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Re: [PATCH 5/5] AArch64 gdbserver port


On 03/01/13 20:39, Tom Tromey wrote:

Thanks for the comments Tom. Revised patch attached.

I'm not a good person to review the main part of the patch.
I did have a couple things though.

Marcus>         * linux-low.c: For various 'ptrace' calls, cast '0's as the 3rd
Marcus>         and 4th arguments to PTRACE_ARG3_TYPE and PTRACE_ARG4_TYPE
Marcus> respectively.

Why is this needed? It seems like it shouldn't be.

The prototype for ptrace() looks like this:


extern long int ptrace (enum __ptrace_request __request, ...) __THROW;

Arguments 3 and 4 are both pointers but are anonymous arguments. The compiler will not promote such anonymous arguments therefore the type of these arguments at each call site must be explicit.

In the following patch fragment:

- ptrace (PTRACE_GETEVENTMSG, lwpid_of (event_child), 0, &new_pid);
+ ptrace (PTRACE_GETEVENTMSG, lwpid_of (event_child), (PTRACE_ARG3_TYPE) 0,
+ &new_pid);


.. the absence of an explicit cast on argument 3 will result in the argument being passed as an integer but received as a pointer.

Cheers
/Marcus

2013-01-07  Jim MacArthur  <jim.macarthur@arm.com>
            Marcus Shawcroft  <marcus.shawcroft@arm.com>
            Nigel Stephens  <nigel.stephens@arm.com>
            Yufeng Zhang  <yufeng.zhang@arm.com>

* Makefile.in: Add AArch64.
* configure.srv: Add AArch64.
* linux-aarch64-low.c: New file.
* linux-low.c: For various 'ptrace' calls, cast '0's as the 3rd
and 4th arguments to PTRACE_ARG3_TYPE and PTRACE_ARG4_TYPE respectively.
diff --git a/gdb/gdbserver/Makefile.in b/gdb/gdbserver/Makefile.in
index f8b1794..dffe8ae 100644
--- a/gdb/gdbserver/Makefile.in
+++ b/gdb/gdbserver/Makefile.in
@@ -316,6 +316,7 @@ clean:
 	rm -f version.c
 	rm -f gdbserver$(EXEEXT) gdbreplay$(EXEEXT) core make.log
 	rm -f $(IPA_LIB)
+	rm -f aarch64.c aarch64-without-fpu.c
 	rm -f reg-arm.c reg-bfin.c i386.c reg-ia64.c reg-m32r.c reg-m68k.c
 	rm -f reg-sh.c reg-sparc.c reg-spu.c amd64.c i386-linux.c
 	rm -f reg-cris.c reg-crisv32.c amd64-linux.c reg-xtensa.c
@@ -561,6 +562,10 @@ linux-low.o: linux-low.c
 
 win32_low_h = $(srcdir)/win32-low.h
 
+aarch64.c : $(srcdir)/../regformats/aarch64.dat $(regdat_sh)
+	$(SHELL) $(regdat_sh) $(srcdir)/../regformats/aarch64.dat aarch64.c
+aarch64-without-fpu.c : $(srcdir)/../regformats/aarch64-without-fpu.dat $(regdat_sh)
+	$(SHELL) $(regdat_sh) $(srcdir)/../regformats/aarch64-without-fpu.dat aarch64-without-fpu.c
 reg-arm.c : $(srcdir)/../regformats/reg-arm.dat $(regdat_sh)
 	$(SHELL) $(regdat_sh) $(srcdir)/../regformats/reg-arm.dat reg-arm.c
 arm-with-iwmmxt.c : $(srcdir)/../regformats/arm-with-iwmmxt.dat $(regdat_sh)
diff --git a/gdb/gdbserver/configure.srv b/gdb/gdbserver/configure.srv
index d1e04a9..54c4a02 100644
--- a/gdb/gdbserver/configure.srv
+++ b/gdb/gdbserver/configure.srv
@@ -42,6 +42,21 @@ srv_amd64_linux_xmlfiles="i386/amd64-linux.xml i386/amd64-avx-linux.xml i386/64b
 # Input is taken from the "${target}" variable.
 
