Move gdbserver to top level

This patch moves gdbserver to the top level.

This patch is as close to a pure move as possible -- gdbserver still
builds its own variant of gnulib and gdbsupport.  Changing this will
be done in a separate patch.

[v2] Note that, per Simon's review comment, this patch changes the
tree so that gdbserver is not built for or1k or score.  This makes
sense, because there is apparently not actually a gdbserver port here.

[v3] This version of the patch also splits out some configury into a
new file, gdbserver/configure.host, so that the top-level configure
script can simply rely on it in order to decide whether gdbserver
should be built.

[v4] This version adds documentation and removes some unnecessary
top-level dependencies.

[v5] Update docs to mention "make all-gdbserver" and change how
top-level configure decides whether to build gdbserver, switching to a
single, shared script.

Tested by the buildbot.

ChangeLog
2020-02-07  Tom Tromey  <tom@tromey.com>
	    Pedro Alves  <palves@redhat.com>

	* src-release.sh (GDB_SUPPORT_DIRS): Add gdbserver.
	* gdbserver: New directory, moved from gdb/gdbserver.
	* configure.ac (host_tools): Add gdbserver.
	Only build gdbserver on certain systems.
	* Makefile.in, configure: Rebuild.
	* Makefile.def (host_modules, dependencies): Add gdbserver.
	* MAINTAINERS: Add gdbserver.

gdb/ChangeLog
2020-02-07  Tom Tromey  <tom@tromey.com>

	* README: Update gdbserver documentation.
	* gdbserver: Move to top level.
	* configure.tgt (build_gdbserver): Remove.
	* configure.ac: Remove --enable-gdbserver.
	* configure: Rebuild.
	* Makefile.in (distclean): Don't mention gdbserver.

