Re: [FIX] sysmips(MIPS_ATMIC_SET, ...) ret_from_sys_call vs. o32_ret_from_sys_call

[Joe deBlaquiere <jadb@redhat.com>]

I'm trying to implement MIPS_ATOMIC_SET for the Vr4181, which has no ll, 
sc operations. It looks to me like the function does something like

sysmips(MIPS_ATOMIC_SET,ptr,val)
{

}

Florian Lohoff wrote:

> On Wed, Jan 24, 2001 at 04:59:19PM +0100, Florian Lohoff wrote:
> 
>> Decoded this is:
>> 
>> Unable to handle kernel paging request at virtual address 00000000, epc == 00000000, ra == 00000000
>> $0 : 00000000 1004fc00 fffffff2 00000001
>> $4 : fffffff2 00000000 00000001 00000000
>> $8 : 00000000 2abf3a94 8800f4a0 00000004
>> $12: 8ec09f10 7ffffaf8 8ec09f18 8ec09f18
>> $16: 8801acf8 00000000 10011510 00000002
>> $20: 10011510 7ffffdd8 7ffffdcc 00000002
>> $24: 00000000 2abf3a80
>> $28: 8ec08000 8ec09ef8 7ffffd10 00000000
>> epc   : 00000000
>> Using defaults from ksymoops -t elf32-bigmips -a mips:3000
>> Status: 1004fc03
>> Cause : 30000008
> 
> 
> Ok - another one (sorry to spam you) 
> 
>>From "handle_sys" i see that system call address and no of
> args are in t2 and t3 which are 0x8800f4a0 and 4 with the register
> dump above.
> 
> 8800f4a0 is sys_sysmips which i also saw in the find strace.
> 
>>From the strace i find
> 
> sysmips(0x7d1, 0x2ac95d24, 0x1, 0)      = 4149
> 
> all the time - 0x7d1 is "MIPS_ATOMIC_SET" - Ok from the trace
> i see the call comes from handle_sys which itself would end with
> o32_ret_from_sys_call.
> 
> sysmips(MIPS_ATOMIC_SET, ...) 
> 
> would itself return with "ret_from_sys_call".
> 
> If i now apply
> 
> Index: arch/mips/kernel/sysmips.c
> ===================================================================
> RCS file: /cvs/linux/arch/mips/kernel/sysmips.c,v
> retrieving revision 1.15
> diff -u -r1.15 sysmips.c
> --- arch/mips/kernel/sysmips.c	2000/11/18 01:19:35	1.15
> +++ arch/mips/kernel/sysmips.c	2001/01/25 15:48:44
> @@ -111,7 +111,7 @@
>  
>  		__asm__ __volatile__(
>  			"move\t$29, %0\n\t"
> -			"j\tret_from_sys_call"
> +			"j\to32_ret_from_sys_call"
>  			: /* No outputs */
>  			: "r" (&cmd));
>  		/* Unreached */
> 
> The machine now at least doesnt crash anymore - Others have to decide
> if this is correct. (Nevertheless find doesnt return but this might
> be a different problem)
> 
> Flo


-- 
Joe deBlaquiere
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