Port GDB to Hurd x86_64.

This port extends the existing i686 port to support x86_64 by reusing
existing code whenever it makes sense.

* gdb/amd64-gnu-tdep.c: Adds logic for handling signal frames and
  position of amd64 registers in the different Hurd structs.
  The signal code is very similar to i686, except the trampoline code
  is adapted.
* gdb/config/i386/nm-i386gnu.h: renamed to gdb/config/i386/nm-x86-gnu.h
  and adapt it for x86_64.
* gdb/config/i386/i386gnu.mn: renamed to gdb/config/i386/nm-x86-gnu.mn
  and reuse it for x86_64.
* gdb/configure.host: recognize gnu64 as a host.
* gdb/configure.nat: recognize gnu64 host and update existing i386gnu to
  reuse the new shared files.
* gdb/configure.tgt: recognize x86_64-*-gnu* triplet and use
  amd64-gnu-tdep.c.
* gdb/i386-gnu-tdep.c: added i386_gnu_thread_state_reg_offset that is
  copied from i386-gnu-nat.c. This makes it similar to amd64.
* gdb/i386-gnu-nat.c: rename it to x86-gnu-nat.c since we reuse this for
  i386 and amd64. Updated REG_ADDR to use one of the structures. Added
  VALID_REGISTER to make sure it's a register we can provide at this time
  (not all of them are available in amd64). FLAGS_REGISTER is either rfl
  or efl depending on the arch. Renamed functions and class from i386 to x86
  whenever they can be reused.

Tested on Hurd x86_64 and i686.