Change-Id: I826b7565b54604711dc7a11edea0499cd51ff39e

1 files changed, 289 insertions, 0 deletions

diff --git a/gdbserver/linux-amd64-ipa.c b/gdbserver/linux-amd64-ipa.c
new file mode 100644
index 0000000..53d98f2
--- /dev/null
+++ b/gdbserver/linux-amd64-ipa.c
@@ -0,0 +1,289 @@
+/* GNU/Linux/x86-64 specific low level interface, for the in-process
+   agent library for GDB.
+
+   Copyright (C) 2010-2020 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/>.  */
+
+#include "server.h"
+#include <sys/mman.h>
+#include "tracepoint.h"
+#include "linux-x86-tdesc.h"
+#include "gdbsupport/x86-xstate.h"
+
+/* Defined in auto-generated file amd64-linux.c.  */
+void init_registers_amd64_linux (void);
+extern const struct target_desc *tdesc_amd64_linux;
+
+/* fast tracepoints collect registers.  */
+
+#define FT_CR_RIP 0
+#define FT_CR_EFLAGS 1
+#define FT_CR_R8 2
+#define FT_CR_R9 3
+#define FT_CR_R10 4
+#define FT_CR_R11 5
+#define FT_CR_R12 6
+#define FT_CR_R13 7
+#define FT_CR_R14 8
+#define FT_CR_R15 9
+#define FT_CR_RAX 10
+#define FT_CR_RBX 11
+#define FT_CR_RCX 12
+#define FT_CR_RDX 13
+#define FT_CR_RSI 14
+#define FT_CR_RDI 15
+#define FT_CR_RBP 16
+#define FT_CR_RSP 17
+
+static const int x86_64_ft_collect_regmap[] = {
+  FT_CR_RAX * 8, FT_CR_RBX * 8, FT_CR_RCX * 8, FT_CR_RDX * 8,
+  FT_CR_RSI * 8, FT_CR_RDI * 8, FT_CR_RBP * 8, FT_CR_RSP * 8,
+  FT_CR_R8 * 8,  FT_CR_R9 * 8,  FT_CR_R10 * 8, FT_CR_R11 * 8,
+  FT_CR_R12 * 8, FT_CR_R13 * 8, FT_CR_R14 * 8, FT_CR_R15 * 8,
+  FT_CR_RIP * 8, FT_CR_EFLAGS * 8
+};
+
+#define X86_64_NUM_FT_COLLECT_GREGS \
+  (sizeof (x86_64_ft_collect_regmap) / sizeof(x86_64_ft_collect_regmap[0]))
+
+void
+supply_fast_tracepoint_registers (struct regcache *regcache,
+				  const unsigned char *buf)
+{
+  int i;
+
+  for (i = 0; i < X86_64_NUM_FT_COLLECT_GREGS; i++)
+    supply_register (regcache, i,
+		     ((char *) buf) + x86_64_ft_collect_regmap[i]);
+}
+
+ULONGEST
+get_raw_reg (const unsigned char *raw_regs, int regnum)
+{
+  if (regnum >= X86_64_NUM_FT_COLLECT_GREGS)
+    return 0;
+
+  return *(ULONGEST *) (raw_regs + x86_64_ft_collect_regmap[regnum]);
+}
+
+#ifdef HAVE_UST
+
+#include <ust/processor.h>
+
+/* "struct registers" is the UST object type holding the registers at
+   the time of the static tracepoint marker call.  This doesn't
+   contain RIP, but we know what it must have been (the marker
+   address).  */
+
+#define ST_REGENTRY(REG)			\
+  {						\
+    offsetof (struct registers, REG),		\
+    sizeof (((struct registers *) NULL)->REG)	\
+  }
+
+static struct
+{
+  int offset;
+  int size;
+} x86_64_st_collect_regmap[] =
+  {
+    ST_REGENTRY(rax),
+    ST_REGENTRY(rbx),
+    ST_REGENTRY(rcx),
+    ST_REGENTRY(rdx),
+    ST_REGENTRY(rsi),
+    ST_REGENTRY(rdi),
+    ST_REGENTRY(rbp),
+    ST_REGENTRY(rsp),
+    ST_REGENTRY(r8),
+    ST_REGENTRY(r9),
+    ST_REGENTRY(r10),
+    ST_REGENTRY(r11),
+    ST_REGENTRY(r12),
+    ST_REGENTRY(r13),
+    ST_REGENTRY(r14),
+    ST_REGENTRY(r15),
+    { -1, 0 },
+    ST_REGENTRY(rflags),
+    ST_REGENTRY(cs),
+    ST_REGENTRY(ss),
+  };
+
+#define X86_64_NUM_ST_COLLECT_GREGS \
+  (sizeof (x86_64_st_collect_regmap) / sizeof (x86_64_st_collect_regmap[0]))
+
+/* GDB's RIP register number.  */
+#define AMD64_RIP_REGNUM 16
+
+void
+supply_static_tracepoint_registers (struct regcache *regcache,
+				    const unsigned char *buf,
+				    CORE_ADDR pc)
+{
+  int i;
+  unsigned long newpc = pc;
+
+  supply_register (regcache, AMD64_RIP_REGNUM, &newpc);
+
+  for (i = 0; i < X86_64_NUM_ST_COLLECT_GREGS; i++)
+    if (x86_64_st_collect_regmap[i].offset != -1)
+      {
+	switch (x86_64_st_collect_regmap[i].size)
+	  {
+	  case 8:
+	    supply_register (regcache, i,
+			     ((char *) buf)
