Re: [ppc64-linux]: Support gdbserver on PPC64 Linux

[Daniel Jacobowitz <drow at mvista dot com>]

A couple of small comments.

On Thu, May 29, 2003 at 01:39:54AM -0500, Jim Blandy wrote:
> + /* GNU/Linux/PowerPC specific low level interface, for the remote server for
> +    GDB.

Comment's out of date.

> +    Copyright 1995, 1996, 1998, 1999, 2000, 2001, 2002

So is the copyright year.

> +    Free Software Foundation, Inc.
> + 
> +    This file is part of GDB.
> + 
> +    This program is free software; you can redistribute it and/or modify
> +    it under the terms of the GNU General Public License as published by
> +    the Free Software Foundation; either version 2 of the License, or
> +    (at your option) any later version.
> + 
> +    This program is distributed in the hope that it will be useful,
> +    but WITHOUT ANY WARRANTY; without even the implied warranty of
> +    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +    GNU General Public License for more details.
> + 
> +    You should have received a copy of the GNU General Public License
> +    along with this program; if not, write to the Free Software
> +    Foundation, Inc., 59 Temple Place - Suite 330,
> +    Boston, MA 02111-1307, USA.  */
> + 
> + #include "server.h"
> + #include "linux-low.h"
> + 
> + #include <asm/ptrace.h>
> + 
> + #define ppc64_num_regs 71
> + 
> + #define FPR(n) ((PT_FPR0 + (n)) * 8)
> + 
> + /* Currently, don't check/send MQ.  */
> + static int ppc64_regmap[] =
> +   {
> +     PT_R0  * 8,    PT_R1  * 8,    PT_R2  * 8,    PT_R3  * 8,
> +     PT_R4  * 8,    PT_R5  * 8,    PT_R6  * 8,    PT_R7  * 8,
> +     PT_R8  * 8,    PT_R9  * 8,    PT_R10 * 8,    PT_R11 * 8,
> +     PT_R12 * 8,    PT_R13 * 8,    PT_R14 * 8,    PT_R15 * 8,
> +     PT_R16 * 8,    PT_R17 * 8,    PT_R18 * 8,    PT_R19 * 8,
> +     PT_R20 * 8,    PT_R21 * 8,    PT_R22 * 8,    PT_R23 * 8,
> +     PT_R24 * 8,    PT_R25 * 8,    PT_R26 * 8,    PT_R27 * 8,
> +     PT_R28 * 8,    PT_R29 * 8,    PT_R30 * 8,    PT_R31 * 8,
> +     FPR (0),       FPR (1),       FPR (2),       FPR (3),
> +     FPR (4),       FPR (5),       FPR (6),       FPR (7),
> +     FPR (8),       FPR (9),       FPR (10),      FPR (11),
> +     FPR (12),      FPR (13),      FPR (14),      FPR (15),
> +     FPR (16),      FPR (17),      FPR (18),      FPR (19),
> +     FPR (20),      FPR (21),      FPR (22),      FPR (23),
> +     FPR (24),      FPR (25),      FPR (26),      FPR (27),
> +     FPR (28),      FPR (29),      FPR (30),      FPR (31),
> +     PT_NIP * 8,    PT_MSR * 8,    PT_CCR * 8,    PT_LNK * 8,
> +     PT_CTR * 8,    PT_XER * 8,    PT_FPSCR * 8,
> +   };
> + 
> + static int
> + ppc64_cannot_store_register (int regno)
> + {
> +   /* Some kernels do not allow us to store fpscr.  */
> +   if (regno == find_regno ("fpscr"))
> +     return 2;

Could you please check whether this applies to any usable PowerPC64
kernel?

> + 
> +   return 0;
> + }
> + 
> + static int
> + ppc64_cannot_fetch_register (int regno)
> + {
> +   return 0;
> + }
> + 
> + static CORE_ADDR
> + ppc64_get_pc (void)
> + {
> +   unsigned long pc;
> + 
> +   collect_register_by_name ("pc", &pc);
> +   return (CORE_ADDR) pc;
> + }
> + 
> + static void
> + ppc64_set_pc (CORE_ADDR pc)
> + {
> +   unsigned long newpc = pc;
> + 
> +   supply_register_by_name ("pc", &newpc);
> + }
> + 
> + /* Correct in either endianness.  Note that this file is
> +    for PowerPC only, not PowerPC64.
> +    This instruction is "twge r2, r2", which GDB uses as a software
> +    breakpoint.  */
> + static const unsigned int ppc64_breakpoint = 0x7d821008;
> + #define ppc64_breakpoint_len 4

The comment is definitely wrong.  How about the breakpoint instruction?

> + 
> + static int
> + ppc64_breakpoint_at (CORE_ADDR where)
> + {
> +   unsigned int insn;
> + 
> +   (*the_target->read_memory) (where, (char *) &insn, 4);
> +   if (insn == ppc64_breakpoint)
> +     return 1;
> +   /* If necessary, recognize more trap instructions here.  GDB only uses the
> +      one.  */
> +   return 0;
> + }
> + 
> + struct linux_target_ops the_low_target = {
> +   ppc64_num_regs,
> +   ppc64_regmap,
> +   ppc64_cannot_fetch_register,
> +   ppc64_cannot_store_register,
> +   ppc64_get_pc,
> +   ppc64_set_pc,
> +   (const char *) &ppc64_breakpoint,
> +   ppc64_breakpoint_len,
> +   NULL,
> +   0,
> +   ppc64_breakpoint_at,
> + };

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer