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Diffstat (limited to 'sysdeps/sparc/elf/start.S')
| -rw-r--r-- | sysdeps/sparc/elf/start.S | 111 |
1 files changed, 111 insertions, 0 deletions
diff --git a/sysdeps/sparc/elf/start.S b/sysdeps/sparc/elf/start.S new file mode 100644 index 0000000000..6dae08bafa --- /dev/null +++ b/sysdeps/sparc/elf/start.S @@ -0,0 +1,111 @@ +/* Startup code compliant to the ELF SPARC ABI. +Copyright (C) 1996 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 Library General Public License as +published by the Free Software Foundation; either version 2 of the +License, or (at your option) any later version. + +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 +Library General Public License for more details. + +You should have received a copy of the GNU Library General Public +License along with the GNU C Library; see the file COPYING.LIB. If +not, write to the Free Software Foundation, Inc., 675 Mass Ave, +Cambridge, MA 02139, USA. */ + +/* This is the canonical entry point, usually the first thing in the text + segment. The SVR4/SPARC ABI (NOTE: I don't actually have it) says that + when the entry point runs, most registers' values are unspecified, + except for: + + %g1 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. + + %sp The stack contains the arguments and environment: + 0(%sp) argc + 4(%sp) argv[0] + ... + (4*argc)(%sp) NULL + (4*(argc+1))(%sp) envp[0] + ... + NULL +*/ + + .text + .align 16 + .global _start +_start: + /* %g1 contains the address of the shared library termination + function, which we will register with `atexit' to be called by + `exit'. I suspect that on some systems, and when statically + linked, this will not be set by anything to any function + pointer; hopefully it will be zero so we don't try to call + random pointers. */ + orcc %g1, %g0, %o0 /* Move %g1 to %o0 while testing it. */ + be nofini + + /* In delay slot: clear the frame pointer. The ABI suggests this + be done, to mark the outermost frame obviously. */ + clr %fp + + /* Call atexit, argument was set in %o0 above. */ + call atexit + nop +nofini: + + /* We will use some local variables in registers below. %g1 and + the %oN registers are call-clobbered, so we can't just use them. */ +#define ARGC %l0 +#define ARGV %l1 +#define ENVP %l2 +#define TMP %l3 + + /* Do essential libc initialization. In statically linked + programs under the GNU Hurd, this is what sets up the + arguments on the stack for the code below. */ + call __libc_init_first + sethi %hi(_environ), TMP /* In delay slot: prepare to use &_environ. */ + + /* Extract the arguments and environment as encoded on the stack + and save them in local variables. */ + ld [%sp + 64], ARGC /* After the register save area, ARGC. */ + add %sp, 64+4, ARGV /* Next, the ARGV elements. */ + /* After ARGC words that are the ARGV elements, and a zero word, + are the ENVP elements. Do ENVP = &ARGV[ARGC + 1]. */ + add ARGC, 1, ENVP + sll ENVP, 2, ENVP + add ARGV, ENVP, ENVP + /* Store ENVP in the global variable `_environ'. */ + st [TMP + %lo(_environ)], ENVP + + /* Call `_init', which is the entry point to our own `.init' + section; and register with `atexit' to have `exit' call + `_fini', which is the entry point to our own `.fini' section. */ + call _init + sethi %hi(_fini), TMP /* In delay slot of call. */ + or TMP, %lo(_fini), %o0 /* Argument to atexit is &_fini. */ + call atexit + nop + + /* Call the user's main function, and exit with its value. */ + mov ARGC, %o0 + mov ARGV, %o1 + call main + mov ENVP, %o2 + + call exit /* This should never return. */ + unimp 0 /* Crash if somehow it does return. */ + +/* Define a symbol for the first piece of initialized data. */ + .data + .global __data_start +__data_start: + .long 0 + .weak data_start + data_start = __data_start |