1 files changed, 231 insertions, 0 deletions

diff --git a/gdb/amd64-gnu-tdep.c b/gdb/amd64-gnu-tdep.c
new file mode 100644
index 0000000..435095e
--- /dev/null
+++ b/gdb/amd64-gnu-tdep.c
@@ -0,0 +1,231 @@
+/* Target-dependent code for the GNU Hurd.
+   Copyright (C) 2024 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 "extract-store-integer.h"
+#include "gdbcore.h"
+#include "osabi.h"
+#include "solib-svr4.h"
+
+#include "amd64-tdep.h"
+#include "glibc-tdep.h"
+
+/* Recognizing signal handler frames.  */
+
+/* When the GNU/Hurd libc calls a signal handler, the return address points
+   inside the trampoline assembly snippet.
+
+   If the trampoline function name can not be identified, we resort to reading
+   memory from the process in order to identify it.  */
+
+static const gdb_byte gnu_sigtramp_code[] =
+{
+/* rpc_wait_trampoline: */
+  0x48, 0xc7, 0xc0, 0xe7, 0xff, 0xff, 0xff,	/* mov    $-25,%rax */
+  0x0f, 0x05,					/* syscall */
+  0x49, 0x89, 0x04, 0x24,			/* mov    %rax,(%r12) */
+  0x48, 0x89, 0xdc,				/* mov    %rbx,%rsp */
+
+/* trampoline: */
+  0x5f,			                        /* pop    %rdi */
+  0x5e,						/* pop    %rsi */
+  0x5a,						/* pop    %rdx */
+  0x48, 0x83, 0xc4, 0x08,			/* add    $0x8,%rsp */
+  0x41, 0xff, 0xd5,				/* call   *%r13 */
+
+/* RA HERE */
+  0x48, 0x8b, 0x7c, 0x24, 0x10,			/* mov    0x10(%rsp),%rdi */
+  0xc3,						/* ret */
+
+/* firewall: */
+  0xf4,						/* hlt */
+};
+
+#define GNU_SIGTRAMP_LEN (sizeof gnu_sigtramp_code)
+#define GNU_SIGTRAMP_TAIL 7			/* length of tail after RA */
+
+/* If THIS_FRAME is a sigtramp routine, return the address of the
+   start of the routine.  Otherwise, return 0.  */
+
+static CORE_ADDR
+amd64_gnu_sigtramp_start (frame_info_ptr this_frame)
+{
+  CORE_ADDR pc = get_frame_pc (this_frame);
+  gdb_byte buf[GNU_SIGTRAMP_LEN];
+
+  if (!safe_frame_unwind_memory (this_frame,
+				 pc + GNU_SIGTRAMP_TAIL - GNU_SIGTRAMP_LEN,
+				 buf))
+    return 0;
+
+  if (memcmp (buf, gnu_sigtramp_code, GNU_SIGTRAMP_LEN) != 0)
+    return 0;
+
+  return pc;
+}
+
+/* Return whether THIS_FRAME corresponds to a Hurd sigtramp routine.  */
+
+static int
+amd64_gnu_sigtramp_p (const frame_info_ptr &this_frame)
+{
+  CORE_ADDR pc = get_frame_pc (this_frame);
+  const char *name;
+
+  find_pc_partial_function (pc, &name, NULL, NULL);
+
+  /* If we have a NAME, we can check for the trampoline function */
+  if (name != NULL && strcmp (name, "trampoline") == 0)
+    return 1;
+
+  return amd64_gnu_sigtramp_start (this_frame) != 0;
+}
+
+/* Offset to sc_i386_thread_state in sigcontext, from <bits/sigcontext.h>.  */
+#define AMD64_GNU_SIGCONTEXT_THREAD_STATE_OFFSET 32
+
+/* Assuming THIS_FRAME is a Hurd sigtramp routine, return the
+   address of the associated sigcontext structure.  */
+
+static CORE_ADDR
+amd64_gnu_sigcontext_addr (const frame_info_ptr &this_frame)
+{
+  struct gdbarch *gdbarch = get_frame_arch (this_frame);
+  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
+  CORE_ADDR pc;
+  CORE_ADDR sp;
+  gdb_byte buf[8];
+
+  get_frame_register (this_frame, AMD64_RSP_REGNUM, buf);
+  sp = extract_unsigned_integer (buf, 8, byte_order);
+
+  pc = amd64_gnu_sigtramp_start (this_frame);
+  if (pc)
+    {
+      CORE_ADDR sigcontext_addr;
+
+      /* The sigcontext structure address is passed as the third argument
+       * of the signal handler but %RDX is not saved across calls. Luckily,
+       * the structured is saved underneath the &__sigreturn and a dummy word
+       * to fill the slot for the address for __sigreturn to return to.
+       */
+      read_memory (sp + 16, buf, 8);
+      sigcontext_addr = extract_unsigned_integer (buf, 8, byte_order);
+      return sigcontext_addr + AMD64_GNU_SIGCONTEXT_THREAD_STATE_OFFSET;
+    }
+
+  error (_("Couldn't recognize signal trampoline."));
+  return 0;
+}
+
+/* Mapping between the general-purpose registers in `struct
+   sigcontext' format (starting at sc_i386_thread_state)
+   and GDB's register cache layout.  */
+
+/* From <bits/sigcontext.h>.  */
+static int amd64_gnu_sc_reg_offset[] =
+{
+  15 * 8,			/* %rax */
+  12 * 8,			/* %rbx */
+  14 * 8,			/* %rcx */
+  13 * 8,			/* %rdx */
+  10 * 8,			/* %rsi */
+  9 * 8,			/* %rdi */
+  10 * 8,			/* %rbp */
+  11 * 8,			/* %rsp */
+  0 * 8,			/* %r8 ...  */
+  8 * 8,
+  7 * 8,
+  6 * 8,
+  3 * 8,
+  2 * 8,
+  1 * 8,
+  0 * 8,			/* ... %r15 */
+  16 * 8,			/* %rip */
+  18 * 8,			/* %eflags */
+  17 * 8,			/* %cs */
+};
+
+/* From <sys/ucontext.h>.  */
+static int amd64_gnu_gregset_reg_offset[] =
+{
+  10 * 8,			/* %rax */
+  5 * 8,			/* %rbx */
+  11 * 8,			/* %rcx */
+  12 * 8,			/* %rdx */
+  13 * 8,			/* %rsi */
+  14 * 8,			/* %rdi */
+  4 * 8,			/* %rbp */
+  19 * 8,			/* %rsp */
+  9 * 8,			/* %r8 ...  */
+  8 * 8,
+  7 * 8,
+  6 * 8,
+  3 * 8,
+  2 * 8,
+  1 * 8,
+  0 * 8,			/* ... %r15 */
+  16 * 8,			/* %rip */
+  18 * 8,			/* %eflags */
+  17 * 8,			/* %cs */
+  -1,				  /* %ss */
+  -1,				  /* %ds */
+  -1,				  /* %es */
+  -1,				  /* %fs */
+  -1,				  /* %gs */
+};
+
+static void
+amd64_gnu_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
+{
+  i386_gdbarch_tdep *tdep = gdbarch_tdep<i386_gdbarch_tdep> (gdbarch);
+
+  amd64_init_abi (info, gdbarch,
+      amd64_target_description (X86_XSTATE_SSE_MASK, true));
+
+  /* Enable TLS support.  */
+  set_gdbarch_fetch_tls_load_module_address (gdbarch,
+      svr4_fetch_objfile_link_map);
+
+  /* Hurd uses SVR4-style shared libraries.  */
+  set_gdbarch_skip_trampoline_code (gdbarch, find_solib_trampoline_target);
+
+  /* Hurd uses the dynamic linker included in the GNU C Library.  */
+  set_gdbarch_skip_solib_resolver (gdbarch, glibc_skip_solib_resolver);
+
+  tdep->gregset_reg_offset = amd64_gnu_gregset_reg_offset;
+  tdep->gregset_num_regs = ARRAY_SIZE (amd64_gnu_gregset_reg_offset);
+  tdep->sizeof_gregset = 21 * 8; /* sizeof (struct i386_thread_state); */
+
+  tdep->sigtramp_p = amd64_gnu_sigtramp_p;
+  tdep->sigcontext_addr = amd64_gnu_sigcontext_addr;
+  tdep->sc_reg_offset = amd64_gnu_sc_reg_offset;
+  tdep->sc_num_regs = ARRAY_SIZE (amd64_gnu_sc_reg_offset);
+
+  /* Hurd uses SVR4-style shared libraries.  */
+  set_solib_svr4_fetch_link_map_offsets
+    (gdbarch, svr4_lp64_fetch_link_map_offsets);
+}
+
+void _initialize_amd64_gnu_tdep ();
+void
+_initialize_amd64_gnu_tdep ()
+{
+  gdbarch_register_osabi (bfd_arch_i386, bfd_mach_x86_64,
+			  GDB_OSABI_HURD, amd64_gnu_init_abi);
+}