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This commit started as adding rv32e support to gdb. The rv32e architecture is a cut-down rv32i, it only has 16 x-registers compared to the usual 32, and an rv32e target should not have any floating point registers. In order to add this I needed to adjust the target description validation checks that are performed from riscv_gdbarch_init, and I finally got fed up with the current scheme of doing these checks and rewrote this code. Unfortunately the rv32e changes are currently mixed in with the rewrite of the validation scheme. I could split these apart if anyone is really interested in seeing these two ideas as separate patches. The main idea behind this change is that where previously I tried to have a purely data driven approach, a set of tables one for each expected feature, and then a single generic function that would validate a feature given a table, I have created a new class for each feature. Each class has its own check member function which allows the logic for how to check each feature to be different. I think the new scheme is much easier to follow. There are some other changes that I made to the validation code as part of this commit. I've relaxed some of the checks related to the floating point CSRs. Previously the 3 CSRs fflags, frm, and fcsr all had to be present in either the fpu feature or the csr feature. This requirement is now relaxed, if the CSRs are not present then gdb will not reject the target description. My thinking here is that there's no gdb functionality that specifically requires these registers, and so, if a target offers a description without these registers nothing else in gdb should stop working. And as part of the rv32e support targets now only have to provide the first 16 x-registers and $pc. The second half of the x-registers (x16 -> x31) are now optional. gdb/ChangeLog: * arch/riscv.c: Include 'rv32e-xregs.c'. (riscv_create_target_description): Update to handle rv32e. * arch/riscv.h (struct riscv_gdbarch_features) <embedded>: New member variable. <operator==>: Update to account for new field. <hash>: Likewise. * features/Makefile (FEATURE_XMLFILES): Add riscv/rv32e-xregs.xml. * features/riscv/rv32e-xregs.c: Generated. * features/riscv/rv32e-xregs.xml: New file. * riscv-tdep.c (riscv_debug_breakpoints): Move from later in the file. (riscv_debug_infcall): Likewise. (riscv_debug_unwinder): Likewise. (riscv_debug_gdbarch): Likewise. (enum riscv_register_required_status): Delete. (struct riscv_register_feature): Add constructor, delete default constructor, copy, and assign constructors. (struct riscv_register_feature::register_info) <required>: Delete. <check>: Update comment and arguments. (struct riscv_register_feature) <name>: Change to member function. <prefer_first_name>: Delete. <tdesc_feature>: New member function. <registers>: Rename to... <m_registers>: ...this. <m_feature_name>: New member variable. (riscv_register_feature::register_info::check): Update arguments. (riscv_xreg_feature): Rewrite as class, create a single static instance of the class. (riscv_freg_feature): Likewise. (riscv_virtual_feature): Likewise. (riscv_csr_feature): Likewise. (riscv_create_csr_aliases): Has become a member function inside riscv_csr_feature class. (riscv_abi_embedded): New function definition. (riscv_register_name): Adjust to use new feature objects. (struct riscv_call_info) <riscv_call_info>: Check for rv32e abi, and adjust available argument registers. (riscv_features_from_gdbarch_info): Check for EF_RISCV_RVE flag. (riscv_check_tdesc_feature): Delete. (riscv_tdesc_unknown_reg): Adjust to use new feature objects. (riscv_gdbarch_init): Delete target description checking code, and instead call to the new feature objects to perform the checks. Reorder handling of no abi information case, allows small code simplification. (_initialize_riscv_tdep): Remove call, this is now done in the riscv_csr_feature constructor. * riscv-tdep.h (riscv_abi_embedded): Declare.
99 lines
3.4 KiB
C++
99 lines
3.4 KiB
C++
/* Common target-dependent functionality for RISC-V
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Copyright (C) 2018-2020 Free Software Foundation, Inc.
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#ifndef ARCH_RISCV_H
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#define ARCH_RISCV_H
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#include "gdbsupport/tdesc.h"
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/* The set of RISC-V architectural features that we track that impact how
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we configure the actual gdbarch instance. We hold one of these in the
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gdbarch_tdep structure, and use it to distinguish between different
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RISC-V gdbarch instances.
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The information in here ideally comes from the target description,
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however, if the target doesn't provide a target description then we will
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create a default target description by first populating one of these
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based on what we know about the binary being executed, and using that to
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drive default target description creation. */
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struct riscv_gdbarch_features
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{
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/* The size of the x-registers in bytes. This is either 4 (RV32), 8
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(RV64), or 16 (RV128). No other value is valid. Initialise to the
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invalid 0 value so we can spot if one of these is used
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uninitialised. */
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int xlen = 0;
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/* The size of the f-registers in bytes. This is either 4 (RV32), 8
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(RV64), or 16 (RV128). This can also hold the value 0 to indicate
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that there are no f-registers. No other value is valid. */
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int flen = 0;
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/* When true this target is RV32E. */
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bool embedded = false;
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/* Equality operator. */
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bool operator== (const struct riscv_gdbarch_features &rhs) const
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{
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return (xlen == rhs.xlen && flen == rhs.flen && embedded == rhs.embedded);
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}
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/* Inequality operator. */
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bool operator!= (const struct riscv_gdbarch_features &rhs) const
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{
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return !((*this) == rhs);
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}
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/* Used by std::unordered_map to hash feature sets. */
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std::size_t hash () const noexcept
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{
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std::size_t val = ((embedded ? 1 : 0) << 10
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| (xlen & 0x1f) << 5
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| (flen & 0x1f) << 0);
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return val;
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}
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};
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#ifdef GDBSERVER
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/* Create and return a target description that is compatible with FEATURES.
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This is only used directly from the gdbserver where the created target
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description is modified after it is return. */
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target_desc_up riscv_create_target_description
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(const struct riscv_gdbarch_features features);
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#else
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/* Lookup an already existing target description matching FEATURES, or
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create a new target description if this is the first time we have seen
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FEATURES. For the same FEATURES the same target_desc is always
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returned. This is important when trying to lookup gdbarch objects as
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GDBARCH_LIST_LOOKUP_BY_INFO performs a pointer comparison on target
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descriptions to find candidate gdbarch objects. */
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const target_desc *riscv_lookup_target_description
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(const struct riscv_gdbarch_features features);
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#endif /* GDBSERVER */
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#endif /* ARCH_RISCV_H */
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