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Preliminary infrastructure to implement alternate stack

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* libc/include/sys/signal.h: Define SS_ONSTACK and SS_DISABLE
	unconditionally.
	(sigaltstack): Enable prototype on Cygwin.

	* common.din (sigaltstack): Export.
	* cygtls.cc (_cygtls::init_thread): Initialize altstack.
	* cygtls.h (__tlsstack_t): Rename from __stack_t to distinguish
	more clearly from stack_t.  Accommodate throughout.
	(_cygtls): Add altstack member.
	* exceptions.cc (exception::handle): Set SIGSEGV handler to SIG_DFL
	if we encounter a stack overflow, and no alternate stack has been
	defined.
	* include/cygwin/signal.h (MINSIGSTKSZ): Define
	(SIGSTKSZ): Define.
	(SA_ONSTACK): Define.
	* signal.cc (sigaltstack): New function.
	* tlsoffset.h: Regenerate.
	* tlsoffset64.h: Ditto.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
This commit is contained in:
Corinna Vinschen
2015-06-19 15:58:23 +02:00
parent 715ac1e872
commit 22465796ed
9 changed files with 215 additions and 153 deletions
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14
winsup/cygwin/exceptions.cc
View File

@ -232,7 +232,7 @@ class stack_info
#ifdef __x86_64__
CONTEXT c;
UNWIND_HISTORY_TABLE hist;
__stack_t *sigstackptr;
__tlsstack_t *sigstackptr;
#endif
public:
STACKFRAME sf; /* For storing the stack information */
@ -696,11 +696,17 @@ exception::handle (EXCEPTION_RECORD *e, exception_list *frame, CONTEXT *in,
}
break;
case STATUS_STACK_OVERFLOW:
/* If we encounter a stack overflow, and if the thread has no alternate
stack, don't even try to call a signal handler. This is in line with
Linux behaviour and also makes a lot of sense on Windows. */
if (me.altstack.ss_flags)
global_sigs[SIGSEGV].sa_handler = SIG_DFL;
/*FALLTHRU*/
case STATUS_ARRAY_BOUNDS_EXCEEDED:
case STATUS_IN_PAGE_ERROR:
case STATUS_NO_MEMORY:
case STATUS_INVALID_DISPOSITION:
case STATUS_STACK_OVERFLOW:
si.si_signo = SIGSEGV;
si.si_code = SEGV_MAPERR;
break;
@ -894,7 +900,7 @@ _cygtls::interrupt_now (CONTEXT *cx, siginfo_t& si, void *handler,
void __reg3
_cygtls::interrupt_setup (siginfo_t& si, void *handler, struct sigaction& siga)
{
push ((__stack_t) sigdelayed);
push ((__tlsstack_t) sigdelayed);
deltamask = siga.sa_mask & ~SIG_NONMASKABLE;
sa_flags = siga.sa_flags;
func = (void (*) (int, siginfo_t *, void *)) handler;
@ -1497,7 +1503,7 @@ _cygtls::call_signal_handler ()
/* Pop the stack if the next "return address" is sigdelayed, since
this function is doing what sigdelayed would have done anyway. */
if (retaddr () == (__stack_t) sigdelayed)
if (retaddr () == (__tlsstack_t) sigdelayed)
pop ();
debug_only_printf ("dealing with signal %d", sig);