 case "${target}" in
+  aarch64*-*-linux*)
+			srv_regobj="aarch64.o aarch64-without-fpu.o"
+			srv_tgtobj="linux-aarch64-low.o"
+			srv_tgtobj="${srv_tgtobj} linux-low.o"
+			srv_tgtobj="${srv_tgtobj} linux-osdata.o"
+			srv_tgtobj="${srv_tgtobj} linux-procfs.o"
+			srv_tgtobj="${srv_tgtobj} linux-ptrace.o"
+			srv_xmlfiles="aarch64.xml"
+			srv_xmlfiles="${srv_xmlfiles} aarch64-core.xml"
+			srv_xmlfiles="${srv_xmlfiles} aarch64-fpu.xml"
+			srv_xmlfiles="${srv_xmlfiles} aarch64-without-fpu.xml"
+			srv_linux_usrregs=yes
+			srv_linux_regsets=yes
+			srv_linux_thread_db=yes
+			;;
   arm*-*-linux*)	srv_regobj="reg-arm.o arm-with-iwmmxt.o"
 			srv_regobj="${srv_regobj} arm-with-vfpv2.o"
 			srv_regobj="${srv_regobj} arm-with-vfpv3.o"
diff --git a/gdb/gdbserver/linux-aarch64-low.c b/gdb/gdbserver/linux-aarch64-low.c
new file mode 100644
index 0000000..08842db
--- /dev/null
+++ b/gdb/gdbserver/linux-aarch64-low.c
@@ -0,0 +1,1260 @@
+/* GNU/Linux/AArch64 specific low level interface, for the remote server for
+   GDB.
+
+   Copyright (C) 2009-2012 Free Software Foundation, Inc.
+   Contributed by ARM Ltd.
+
+   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 "linux-low.h"
+#include "elf/common.h"
+
+#include <signal.h>
+#include <sys/user.h>
+#include <sys/ptrace.h>
+#include <sys/uio.h>
+
+#include "gdb_proc_service.h"
+
+/* Defined in auto-generated files.  */
+void init_registers_aarch64 (void);
+
+/* Defined in auto-generated files.  */
+void init_registers_aarch64_without_fpu (void);
+
+#ifdef HAVE_SYS_REG_H
+#include <sys/reg.h>
+#endif
+
+#define AARCH64_X_REGS_NUM 31
+#define AARCH64_V_REGS_NUM 32
+#define AARCH64_X0_REGNO    0
+#define AARCH64_SP_REGNO   31
+#define AARCH64_PC_REGNO   32
+#define AARCH64_CPSR_REGNO 33
+#define AARCH64_V0_REGNO   34
+
+#define AARCH64_NUM_REGS (AARCH64_V0_REGNO + AARCH64_V_REGS_NUM)
+
+#define TRAP_HWBKPT 0x0004
+
+static int
+aarch64_regmap [] =
+{
+  /* These offsets correspond to GET/SETREGSET */
+  /* x0...  */
+   0*8,  1*8,  2*8,  3*8,  4*8,  5*8,  6*8,  7*8,
+   8*8,  9*8, 10*8, 11*8, 12*8, 13*8, 14*8, 15*8,
+  16*8, 17*8, 18*8, 19*8, 20*8, 21*8, 22*8, 23*8,
+  24*8, 25*8, 26*8, 27*8, 28*8,
+  29*8,
+  30*8,				/* x30 lr */
+  31*8,				/* x31 sp */
+  32*8,				/*     pc */
+  33*8,				/*     cpsr    4 bytes!*/
+
+  /* FP register offsets correspond to GET/SETFPREGSET */
+   0*16,  1*16,  2*16,  3*16,  4*16,  5*16,  6*16,  7*16,
+   8*16,  9*16, 10*16, 11*16, 12*16, 13*16, 14*16, 15*16,
+  16*16, 17*16, 18*16, 19*16, 20*16, 21*16, 22*16, 23*16,
+  24*16, 25*16, 26*16, 27*16, 28*16, 29*16, 30*16, 31*16
+};
+
+/* Here starts the macro definitions, data structures, and code for
+   the hardware breakpoint and hardware watchpoint support.  The
+   following is the abbreviations that are used frequently in the code
+   and comment:
+
+   hw - hardware
+   bp - breakpoint
+   wp - watchpoint  */
+
+/* Maximum number of hardware breakpoints/watchpoints.
+   N.B.  when change, especially increase, the numbers, also make sure
+   the type dr_changed_t still be wide enough, i.e. the number of its
+   bits is equal to or larger than the maximum value of the two
+   macros.  */
+
+#define AARCH64_HBP_MAX_NUM 16
+#define AARCH64_HWP_MAX_NUM 16
+
+/* Alignment requirement in bytes of hardware breakpoint and
+   watchpoint address.  This is the requirement for the addresses that
+   can be written to the hardware breakpoint/watchpoint value
+   registers.  The kernel currently does not do any alignment on
+   addresses when receiving a writing request (via ptrace call) to
+   these debug registers, and it will reject any address that is
+   unaligned.
+   Some limited support has been provided in this gdbserver port for
+   unaligned watchpoints, so that from a gdb user point of view, an
+   unaligned watchpoint can still be set.  This is achieved by
+   minimally enlarging the watched area to meet the alignment
+   requirement, and if necessary, splitting the watchpoint over
+   several hardware watchpoint registers.  */
+
+#define AARCH64_HBP_ALIGNMENT 4
+#define AARCH64_HWP_ALIGNMENT 8
+
+/* The maximum length of a memory region that can be watched by one
+   hardware watchpoint register.  */
+
+#define AARCH64_HWP_MAX_LEN_PER_REG 8
+
+/* Each bit of a variable of this type is used to indicate whether a
+   hardware breakpoint or watchpoint setting has been changed since
+   the last updating.  Bit N corresponds to the Nth hardware
+   breakpoint or watchpoint setting which is managed in
+   aarch64_debug_reg_state.  Where N is valid between 0 and the total
+   number of the hardware breakpoint or watchpoint debug registers
+   minus 1.  When the bit N is 1, it indicates the corresponding
+   breakpoint or watchpoint setting is changed, and thus the
+   corresponding hardware debug register needs to be updated via the
+   ptrace interface.
+
+   In the per-thread arch-specific data area, we define two such
+   variables for per-thread hardware breakpoint and watchpoint
+   settings respectively.
+
+   This type is part of the mechanism which helps reduce the number of
+   ptrace calls to the kernel, i.e. avoid asking the kernel to write
+   to the debug registers with unchanged values.  */
+
+typedef unsigned long long dr_changed_t;
+
+/* Set each of the lower M bits of X to 1; assert X is wide enough.  */
+
+#define DR_MARK_ALL_CHANGED(x, m)					\
+  do									\
+    {									\
+      gdb_assert (sizeof ((x)) * 8 >= (m));				\
+      (x) = (((dr_changed_t)1 << (m)) - 1);				\
+    } while (0)
+
+#define DR_MARK_N_CHANGED(x, n)						\
+  do									\
+    {									\
+      (x) |= ((dr_changed_t)1 << (n));					\
+    } while (0)
+
+#define DR_CLEAR_CHANGED(x)						\
+  do									\
+    {									\
+      (x) = 0;								\
+    } while (0)
+
+#define DR_HAS_CHANGED(x) ((x) != 0)
+#define DR_N_HAS_CHANGED(x, n) ((x) & ((dr_changed_t)1 << (n)))
+
+/* Structure for managing the hardware breakpoint/watchpoint resources.
+   DR_ADDR_* stores the address, DR_CTRL_* stores the control register
+   content, and DR_REF_COUNT_* counts the numbers of references to the
+   corresponding bp/wp, by which way the limited hardware resources
+   are not wasted on duplicated bp/wp settings (though so far gdb has
+   done a good job by not sending duplicated bp/wp requests).  */
+
+struct aarch64_debug_reg_state
+{
+  /* hardware breakpoint */
+  CORE_ADDR dr_addr_bp[AARCH64_HBP_MAX_NUM];
+  unsigned int dr_ctrl_bp[AARCH64_HBP_MAX_NUM];
+  unsigned int dr_ref_count_bp[AARCH64_HBP_MAX_NUM];
+
+  /* hardware watchpoint */
+  CORE_ADDR dr_addr_wp[AARCH64_HWP_MAX_NUM];
+  unsigned int dr_ctrl_wp[AARCH64_HWP_MAX_NUM];
+  unsigned int dr_ref_count_wp[AARCH64_HWP_MAX_NUM];
+};
+
+/* Per-process arch-specific data we want to keep.  */
