| /* 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, 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. 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 |
| |
| /* 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 |
