--- /dev/null
+/* Target-dependent code for the LoongArch architecture, for GDB.
+
+ Copyright (C) 2022 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/>. */
+
+#include "defs.h"
+#include "arch-utils.h"
+#include "dwarf2/frame.h"
+#include "elf-bfd.h"
+#include "frame-unwind.h"
+#include "loongarch-tdep.h"
+#include "target-descriptions.h"
+#include "trad-frame.h"
+#include "user-regs.h"
+
+/* Implement the loongarch_skip_prologue gdbarch method. */
+
+static CORE_ADDR
+loongarch_skip_prologue (struct gdbarch *gdbarch, CORE_ADDR pc)
+{
+ CORE_ADDR func_addr;
+
+ /* See if we can determine the end of the prologue via the symbol table.
+ If so, then return either PC, or the PC after the prologue, whichever
+ is greater. */
+ if (find_pc_partial_function (pc, nullptr, &func_addr, nullptr))
+ {
+ CORE_ADDR post_prologue_pc
+ = skip_prologue_using_sal (gdbarch, func_addr);
+ if (post_prologue_pc != 0)
+ return std::max (pc, post_prologue_pc);
+ }
+
+ return 0;
+}
+
+/* Adjust the address downward (direction of stack growth) so that it
+ is correctly aligned for a new stack frame. */
+
+static CORE_ADDR
+loongarch_frame_align (struct gdbarch *gdbarch, CORE_ADDR addr)
+{
+ return align_down (addr, 16);
+}
+
+/* Generate, or return the cached frame cache for LoongArch frame unwinder. */
+
+static struct trad_frame_cache *
+loongarch_frame_cache (struct frame_info *this_frame, void **this_cache)
+{
+ struct gdbarch *gdbarch = get_frame_arch (this_frame);
+ struct trad_frame_cache *cache;
+ CORE_ADDR pc;
+
+ if (*this_cache != nullptr)
+ return (struct trad_frame_cache *) *this_cache;
+
+ cache = trad_frame_cache_zalloc (this_frame);
+ *this_cache = cache;
+
+ loongarch_gdbarch_tdep *tdep = (loongarch_gdbarch_tdep *) gdbarch_tdep (gdbarch);
+ trad_frame_set_reg_realreg (cache, gdbarch_pc_regnum (gdbarch), tdep->regs.ra);
+
+ pc = get_frame_address_in_block (this_frame);
+ trad_frame_set_id (cache, frame_id_build_unavailable_stack (pc));
+
+ return cache;
+}
+
+/* Implement the this_id callback for LoongArch frame unwinder. */
+
+static void
+loongarch_frame_this_id (struct frame_info *this_frame, void **prologue_cache,
+ struct frame_id *this_id)
+{
+ struct trad_frame_cache *info;
+
+ info = loongarch_frame_cache (this_frame, prologue_cache);
+ trad_frame_get_id (info, this_id);
+}
+
+/* Implement the prev_register callback for LoongArch frame unwinder. */
+
+static struct value *
+loongarch_frame_prev_register (struct frame_info *this_frame,
+ void **prologue_cache, int regnum)
+{
+ struct trad_frame_cache *info;
+
+ info = loongarch_frame_cache (this_frame, prologue_cache);
+ return trad_frame_get_register (info, this_frame, regnum);
+}
+
+static const struct frame_unwind loongarch_frame_unwind = {
+ "loongarch prologue",
+ /*.type =*/NORMAL_FRAME,
+ /*.stop_reason =*/default_frame_unwind_stop_reason,
+ /*.this_id =*/loongarch_frame_this_id,
+ /*.prev_register =*/loongarch_frame_prev_register,
+ /*.unwind_data =*/nullptr,
+ /*.sniffer =*/default_frame_sniffer,
+ /*.dealloc_cache =*/nullptr,
+ /*.prev_arch =*/nullptr,
+};
+
+/* Implement the "dwarf2_reg_to_regnum" gdbarch method. */
+
+static int
+loongarch_dwarf2_reg_to_regnum (struct gdbarch *gdbarch, int num)
+{
+ loongarch_gdbarch_tdep *tdep = (loongarch_gdbarch_tdep *) gdbarch_tdep (gdbarch);
+ auto regs = tdep->regs;
+
+ if (0 <= num && num < 32)
+ return regs.r + num;
