Fix the exit syscall stub's name.

I've left the exit_group syscall as _exit because otherwise we'd have to
convince the compiler that our _exit (which just calls __exit_group) is
actually "noreturn", and it seems like that would be less clean than just
cutting out the middleman.

We'll just have to trust ourselves not to add anything to SYSCALLS.TXT
that ought to be private but that only has a single leading underscore.
Hopefully we can manage that.

Change-Id: Iac47faea9f516186e1774381846c54cafabc4354

libc/SYSCALLS.TXT

@@ -24,13 +24,6 @@
 #
 # This file is processed by a python script named gensyscalls.py.
 
-# process management
-void    _exit:exit_group(int)      all
-void    _exit_thread:exit(int)     all
-
-pid_t wait4(pid_t, int*, int, struct rusage*)  all
-int __waitid:waitid(int, pid_t, struct siginfo_t*, int, void*)  all
-
 int     execve(const char*, char* const*, char* const*)  all
 
 uid_t   getuid:getuid32()         arm,x86
@@ -289,6 +282,9 @@ int __epoll_pwait:epoll_pwait(int, struct epoll_event*, int, int, const sigset_t
 
 int eventfd:eventfd2(unsigned int, int)  all
 
+void _exit:exit_group(int)  all
+void __exit:exit(int)  all
+
 int futex(void*, int, int, void*, void*, int)  all
 
 int inotify_init1(int)  all
@@ -298,6 +294,9 @@ int inotify_rm_watch(int, unsigned int)  all
 int __pselect6:pselect6(int, fd_set*, fd_set*, fd_set*, timespec*, void*)  all
 int __ppoll:ppoll(pollfd*, unsigned int, timespec*, const sigset_t*, size_t)  all
 
+pid_t wait4(pid_t, int*, int, struct rusage*)  all
+int __waitid:waitid(int, pid_t, struct siginfo_t*, int, void*)  all
+
 # ARM-specific
 int     __set_tls:__ARM_NR_set_tls(void*)                                 arm
 int     cacheflush:__ARM_NR_cacheflush(long start, long end, long flags)  arm

libc/arch-arm/syscalls.mk

@@ -3,6 +3,7 @@ syscall_src :=
 syscall_src += arch-arm/syscalls/__brk.S
 syscall_src += arch-arm/syscalls/__clone.S
 syscall_src += arch-arm/syscalls/__epoll_pwait.S
+syscall_src += arch-arm/syscalls/__exit.S
 syscall_src += arch-arm/syscalls/__fcntl.S
 syscall_src += arch-arm/syscalls/__fcntl64.S
 syscall_src += arch-arm/syscalls/__fstatfs64.S
@@ -34,7 +35,6 @@ syscall_src += arch-arm/syscalls/__timer_gettime.S
 syscall_src += arch-arm/syscalls/__timer_settime.S
 syscall_src += arch-arm/syscalls/__waitid.S
 syscall_src += arch-arm/syscalls/_exit.S
-syscall_src += arch-arm/syscalls/_exit_thread.S
 syscall_src += arch-arm/syscalls/accept.S
 syscall_src += arch-arm/syscalls/acct.S
 syscall_src += arch-arm/syscalls/bind.S

libc/arch-arm/syscalls/__exit.S

@@ -4,7 +4,7 @@
 #include <linux/err.h>
 #include <machine/asm.h>
 
-ENTRY(_exit_thread)
+ENTRY(__exit)
     mov     ip, r7
     ldr     r7, =__NR_exit
     swi     #0
@@ -13,4 +13,4 @@ ENTRY(_exit_thread)
     bxls    lr
     neg     r0, r0
     b       __set_errno
-END(_exit_thread)
+END(__exit)

libc/arch-mips/syscalls.mk

@@ -3,6 +3,7 @@ syscall_src :=
 syscall_src += arch-mips/syscalls/__brk.S
 syscall_src += arch-mips/syscalls/__clone.S
 syscall_src += arch-mips/syscalls/__epoll_pwait.S
+syscall_src += arch-mips/syscalls/__exit.S
 syscall_src += arch-mips/syscalls/__fcntl.S
 syscall_src += arch-mips/syscalls/__fcntl64.S
 syscall_src += arch-mips/syscalls/__fstatfs64.S
@@ -34,7 +35,6 @@ syscall_src += arch-mips/syscalls/__timer_gettime.S
 syscall_src += arch-mips/syscalls/__timer_settime.S
 syscall_src += arch-mips/syscalls/__waitid.S
 syscall_src += arch-mips/syscalls/_exit.S
-syscall_src += arch-mips/syscalls/_exit_thread.S
 syscall_src += arch-mips/syscalls/_flush_cache.S
 syscall_src += arch-mips/syscalls/accept.S
 syscall_src += arch-mips/syscalls/acct.S

libc/arch-mips/syscalls/__exit.S

@@ -2,11 +2,11 @@
 
 #include <asm/unistd.h>
     .text
-    .globl _exit_thread
+    .globl __exit
     .align 4
-    .ent _exit_thread
+    .ent __exit
 
