diff options
Diffstat (limited to 'usr/klibc/arch/sparc/crt0i.S')
| -rw-r--r-- | usr/klibc/arch/sparc/crt0i.S | 100 |
1 files changed, 100 insertions, 0 deletions
diff --git a/usr/klibc/arch/sparc/crt0i.S b/usr/klibc/arch/sparc/crt0i.S new file mode 100644 index 0000000..0220b01 --- /dev/null +++ b/usr/klibc/arch/sparc/crt0i.S @@ -0,0 +1,100 @@ +! 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 |