xtensa: drop references to C library

C library is not actually used by the xtensa port, we only need the
'exit' function. Implement 'exit' in crt1-* and drop remaining
references to the C library.

Change-Id: I8a562363956b4755a6b5baee7acf3726485e5ce3
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

arch/xtensa/core/crt1-boards.S

@@ -18,11 +18,10 @@
 
 /* Exports */
 .global _start
+.global exit
 
 /*
  * Imports
- *   __clibrary_init		from C library (eg. newlib or uclibc)
- *   exit			from C library
  *   main			from user application
  *   board_init			board-specific (uart/mingloss/tinygloss.c)
  *   xthal_dcache_all_writeback	from HAL library
@@ -214,28 +213,12 @@ _start:
 #else /* !HALT */
 
 	.type	board_init, @function
-	.type	__clibrary_init, @function
 	.type	exit, @function
 
 
 	 /*  Initialize the board (eg. UART, etc). */
 	CALL	board_init
 
-	/*
-	 *  Call __clibrary_init to initialize the C library:
-	 *
-	 *  void __clibrary_init(int argc, char ** argv, char ** environ,
-	 *		void(*init_func)(void), void(*fini_func)(void));
-	 *  Pass an empty argv array, with an empty string as the program name
-	 */
-	movi	ARG1, _start_argc	/* argc address */
-	movi	ARG2, _start_argv	/* argv = ["", 0] */
-	movi	ARG3, _start_envp	/* envp = [0] */
-	movi 	ARG4, _init		/* function that calls constructors */
-	movi	ARG5, _fini		/* function that calls destructors */
-	l32i	ARG1, ARG1, 0		/* argc = 1 */
-	CALL	__clibrary_init
-
 	/*  Call:   int main(int argc, char ** argv, char ** environ); */
 	movi	ARG1, _start_argc	/* argc address */
 	movi	ARG2, _start_argv	/* argv = ["", 0] */
@@ -269,3 +252,12 @@ _start_argc:
 
 	.size	_start, . - _start
 
+	.align 4
+exit:
+#if XCHAL_HAVE_INTERRUPTS
+	waiti	15
+#endif
+	j	exit
+
+	.size exit, . - exit
+

arch/xtensa/core/crt1-sim.S

@@ -17,16 +17,14 @@
 /* Exports */
 .global _start
 .global __start
+.global exit
 
 /*
  * Imports
- *   __clibrary_init	from C library (eg. newlib or uclibc)
- *   exit		from C library
  *   main		from user application
  *   __stack		from linker script (see LSP Ref Manual)
  */
 
-.type	__clibrary_init, @function
 .type	_Cstart, @function
 .type	exit, @function
 
@@ -34,6 +32,7 @@
 /* Macros to abstract away ABI differences */
 
 #if __XTENSA_CALL0_ABI__
+# define ENTRY
 # define CALL	call0
 # define CALLX	callx0
 # define ARG1	a2	/* 1st outgoing call argument */
@@ -42,6 +41,7 @@
 # define ARG4	a5	/* 4th outgoing call argument */
 # define ARG5	a6	/* 5th outgoing call argument */
 #else
+# define ENTRY	entry	sp, 0x20
 # define CALL	call4
 # define CALLX	callx4
 # define ARG1	a6	/* 1st outgoing call argument */
@@ -210,13 +210,6 @@ __start:
 #endif
 
 
-	/*
-	 *  Call __clibrary_init to initialize the C library:
-	 *
-	 *  void __clibrary_init(int argc, char ** argv, char ** environ,
-	 *		void(*init_func)(void), void(*fini_func)(void));
-	 */
-
 	/* Get argv with the arguments from the ISS */
 	mov	a3, sp		 /* tell simcall where to write argv[] */
 	movi	a2, SYS_iss_set_argv
@@ -236,6 +229,14 @@ __start:
 
 	.size	_start, . - _start
 
+	.align 4
+exit:
+	ENTRY
+	mov	a3, a2
+	movi	a2, SYS_exit
+	simcall
+
+	.size exit, . - exit
 
 /*
  * Local Variables:

scripts/Makefile.toolchain.xcc

@@ -53,7 +53,7 @@ XTSC_INC_FILE=$(notdir ${XTSC_INC})
 
 # Include XCC standard libraries so that users used to Xplorer IDE can port
 # their code easily
-TOOLCHAIN_LIBS += gcc c sim hal
+TOOLCHAIN_LIBS += gcc hal
 LIB_INCLUDE_DIR += -L${XTENSA_BUILD}/xtensa-elf/lib/xcc \
                    -L${XTENSA_BUILD}/xtensa-elf/lib \
                    -L${XTENSA_BUILD}/xtensa-elf/arch/lib