[u-boot.git] / examples / stubs.c

#include <exports.h>

#ifndef GCC_VERSION
#define GCC_VERSION (__GNUC__ * 1000 + __GNUC_MINOR__)
#endif /* GCC_VERSION */

#if defined(CONFIG_I386)
/*
 * x86 does not have a dedicated register to store the pointer to
 * the global_data. Thus the jump table address is stored in a
 * global variable, but such approach does not allow for execution
 * from flash memory. The global_data address is passed as argv[-1]
 * to the application program.
 */
static void **jt;
gd_t *global_data;

#define EXPORT_FUNC(x) \
	asm volatile (			\
"	.globl " #x "\n"		\
#x ":\n"				\
"	movl	%0, %%eax\n"		\
"	movl	jt, %%ecx\n"		\
"	jmp	*(%%ecx, %%eax)\n"	\
	: : "i"(XF_ ## x * sizeof(void *)) : "eax", "ecx");
#elif defined(CONFIG_PPC)
/*
 * r29 holds the pointer to the global_data, r11 is a call-clobbered
 * register
 */
#define EXPORT_FUNC(x) \
	asm volatile (			\
"	.globl " #x "\n"		\
#x ":\n"				\
"	lwz	%%r11, %0(%%r29)\n"	\
"	lwz	%%r11, %1(%%r11)\n"	\
"	mtctr	%%r11\n"		\
"	bctr\n"				\
	: : "i"(offsetof(gd_t, jt)), "i"(XF_ ## x * sizeof(void *)) : "r11");
#elif defined(CONFIG_ARM)
/*
 * r8 holds the pointer to the global_data, ip is a call-clobbered
 * register
 */
#define EXPORT_FUNC(x) \
	asm volatile (			\
"	.globl " #x "\n"		\
#x ":\n"				\
"	ldr	ip, [r8, %0]\n"		\
"	ldr	pc, [ip, %1]\n"		\
	: : "i"(offsetof(gd_t, jt)), "i"(XF_ ## x * sizeof(void *)) : "ip");
#elif defined(CONFIG_MIPS)
/*
 * k0 ($26) holds the pointer to the global_data; t9 ($25) is a call-
 * clobbered register that is also used to set gp ($26). Note that the
 * jr instruction also executes the instruction immediately following
 * it; however, GCC/mips generates an additional `nop' after each asm
 * statement
 */
#define EXPORT_FUNC(x) \
	asm volatile (			\
"	.globl " #x "\n"		\
#x ":\n"				\
"	lw	$25, %0($26)\n"		\
"	lw	$25, %1($25)\n"		\
"	jr	$25\n"			\
	: : "i"(offsetof(gd_t, jt)), "i"(XF_ ## x * sizeof(void *)) : "t9");
#elif defined(CONFIG_NIOS)
/*
 * %g7 holds the pointer to the global_data. %g0 is call clobbered.
 */
#define EXPORT_FUNC(x) \
	asm volatile (			\
"	.globl " #x "\n"		\
#x ":\n"				\
"	pfx	%%hi(%0)\n"		\
"	movi	%%g0, %%lo(%0)\n"	\
"	add	%%g0, %%g7\n"		\
"	ld	%%g0, [%%g0]\n"		\
"	pfx	%1\n"			\
"	ld	%%g0, [%%g0]\n"		\
"	jmp	%%g0\n"			\
"	nop	\n"			\
	: : "i"(offsetof(gd_t, jt)), "i"(XF_ ## x) : "r0");
#elif defined(CONFIG_NIOS2)
/*
 * r15 holds the pointer to the global_data, r8 is call-clobbered
 */
#define EXPORT_FUNC(x) \
	asm volatile (			\
"	.globl " #x "\n"		\
#x ":\n"				\
"	movhi	r8, %%hi(%0)\n"		\
"	ori	r8, r0, %%lo(%0)\n"	\
"	add	r8, r0, r15\n"		\
"	ldw	r8, 0(r8)\n"		\
"	ldw	r8, %1(r8)\n"		\
"	jmp	r8\n"			\
	: : "i"(offsetof(gd_t, jt)), "i"(XF_ ## x * sizeof(void *)) : "r15");
#elif defined(CONFIG_M68K)
/*
 * d7 holds the pointer to the global_data, a0 is a call-clobbered
 * register
 */
#define EXPORT_FUNC(x) \
	asm volatile (			\
"	.globl " #x "\n"		\
#x ":\n"				\
"	move.l	%%d7, %%a0\n"		\
"	adda.l	%0, %%a0\n"		\
"	move.l	(%%a0), %%a0\n"		\
"	adda.l	%1, %%a0\n"		\
"	move.l	(%%a0), %%a0\n"		\
"	jmp	(%%a0)\n"			\
	: : "i"(offsetof(gd_t, jt)), "i"(XF_ ## x * sizeof(void *)) : "a0");
#elif defined(CONFIG_MICROBLAZE)
/*
 * r31 holds the pointer to the global_data. r5 is a call-clobbered.
 */
#define EXPORT_FUNC(x)				\
	asm volatile (				\
"	.globl " #x "\n"			\
#x ":\n"					\
"	lwi	r5, r31, %0\n"			\
"	lwi	r5, r5, %1\n"			\
"	bra	r5\n"				\
	: : "i"(offsetof(gd_t, jt)), "i"(XF_ ## x * sizeof(void *)) : "r5");
#else
#error stubs definition missing for this architecture
#endif