+
+struct arch_process_info
+{
+  /* Hardware breakpoint/watchpoint data.
+     The reason for them to be per-process rather than per-thread is
+     due to the lack of information in the gdbserver environment;
+     gdbserver is not told that whether a requested hardware
+     breakpoint/watchpoint is thread specific or not, so it has to set
+     each hw bp/wp for every thread in the current process.  The
+     higher level bp/wp management in gdb will resume a thread if a hw
+     bp/wp trap is not expected for it.  Since the hw bp/wp setting is
+     same for each thread, it is reasonable for the data to live here.
+     */
+  struct aarch64_debug_reg_state debug_reg_state;
+};
+
+/* Per-thread arch-specific data we want to keep.  */
+
+struct arch_lwp_info
+{
+  /* When bit N is 1, it indicates the Nth hardware breakpoint or
+     watchpoint register pair needs to be updated when the thread is
+     resumed; see aarch64_linux_prepare_to_resume.  */
+  dr_changed_t dr_changed_bp;
+  dr_changed_t dr_changed_wp;
+};
+
+/* Number of hardware breakpoints/watchpoints the target supports.
+   They are initialized with values obtained via the ptrace calls
+   with NT_ARM_HW_BREAK and NT_ARM_HW_WATCH respectively.  */
+
+static int aarch64_num_bp_regs;
+static int aarch64_num_wp_regs;
+
+/* Hardware breakpoint/watchpoint types.
+   The values map to their encodings in the bit 4 and bit 3 of the
+   hardware breakpoint/watchpoint control registers.  */
+
+enum target_point_type
+{
+  hw_execute = 0,		/* Execute HW breakpoint */
+  hw_read = 1,			/* Read    HW watchpoint */
+  hw_write = 2,			/* Common  HW watchpoint */
+  hw_access = 3,		/* Access  HW watchpoint */
+  point_type_unsupported
+};
+
+#define Z_PACKET_SW_BP '0'
+#define Z_PACKET_HW_BP '1'
+#define Z_PACKET_WRITE_WP '2'
+#define Z_PACKET_READ_WP '3'
+#define Z_PACKET_ACCESS_WP '4'
+
+/* Map the protocol breakpoint/watchpoint type TYPE to
+   enum target_point_type.  */
+
+static enum target_point_type
+Z_packet_to_point_type (char type)
+{
+  switch (type)
+    {
+    case Z_PACKET_SW_BP:
+      /* Leave the handling of the sw breakpoint with the gdb client.  */
+      return point_type_unsupported;
+    case Z_PACKET_HW_BP:
+      return hw_execute;
+    case Z_PACKET_WRITE_WP:
+      return hw_write;
+    case Z_PACKET_READ_WP:
+      return hw_read;
+    case Z_PACKET_ACCESS_WP:
+      return hw_access;
+    default:
+      return point_type_unsupported;
+    }
+}
+
+static int
+aarch64_cannot_store_register (int regno)
+{
+  return regno >= AARCH64_NUM_REGS;
+}
+
+static int
+aarch64_cannot_fetch_register (int regno)
+{
+  return regno >= AARCH64_NUM_REGS;
+}
+
+static void
+aarch64_fill_gregset (struct regcache *regcache, void *buf)
+{
+  struct user_pt_regs *regset = buf;
+  int i;
+
+  for (i = 0; i < AARCH64_X_REGS_NUM; i++)
+    collect_register (regcache, AARCH64_X0_REGNO + i, &regset->regs[i]);
+  collect_register (regcache, AARCH64_SP_REGNO, &regset->sp);
+  collect_register (regcache, AARCH64_PC_REGNO, &regset->pc);
+  collect_register (regcache, AARCH64_CPSR_REGNO, &regset->pstate);
+}
+
+static void
+aarch64_store_gregset (struct regcache *regcache, const void *buf)
+{
+  const struct user_pt_regs *regset = buf;
+  int i;
+
+  for (i = 0; i < AARCH64_X_REGS_NUM; i++)
+    supply_register (regcache, AARCH64_X0_REGNO + i, &regset->regs[i]);
