examples/standalone/stubs.c - u-boot-mtk - Git at Google

 #include <common.h>
 #include <exports.h>
 #include <linux/compiler.h>

 #define FO(x) offsetof(struct jt_funcs, x)

 #if defined(CONFIG_X86)
 /*
  * 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 struct jt_funcs *jt;
 gd_t *global_data;

 #define EXPORT_FUNC(f, a, x, ...) \
 	asm volatile (			\
 "	.globl " #x "\n"		\
 #x ":\n"				\
 "	movl	%0, %%eax\n"		\
 "	movl	jt, %%ecx\n"		\
 "	jmp	*(%%ecx, %%eax)\n"	\
 	: : "i"(FO(x)) : "eax", "ecx");
 #elif defined(CONFIG_PPC)
 /*
  * r2 holds the pointer to the global_data, r11 is a call-clobbered
  * register
  */
 #define EXPORT_FUNC(f, a, x, ...) \
 	asm volatile (			\
 "	.globl " #x "\n"		\
 #x ":\n"				\
 "	lwz	%%r11, %0(%%r2)\n"	\
 "	lwz	%%r11, %1(%%r11)\n"	\
 "	mtctr	%%r11\n"		\
 "	bctr\n"				\
 	: : "i"(offsetof(gd_t, jt)), "i"(FO(x)) : "r11");
 #elif defined(CONFIG_ARM)
 #ifdef CONFIG_ARM64
 /*
  * x18 holds the pointer to the global_data, x9 is a call-clobbered
  * register
  */
 #define EXPORT_FUNC(f, a, x, ...) \
 	asm volatile (			\
 "	.globl " #x "\n"		\
 #x ":\n"				\
 "	ldr	x9, [x18, %0]\n"		\
 "	ldr	x9, [x9, %1]\n"		\
 "	br	x9\n"		\
 	: : "i"(offsetof(gd_t, jt)), "i"(FO(x)) : "x9");
 #else
 /*
  * r9 holds the pointer to the global_data, ip is a call-clobbered
  * register
  */
 #define EXPORT_FUNC(f, a, x, ...) \
 	asm volatile (			\
 "	.globl " #x "\n"		\
 #x ":\n"				\
 "	ldr	ip, [r9, %0]\n"		\
 "	ldr	pc, [ip, %1]\n"		\
 	: : "i"(offsetof(gd_t, jt)), "i"(FO(x)) : "ip");
 #endif
 #elif defined(CONFIG_MIPS)
 #ifdef CONFIG_CPU_MIPS64
 /*
  * 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(f, a, x, ...) \
 	asm volatile (			\
 "	.globl " #x "\n"		\
 #x ":\n"				\
 "	ld	$25, %0($26)\n"		\
 "	ld	$25, %1($25)\n"		\
 "	jr	$25\n"			\
         : : "i"(offsetof(gd_t, jt)), "i"(FO(x)) : "t9");
 #else
 /*
  * 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(f, a, 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"(FO(x)) : "t9");
 #endif
 #elif defined(CONFIG_NIOS2)
 /*
  * gp holds the pointer to the global_data, r8 is call-clobbered
  */
 #define EXPORT_FUNC(f, a, x, ...) \
 	asm volatile (			\
 "	.globl " #x "\n"		\
 #x ":\n"				\
 "	movhi	r8, %%hi(%0)\n"		\
 "	ori	r8, r0, %%lo(%0)\n"	\
 "	add	r8, r8, gp\n"		\
 "	ldw	r8, 0(r8)\n"		\
 "	ldw	r8, %1(r8)\n"		\
 "	jmp	r8\n"			\
 	: : "i"(offsetof(gd_t, jt)), "i"(FO(x)) : "gp");
 #elif defined(CONFIG_M68K)
 /*
  * d7 holds the pointer to the global_data, a0 is a call-clobbered
  * register
  */
 #define EXPORT_FUNC(f, a, 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"(FO(x)) : "a0");
 #elif defined(CONFIG_MICROBLAZE)
 /*
  * r31 holds the pointer to the global_data. r5 is a call-clobbered.
  */
 #define EXPORT_FUNC(f, a, 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"(FO(x)) : "r5");
 #elif defined(CONFIG_SH)
 /*
  * r13 holds the pointer to the global_data. r1 is a call clobbered.
  */
 #define EXPORT_FUNC(f, a, x, ...)					\
 	asm volatile (					\
 		"	.align	2\n"			\
 		"	.globl " #x "\n"		\
 		#x ":\n"				\
 		"	mov	r13, r1\n"		\
 		"	add	%0, r1\n"		\
 		"	mov.l @r1, r2\n"	\
 		"	add	%1, r2\n"		\
 		"	mov.l @r2, r1\n"	\
 		"	jmp	@r1\n"			\
 		"	nop\n"				\
 		"	nop\n"				\
 		: : "i"(offsetof(gd_t, jt)), "i"(FO(x)) : "r1", "r2");
 #elif defined(CONFIG_NDS32)
 /*
  * r16 holds the pointer to the global_data. gp is call clobbered.
  * not support reduced register (16 GPR).
  */
 #define EXPORT_FUNC(f, a, x, ...) \
 	asm volatile (			\
 "	.globl " #x "\n"		\
 #x ":\n"				\
 "	lwi	$r16, [$gp + (%0)]\n"	\
 "	lwi	$r16, [$r16 + (%1)]\n"	\
 "	jr	$r16\n"			\
 	: : "i"(offsetof(gd_t, jt)), "i"(FO(x)) : "$r16");
 #elif defined(CONFIG_RISCV)
 /*
  * gp holds the pointer to the global_data. t0 is call clobbered.
  */
 #ifdef CONFIG_ARCH_RV64I
 #define EXPORT_FUNC(f, a, x, ...)	\
 	asm volatile (			\
 "	.globl " #x "\n"		\
 #x ":\n"				\
 "	ld	t0, %0(gp)\n"		\
 "	ld	t0, %1(t0)\n"		\
 "	jr	t0\n"			\
 	: : "i"(offsetof(gd_t, jt)), "i"(FO(x)) : "t0");
 #else
 #define EXPORT_FUNC(f, a, x, ...)	\
 	asm volatile (			\
 "	.globl " #x "\n"		\
 #x ":\n"				\
 "	lw	t0, %0(gp)\n"		\
 "	lw	t0, %1(t0)\n"		\
 "	jr	t0\n"			\
 	: : "i"(offsetof(gd_t, jt)), "i"(FO(x)) : "t0");
 #endif
 #elif defined(CONFIG_ARC)
 /*
  * r25 holds the pointer to the global_data. r10 is call clobbered.
   */
 #define EXPORT_FUNC(f, a, x, ...) \
 	asm volatile( \
 "	.align 4\n" \
 "	.globl " #x "\n" \
 #x ":\n" \
 "	ld	r10, [r25, %0]\n" \
 "	ld	r10, [r10, %1]\n" \
 "	j	[r10]\n" \
 	: : "i"(offsetof(gd_t, jt)), "i"(FO(x)) : "r10");
 #elif defined(CONFIG_XTENSA)
 /*
  * Global data ptr is in global_data, jump table ptr is in jt.
  * Windowed ABI: Jump just past 'entry' in target and adjust stack frame
  * (extract stack frame size from target 'entry' instruction).
  */

