diff options
Diffstat (limited to 'sysdeps/or1k/start.S')
-rw-r--r-- | sysdeps/or1k/start.S | 99 |
1 files changed, 99 insertions, 0 deletions
diff --git a/sysdeps/or1k/start.S b/sysdeps/or1k/start.S new file mode 100644 index 0000000000..3577fc93e8 --- /dev/null +++ b/sysdeps/or1k/start.S @@ -0,0 +1,99 @@ +/* start, OpenRISC version. + Copyright (C) 2022 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. + + 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., 59 Temple Place, Suite 330, Boston, MA + 02111-1307 USA. */ + +/* This is the canonical entry point, usually the first thing in the text + segment. + + 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 + */ + +#define __ASSEMBLY__ +#include <sysdep.h> +#include <entry.h> + +ENTRY (ENTRY_POINT) + + /* Setup Arguments to the __libc_start_main function. */ + + /* Take values for argc and argv off the stack. + These will be passed as arguments two and three to main + and thus go in registers r4 and r5, respectively. */ + l.lwz r4, 0(r1) + l.addi r5, r1, 4 + + /* Pass in rtld_fini from dl-start.S. */ + l.or r8, r3, r3 + +#ifdef PIC + /* Obtain a pointer to .got in r16 */ + l.jal 0x8 + l.movhi r16, gotpchi(_GLOBAL_OFFSET_TABLE_-4) + l.ori r16, r16, gotpclo(_GLOBAL_OFFSET_TABLE_+0) + l.add r16, r16, r9 + + /* Pass in the the main symbol. */ + l.lwz r3, got(main)(r16) +#else + /* Pass in the the main symbol. */ + l.movhi r3, hi(main) + l.ori r3, r3, lo(main) +#endif + /* Used to be init and fini. */ + l.movhi r6, 0x0 + l.movhi r7, 0x0 + + /* Push stack limit onto the stack. + This provides the highest stack address to user code (as stack grows + downwards. + This is the seventh argument to __libc_start_main and thus needs to + be passed on the stack. */ + l.sw -4(r1), r1 + + /* Adjust stack to account for a total of 7 args (i.e. the last one is + on the stack. */ + l.addi r1, r1, -4 + + /* Clear the frame pointer and link register since this is the + outermost frame. */ + l.movhi r2, 0x0 + l.movhi r9, 0x0 + + /* Let the libc call main and exit with its return code. */ +#ifdef PIC + l.j plt(__libc_start_main) +#else + l.j __libc_start_main +#endif + l.nop +END (ENTRY_POINT) + + /* Define a symbol for the first piece of initialized data. */ + .data + .globl __data_start +__data_start: + .long 0 + .weak data_start + data_start = __data_start |