match glibc/lsb cancellation abi on i386

glibc made the ridiculous choice to use pass-by-register calling
convention for these functions, which is impossible to duplicate
directly on non-gcc compilers. instead, we use ugly asm to wrap and
convert the calling convention. presumably this works with every
compiler anyone could potentially want to use.

arch/i386/bits/pthread.h

@@ -4,3 +4,22 @@ struct __ptcb {
 	struct __ptcb *__next;
 	void *__ptrs[3];
 };
+
+static inline void __pthread_register_cancel_2(struct __ptcb *__cb)
+{
+	__asm__ __volatile__( "call __pthread_register_cancel" : : "a"(__cb) );
+}
+
+static inline void __pthread_unregister_cancel_2(struct __ptcb *__cb)
+{
+	__asm__ __volatile__( "call __pthread_unregister_cancel" : : "a"(__cb) );
+}
+
+static inline void __pthread_unwind_next_2(struct __ptcb *__cb)
+{
+	__asm__ __volatile__( "call __pthread_unwind_next" : : "a"(__cb) );
+}
+
+#define __pthread_register_cancel __pthread_register_cancel_2
+#define __pthread_unregister_cancel __pthread_unregister_cancel_2
+#define __pthread_unwind_next __pthread_unwind_next_2

include/pthread.h

@@ -181,9 +181,11 @@ int pthread_atfork(void (*)(void), void (*)(void), void (*)(void));
 #include <bits/pthread.h>
 
 int __setjmp(void *);
+#ifndef __pthread_register_cancel
 void __pthread_register_cancel(struct __ptcb *);
 void __pthread_unregister_cancel(struct __ptcb *);
 void __pthread_unwind_next(struct __ptcb *);
+#endif
 
 #define pthread_cleanup_push(f, x) \
 do { struct __ptcb __cb; void (*__f)(void *) = (f); void *__x = (x); \

src/thread/cancellation.c

 #include "pthread_impl.h"
 
+#ifdef __pthread_register_cancel
+#undef __pthread_register_cancel
+#undef __pthread_unregister_cancel
+#define __pthread_register_cancel __pthread_register_cancel_3
+#define __pthread_unregister_cancel __pthread_unregister_cancel_3
+#endif
+
 void __pthread_register_cancel(struct __ptcb *cb)
 {
 	struct pthread *self = pthread_self();

src/thread/i386/cancellation2.s

+.text
+.global __pthread_register_cancel
+.type   __pthread_register_cancel,%function
+__pthread_register_cancel:
+	pushl %eax
+	call __pthread_register_cancel_3
+	popl %eax
+	ret
+
+.global __pthread_unregister_cancel
+.type   __pthread_unregister_cancel,%function
+__pthread_unregister_cancel:
+	pushl %eax
+	call __pthread_unregister_cancel_3
+	popl %eax
+	ret

src/thread/i386/cancellation3.s

+.text
+.global __pthread_unwind_next
+.type   __pthread_unwind_next,%function
+__pthread_unwind_next:
+	pushl %eax
+	call __pthread_unwind_next_3
+	popl %eax
+	ret

src/thread/pthread_create.c

 #include "pthread_impl.h"
 
+#ifdef __pthread_unwind_next
+#undef __pthread_unwind_next
+#define __pthread_unwind_next __pthread_unwind_next_3
+#endif
+
 void __pthread_unwind_next(struct __ptcb *cb)
 {
 	int i, j, not_finished;