 static void **jt;

 #if defined(__XTENSA_CALL0_ABI__)
 #define EXPORT_FUNC(f, a, x, ...)	\
 	asm volatile (			\
 "	.extern jt\n"			\
 "	.globl " #x "\n"		\
 "	.align 4\n"			\
 #x ":\n"				\
 "	l32i	a8, %0, 0\n"		\
 "	l32i	a8, a8, %1\n"		\
 "	jx	a8\n"			\
 	: : "r"(jt), "i" (FO(x)) : "a8");
 #elif defined(__XTENSA_WINDOWED_ABI__)
 #if XCHAL_HAVE_BE
 # define SFT "8"
 #else
 # define SFT "12"
 #endif
 #define EXPORT_FUNC(f, a, x, ...)	\
 	asm volatile (			\
 "	.extern jt\n"			\
 "	.globl " #x "\n"		\
 "	.align 4\n"			\
 #x ":\n"				\
 "	entry	sp, 16\n"		\
 "	l32i	a8, %0, 0\n"		\
 "	l32i	a8, a8, %1\n"		\
 "	l32i	a9, a8, 0\n"		\
 "	extui	a9, a9, " SFT ", 12\n"	\
 "	subx8	a9, a9, sp\n"		\
 "	movi	a10, 16\n"		\
 "	sub	a9, a10, a9\n"		\
 "	movsp	sp, a9\n"		\
 "	addi	a8, a8, 3\n"		\
 "	jx	a8\n"			\
 	: : "r"(jt), "i" (FO(x)) : "a8", "a9", "a10");
 #else
 #error Unsupported Xtensa ABI
 #endif
 #else
 /*"	addi	$sp, $sp, -24\n"	\
 "	br	$r16\n"			\*/

