| ! This file derived from the equivalent in newlib |
| ! |
| ! C run time start off |
| |
| ! This file supports: |
| ! |
| ! - both 32bit pointer and 64bit pointer environments (at compile time) |
| ! - an imposed stack bias (of 2047) (at run time) |
| ! - medium/low and medium/anywhere code models (at run time) |
| |
| ! Initial stack setup: |
| ! |
| ! bottom of stack (higher memory address) |
| ! ... |
| ! text of environment strings |
| ! text of argument strings |
| ! envp[envc] = 0 (4/8 bytes) |
| ! ... |
| ! env[0] (4/8 bytes) |
| ! argv[argc] = 0 (4/8 bytes) |
| ! ... |
| ! argv[0] (4/8 bytes) |
| ! argc (4/8 bytes) |
| ! register save area (64 bits by 16 registers = 128 bytes) |
| ! top of stack (%sp) |
| |
| ! Stack Bias: |
| ! |
| ! It is the responsibility of the o/s to set this up. |
| ! We handle both a 0 and 2047 value for the stack bias. |
| |
| ! Medium/Anywhere code model support: |
| ! |
| ! In this model %g4 points to the start of the data segment. |
| ! The text segment can go anywhere, but %g4 points to the *data* segment. |
| ! It is up to the compiler/linker to get this right. |
| ! |
| ! Since this model is statically linked the start of the data segment |
| ! is known at link time. Eg: |
| ! |
| ! sethi %hh(data_start), %g1 |
| ! sethi %lm(data_start), %g4 |
| ! or %g1, %hm(data_start), %g1 |
| ! or %g4, %lo(data_start), %g4 |
| ! sllx %g1, 32, %g1 |
| ! or %g4, %g1, %g4 |
| ! |
| ! FIXME: For now we just assume 0. |
| |
| ! FIXME: if %g1 contains a non-zero value, atexit() should be invoked |
| ! with this value. |
| |
| |
| .text |
| .align 4 |
| .globl _start |
| .type _start, @function |
| _start: |
| clr %fp |
| |
| ! We use %g4 even if the code model is Medium/Low (simplifies the code). |
| |
| clr %g4 ! Medium/Anywhere base reg |
| |
| ! If there is a stack bias in effect, account for it in %g5. Then always |
| ! add %g5 to stack references below. This way the code can be used with |
| ! or without an imposed bias. |
| |
| andcc %sp, 1, %g5 |
| bz,a .LNoBias |
| nop |
| mov 2047, %g5 |
| .LNoBias: |
| add %sp, %g5, %g5 |
| |
| ! On entry, the kernel leaves room for one register frame, but |
| ! the C API wants more free space. Thus, we need to drop the stack |
| ! pointer additionally. |
| |
| #if TARGET_PTR_SIZE == 32 |
| sub %sp, 32, %sp ! make room for incoming arguments |
| #else /* TARGET_PTR_SIZE == 64 */ |
| sub %sp, 64, %sp ! make room for incoming arguments |
| #endif |
| |
| ! Set up pointers to the ELF data structure (argc, argv, ...) |
| ! Pass as the first argument to __libc_init |
| #if TARGET_PTR_SIZE == 32 |
| add %g5, 0x40, %o0 |
| #else /* TARGET_PTR_SIZE == 64 */ |
| add %g5, 0x80, %o0 |
| #endif |
| |
| call __libc_init |
| mov %g1, %o1 ! This is the "atexit" pointer; |
| ! pass as the second argument to __libc_init |
| |
| ! If __libc_init returns, something is hosed. Try an illegal insn. |
| ! If that does not work, the o/s is hosed more than we are. |
| .long 0 |