u-boot/examples/standalone/stubs.c
Robin Getz c4db335c2e Blackfin: change global data register from P5 to P3
Since the Blackfin ABI favors higher scratch registers by default, use the
last scratch register (P3) for global data rather than the first (P5).
This allows the compiler's register allocator to use higher number scratch
P registers, which in turn better matches the Blackfin instruction set,
which reduces the size of U-Boot by more than 1024 bytes...

Signed-off-by: Robin Getz <robin.getz@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
2009-09-02 05:14:02 -04:00

225 lines
5.7 KiB
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)
/*
* r2 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(%%r2)\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, r8, 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");
#elif defined(CONFIG_BLACKFIN)
/*
* P3 holds the pointer to the global_data, P0 is a call-clobbered
* register
*/
#define EXPORT_FUNC(x) \
asm volatile ( \
" .globl _" #x "\n_" \
#x ":\n" \
" P0 = [P3 + %0]\n" \
" P0 = [P0 + %1]\n" \
" JUMP (P0)\n" \
: : "i"(offsetof(gd_t, jt)), "i"(XF_ ## x * sizeof(void *)) : "P0");
#elif defined(CONFIG_AVR32)
/*
* r6 holds the pointer to the global_data. r8 is call clobbered.
*/
#define EXPORT_FUNC(x) \
asm volatile( \
" .globl\t" #x "\n" \
#x ":\n" \
" ld.w r8, r6[%0]\n" \
" ld.w pc, r8[%1]\n" \
: \
: "i"(offsetof(gd_t, jt)), "i"(XF_ ##x) \
: "r8");
#elif defined(CONFIG_SH)
/*
* r13 holds the pointer to the global_data. r1 is a call clobbered.
*/
#define EXPORT_FUNC(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"(XF_ ## x * sizeof(void *)) : "r1", "r2");
#elif defined(CONFIG_SPARC)
/*
* g7 holds the pointer to the global_data. g1 is call clobbered.
*/
#define EXPORT_FUNC(x) \
asm volatile( \
" .globl\t" #x "\n" \
#x ":\n" \
" set %0, %%g1\n" \
" or %%g1, %%g7, %%g1\n" \
" ld [%%g1], %%g1\n" \
" ld [%%g1 + %1], %%g1\n" \
" call %%g1\n" \
" nop\n" \
: : "i"(offsetof(gd_t, jt)), "i"(XF_ ## x) : "g1" );
#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 char * cp = (unsigned char *) &__bss_start;
/* Zero out BSS */
while (cp < (unsigned char *)&_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