+  supply_register (regcache, AARCH64_SP_REGNO, &regset->sp);
+  supply_register (regcache, AARCH64_PC_REGNO, &regset->pc);
+  supply_register (regcache, AARCH64_CPSR_REGNO, &regset->pstate);
+}
+
+static void
+aarch64_fill_fpregset (struct regcache *regcache, void *buf)
+{
+  struct user_fpsimd_state *regset = buf;
+  int i;
+
+  for (i = 0; i < AARCH64_V_REGS_NUM; i++)
+    collect_register (regcache, AARCH64_V0_REGNO + i, &regset->vregs[i]);
+}
+
+static void
+aarch64_store_fpregset (struct regcache *regcache, const void *buf)
+{
+  const struct user_fpsimd_state *regset = buf;
+  int i;
+
+  for (i = 0; i < AARCH64_V_REGS_NUM; i++)
+    supply_register (regcache, AARCH64_V0_REGNO + i, &regset->vregs[i]);
+}
+
+/* Debugging of hardware breakpoint/watchpoint support.  */
+extern int debug_hw_points;
+
+/* Enable miscellaneous debugging output.  The name is historical - it
+   was originally used to debug LinuxThreads support.  */
+extern int debug_threads;
+
+static CORE_ADDR
+aarch64_get_pc (struct regcache *regcache)
+{
+  unsigned long pc;
+  collect_register_by_name (regcache, "pc", &pc);
+  if (debug_threads)
+    fprintf (stderr, "stop pc is %08lx\n", pc);
+  return pc;
+}
+
+static void
+aarch64_set_pc (struct regcache *regcache, CORE_ADDR pc)
+{
+  unsigned long newpc = pc;
+  supply_register_by_name (regcache, "pc", &newpc);
+}
+
+/* Correct in either endianness.  */
+
+#define aarch64_breakpoint_len 4
+
+static const unsigned long aarch64_breakpoint = 0x00800011;
+
+static int
+aarch64_breakpoint_at (CORE_ADDR where)
+{
+  unsigned long insn;
+
+  (*the_target->read_memory) (where, (unsigned char *) &insn, 4);
+  if (insn == aarch64_breakpoint)
+    return 1;
+
+  return 0;
+}
+
+/* Print the values of the cached breakpoint/watchpoint registers.
+   This is enabled via the "set debug-hw-points" monitor command.  */
+
+static void
+aarch64_show_debug_reg_state (struct aarch64_debug_reg_state *state,
+			      const char *func, CORE_ADDR addr,
+			      int len, enum target_point_type type)
+{
+  int i;
+
+  fprintf (stderr, "%s", func);
+  if (addr || len)
+    fprintf (stderr, " (addr=0x%08lx, len=%d, type=%s)",
+	     (unsigned long) addr, len,
+	     type == hw_write ? "hw-write-watchpoint"
+	     : (type == hw_read ? "hw-read-watchpoint"
+		: (type == hw_access ? "hw-access-watchpoint"
+		   : (type == hw_execute ? "hw-breakpoint"
+		      : "??unknown??"))));
+  fprintf (stderr, ":\n");
+
+  fprintf (stderr, "\tBREAKPOINTs:\n");
+  for (i = 0; i < aarch64_num_bp_regs; i++)
+    fprintf (stderr, "\tBP%d: addr=0x%s, ctrl=0x%08x, ref.count=%d\n",
+	     i, paddress (state->dr_addr_bp[i]),
+	     state->dr_ctrl_bp[i], state->dr_ref_count_bp[i]);
+
+  fprintf (stderr, "\tWATCHPOINTs:\n");
+  for (i = 0; i < aarch64_num_wp_regs; i++)
+    fprintf (stderr, "\tWP%d: addr=0x%s, ctrl=0x%08x, ref.count=%d\n",
+	     i, paddress (state->dr_addr_wp[i]),
+	     state->dr_ctrl_wp[i], state->dr_ref_count_wp[i]);
+}
+
+static void
+aarch64_init_debug_reg_state (struct aarch64_debug_reg_state *state)
+{
+  int i;
+
+  for (i = 0; i < AARCH64_HBP_MAX_NUM; ++i)
+    {
+      state->dr_addr_bp[i] = 0;
+      state->dr_ctrl_bp[i] = 0;
+      state->dr_ref_count_bp[i] = 0;
+    }
+
+  for (i = 0; i < AARCH64_HWP_MAX_NUM; ++i)
+    {
+      state->dr_addr_wp[i] = 0;
+      state->dr_ctrl_wp[i] = 0;
