is a small span of time between runtime_siginit
and sigaltstack when the program starts.) */
gp = runtime_g ();
mp = runtime_m ();
if (gp != NULL)
__splitstack_getcontext (&gp->stack_context[0]);
if (gp != NULL && mp->gsignal != NULL)
{
/* We are running on the signal stack. Set the split stack
context so that the stack guards are checked correctly. */
#ifdef USING_SPLIT_STACK
__splitstack_setcontext (&mp->gsignal->stack_context[0]);
#endif
}
sig_handler (sig);
/* We are going to return back to the signal trampoline and then to
whatever we were doing before we got the signal. Restore the
split stack context so that stack guards are checked
correctly. */
if (gp != NULL)
{
#ifdef USING_SPLIT_STACK
__splitstack_setcontext (&gp->stack_context[0]);
#endif
}
}
/* Initialize signal handling for Go. This is called when the program
starts. */
@ -237,21 +385,44 @@ runtime_initsig (int32 queue)
memset (&sa, 0, sizeof sa);
sa.sa_handler = sighandler;
i = sigfillset (&sa.sa_mask);
__go_assert (i == 0);
for (i = 0; signals[i].sig != -1; ++i)
for (i = 0; runtime_sigtab[i].sig != -1; ++i)
{
if (signals[i].queue != (queue ? 1 : 0))
if (runtime_sigtab[i].flags == 0)
continue;
if (signals[i].catch || signals[i].queue)
sa.sa_handler = sighandler;
if ((runtime_sigtab[i].flags & SigQueue) != queue)
continue;
if ((runtime_sigtab[i].flags & (SigCatch | SigQueue)) != 0)
{
if ((runtime_sigtab[i].flags & SigPanic) == 0)
{
sa.sa_flags = SA_ONSTACK;
sa.sa_handler = sig_tramp;
}
else
{
#ifdef SA_SIGINFO
sa.sa_flags = SA_SIGINFO;
sa.sa_sigaction = sig_panic_info_handler;
#else
sa.sa_flags = 0;
sa.sa_handler = sig_panic_handler;
#endif
}
}
else
sa.sa_handler = sig_ignore;
sa.sa_flags = signals[i].restart ? SA_RESTART : 0;
if (sigaction (signals[i].sig, &sa, NULL) != 0)
{
sa.sa_flags = SA_ONSTACK;
sa.sa_handler = sig_ignore;
}
if ((runtime_sigtab[i].flags & SigRestart) != 0)
sa.sa_flags |= SA_RESTART;
if (sigaction (runtime_sigtab[i].sig, &sa, NULL) != 0)
__go_assert (0);
}
}
@ -281,7 +452,7 @@ runtime_resetcpuprofiler(int32 hz)
}
else
{
sa.sa_handler = sighandler;
sa.sa_handler = sig_handler;
sa.sa_flags = SA_RESTART;
i = sigaction (SIGPROF, &sa, NULL);
__go_assert (i == 0);

10
libgo/runtime/mem.c
View File

@ -47,7 +47,7 @@ runtime_SysAlloc(uintptr n)
if (dev_zero == -1) {
dev_zero = open("/dev/zero", O_RDONLY);
if (dev_zero < 0) {
printf("open /dev/zero: errno=%d\n", errno);
runtime_printf("open /dev/zero: errno=%d\n", errno);
exit(2);
}
}
@ -57,8 +57,8 @@ runtime_SysAlloc(uintptr n)
p = runtime_mmap(nil, n, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_ANON|MAP_PRIVATE, fd, 0);
if (p == MAP_FAILED) {
if(errno == EACCES) {
printf("runtime: mmap: access denied\n");
printf("if you're running SELinux, enable execmem for this process.\n");
runtime_printf("runtime: mmap: access denied\n");
runtime_printf("if you're running SELinux, enable execmem for this process.\n");
exit(2);
}
return nil;
@ -97,7 +97,7 @@ runtime_SysReserve(void *v, uintptr n)
if (dev_zero == -1) {
dev_zero = open("/dev/zero", O_RDONLY);
if (dev_zero < 0) {
printf("open /dev/zero: errno=%d\n", errno);
runtime_printf("open /dev/zero: errno=%d\n", errno);
exit(2);
}
}
@ -123,7 +123,7 @@ runtime_SysMap(void *v, uintptr n)
if (dev_zero == -1) {
dev_zero = open("/dev/zero", O_RDONLY);
if (dev_zero < 0) {
printf("open /dev/zero: errno=%d\n", errno);
runtime_printf("open /dev/zero: errno=%d\n", errno);
exit(2);
}
}

