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Diffstat (limited to 'sysdeps/s390/s390-32/start.S')
| -rw-r--r-- | sysdeps/s390/s390-32/start.S | 212 |
1 files changed, 212 insertions, 0 deletions
diff --git a/sysdeps/s390/s390-32/start.S b/sysdeps/s390/s390-32/start.S new file mode 100644 index 0000000000..d7f3df7f66 --- /dev/null +++ b/sysdeps/s390/s390-32/start.S @@ -0,0 +1,212 @@ +/* Startup code compliant to the ELF s390 ABI. + Copyright (C) 2000, 2001, 2002, 2003, 2004, 2006 + Free Software Foundation, Inc. + Contributed by Martin Schwidefsky (schwidefsky@de.ibm.com). + 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, see + <http://www.gnu.org/licenses/>. */ + +/* + This is the canonical entry point, usually the first thing in the text + segment. Most registers' values are unspecified, except for: + + %r14 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. + + %r15 The stack contains the arguments and environment: + 0(%r15) argc + 4(%r15) argv[0] + ... + (4*argc)(%r15) NULL + (4*(argc+1))(%r15) envp[0] + ... + NULL +*/ + + .text + .globl _start + .type _start,@function +_start: + /* Check if the kernel provides highgprs facility if needed by + the binary. */ + + lr %r6,%r15 + la %r6,4(%r6) /* Skip the argument counter. */ + +.L11: l %r5,0(%r6) /* Skip the argument vector. */ + la %r6,4(%r6) + ltr %r5,%r5 + jne .L11 + +.L12: l %r5,0(%r6) /* Skip the environment vector. */ + la %r6,4(%r6) + ltr %r5,%r5 + jne .L12 + + /* Usually the auxiliary vector can be expected directly after + the environment variables. But we have to skip extra zeros + because the loader might have removed unsecure variables for + setuid programs. */ + +.L26: l %r5,0(%r6) + la %r6,4(%r6) + ltr %r5,%r5 + jz .L26 + + ahi %r6,-4 + + /* Obtain the needed values from the auxiliary vector. */ + + lhi %r7,16 /* AT_HWCAP */ + lhi %r8,3 /* AT_PHDR */ + lhi %r9,5 /* AT_PHNUM */ + lhi %r2,4 /* AT_PHENT */ +.L13: l %r5,0(%r6) + clr %r5,%r7 + jne .L15 + l %r10,4(%r6) /* r10 = AT_HWCAP value. */ +.L15: clr %r5,%r8 + jne .L16 + l %r11,4(%r6) /* r11 = AT_PHDR value. */ +.L16: clr %r5,%r9 + jne .L17 + l %r12,4(%r6) /* r12 = AT_PHNUM value. */ +.L17: clr %r5,%r2 + jne .L18 + l %r0,4(%r6) /* r0 = AT_PHENT value. */ +.L18: ltr %r5,%r5 + la %r6,8(%r6) + jnz .L13 + + /* Locate the ELF header by looking for the first PT_LOAD + segment with a p_offset of zero. */ + + lr %r4,%r11 /* Backup AT_PHDR. */ + lhi %r7,1 /* PT_LOAD id */ + lhi %r8,0 +.L19: cl %r7,0(%r4) /* p_type == PT_LOAD? */ + jne .L20 + cl %r8,4(%r4) /* p_offset == 0? */ + jne .L20 + l %r9,8(%r4) /* r9 = PT_LOAD.p_vaddr <- ELF header address */ + j .L24 +.L20: alr %r4,%r0 /* r4 += AT_PHENT value */ + brct %r12,.L19 + + j .+2 /* Trap, there must be such a phdr. */ + +.L24: lr %r4,%r11 /* Backup AT_PHDR. */ + lhi %r2,6 /* PT_PHDR id */ +.L23: cl %r2,0(%r4) + jne .L22 + l %r3,8(%r4) /* r3 = PT_PHDR p_vaddr */ + j .L25 +.L22: alr %r4,%r0 /* r4 += AT_PHENT value */ + brct %r12,.L23 + + j .L14 /* No PT_PHDR found - skip checking. */ + +.L25: slr %r11,%r3 /* AT_PHDR - PT_PHDR.p_vaddr (relocation offset)*/ + alr %r9,%r11 /* PT_LOAD.p_vaddr += relocation offset */ + + l %r5,36(%r9) /* Load the e_flags field. */ + tml %r5,1 + jz .L14 /* Binary does not require highgprs facility. */ + + tml %r10,512 /* Check the AT_HWCAP value. */ + jz 2 /* Trap if no highgprs facility available. */ +.L14: + + /* Setup pointer to literal pool of _start */ + basr %r13,0 +.L0: ahi %r13,.Llit-.L0 + + /* load argc and argv from stack */ + la %r4,4(%r15) # get argv + l %r3,0(%r15) # get argc + + /* align the stack to a double word boundary */ + lhi %r0,-8 + nr %r15,%r0 + + /* Setup a stack frame and a parameter area */ + ahi %r15,-104 # make room on stack + xc 0(4,%r15),0(%r15) # clear back-chain + + /* set up arguments for __libc_start_main: + main, argc, argv, envp, _init, _fini, rtld_fini, stack_end + Note that envp will be determined later in __libc_start_main + */ + stm %r14,%r15,96(%r15) # store rtld_fini/stack_end to parameter area + la %r7,96(%r15) + l %r6,.L2-.Llit(%r13) # load pointer to __libc_csu_fini + l %r5,.L1-.Llit(%r13) # load pointer to __libc_csu_init + l %r2,.L3-.Llit(%r13) # load pointer to main + l %r1,.L4-.Llit(%r13) # load pointer to __libc_start_main +#ifdef PIC + l %r12,.L5-.Llit(%r13) # load .got pointer + la %r6,0(%r13,%r6) + la %r5,0(%r13,%r5) + la %r12,0(%r13,%r12) + l %r2,0(%r12,%r2) + la %r1,0(%r13,%r1) +#endif + + /* ok, now branch to the libc main routine */ + basr %r14,%r1 + + /* crash if __libc_start_main returns */ + .word 0 + +.Llit: +#ifndef PIC +.L1: .long __libc_csu_init +.L2: .long __libc_csu_fini +.L3: .long main +.L4: .long __libc_start_main +#else +.L1: .long __libc_csu_init-.Llit +.L2: .long __libc_csu_fini-.Llit +.L3: .long main@GOT +.L4: .long __libc_start_main@plt-.Llit +.L5: .long _GLOBAL_OFFSET_TABLE_-.Llit +#endif + +/* 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 |