+ else
+ return -1;
+}
+
+static constexpr gdb_byte loongarch_default_breakpoint[] = {0x05, 0x00, 0x2a, 0x00};
+typedef BP_MANIPULATION (loongarch_default_breakpoint) loongarch_breakpoint;
+
+/* Extract a set of required target features out of ABFD. If ABFD is nullptr
+ then a LOONGARCH_GDBARCH_FEATURES is returned in its default state. */
+
+static struct loongarch_gdbarch_features
+loongarch_features_from_bfd (const bfd *abfd)
+{
+ struct loongarch_gdbarch_features features;
+
+ /* Now try to improve on the defaults by looking at the binary we are
+ going to execute. We assume the user knows what they are doing and
+ that the target will match the binary. Remember, this code path is
+ only used at all if the target hasn't given us a description, so this
+ is really a last ditched effort to do something sane before giving
+ up. */
+ if (abfd != nullptr && bfd_get_flavour (abfd) == bfd_target_elf_flavour)
+ {
+ unsigned char eclass = elf_elfheader (abfd)->e_ident[EI_CLASS];
+
+ if (eclass == ELFCLASS32)
+ features.xlen = 4;
+ else if (eclass == ELFCLASS64)
+ features.xlen = 8;
+ else
+ internal_error (__FILE__, __LINE__,
+ _("unknown ELF header class %d"), eclass);
+ }
+
+ return features;
+}
+
+/* Find a suitable default target description. Use the contents of INFO,
+ specifically the bfd object being executed, to guide the selection of a
+ suitable default target description. */
+
+static const struct target_desc *
+loongarch_find_default_target_description (const struct gdbarch_info info)
+{
+ /* Extract desired feature set from INFO. */
+ struct loongarch_gdbarch_features features
+ = loongarch_features_from_bfd (info.abfd);
+
+ /* If the XLEN field is still 0 then we got nothing useful from INFO.BFD,
+ maybe there was no bfd object. In this case we fall back to a minimal
+ useful target with no floating point, the x-register size is selected
+ based on the architecture from INFO. */
+ if (features.xlen == 0)
+ features.xlen = info.bfd_arch_info->bits_per_address == 32 ? 4 : 8;
+
+ /* Now build a target description based on the feature set. */
+ return loongarch_lookup_target_description (features);
+}
+
+/* Initialize the current architecture based on INFO */
+
+static struct gdbarch *
+loongarch_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
+{
+ const struct target_desc *tdesc = info.target_desc;
+
+ /* Ensure we always have a target description. */
+ if (!tdesc_has_registers (tdesc))
+ tdesc = loongarch_find_default_target_description (info);
+
+ const struct tdesc_feature *feature_cpu
+ = tdesc_find_feature (tdesc, "org.gnu.gdb.loongarch.base");
+ if (feature_cpu == nullptr)
+ return nullptr;
+
+ int xlen_bitsize = tdesc_register_bitsize (feature_cpu, "pc");
+ struct loongarch_gdbarch_features features;
+ features.xlen = (xlen_bitsize / 8);
+
+ size_t regnum = 0;
+ tdesc_arch_data_up tdesc_data = tdesc_data_alloc ();
+ loongarch_gdbarch_tdep *tdep = new loongarch_gdbarch_tdep;
+ tdep->regs.r = regnum;
+
+ /* Validate the description provides the mandatory base registers
+ and allocate their numbers. */
+ bool valid_p = true;
+ for (int i = 0; i < 32; i++)
+ valid_p &= tdesc_numbered_register (feature_cpu, tdesc_data.get (), regnum++,
+ loongarch_r_normal_name[i] + 1);
+ valid_p &= tdesc_numbered_register (feature_cpu, tdesc_data.get (),
+ tdep->regs.pc = regnum++, "pc");
