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/*
* Xtensa ELF code used by dl-startup.c.
*
* Copyright (C) 2007 Tensilica Inc.
*
* Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball.
* Parts taken from glibc/sysdeps/xtensa/dl-machine.h.
*/
__asm__ (
" .text\n"
" .align 4\n"
" .literal_position\n"
" .global _start\n"
" .type _start, @function\n"
" .hidden _start\n"
"_start:\n"
" # Compute load offset in a2: the GOT has not yet been relocated\n"
" # but the entries for local symbols contain the relative offsets\n"
" # and we can explicitly add the load offset in this code.\n"
" _call0 0f\n"
" .align 4\n"
"0: movi a3, _start+3\n"
" sub a2, a0, a3\n"
#if defined(__XTENSA_WINDOWED_ABI__)
" # Make sure a0 is cleared to mark the top of stack.\n"
" movi a0, 0\n"
" # user_entry_point = _dl_start(pointer to argument block)\n"
" movi a4, _dl_start\n"
" mov a6, sp\n"
" add a4, a4, a2\n"
" callx4 a4\n"
" # Save user_entry_point so we can jump to it.\n"
" mov a3, a6\n"
#elif defined(__XTENSA_CALL0_ABI__)
" # user_entry_point = _dl_start(pointer to argument block)\n"
" movi a0, _dl_start\n"
" add a0, a0, a2\n"
" mov a2, sp\n"
" callx0 a0\n"
" # Save user_entry_point so we can jump to it.\n"
" mov a3, a2\n"
#else
#error Unsupported Xtensa ABI
#endif
" l32i a7, sp, 0 # load argc\n"
" # Load _dl_skip_args into a4.\n"
" movi a4, _dl_skip_args\n"
" l32i a4, a4, 0\n"
" bnez a4, .Lfixup_stack\n"
".Lfixup_stack_ret:\n"
" # Pass finalizer (_dl_fini) in a2 to the user entry point.\n"
" movi a2, _dl_fini\n"
" # Jump to user's entry point (_start).\n"
" jx a3\n"
".Lfixup_stack:\n"
" # argc -= _dl_skip_args (with argc @ sp+0)\n"
" sub a7, a7, a4\n"
" s32i a7, sp, 0\n"
" # Shift everything by _dl_skip_args.\n"
" addi a5, sp, 4 # a5 = destination ptr = argv\n"
" add a4, a5, a4 # a4 = source ptr = argv + _dl_skip_args\n"
" # Shift argv.\n"
"1: l32i a6, a4, 0\n"
" addi a4, a4, 4\n"
" s32i a6, a5, 0\n"
" addi a5, a5, 4\n"
" bnez a6, 1b\n"
" # Shift envp.\n"
"2: l32i a6, a4, 0\n"
" addi a4, a4, 4\n"
" s32i a6, a5, 0\n"
" addi a5, a5, 4\n"
" bnez a6, 2b\n"
" # Shift auxiliary table.\n"
"3: l32i a6, a4, 0\n"
" l32i a8, a4, 4\n"
" addi a4, a4, 8\n"
" s32i a6, a5, 0\n"
" s32i a8, a5, 4\n"
" addi a5, a5, 8\n"
" bnez a6, 3b\n"
" j .Lfixup_stack_ret");
/* Get a pointer to the argv value. */
#define GET_ARGV(ARGVP, ARGS) ARGVP = (((unsigned long *) ARGS) + 1)
/* Function calls are not safe until the GOT relocations have been done. */
#define NO_FUNCS_BEFORE_BOOTSTRAP
#if defined(__ARCH_USE_MMU__)
#define PERFORM_BOOTSTRAP_GOT(tpnt) \
do { \
xtensa_got_location *got_loc; \
unsigned long l_addr = tpnt->loadaddr; \
Elf32_Addr prev_got_start = 0, prev_got_end = 0; \
int x; \
\
got_loc = (xtensa_got_location *) \
(tpnt->dynamic_info[DT_XTENSA (GOT_LOC_OFF)] + l_addr); \
\
for (x = 0; x < tpnt->dynamic_info[DT_XTENSA (GOT_LOC_SZ)]; x++) { \
Elf32_Addr got_start, got_end; \
got_start = got_loc[x].offset & ~(PAGE_SIZE - 1); \
got_end = ((got_loc[x].offset + got_loc[x].length + PAGE_SIZE - 1) \
& ~(PAGE_SIZE - 1)); \
if (got_end >= prev_got_start && got_start <= prev_got_end) { \
if (got_end > prev_got_end) \
prev_got_end = got_end; \
if (got_start < prev_got_start) \
prev_got_start = got_start; \
continue; \
} else if (prev_got_start != prev_got_end) { \
_dl_mprotect ((void *)(prev_got_start + l_addr), \
prev_got_end - prev_got_start, \
PROT_READ | PROT_WRITE | PROT_EXEC); \
} \
prev_got_start = got_start; \
prev_got_end = got_end; \
} \
\
if (prev_got_start != prev_got_end) { \
_dl_mprotect ((void *)(prev_got_start + l_addr), \
prev_got_end - prev_got_start, \
PROT_READ | PROT_WRITE | PROT_EXEC); \
} \
} while (0)
#endif
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