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

Daniel Jacobowitz
2003-05-29T15:33:09Z

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Comment's out of date.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