+ valid_p &= tdesc_numbered_register (feature_cpu, tdesc_data.get (),
+ tdep->regs.badv = regnum++, "badv");
+ if (!valid_p)
+ return nullptr;
+
+ /* LoongArch code is always little-endian. */
+ info.byte_order_for_code = BFD_ENDIAN_LITTLE;
+
+ /* Have a look at what the supplied (if any) bfd object requires of the
+ target, then check that this matches with what the target is
+ providing. */
+ struct loongarch_gdbarch_features abi_features
+ = loongarch_features_from_bfd (info.abfd);
+
+ /* If the ABI_FEATURES xlen is 0 then this indicates we got no useful abi
+ features from the INFO object. In this case we just treat the
+ hardware features as defining the abi. */
+ if (abi_features.xlen == 0)
+ abi_features = features;
+
+ /* Find a candidate among the list of pre-declared architectures. */
+ for (arches = gdbarch_list_lookup_by_info (arches, &info);
+ arches != nullptr;
+ arches = gdbarch_list_lookup_by_info (arches->next, &info))
+ {
+ /* Check that the feature set of the ARCHES matches the feature set
+ we are looking for. If it doesn't then we can't reuse this
+ gdbarch. */
+ loongarch_gdbarch_tdep *candidate_tdep
+ = (loongarch_gdbarch_tdep *) gdbarch_tdep (arches->gdbarch);
+
+ if (candidate_tdep->abi_features != abi_features)
+ continue;
+
+ break;
+ }
+
+ if (arches != nullptr)
+ return arches->gdbarch;
+
+ /* None found, so create a new architecture from the information provided. */
+ struct gdbarch *gdbarch = gdbarch_alloc (&info, tdep);
+ tdep->abi_features = abi_features;
+
+ /* Target data types. */
+ set_gdbarch_short_bit (gdbarch, 16);
+ set_gdbarch_int_bit (gdbarch, 32);
+ set_gdbarch_long_bit (gdbarch, info.bfd_arch_info->bits_per_address);
+ set_gdbarch_long_long_bit (gdbarch, 64);
+ set_gdbarch_ptr_bit (gdbarch, info.bfd_arch_info->bits_per_address);
+ set_gdbarch_char_signed (gdbarch, 0);
+
+ info.target_desc = tdesc;
+ info.tdesc_data = tdesc_data.get ();
+
+ /* Information about registers. */
+ tdep->regs.ra = tdep->regs.r + 1;
+ tdep->regs.sp = tdep->regs.r + 3;
+ set_gdbarch_num_regs (gdbarch, regnum);
+ set_gdbarch_sp_regnum (gdbarch, tdep->regs.sp);
+ set_gdbarch_pc_regnum (gdbarch, tdep->regs.pc);
+
+ /* Finalise the target description registers. */
+ tdesc_use_registers (gdbarch, tdesc, std::move (tdesc_data));
+
+ /* Advance PC across function entry code. */
+ set_gdbarch_skip_prologue (gdbarch, loongarch_skip_prologue);
+
+ /* Stack grows downward. */
+ set_gdbarch_inner_than (gdbarch, core_addr_lessthan);
+
+ /* Frame info. */
+ set_gdbarch_frame_align (gdbarch, loongarch_frame_align);
+
+ /* Breakpoint manipulation. */
+ set_gdbarch_breakpoint_kind_from_pc (gdbarch, loongarch_breakpoint::kind_from_pc);
+ set_gdbarch_sw_breakpoint_from_kind (gdbarch, loongarch_breakpoint::bp_from_kind);
+
+ /* Frame unwinders. Use DWARF debug info if available, otherwise use our own unwinder. */
+ set_gdbarch_dwarf2_reg_to_regnum (gdbarch, loongarch_dwarf2_reg_to_regnum);
+ dwarf2_append_unwinders (gdbarch);
+ frame_unwind_append_unwinder (gdbarch, &loongarch_frame_unwind);
+
+ /* Hook in OS ABI-specific overrides, if they have been registered. */
+ gdbarch_init_osabi (info, gdbarch);
+
+ return gdbarch;
+}
+
+void _initialize_loongarch_tdep ();
+void
+_initialize_loongarch_tdep ()
+{
+ gdbarch_register (bfd_arch_loongarch, loongarch_gdbarch_init, nullptr);
+}
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