 #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 < 30400
 static
 #endif /* GCC_VERSION */
 void __attribute__((unused)) dummy(void)
 {
 #include <_exports.h>
 }

 #include <asm/sections.h>

 void app_startup(char * const *argv)
 {
 	char *cp = __bss_start;

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

 #if defined(CONFIG_X86)
 	/* 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
	#include <common.h>
	#include <exports.h>
	#include <linux/compiler.h>

	#define FO(x) offsetof(struct jt_funcs, x)

	#if defined(CONFIG_X86)
	/*
	* 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 struct jt_funcs *jt;
	gd_t *global_data;

	#define EXPORT_FUNC(f, a, x, ...) \
	asm volatile ( \
	" .globl " #x "\n" \
	#x ":\n" \
	" movl %0, %%eax\n" \
	" movl jt, %%ecx\n" \
	" jmp *(%%ecx, %%eax)\n" \
	: : "i"(FO(x)) : "eax", "ecx");
	#elif defined(CONFIG_PPC)
	/*
	* r2 holds the pointer to the global_data, r11 is a call-clobbered
	* register
	*/
	#define EXPORT_FUNC(f, a, x, ...) \
	asm volatile ( \
	" .globl " #x "\n" \
	#x ":\n" \
	" lwz %%r11, %0(%%r2)\n" \
	" lwz %%r11, %1(%%r11)\n" \
	" mtctr %%r11\n" \
	" bctr\n" \
	: : "i"(offsetof(gd_t, jt)), "i"(FO(x)) : "r11");
	#elif defined(CONFIG_ARM)
	#ifdef CONFIG_ARM64
	/*
	* x18 holds the pointer to the global_data, x9 is a call-clobbered
	* register
	*/
	#define EXPORT_FUNC(f, a, x, ...) \
	asm volatile ( \
	" .globl " #x "\n" \
	#x ":\n" \
	" ldr x9, [x18, %0]\n" \
	" ldr x9, [x9, %1]\n" \
	" br x9\n" \
	: : "i"(offsetof(gd_t, jt)), "i"(FO(x)) : "x9");
	#else
	/*
	* r9 holds the pointer to the global_data, ip is a call-clobbered
	* register
	*/
	#define EXPORT_FUNC(f, a, x, ...) \
	asm volatile ( \
	" .globl " #x "\n" \
	#x ":\n" \
	" ldr ip, [r9, %0]\n" \
	" ldr pc, [ip, %1]\n" \
	: : "i"(offsetof(gd_t, jt)), "i"(FO(x)) : "ip");
	#endif
	#elif defined(CONFIG_MIPS)
	#ifdef CONFIG_CPU_MIPS64
	/*
	* 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(f, a, x, ...) \
	asm volatile ( \
	" .globl " #x "\n" \
	#x ":\n" \
	" ld $25, %0($26)\n" \
	" ld $25, %1($25)\n" \
	" jr $25\n" \
	: : "i"(offsetof(gd_t, jt)), "i"(FO(x)) : "t9");
	#else
	/*
	* 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(f, a, 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"(FO(x)) : "t9");
	#endif
	#elif defined(CONFIG_NIOS2)
	/*
	* gp holds the pointer to the global_data, r8 is call-clobbered
	*/
	#define EXPORT_FUNC(f, a, x, ...) \
	asm volatile ( \
	" .globl " #x "\n" \
	#x ":\n" \
	" movhi r8, %%hi(%0)\n" \
	" ori r8, r0, %%lo(%0)\n" \
	" add r8, r8, gp\n" \
	" ldw r8, 0(r8)\n" \
	" ldw r8, %1(r8)\n" \
	" jmp r8\n" \
	: : "i"(offsetof(gd_t, jt)), "i"(FO(x)) : "gp");
	#elif defined(CONFIG_M68K)
	/*
	* d7 holds the pointer to the global_data, a0 is a call-clobbered
	* register
	*/
	#define EXPORT_FUNC(f, a, 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"(FO(x)) : "a0");
	#elif defined(CONFIG_MICROBLAZE)
	/*
	* r31 holds the pointer to the global_data. r5 is a call-clobbered.
	*/
	#define EXPORT_FUNC(f, a, 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"(FO(x)) : "r5");
	#elif defined(CONFIG_SH)
	/*
	* r13 holds the pointer to the global_data. r1 is a call clobbered.
	*/
	#define EXPORT_FUNC(f, a, x, ...) \
	asm volatile ( \
	" .align 2\n" \
	" .globl " #x "\n" \
	#x ":\n" \
	" mov r13, r1\n" \
	" add %0, r1\n" \
	" mov.l @r1, r2\n" \
	" add %1, r2\n" \
	" mov.l @r2, r1\n" \
	" jmp @r1\n" \
	" nop\n" \
	" nop\n" \
	: : "i"(offsetof(gd_t, jt)), "i"(FO(x)) : "r1", "r2");
	#elif defined(CONFIG_NDS32)
	/*
	* r16 holds the pointer to the global_data. gp is call clobbered.
	* not support reduced register (16 GPR).
	*/
	#define EXPORT_FUNC(f, a, x, ...) \
	asm volatile ( \
	" .globl " #x "\n" \
	#x ":\n" \
	" lwi $r16, [$gp + (%0)]\n" \
	" lwi $r16, [$r16 + (%1)]\n" \
	" jr $r16\n" \
	: : "i"(offsetof(gd_t, jt)), "i"(FO(x)) : "$r16");
	#elif defined(CONFIG_RISCV)
	/*
	* gp holds the pointer to the global_data. t0 is call clobbered.
	*/
	#ifdef CONFIG_ARCH_RV64I
	#define EXPORT_FUNC(f, a, x, ...) \
	asm volatile ( \
	" .globl " #x "\n" \
	#x ":\n" \
	" ld t0, %0(gp)\n" \
	" ld t0, %1(t0)\n" \
	" jr t0\n" \
	: : "i"(offsetof(gd_t, jt)), "i"(FO(x)) : "t0");
	#else
	#define EXPORT_FUNC(f, a, x, ...) \
	asm volatile ( \
	" .globl " #x "\n" \
	#x ":\n" \
	" lw t0, %0(gp)\n" \
	" lw t0, %1(t0)\n" \
	" jr t0\n" \
	: : "i"(offsetof(gd_t, jt)), "i"(FO(x)) : "t0");
	#endif
	#elif defined(CONFIG_ARC)
	/*
	* r25 holds the pointer to the global_data. r10 is call clobbered.
	*/
	#define EXPORT_FUNC(f, a, x, ...) \
	asm volatile( \
	" .align 4\n" \
	" .globl " #x "\n" \
	#x ":\n" \
	" ld r10, [r25, %0]\n" \
	" ld r10, [r10, %1]\n" \
	" j [r10]\n" \
	: : "i"(offsetof(gd_t, jt)), "i"(FO(x)) : "r10");
	#elif defined(CONFIG_XTENSA)
	/*
	* Global data ptr is in global_data, jump table ptr is in jt.
	* Windowed ABI: Jump just past 'entry' in target and adjust stack frame
	* (extract stack frame size from target 'entry' instruction).
	*/

