binutils-gdb/gdb/riscv-tdep.h
Andrew Burgess 2e52d03824 gdb/riscv: Record information about unknown tdesc registers
Making use of the previous commit, record information about unknown
registers in the target description, and use this to resolve two
issues.

1. Some targets (QEMU) are reporting three register fflags, frm, and
   fcsr, twice, once in the FPU feature, and once in the CSR feature.
   GDB does create two registers with identical names, but this
   is (sort of) fine, we only ever use the first one, and as both
   registers access the same target state things basically work OK.
   The only real problem is that the register names show up twice in
   'info registers all' output.

   In this commit we spot the duplicates of these registers and then
   return NULL when asked for the name of these registers.  This
   causes GDB to hide these registers from the user, fixing this
   problem.

2. Some targets (QEMU) advertise CSRs that GDB then can't read.  The
   problem is these targets also say these CSRs are part of the
   save/restore register groups.

   This means that before an inferior call GDB tries to save all of
   these CSRs, and a failure to read one causes the inferior call to
   be abandoned.

   We already work around this issue to some degree, known CSRs are
   removed from the save/restore groups, despite what the target might
   say.  However, any unknown CSRs are (currently) not removed in this
   way.

   After this commit we keep a log of the register numbers for all
   unknown CSRs, then when asked about the register groups, we
   override the group information for unknown CSRs, removing them from
   the save and restore groups.

gdb/ChangeLog:

	* riscv-tdep.c (riscv_register_name): Return NULL for duplicate
	fflags, frm, and fcsr registers.
	(riscv_register_reggroup_p): Remove unknown CSRs from save and
	restore groups.
	(riscv_tdesc_unknown_reg): New function.
	(riscv_gdbarch_init): Pass riscv_tdesc_unknown_reg to
	tdesc_use_registers.
	* riscv-tdep.h (struct gdbarch_tdep): Add
	unknown_csrs_first_regnum, unknown_csrs_count,
	duplicate_fflags_regnum, duplicate_frm_regnum, and
	duplicate_fcsr_regnum fields.

gdb/testsuite/ChangeLog:

	* gdb.arch/riscv-tdesc-regs.exp: Extend test case.
2020-06-25 18:07:32 +01:00

134 lines
5.1 KiB
C++

/* Target-dependent header for the RISC-V architecture, for GDB, the
GNU Debugger.
Copyright (C) 2018-2020 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 3 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, see <http://www.gnu.org/licenses/>. */
#ifndef RISCV_TDEP_H
#define RISCV_TDEP_H
#include "arch/riscv.h"
/* RiscV register numbers. */
enum
{
RISCV_ZERO_REGNUM = 0, /* Read-only register, always 0. */
RISCV_RA_REGNUM = 1, /* Return Address. */
RISCV_SP_REGNUM = 2, /* Stack Pointer. */
RISCV_GP_REGNUM = 3, /* Global Pointer. */
RISCV_TP_REGNUM = 4, /* Thread Pointer. */
RISCV_FP_REGNUM = 8, /* Frame Pointer. */
RISCV_A0_REGNUM = 10, /* First argument. */
RISCV_A1_REGNUM = 11, /* Second argument. */
RISCV_PC_REGNUM = 32, /* Program Counter. */
RISCV_NUM_INTEGER_REGS = 32,
RISCV_FIRST_FP_REGNUM = 33, /* First Floating Point Register */
RISCV_FA0_REGNUM = 43,
RISCV_FA1_REGNUM = RISCV_FA0_REGNUM + 1,
RISCV_LAST_FP_REGNUM = 64, /* Last Floating Point Register */
RISCV_FIRST_CSR_REGNUM = 65, /* First CSR */
#define DECLARE_CSR(name, num, class, define_version, abort_version) \
RISCV_ ## num ## _REGNUM = RISCV_FIRST_CSR_REGNUM + num,
#include "opcode/riscv-opc.h"
#undef DECLARE_CSR
RISCV_LAST_CSR_REGNUM = 4160,
RISCV_CSR_LEGACY_MISA_REGNUM = 0xf10 + RISCV_FIRST_CSR_REGNUM,
RISCV_PRIV_REGNUM = 4161,
RISCV_LAST_REGNUM = RISCV_PRIV_REGNUM
};
/* RiscV DWARF register numbers. */
enum
{
RISCV_DWARF_REGNUM_X0 = 0,
RISCV_DWARF_REGNUM_X31 = 31,
RISCV_DWARF_REGNUM_F0 = 32,
RISCV_DWARF_REGNUM_F31 = 63,
};
/* RISC-V specific per-architecture information. */
struct gdbarch_tdep
{
/* Features about the target hardware that impact how the gdbarch is
configured. Two gdbarch instances are compatible only if this field
matches. */
struct riscv_gdbarch_features isa_features;
/* Features about the abi that impact how the gdbarch is configured. Two
gdbarch instances are compatible only if this field matches. */
struct riscv_gdbarch_features abi_features;
/* ISA-specific data types. */
struct type *riscv_fpreg_d_type = nullptr;
/* Use for tracking unknown CSRs in the target description.
UNKNOWN_CSRS_FIRST_REGNUM is the number assigned to the first unknown
CSR. All other unknown CSRs will be assigned sequential numbers after
this, with UNKNOWN_CSRS_COUNT being the total number of unknown CSRs. */
int unknown_csrs_first_regnum = -1;
int unknown_csrs_count = 0;
/* Some targets (QEMU) are reporting three registers twice in the target
description they send. These three register numbers, when not set to
-1, are for the duplicate copies of these registers. */
int duplicate_fflags_regnum = -1;
int duplicate_frm_regnum = -1;
int duplicate_fcsr_regnum = -1;
};
/* Return the width in bytes of the general purpose registers for GDBARCH.
Possible return values are 4, 8, or 16 for RiscV variants RV32, RV64, or
RV128. */
extern int riscv_isa_xlen (struct gdbarch *gdbarch);
/* Return the width in bytes of the hardware floating point registers for
GDBARCH. If this architecture has no floating point registers, then
return 0. Possible values are 4, 8, or 16 for depending on which of
single, double or quad floating point support is available. */
extern int riscv_isa_flen (struct gdbarch *gdbarch);
/* Return the width in bytes of the general purpose register abi for
GDBARCH. This can be equal to, or less than RISCV_ISA_XLEN and reflects
how the binary was compiled rather than the hardware that is available.
It is possible that a binary compiled for RV32 is being run on an RV64
target, in which case the isa xlen is 8-bytes, and the abi xlen is
4-bytes. This will impact how inferior functions are called. */
extern int riscv_abi_xlen (struct gdbarch *gdbarch);
/* Return the width in bytes of the floating point register abi for
GDBARCH. This reflects how the binary was compiled rather than the
hardware that is available. It is possible that a binary is compiled
for single precision floating point, and then run on a target with
double precision floating point. A return value of 0 indicates that no
floating point abi is in use (floating point arguments will be passed
in integer registers) other possible return value are 4, 8, or 16 as
with RISCV_ISA_FLEN. */
extern int riscv_abi_flen (struct gdbarch *gdbarch);
/* Single step based on where the current instruction will take us. */
extern std::vector<CORE_ADDR> riscv_software_single_step
(struct regcache *regcache);
#endif /* RISCV_TDEP_H */