+      state->dr_ref_count_wp[i] = 0;
+    }
+}
+
+/* ptrace expects control registers to be formatted as follows:
+
+   31                             13          5      3      1     0
+   +--------------------------------+----------+------+------+----+
+   |         RESERVED (SBZ)         |  LENGTH  | TYPE | PRIV | EN |
+   +--------------------------------+----------+------+------+----+
+
+   The TYPE field is ignored for breakpoints.  */
+
+#define DR_CONTROL_ENABLED(ctrl)	(((ctrl) & 0x1) == 1)
+#define DR_CONTROL_LENGTH(ctrl)		(((ctrl) >> 5) & 0xff)
+
+/* Utility function that returns the length in bytes of a watchpoint
+   according to the content of a hardware debug control register CTRL.
+   Note that the kernel currently only supports the following Byte
+   Address Select (BAS) values: 0x1, 0x3, 0xf and 0xff, which means
+   that for a hardware watchpoint, its valid length can only be 1
+   byte, 2 bytes, 4 bytes or 8 bytes.  */
+
+static inline unsigned int
+aarch64_watchpoint_length (unsigned int ctrl)
+{
+  switch (DR_CONTROL_LENGTH (ctrl))
+    {
+    case 0x01: return 1; break;
+    case 0x03: return 2; break;
+    case 0x0f: return 4; break;
+    case 0xff: return 8; break;
+    default: return 0;
+    }
+}
+
+/* Given the hardware breakpoint or watchpoint type TYPE and its
+   length LEN, return the expected encoding for a hardware
+   breakpoint/watchpoint control register.  */
+
+static unsigned int
+aarch64_point_encode_ctrl_reg (enum target_point_type type, int len)
+{
+  unsigned int ctrl;
+
+  /* type */
+  ctrl = type << 3;
+  /* length bitmask */
+  ctrl |= ((1 << len) - 1) << 5;
+  /* enabled at el0 */
+  ctrl |= (2 << 1) | 1;
+
+  return ctrl;
+}
+
+/* Addresses to be written to the hardware breakpoint and watchpoint
+   value registers need to be aligned; the alignment is 4-byte and
+   8-type respectively.  Linux kernel rejects any non-aligned address
+   it receives from the related ptrace call.  Furthermore, the kernel
+   currently only supports the following Byte Address Select (BAS)
+   values: 0x1, 0x3, 0xf and 0xff, which means that for a hardware
+   watchpoint to be accepted by the kernel (via ptrace call), its
+   valid length can only be 1 byte, 2 bytes, 4 bytes or 8 bytes.
+   Despite these limitations, the unaligned watchpoint is supported in
+   this gdbserver port.
+
+   Return 0 for any non-compliant ADDR and/or LEN; return 1 otherwise.  */
+
+static int
+aarch64_point_is_aligned (int is_watchpoint, CORE_ADDR addr, int len)
+{
+  unsigned int alignment = is_watchpoint ? AARCH64_HWP_ALIGNMENT
+    : AARCH64_HBP_ALIGNMENT;
+
+  if (addr & (alignment - 1))
+    return 0;
+
+  if (len != 8 && len != 4 && len != 2 && len != 1)
+    return 0;
+
+  return 1;
+}
+
+/* Given the (potentially unaligned) watchpoint address in ADDR and
+   length in LEN, return the aligned address and aligned length in
+   *ALIGNED_ADDR_P and *ALIGNED_LEN_P, respectively.  The returned
+   aligned address and length will be valid to be written to the
+   hardware watchpoint value and control registers.  See the comment
+   above aarch64_point_is_aligned for the information about the
+   alignment requirement.  The given watchpoint may get truncated if
+   more than one hardware register is needed to cover the watched
+   region.  *NEXT_ADDR_P and *NEXT_LEN_P, if non-NULL, will return the