	static void **jt;

	#if defined(__XTENSA_CALL0_ABI__)
	#define EXPORT_FUNC(f, a, x, ...) \
	asm volatile ( \
	" .extern jt\n" \
	" .globl " #x "\n" \
	" .align 4\n" \
	#x ":\n" \
	" l32i a8, %0, 0\n" \
	" l32i a8, a8, %1\n" \
	" jx a8\n" \
	: : "r"(jt), "i" (FO(x)) : "a8");
	#elif defined(__XTENSA_WINDOWED_ABI__)
	#if XCHAL_HAVE_BE
	# define SFT "8"
	#else
	# define SFT "12"
	#endif
	#define EXPORT_FUNC(f, a, x, ...) \
	asm volatile ( \
	" .extern jt\n" \
	" .globl " #x "\n" \
	" .align 4\n" \
	#x ":\n" \
	" entry sp, 16\n" \
	" l32i a8, %0, 0\n" \
	" l32i a8, a8, %1\n" \
	" l32i a9, a8, 0\n" \
	" extui a9, a9, " SFT ", 12\n" \
	" subx8 a9, a9, sp\n" \
	" movi a10, 16\n" \
	" sub a9, a10, a9\n" \
	" movsp sp, a9\n" \
	" addi a8, a8, 3\n" \
	" jx a8\n" \
	: : "r"(jt), "i" (FO(x)) : "a8", "a9", "a10");
	#else
	#error Unsupported Xtensa ABI
	#endif
	#else
	/*" addi $sp, $sp, -24\n" \
	" br $r16\n" \*/

	#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 < 30400
	static
	#endif /* GCC_VERSION */
	void __attribute__((unused)) dummy(void)
	{
	#include <_exports.h>
	}

	#include <asm/sections.h>

	void app_startup(char * const *argv)
	{
	char *cp = __bss_start;

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

	#if defined(CONFIG_X86)
	/* 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