/* This function is necessary to prevent the compiler from
 * generating prologue/epilogue, preparing stack frame etc.
 * The stub functions are special, they do not use the stack
 * frame passed to them, but pass it intact to the actual
 * implementation. On the other hand, asm() statements with
 * arguments can be used only inside the functions (gcc limitation)
 */
#if GCC_VERSION < 3004
static
#endif /* GCC_VERSION */
void __attribute__((unused)) dummy(void)
{
#include <_exports.h>
}

extern unsigned long __bss_start, _end;

void app_startup(char **argv)
{
	unsigned long * cp = &__bss_start;

	/* Zero out BSS */
	while (cp < &_end) {
		*cp++ = 0;
	}

#if defined(CONFIG_I386)
	/* x86 does not have a dedicated register for passing global_data */
	global_data = (gd_t *)argv[-1];
	jt = global_data->jt;
#endif
}

#undef EXPORT_FUNC
Commit	Line	Data
27b207fd WD	1	#include <exports.h>
27b207fd WD	2
93f6a677 WD	3	#ifndef GCC_VERSION
	4	#define GCC_VERSION (__GNUC__ * 1000 + __GNUC_MINOR__)
	5	#endif /* GCC_VERSION */
	6
27b207fd WD	7	#if defined(CONFIG_I386)
	8	/*
	9	* x86 does not have a dedicated register to store the pointer to
	10	* the global_data. Thus the jump table address is stored in a
	11	* global variable, but such approach does not allow for execution
	12	* from flash memory. The global_data address is passed as argv[-1]
	13	* to the application program.
	14	*/
	15	static void **jt;
77846748	16	gd_t *global_data;
27b207fd WD	17
	18	#define EXPORT_FUNC(x) \
	19	asm volatile ( \
	20	" .globl " #x "\n" \
	21	#x ":\n" \
	22	" movl %0, %%eax\n" \
	23	" movl jt, %%ecx\n" \
	24	" jmp *(%%ecx, %%eax)\n" \
	25	: : "i"(XF_ ## x * sizeof(void *)) : "eax", "ecx");
	26	#elif defined(CONFIG_PPC)
	27	/*
	28	* r29 holds the pointer to the global_data, r11 is a call-clobbered
	29	* register
	30	*/
	31	#define EXPORT_FUNC(x) \
	32	asm volatile ( \
	33	" .globl " #x "\n" \
	34	#x ":\n" \
	35	" lwz %%r11, %0(%%r29)\n" \
	36	" lwz %%r11, %1(%%r11)\n" \
	37	" mtctr %%r11\n" \
	38	" bctr\n" \
	39	: : "i"(offsetof(gd_t, jt)), "i"(XF_ ## x * sizeof(void *)) : "r11");
	40	#elif defined(CONFIG_ARM)
	41	/*
	42	* r8 holds the pointer to the global_data, ip is a call-clobbered
	43	* register
	44	*/
	45	#define EXPORT_FUNC(x) \
	46	asm volatile ( \
	47	" .globl " #x "\n" \
	48	#x ":\n" \
	49	" ldr ip, [r8, %0]\n" \
	50	" ldr pc, [ip, %1]\n" \
	51	: : "i"(offsetof(gd_t, jt)), "i"(XF_ ## x * sizeof(void *)) : "ip");
	52	#elif defined(CONFIG_MIPS)
	53	/*
	54	* k0 ($26) holds the pointer to the global_data; t9 ($25) is a call-
	55	* clobbered register that is also used to set gp ($26). Note that the
	56	* jr instruction also executes the instruction immediately following
	57	* it; however, GCC/mips generates an additional `nop' after each asm
	58	* statement
	59	*/
	60	#define EXPORT_FUNC(x) \
	61	asm volatile ( \
	62	" .globl " #x "\n" \
	63	#x ":\n" \
	64	" lw $25, %0($26)\n" \
	65	" lw $25, %1($25)\n" \
	66	" jr $25\n" \
	67	: : "i"(offsetof(gd_t, jt)), "i"(XF_ ## x * sizeof(void *)) : "t9");