-_exit_thread:
+__exit:
     .set noreorder
     .cpload $t9
     li $v0, __NR_exit
@@ -20,4 +20,4 @@ _exit_thread:
     j $t9
     nop
     .set reorder
-    .end _exit_thread
+    .end __exit

libc/arch-x86/syscalls.mk

@@ -3,6 +3,7 @@ syscall_src :=
 syscall_src += arch-x86/syscalls/__brk.S
 syscall_src += arch-x86/syscalls/__clone.S
 syscall_src += arch-x86/syscalls/__epoll_pwait.S
+syscall_src += arch-x86/syscalls/__exit.S
 syscall_src += arch-x86/syscalls/__fcntl.S
 syscall_src += arch-x86/syscalls/__fcntl64.S
 syscall_src += arch-x86/syscalls/__fstatfs64.S
@@ -34,7 +35,6 @@ syscall_src += arch-x86/syscalls/__timer_gettime.S
 syscall_src += arch-x86/syscalls/__timer_settime.S
 syscall_src += arch-x86/syscalls/__waitid.S
 syscall_src += arch-x86/syscalls/_exit.S
-syscall_src += arch-x86/syscalls/_exit_thread.S
 syscall_src += arch-x86/syscalls/accept.S
 syscall_src += arch-x86/syscalls/acct.S
 syscall_src += arch-x86/syscalls/bind.S

libc/arch-x86/syscalls/__exit.S

@@ -4,7 +4,7 @@
 #include <linux/err.h>
 #include <machine/asm.h>
 
-ENTRY(_exit_thread)
+ENTRY(__exit)
     pushl   %ebx
     mov     8(%esp), %ebx
     movl    $__NR_exit, %eax
@@ -19,4 +19,4 @@ ENTRY(_exit_thread)
 1:
     popl    %ebx
     ret
-END(_exit_thread)
+END(__exit)

libc/arch-x86_64/syscalls.mk

@@ -4,6 +4,7 @@ syscall_src += arch-x86_64/syscalls/__arch_prctl.S
 syscall_src += arch-x86_64/syscalls/__brk.S
 syscall_src += arch-x86_64/syscalls/__clone.S
 syscall_src += arch-x86_64/syscalls/__epoll_pwait.S
+syscall_src += arch-x86_64/syscalls/__exit.S
 syscall_src += arch-x86_64/syscalls/__getcpu.S
 syscall_src += arch-x86_64/syscalls/__getcwd.S
 syscall_src += arch-x86_64/syscalls/__getpriority.S
@@ -27,7 +28,6 @@ syscall_src += arch-x86_64/syscalls/__timer_gettime.S
 syscall_src += arch-x86_64/syscalls/__timer_settime.S
 syscall_src += arch-x86_64/syscalls/__waitid.S
 syscall_src += arch-x86_64/syscalls/_exit.S
-syscall_src += arch-x86_64/syscalls/_exit_thread.S
 syscall_src += arch-x86_64/syscalls/accept.S
 syscall_src += arch-x86_64/syscalls/acct.S
 syscall_src += arch-x86_64/syscalls/bind.S

libc/arch-x86_64/syscalls/__exit.S

@@ -4,7 +4,7 @@
 #include <linux/err.h>
 #include <machine/asm.h>
 
-ENTRY(_exit_thread)
+ENTRY(__exit)
     movl    $__NR_exit, %eax
     syscall
     cmpq    $-MAX_ERRNO, %rax
@@ -15,4 +15,5 @@ ENTRY(_exit_thread)
     orq     $-1, %rax
 1:
     ret
-END(_exit_thread)
+END(__exit)
+.hidden _C_LABEL(__exit)

libc/bionic/bionic_clone.c

@@ -39,14 +39,14 @@ extern int  __bionic_clone(unsigned long   clone_flags,
                            int            (*fn)(void *),
                            void          *arg);
 
-extern void _exit_thread(int status);
+extern void __exit(int status);
 
 /* this function is called from the __bionic_clone
  * assembly fragment to call the thread function
  * then exit. */
 extern void __bionic_clone_entry(int (*fn)(void*), void* arg) {
   int status = (*fn)(arg);
-  _exit_thread(status);
+  __exit(status);
 }
 
 int clone(int (*fn)(void*), void* child_stack, int flags, void* arg, ...) {

libc/bionic/pthread.c

@@ -46,7 +46,7 @@ extern void pthread_debug_mutex_lock_check(pthread_mutex_t *mutex);
 extern void pthread_debug_mutex_unlock_check(pthread_mutex_t *mutex);
 
 extern void _exit_with_stack_teardown(void * stackBase, size_t stackSize, int status);
-extern void _exit_thread(int status);
+extern void __exit(int status);
 
 int  __futex_wake_ex(volatile void *ftx, int pshared, int val)
 {
@@ -148,7 +148,7 @@ void pthread_exit(void * retval)
 
     if (user_stack) {
         // Cleaning up this thread's stack is the creator's responsibility, not ours.
-        _exit_thread(0);
+        __exit(0);
     } else {
         // We need to munmap the stack we're running on before calling exit.
         // That's not something we can do in C.

libc/tools/gensyscalls.py

@@ -240,7 +240,6 @@ def add_footer(pointer_length, stub, syscall):
         stub += function_alias % { "func" : syscall["func"], "alias" : alias }
 
     # Use hidden visibility for any functions beginning with underscores.
-    # TODO: clean up single-underscore names too.
     if pointer_length == 64 and syscall["func"].startswith("__"):
         stub += '.hidden _C_LABEL(' + syscall["func"] + ')\n'