[PATCH] Add support for Xtensa

[Dmitry V. Levin]

Hi,

On Fri, Mar 22, 2013 at 05:09:23PM -0700, Chris Zankel wrote:
> 
> It would be great if you could apply the attached patch to add support
> for the Xtensa architecture. Xtensa was added to the kernel a long time
> ago, and we have kept local patches for strace for a long time, but it
> would be easier to support it in the mainline repository.
[...]
> diff --git a/linux/xtensa/syscallent.h b/linux/xtensa/syscallent.h
> new file mode 100644
> index 0000000..2ef4fd8
> --- /dev/null
> +++ b/linux/xtensa/syscallent.h
> @@ -0,0 +1,434 @@
> +	{ 0,	0,	printargs,		"spill"		}, /* 0 */
> +	{ 0,	0,	printargs,		"xtensa"	}, /* 1 */
> +	{ MA,	0,	printargs,		"SYS_2"		}, /* 2 */
> +	{ MA,	0,	printargs,		"SYS_3"		}, /* 3 */
> +	{ MA,	0,	printargs,		"SYS_4"		}, /* 4 */
> +	{ MA,	0,	printargs,		"SYS_5"		}, /* 5 */
> +	{ MA,	0,	printargs,		"SYS_6"		}, /* 6 */
> +	{ MA,	0,	printargs,		"SYS_7"		}, /* 7 */

In this and other similar places, please collapse blocks of undefined
syscall entries using "[N1 ... N2] = {}" notation.

[...]
> --- a/syscall.c
> +++ b/syscall.c
> @@ -76,6 +76,10 @@
>  # include <asm/ptrace.h>
>  #endif
>  
> +#if defined(XTENSA)
> +# include <asm/ptrace.h>
> +#endif
> +
>  #ifndef ERESTARTSYS
>  # define ERESTARTSYS	512
>  #endif
> @@ -799,6 +803,8 @@ static struct user_regs_struct or1k_regs;
>  #elif defined(METAG)
>  static struct user_gp_regs metag_regs;
>  # define ARCH_REGS_FOR_GETREGSET metag_regs
> +#elif defined(XTENSA)
> +static long xtensa_a2;
>  #endif
>  
>  void
> @@ -936,6 +942,13 @@ printcall(struct tcb *tcp)
>  	tprintf("[%08lx] ", or1k_regs.pc);
>  #elif defined(METAG)
>  	tprintf("[%08lx] ", metag_regs.pc);
> +#elif defined(XTENSA)
> +	long pc;
> +	if (upeek(tcp, REG_PC, &pc) < 0) {
> +		PRINTBADPC;
> +		return;
> +	}
> +	tprintf("[%08lx] ", pc);
>  #endif /* architecture */
>  }
>  
> @@ -1516,6 +1529,9 @@ get_scno(struct tcb *tcp)
>  	scno = or1k_regs.gpr[11];
>  #elif defined(METAG)
>  	scno = metag_regs.dx[0][1];	/* syscall number in D1Re0 (D1.0) */
> +#elif defined(XTENSA)
> +	if (upeek(tcp, SYSCALL_NR, &scno) < 0)
> +		return -1;
>  #endif
>  
>  	tcp->scno = scno;
> @@ -1916,6 +1932,12 @@ get_syscall_args(struct tcb *tcp)
>  	for (i = 0; i < nargs; i++)
>  		/* arguments go backwards from D1Ar1 (D1.3) */
>  		tcp->u_arg[i] = ((unsigned long *)&metag_regs.dx[3][1])[-i];
> +#elif defined(XTENSA)
> +	/* arg0: a6, arg1: a3, arg2: a4, arg3: a5, arg4: a8, arg5: a9 */
> +	static const int xtensaregs[MAX_ARGS] = { 6, 3, 4, 5, 8, 9 };
> +	for (i = 0; i < nargs; ++i)
> +		if (upeek(tcp, REG_A_BASE + xtensaregs[i], &tcp->u_arg[i]) < 0)
> +			return -1;
>  #else /* Other architecture (32bits specific) */
>  	for (i = 0; i < nargs; ++i)
>  		if (upeek(tcp, i*4, &tcp->u_arg[i]) < 0)
> @@ -2112,6 +2134,9 @@ get_syscall_result(struct tcb *tcp)
>  	/* already done by get_regs */
>  #elif defined(METAG)
>  	/* already done by get_regs */
> +#elif defined(XTENSA)
> +	if (upeek(tcp, REG_A_BASE + 2, &xtensa_a2) < 0)
> +		return -1;
>  #endif
>  	return 1;
>  }
> @@ -2411,6 +2436,14 @@ get_error(struct tcb *tcp)
>  	else {
>  		tcp->u_rval = or1k_regs.gpr[11];
>  	}
> +#elif defined(XTENSA)
> +	if (check_errno && is_negated_errno(xtensa_a2)) {
> +		tcp->u_rval = -1;
> +		u_error = -xtensa_a2;
> +	}
> +	else {
> +		tcp->u_rval = xtensa_a2;
> +	}
>  #endif
>  	tcp->u_error = u_error;
>  }

Is there any reason to upeek one register at a time instead of fetching
the whole set using PTRACE_GETREGS or PTRACE_GETREGSET?


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