+			     + x86_64_st_collect_regmap[i].offset);
+	    break;
+	  case 2:
+	    {
+	      unsigned long reg
+		= * (short *) (((char *) buf)
+			       + x86_64_st_collect_regmap[i].offset);
+	      reg &= 0xffff;
+	      supply_register (regcache, i, &reg);
+	    }
+	    break;
+	  default:
+	    internal_error (__FILE__, __LINE__,
+			    "unhandled register size: %d",
+			    x86_64_st_collect_regmap[i].size);
+	    break;
+	  }
+      }
+}
+
+#endif /* HAVE_UST */
+
+#if !defined __ILP32__
+/* Map the tdesc index to xcr0 mask.  */
+static uint64_t idx2mask[X86_TDESC_LAST] = {
+  X86_XSTATE_X87_MASK,
+  X86_XSTATE_SSE_MASK,
+  X86_XSTATE_AVX_MASK,
+  X86_XSTATE_MPX_MASK,
+  X86_XSTATE_AVX_MPX_MASK,
+  X86_XSTATE_AVX_AVX512_MASK,
+  X86_XSTATE_AVX_MPX_AVX512_PKU_MASK,
+};
+#endif
+
+/* Return target_desc to use for IPA, given the tdesc index passed by
+   gdbserver.  */
+
+const struct target_desc *
+get_ipa_tdesc (int idx)
+{
+  if (idx >= X86_TDESC_LAST)
+    {
+      internal_error (__FILE__, __LINE__,
+		      "unknown ipa tdesc index: %d", idx);
+    }
+
+#if defined __ILP32__
+  switch (idx)
+    {
+    case X86_TDESC_SSE:
+      return amd64_linux_read_description (X86_XSTATE_SSE_MASK, true);
+    case X86_TDESC_AVX:
+      return amd64_linux_read_description (X86_XSTATE_AVX_MASK, true);
+    case X86_TDESC_AVX_AVX512:
+      return amd64_linux_read_description (X86_XSTATE_AVX_AVX512_MASK, true);
+    default:
+      break;
+    }
+#else
+  return amd64_linux_read_description (idx2mask[idx], false);
+#endif
+
+  internal_error (__FILE__, __LINE__,
+		  "unknown ipa tdesc index: %d", idx);
+}
+
+/* Allocate buffer for the jump pads.  The branch instruction has a
+   reach of +/- 31-bit, and the executable is loaded at low addresses.
+
+   64-bit: Use MAP_32BIT to allocate in the first 2GB.  Shared
+   libraries, being allocated at the top, are unfortunately out of
+   luck.
+
+   x32: Since MAP_32BIT is 64-bit only, do the placement manually.
+   Try allocating at '0x80000000 - SIZE' initially, decreasing until
+   we hit a free area.  This ensures the executable is fully covered,
+   and is as close as possible to the shared libraries, which are
+   usually mapped at the top of the first 4GB of the address space.
+*/
+
+void *
+alloc_jump_pad_buffer (size_t size)
+{
+#if __ILP32__
+  uintptr_t addr;
+  int pagesize;
+
+  pagesize = sysconf (_SC_PAGE_SIZE);
+  if (pagesize == -1)
+    perror_with_name ("sysconf");
+
+  addr = 0x80000000 - size;
+
+  /* size should already be page-aligned, but this can't hurt.  */
+  addr &= ~(pagesize - 1);
+
+  /* Search for a free area.  If we hit 0, we're out of luck.  */
+  for (; addr; addr -= pagesize)
+    {
+      void *res;
+
+      /* No MAP_FIXED - we don't want to zap someone's mapping.  */
+      res = mmap ((void *) addr, size,
+		  PROT_READ | PROT_WRITE | PROT_EXEC,
+		  MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+
+      /* If we got what we wanted, return.  */
+      if ((uintptr_t) res == addr)
+	return res;
+
+      /* If we got a mapping, but at a wrong address, undo it.  */
+      if (res != MAP_FAILED)
+	munmap (res, size);
+    }
+
+  return NULL;
+#else
+  void *res = mmap (NULL, size, PROT_READ | PROT_WRITE | PROT_EXEC,
+		    MAP_PRIVATE | MAP_ANONYMOUS | MAP_32BIT, -1, 0);
+
+  if (res == MAP_FAILED)
+    return NULL;
+
+  return res;
+#endif
+}
+
+void
+initialize_low_tracepoint (void)
+{
+#if defined __ILP32__
+  amd64_linux_read_description (X86_XSTATE_SSE_MASK, true);
+  amd64_linux_read_description (X86_XSTATE_AVX_MASK, true);
+  amd64_linux_read_description (X86_XSTATE_AVX_AVX512_MASK, true);
+#else
+  for (auto i = 0; i < X86_TDESC_LAST; i++)
+    amd64_linux_read_description (idx2mask[i], false);
+#endif
+}