diff options
Diffstat (limited to 'libgloss/mips/crt0.S')
| -rw-r--r-- | libgloss/mips/crt0.S | 86 |
1 files changed, 20 insertions, 66 deletions
diff --git a/libgloss/mips/crt0.S b/libgloss/mips/crt0.S index 8810afa6c..8bd46ebf0 100644 --- a/libgloss/mips/crt0.S +++ b/libgloss/mips/crt0.S @@ -37,12 +37,13 @@ # else # define LA(t,x) la t,x-PICBASE ; addu t,s0,t # endif -#else /* __mips_embedded_pic */ +#else /* __mips_embedded_pic */ # define LA(t,x) la t,x -#endif /* __mips_embedded_pic */ +#endif /* __mips_embedded_pic */ .comm __memsize, 12 .comm __lstack, STARTUP_STACK_SIZE + .comm __stackbase,4 .text .align 2 @@ -53,19 +54,17 @@ */ nop - .globl hardware_hazard_hook .text .globl _start .ent _start _start: .set noreorder #ifdef __mips_embedded_pic -#define PICBASE start_PICBASE PICBASE = .+8 bal PICBASE nop move s0,$31 #endif -#if !defined(__mips64) || (__mips_fpr==32) +#if (__mips < 3) || (__mips_fpr==32) #define STATUS_MASK (SR_CU1|SR_PE) #else # For mips3 or mips4, turn on 64-bit addressing and additional float regs @@ -76,14 +75,6 @@ _start: mtc0 zero, C0_CAUSE nop - /* Avoid hazard from FPU enable and other SR changes. */ - LA (t0, hardware_hazard_hook) - beq t0,zero,1f - nop - jal t0 - nop -1: - /* Check for FPU presence. Don't check if we know that soft_float is being used. (This also avoids illegal instruction exceptions.) */ @@ -106,16 +97,10 @@ _start: li v0, (STATUS_MASK-(STATUS_MASK & SR_CU1)) mtc0 v0, C0_SR nop - /* Avoid hazard from FPU disable. */ - LA (t0, hardware_hazard_hook) - beq t0,zero,2f - nop - jal t0 - nop 2: -/* Fix high bits, if any, of the PC so that exception handling +/* Fix high bits, if any, of the PC so that exception handling doesn't get confused. */ LA (v0, 3f) jr v0 @@ -153,16 +138,22 @@ zerobss: /* NOTE: a0[0] contains the amount of memory available, and not the last memory address. */ - la a0, __memsize lw t0,0(a0) # last address of memory available la t1,K0BASE # cached kernel memory addu t0,t0,t1 # get the end of memory address - /* Allocate 32 bytes for the register parameters. Allocate 16 - bytes for a null argv and envp. Round the result up to 64 - bytes to preserve alignment. */ - subu t0,t0,64 + /* We must subtract 24 bytes for the 3 8 byte arguments to main, in + case main wants to write them back to the stack. The caller is + supposed to allocate stack space for parameters in registers in + the old MIPS ABIs. We must do this even though we aren't passing + arguments, because main might be declared to have them. + + Some ports need a larger alignment for the stack, so we subtract + 32, which satisifes the stack for the arguments and keeps the + stack pointer better aligned. */ + subu t0,t0,32 # and generate a starting stack-pointer 4: move sp,t0 # set stack pointer + sw sp,__stackbase # keep this for future ref .end zerobss /* @@ -202,33 +193,18 @@ init: nop #endif - jal _init # run global constructors nop - addiu a1,sp,32 # argv = sp + 32 - addiu a2,sp,40 # envp = sp + 40 -#if __mips64 - sd zero,(a1) # argv[argc] = 0 - sd zero,(a2) # envp[0] = 0 -#else - sw zero,(a1) - sw zero,(a2) -#endif - jal main # call the program start function move a0,zero # set argc to 0 + jal main # call the program start function + nop # fall through to the "exit" routine jal exit # call libc exit to run the G++ # destructors move a0,v0 # pass through the exit code .end init - - -/* Assume the PICBASE set up above is no longer valid below here. */ -#ifdef __mips_embedded_pic -#undef PICBASE -#endif /* * _exit -- Exit from the application. Normally we cause a user trap @@ -238,41 +214,19 @@ init: * executables that contain a complete world to be linked with * just the crt0.o object. */ - .globl hardware_exit_hook .text .globl _exit .ent _exit _exit: 7: -#ifdef __mips_embedded_pic - /* Need to reinit PICBASE, since we might be called via exit() - rather than via a return path which would restore old s0. */ -#define PICBASE exit_PICBASE - PICBASE = .+8 - bal PICBASE - nop - move s0,$31 -#endif #ifdef GCRT0 - LA (t0, _mcleanup) - jal t0 + jal _mcleanup nop #endif - LA (t0, hardware_exit_hook) - beq t0,zero,1f - nop - jal t0 - nop -1: - # break instruction can cope with 0xfffff, but GAS limits the range: break 1023 + nop b 7b # but loop back just in-case nop .end _exit - -/* Assume the PICBASE set up above is no longer valid below here. */ -#ifdef __mips_embedded_pic -#undef PICBASE -#endif /* EOF crt0.S */ |