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Diffstat (limited to 'ports/sysdeps/tile/dl-start.S')
| -rw-r--r-- | ports/sysdeps/tile/dl-start.S | 114 |
1 files changed, 114 insertions, 0 deletions
diff --git a/ports/sysdeps/tile/dl-start.S b/ports/sysdeps/tile/dl-start.S new file mode 100644 index 0000000000..97cdac3fce --- /dev/null +++ b/ports/sysdeps/tile/dl-start.S @@ -0,0 +1,114 @@ +/* Copyright (C) 2011 Free Software Foundation, Inc. + This file is part of the GNU C Library. + Contributed by Chris Metcalf <cmetcalf@tilera.com>, 2011. + + 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, see + <http://www.gnu.org/licenses/>. */ + +#include <sysdep.h> + + /* Get address of "sym" in "reg" assuming r51 holds ".Llink". */ + .macro pic_addr reg, sym +#ifdef __tilegx__ + moveli \reg, hw1_last(\sym - .Llink) + shl16insli \reg, \reg, hw0(\sym - .Llink) + ADD_PTR \reg, r51, \reg +#else + ADDLI_PTR \reg, r51, lo16(\sym - .Llink) + auli \reg, \reg, ha16(\sym - .Llink) +#endif + .endm + + .text +ENTRY (_start) + /* Linux starts us with sp pointing at the conventional Elf layout, + but we need to allow two 'caller' words for our ABI convention. */ + { + move r52, sp + andi sp, sp, -8 + } + cfi_def_cfa_register (r52) + { + /* Point sp at base of ABI area; point r4 to the caller-sp word. */ + ADDI_PTR sp, sp, -(2 * REGSIZE) + ADDI_PTR r4, sp, -REGSIZE + } + { + /* Save zero for caller sp in our 'caller' save area, and make + sure lr has a zero value, to limit backtraces. */ + move lr, zero + ST r4, zero + } + { + move r0, r52 + jal _dl_start + } + /* Save returned start of user program address for later. */ + move r50, r0 + + /* See if we were invoked explicitly with the dynamic loader, + in which case we have to adjust the argument vector. */ + lnk r51; .Llink: + pic_addr r4, _dl_skip_args + LD4U r4, r4 + BEQZT r4, .Lno_skip + + /* Load the argc word at the initial sp and adjust it. + We basically jump "sp" up over the first few argv entries + and write "argc" a little higher up in memory, to be the + base of the new kernel-initialized stack area. */ + LD_PTR r0, r52 + { + sub r0, r0, r4 + SHL_PTR_ADD r52, r4, r52 + } + { + ST_PTR r52, r0 + SHL_PTR_ADD sp, r4, sp + } + andi sp, sp, -8 + +.Lno_skip: + /* Call_dl_init (_dl_loaded, argc, argv, envp). See elf/start.s + for the layout of memory here; r52 is pointing to "+0". */ + pic_addr r0, _rtld_local + { + LD_PTR r1, r52 /* load argc in r1 */ + ADDLI_PTR r2, r52, __SIZEOF_POINTER__ /* point r2 at argv */ + } + { + LD_PTR r0, r0 /* yields _rtld_global._ns_loaded */ + addi r3, r1, 1 + move lr, zero + } + { + SHL_PTR_ADD r3, r3, r2 /* point r3 at envp */ + jal _dl_init_internal + } + + /* Call user program whose address we saved in r50. + We invoke it just like a static binary, but with _dl_fini + in r0 so we can distinguish. */ + + pic_addr r0, _dl_fini + move lr, zero + { + move sp, r52 + jr r50 + } + + /* Tell backtracer to give up (_start has no caller). */ + info 2 /* INFO_OP_CANNOT_BACKTRACE */ + +END (_start) |