21
libgo/runtime/proc.c
View File

@ -29,6 +29,11 @@ extern void * __splitstack_resetcontext(void *context[10], size_t *);
extern void *__splitstack_find(void *, void *, size_t *, void **, void **,
void **);
extern void __splitstack_block_signals (int *, int *);
extern void __splitstack_block_signals_context (void *context[10], int *,
int *);
#endif
#if defined(USING_SPLIT_STACK) && defined(LINKER_SUPPORTS_SPLIT_STACK)
@ -862,6 +867,14 @@ runtime_mstart(void* mp)
*(int*)0x21 = 0x21;
}
runtime_minit();
#ifdef USING_SPLIT_STACK
{
int dont_block_signals = 0;
__splitstack_block_signals(&dont_block_signals, nil);
}
#endif
schedule(nil);
return nil;
}
@ -1142,9 +1155,13 @@ runtime_malg(int32 stacksize, byte** ret_stack, size_t* ret_stacksize)
newg = runtime_malloc(sizeof(G));
if(stacksize >= 0) {
#if USING_SPLIT_STACK
int dont_block_signals = 0;
*ret_stack = __splitstack_makecontext(stacksize,
&newg->stack_context[0],
ret_stacksize);
__splitstack_block_signals_context(&newg->stack_context[0],
&dont_block_signals, nil);
#else
*ret_stack = runtime_mallocgc(stacksize, FlagNoProfiling|FlagNoGC, 0, 0);
*ret_stacksize = stacksize;
@ -1186,8 +1203,12 @@ __go_go(void (*fn)(void*), void* arg)
if((newg = gfget()) != nil){
#ifdef USING_SPLIT_STACK
int dont_block_signals = 0;
sp = __splitstack_resetcontext(&newg->stack_context[0],
&spsize);
__splitstack_block_signals_context(&newg->stack_context[0],
&dont_block_signals, nil);
#else
sp = newg->gcinitial_sp;
spsize = newg->gcstack_size;

17
libgo/runtime/runtime.h
View File

@ -52,6 +52,7 @@ typedef struct G G;
typedef union Lock Lock;
typedef struct M M;
typedef union Note Note;
typedef struct SigTab SigTab;
typedef struct MCache MCache;
typedef struct FixAlloc FixAlloc;
typedef struct Hchan Hchan;
@ -179,6 +180,20 @@ struct M
uint32 waitsemalock;
};
struct SigTab
{
int32 sig;
int32 flags;
};
enum
{
SigCatch = 1<<0,
SigIgnore = 1<<1,
SigRestart = 1<<2,
SigQueue = 1<<3,
SigPanic = 1<<4,
};
/* Macros. */
#ifdef __WINDOWS__
@ -251,7 +266,7 @@ void runtime_args(int32, byte**);
void runtime_osinit();
void runtime_goargs(void);
void runtime_goenvs(void);
void runtime_throw(const char*);
void runtime_throw(const char*) __attribute__ ((noreturn));
void runtime_panicstring(const char*) __attribute__ ((noreturn));
void* runtime_mal(uintptr);
void runtime_schedinit(void);

2
libgo/runtime/sigqueue.goc
View File

@ -110,6 +110,6 @@ func Signame(sig int32) (name String) {
}
func Siginit() {
runtime_initsig(1);
runtime_initsig(SigQueue);
sig.inuse = true; // enable reception of signals; cannot disable
}