diff options
Diffstat (limited to 'rtl/linux/x86_64/cprt0.as')
| -rw-r--r-- | rtl/linux/x86_64/cprt0.as | 164 |
1 files changed, 164 insertions, 0 deletions
diff --git a/rtl/linux/x86_64/cprt0.as b/rtl/linux/x86_64/cprt0.as new file mode 100644 index 0000000000..2b4efd8bab --- /dev/null +++ b/rtl/linux/x86_64/cprt0.as @@ -0,0 +1,164 @@ +/* + $Id: cprt0.as,v 1.4 2004/11/02 21:49:46 florian Exp $ + Dummy implementation + +*/ + +/* This is the canonical entry point, usually the first thing in the text + segment. The SVR4/i386 ABI (pages 3-31, 3-32) says that when the entry + point runs, most registers' values are unspecified, except for: + + %rdx 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. + + %rsp The stack contains the arguments and environment: + 0(%rsp) argc + 8(%rsp) argv[0] + ... + (8*argc)(%rsp) NULL + (8*(argc+1))(%rsp) envp[0] + ... + NULL +*/ + + .text + .globl _start + .type _start,@function +_start: + /* Clear the frame pointer. The ABI suggests this be done, to mark + the outermost frame obviously. */ + xorq %rbp, %rbp + + /* Extract the arguments as encoded on the stack and set up + the arguments for __libc_start_main (int (*main) (int, char **, char **), + int argc, char *argv, + void (*init) (void), void (*fini) (void), + void (*rtld_fini) (void), void *stack_end). + The arguments are passed via registers and on the stack: + main: %rdi + argc: %rsi + argv: %rdx + init: %rcx + fini: %r8 + rtld_fini: %r9 + stack_end: stack. */ + + movq %rdx, %r9 /* Address of the shared library termination + function. */ + popq %rsi /* Pop the argument count. */ + movq %rsp, %rdx /* argv starts just at the current stack top. */ + + movq %rsi,operatingsystem_parameter_argc + movq %rsp,operatingsystem_parameter_argv /* argv starts just at the current stack top. */ + leaq 8(,%rsi,8),%rax + addq %rsp,%rax + movq %rax,operatingsystem_parameter_envp + + /* Align the stack to a 16 byte boundary to follow the ABI. */ + andq $~15, %rsp + + pushq %rax /* Push garbage because we push 8 more bytes. */ + + /* Provide the highest stack address to the user code (for stacks + which grow downwards). */ + pushq %rsp + + /* Pass address of our own entry points to .fini and .init. */ + movq $_init_dummy, %r8 + movq $_fini_dummy, %rcx + + movq $main_stub, %rdi + + /* Call the user's main function, and exit with its value. + But let the libc call main. */ + call __libc_start_main + + hlt /* Crash if somehow `exit' does return. */ + +/* fake main routine which will be run from libc */ +main_stub: + /* save return address */ + popq %rax + + // stack alignment + pushq %rax + + movq %rax,___fpc_ret + movq %rbp,___fpc_ret_rbp + pushq %rax + + /* start the program */ + xorq %rbp,%rbp + call PASCALMAIN + hlt + + .globl _haltproc + .type _haltproc,@function +_haltproc: + movzwq operatingsystem_result,%rax /* load and save exitcode */ + + movq ___fpc_ret,%rdx /* return to libc */ + movq ___fpc_ret_rbp,%rbp + pushq %rdx +_init_dummy: +_fini_dummy: + ret + +/* 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 + + .globl ___fpc_brk_addr /* heap management */ + .type ___fpc_brk_addr,@object + .size ___fpc_brk_addr,8 +___fpc_brk_addr: + .quad 0 + +___fpc_ret: /* return address to libc */ + .quad 0 +___fpc_ret_rbp: + .quad 0 + +.bss + .comm operatingsystem_parameter_envp,8 + .comm operatingsystem_parameter_argc,8 + .comm operatingsystem_parameter_argv,8 + +/* We need this stuff to make gdb behave itself, otherwise + gdb will chokes with SIGILL when trying to debug apps. +*/ + .section ".note.ABI-tag", "a" + .align 4 + .long 1f - 0f + .long 3f - 2f + .long 1 +0: .asciz "GNU" +1: .align 4 +2: .long 0 + .long 2,4,0 +3: .align 4 + + .section .note.GNU-stack,"",@progbits + + +/* + $Log: cprt0.as,v $ + Revision 1.4 2004/11/02 21:49:46 florian + * x86_64 requires always 16 byte alignment of the stack + + Revision 1.3 2004/07/03 21:50:31 daniel + * Modified bootstrap code so separate prt0.as/prt0_10.as files are no + longer necessary + + Revision 1.2 2004/02/20 23:48:27 peter + * c stub implemented + + Revision 1.1 2003/01/06 19:39:17 florian + + dummy implementations +*/ |