4a551709 WD	68	#elif defined(CONFIG_NIOS)
	69	/*
	70	* %g7 holds the pointer to the global_data. %g0 is call clobbered.
	71	*/
	72	#define EXPORT_FUNC(x) \
	73	asm volatile ( \
	74	" .globl " #x "\n" \
	75	#x ":\n" \
	76	" pfx %%hi(%0)\n" \
	77	" movi %%g0, %%lo(%0)\n" \
	78	" add %%g0, %%g7\n" \
	79	" ld %%g0, [%%g0]\n" \
	80	" pfx %1\n" \
	81	" ld %%g0, [%%g0]\n" \
	82	" jmp %%g0\n" \
	83	" nop \n" \
	84	: : "i"(offsetof(gd_t, jt)), "i"(XF_ ## x) : "r0");
5c952cf0 WD	85	#elif defined(CONFIG_NIOS2)
	86	/*
	87	* r15 holds the pointer to the global_data, r8 is call-clobbered
	88	*/
	89	#define EXPORT_FUNC(x) \
	90	asm volatile ( \
	91	" .globl " #x "\n" \
	92	#x ":\n" \
	93	" movhi r8, %%hi(%0)\n" \
	94	" ori r8, r0, %%lo(%0)\n" \
	95	" add r8, r0, r15\n" \
	96	" ldw r8, 0(r8)\n" \
	97	" ldw r8, %1(r8)\n" \
	98	" jmp r8\n" \
	99	: : "i"(offsetof(gd_t, jt)), "i"(XF_ ## x * sizeof(void *)) : "r15");
bf9e3b38 WD	100	#elif defined(CONFIG_M68K)
	101	/*
	102	* d7 holds the pointer to the global_data, a0 is a call-clobbered
	103	* register
	104	*/
	105	#define EXPORT_FUNC(x) \
	106	asm volatile ( \
	107	" .globl " #x "\n" \
	108	#x ":\n" \
	109	" move.l %%d7, %%a0\n" \
	110	" adda.l %0, %%a0\n" \
	111	" move.l (%%a0), %%a0\n" \
	112	" adda.l %1, %%a0\n" \
	113	" move.l (%%a0), %%a0\n" \
	114	" jmp (%%a0)\n" \
	115	: : "i"(offsetof(gd_t, jt)), "i"(XF_ ## x * sizeof(void *)) : "a0");
857cad37	116	#elif defined(CONFIG_MICROBLAZE)
507bbe3e WD	117	/*
	118	* r31 holds the pointer to the global_data. r5 is a call-clobbered.
	119	*/
	120	#define EXPORT_FUNC(x) \
	121	asm volatile ( \
	122	" .globl " #x "\n" \
	123	#x ":\n" \
	124	" lwi r5, r31, %0\n" \
	125	" lwi r5, r5, %1\n" \
	126	" bra r5\n" \
	127	: : "i"(offsetof(gd_t, jt)), "i"(XF_ ## x * sizeof(void *)) : "r5");
27b207fd WD	128	#else
	129	#error stubs definition missing for this architecture
	130	#endif
	131
	132	/* This function is necessary to prevent the compiler from
	133	* generating prologue/epilogue, preparing stack frame etc.
	134	* The stub functions are special, they do not use the stack
	135	* frame passed to them, but pass it intact to the actual
	136	* implementation. On the other hand, asm() statements with
	137	* arguments can be used only inside the functions (gcc limitation)
	138	*/
93f6a677 WD	139	#if GCC_VERSION < 3004
	140	static
	141	#endif /* GCC_VERSION */
	142	void __attribute__((unused)) dummy(void)
27b207fd WD	143	{
	144	#include <_exports.h>
	145	}
	146
d716b126 WD	147	extern unsigned long __bss_start, _end;
d716b126 WD	148
27b207fd WD	149	void app_startup(char **argv)
27b207fd WD	150	{
d716b126 WD	151	unsigned long * cp = &__bss_start;
	152
	153	/* Zero out BSS */
	154	while (cp < &_end) {
	155	*cp++ = 0;
	156	}
	157
27b207fd WD	158	#if defined(CONFIG_I386)
27b207fd WD	159	/* x86 does not have a dedicated register for passing global_data */
77846748 WD	160	global_data = (gd_t *)argv[-1];
77846748 WD	161	jt = global_data->jt;
27b207fd WD	162	#endif
	163	}
	164
	165	#undef EXPORT_FUNC