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#define WANT_BSDTHREAD_TERMINATE
#define WANT_SEMAPHORE_WAIT_TRAP
#include "darwin/manual-syscall.h"
#ifdef __arm64__
#define _PAGE_SIZE 0x4000
#else
#define _PAGE_SIZE 0x1000
#endif
int manual_bsdthread_terminate(void *, unsigned long, unsigned, unsigned);
GEN_SYSCALL(bsdthread_terminate, 361);
int manual_semaphore_wait_trap(int);
GEN_SYSCALL(semaphore_wait_trap, -36);
/* This is somewhat more complicated than it has to be because it does not use
* pthread_join, which depends on pthread_self, which would need to be
* initialized manually; the format of this has changed in the past, and could
* again. */
struct baton {
int (*pthread_create)(int *, void *, void *(*)(void *), void *);
int (*pthread_detach)(int);
void *(*dlopen)(const char *, int);
void *(*dlsym)(void *, const char *);
int (*munmap)(void *, long);
const char *path;
/* bsd_thread_func uses this to wait for entry to go away */
long sem_port;
long nshuttle;
char shuttle[0];
};
static int bsd_thread_func(void *);
#if defined(__i386__)
__attribute__((fastcall))
#endif
void entry(struct baton *baton) {
int pt = 0;
baton->pthread_create(&pt, 0, (void *) bsd_thread_func, baton);
baton->pthread_detach(pt);
manual_bsdthread_terminate(0, 0, 0, baton->sem_port);
((void (*)()) 0xbad)();
}
static int bsd_thread_func(void *arg) {
struct baton *baton = arg;
void *r = baton->dlopen(baton->path, 0);
if (r) {
__attribute__((section("__TEXT,__text"), aligned(4)))
static char name[] = "substitute_init";
void (*init)(void *, unsigned long) = baton->dlsym(r, name);
if (init)
init(baton->shuttle, baton->nshuttle);
}
manual_semaphore_wait_trap(baton->sem_port);
#ifndef __i386__
/* since we're munmapping our own code, this must be optimized into a jump
* (tail call elimination) */
enum { page_size =
#ifdef __arm64__
0x4000
#else
0x1000
#endif
};
unsigned long ptr = (unsigned long) baton & ~(_PAGE_SIZE - 1);
return baton->munmap((void *) ptr, 2 * page_size);
#else
/* i386 can't normally eliminate tail calls in caller-cleanup calling
* conventions, unless the number of arguments is the same, so use a nasty
* hack */
extern int jump_to_munmap(void *);
return jump_to_munmap(baton);
#endif
}
#ifdef __i386__
/* yuck */
asm(".globl _jump_to_munmap;"
"_jump_to_munmap:"
"push %ebp;"
"mov %esp, %ebp;"
"sub $0x400, %ebp;"
"mov 8(%esp), %edx;" /* baton */
"mov 16(%edx), %eax;" /* munmap */
"and $~0xfff, %edx;"
"mov %edx, 8(%ebp);"
"movl $0x2000, 12(%ebp);"
"add $3, %eax;" /* !? */
"jmp *%eax;"
);
#endif
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