Re: [PATCH V2] score: add regset support

[Arnd Bergmann <arnd@arndb.de>]

On Monday 13 July 2009, liqin.chen@sunplusct.com wrote:
> 
> unsigned long pad0[6];
> 
> was place at the start of pt_regs use 
> to hold the arguments from userland.
> caller(exception handler) not need to
> change stack pointer.
>
> unsigned long orig_r4;
> unsigned long orig_r7;
> move to end of the pt_regs haven't 
> problem.

Ok, I see.

Maybe to get a nicer layout, you can define separate
structures then:

struct user_regs_struct {
        unsigned long regs[32];

        unsigned long cel;
        unsigned long ceh;
 
        unsigned long sr0;      /* cnt */
        unsigned long sr1;      /* lcr */
        unsigned long sr2;      /* scr */
 
        unsigned long cp0_epc;
        unsigned long cp0_ema;
        unsigned long cp0_psr;
        unsigned long cp0_ecr;
        unsigned long cp0_condition;

	unsigned long reserved[6]; /* future extensions */
};

#ifdef __KERNEL__
struct pt_regs {
	/* stack arguments */
        unsigned long pad0[6];

	/* internal use */
        unsigned long orig_r4;
        unsigned long orig_r7;
        long is_syscall;

	/* saved registers */
	struct user_regs_struct uregs;
};
#endif

That would keep the user struct relatively clean.

	Arnd <><