[PATCH] sh: Fix args for __uClibc_main() in crt1.S

[Carmelo AMOROSO]

Takashi Yoshii wrote:
> Hi,
> 
> As a comment in libc/sysdeps/linux/sh/crt1.S says
>> 	/* __uClibc_main (main, argc, argv, init, fini) */
> , something wrong here. There should be two more args.
> 
> 7th arg "stack_end" seems to be missing.
> 6th one is not listed, but the original code pushed register "r4" here.
> It is not documented, but because ldso/ldso/sh/dl-startup.h explicitly sets
>  0 to r4 just before jump here, there must be a kind of calling convention.
> So, I preserve the code, and add a comment that this is the way to pass
> rtld_fini from prior routine.
> I really can't find any documents about this convention, though.
> 
> /yoshii
> 
> ---
> sh: Fix args for __uClibc_main() in crt1.S
>   add missing 7th arg "stack_end".
>   add comment of undocumented usage of r4.
>   fix comment of expected __uClibc_main() prototype.
> 
> diff --git a/libc/sysdeps/linux/sh/crt1.S b/libc/sysdeps/linux/sh/crt1.S
> --- a/libc/sysdeps/linux/sh/crt1.S
> +++ b/libc/sysdeps/linux/sh/crt1.S
> @@ -24,6 +24,11 @@
>  
>  	At this entry point, most registers' values are unspecified, except:
>  
> +   r4		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.
> +
>     sp		The stack contains the arguments and environment:
>     		0(sp)			argc
>  		4(sp)			argv[0]
> @@ -48,7 +53,8 @@ _start:
>  	mov.l @r15+,r5
>  	mov r15, r6
>  
> -	/* Push the fini func onto the stack */
> +	/* Push the stack_end, rtld_fini and fini func onto the stack */
> +	mov.l r6, at -r15
>  	mov.l r4, at -r15
>  	mov.l L_fini,r0
>  	mov.l r0, at -r15
> @@ -57,7 +63,7 @@ _start:
>  	mov.l L_main,r4
>  	mov.l L_init,r7
>  
> -	/* __uClibc_main (main, argc, argv, init, fini) */
> +	/* __uClibc_main (main, argc, argv, init, fini, rtld_fini, stack_end) */
>  
>  	/* Let the libc call main and exit with its return code.  */
>  	mov.l L_uClibc_main,r1
> 

Hi Takashi,
your point is correct and the patch looks fine. Looking again at the 
ld.so -> _start flow, yes sh4 forces rtld_fini to be NULL (r4 = 0 set in 
dl-startup.h as you told), so this means that on sh4 we do not call the 
_dl_fini destructor, loosing eventually to call the destructors of the 
dependant shared objects.
It should be simple enough to write a test showing this.
I'll spend a few time longer to look at what it's happening on glibc 
part, and eventually integrate your patch by setting the rtld_fini (6 ^ 
args) too.

Thanks a lot,
Carmelo
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