/* Startup code compliant to the ELF Xtensa ABI. Copyright (C) 2001, 2007 Free Software Foundation, Inc. This file is part of the GNU C Library. The GNU C Library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. In addition to the permissions in the GNU Lesser General Public License, the Free Software Foundation gives you unlimited permission to link the compiled version of this file with other programs, and to distribute those programs without any restriction coming from the use of this file. (The GNU Lesser General Public License restrictions do apply in other respects; for example, they cover modification of the file, and distribution when not linked into another program.) Note that people who make modified versions of this file are not obligated to grant this special exception for their modified versions; it is their choice whether to do so. The GNU Lesser General Public License gives permission to release a modified version without this exception; this exception also makes it possible to release a modified version which carries forward this exception. The GNU C Library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with the GNU C Library; if not, write to the Free Software Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA. */ #include <features.h> #ifndef __UCLIBC_CTOR_DTOR__ .weak _init .weak _fini #endif /* This is the canonical entry point, usually the first thing in the text segment. When the entry point runs, most register values are unspecified, except for: a2 Contains a function pointer to be registered with `atexit'. This is how the dynamic linker arranges to have DT_FINI functions called for shared libraries that have been loaded before this code runs. a1 The stack (i.e., a1+16) contains the arguments and environment: a1+0 argc a1+4 argv[0] ... a1+(4*argc) NULL a1+(4*(argc+1)) envp[0] ... NULL Setup parameters accordingly (for a call4). See function prototype from sysdeps/generic/libc-start.c a6 = *main a7 = argc a8 = ubp_av a9 = *init a10 = *fini a11 = *rtld_fini [sp+0] = stack_end */ .text .align 4 .literal_position .global _start .type _start, @function _start: /* Clear a0 to obviously mark the outermost frame. */ movi a0, 0 /* Load up the user's main function. */ movi a6, main /* Extract the arguments as encoded on the stack and set up the arguments for `main': argc, argv. envp will be determined later in __uClibc_main. */ l32i a7, a1, 0 /* Load the argument count. */ addi a8, a1, 4 /* Compute the argv pointer. */ /* Push address of our own entry points to .fini and .init. */ movi a9, _init movi a10, _fini /* Setup the shared library termination function. */ mov a11, a2 /* Provide the highest stack address to the user code (for stacks which grow downwards). Note that we destroy the stack version of argc here. */ s32i a1, a1, 0 /* Call the user's main function, and exit with its value. But let the libc call main. */ movi a4, __uClibc_main callx4 a4 /* Crash if somehow `exit' does return. */ ill /* Define a symbol for the first piece of initialized data. */ .data .align 4 .global __data_start __data_start: .long 0 .weak data_start data_start = __data_start