+   address and length of the remaining part of the watchpoint (which
+   can be processed by calling this routine again to generate another
+   aligned address and length pair.
+
+   Essentially, unaligned watchpoint is achieved by minimally
+   enlarging the watched area to meet the alignment requirement, and
+   if necessary, splitting the watchpoint over several hardware
+   watchpoint registers.  The trade-off is that there will be
+   false-positive hits for the read-type or the access-type hardware
+   watchpoints; for the write type, which is more commonly used, there
+   will be no such issues, as the higher-level breakpoint management
+   in gdb always examines the exact watched region for any content
+   change, and transparently resumes a thread from a watchpoint trap
+   if there is no change to the watched region.
+
+   Another limitation is that because the watched region is enlarged,
+   the watchpoint fault address returned by
+   aarch64_stopped_data_address may be outside of the original watched
+   region, especially when the triggering instruction is accessing a
+   larger region.  When the fault address is not within any known
+   range, watchpoints_triggered in gdb will get confused, as the
+   higher-level watchpoint management is only aware of original
+   watched regions, and will think that some unknown watchpoint has
+   been triggered.  In such a case, gdb may stop without displaying
+   any detailed information.
+
+   Once the kernel provides the full support for Byte Address Select
+   (BAS) in the hardware watchpoint control register, these
+   limitations can be largely relaxed with some further work.  */
+
+static void
+aarch64_align_watchpoint (CORE_ADDR addr, int len, CORE_ADDR * aligned_addr_p,
+			  int *aligned_len_p, CORE_ADDR * next_addr_p,
+			  int *next_len_p)
+{
+  int aligned_len;
+  unsigned int offset;
+  CORE_ADDR aligned_addr;
+  const unsigned int alignment = AARCH64_HWP_ALIGNMENT;
+  const unsigned int max_wp_len = AARCH64_HWP_MAX_LEN_PER_REG;
+
+  /* As assumed by the algorithm.  */
+  gdb_assert (alignment == max_wp_len);
+
+  if (len <= 0)
+    return;
+
+  /* Address to be put into the hardware watchpoint value register
+     must be aligned.  */
+  offset = addr & (alignment - 1);
+  aligned_addr = addr - offset;
+
+  gdb_assert (offset >= 0 && offset < alignment);
+  gdb_assert (aligned_addr >= 0 && aligned_addr <= addr);
+  gdb_assert ((offset + len) > 0);
+
+  if (offset + len >= max_wp_len)
+    {
+      /* Need more than one watchpoint registers; truncate it at the
+	 alignment boundary.  */
+      aligned_len = max_wp_len;
+      len -= (max_wp_len - offset);
+      addr += (max_wp_len - offset);
+      gdb_assert ((addr & (alignment - 1)) == 0);
+    }
+  else
+    {
+      /* Find the smallest valid length that is large enough to
+	 accommodate this watchpoint.  */
+      static const unsigned char
+	aligned_len_array[AARCH64_HWP_MAX_LEN_PER_REG] =
+	{ 1, 2, 4, 4, 8, 8, 8, 8 };
+
+      aligned_len = aligned_len_array[offset + len - 1];
+      addr += len;
+      len = 0;
+    }
+
+  if (aligned_addr_p)
+    *aligned_addr_p = aligned_addr;
+  if (aligned_len_p)
+    *aligned_len_p = aligned_len;
+  if (next_addr_p)
+    *next_addr_p = addr;
+  if (next_len_p)
+    *next_len_p = len;
+}
+
+/* Call ptrace to set the thread TID's hardware breakpoint/watchpoint
+   registers with data from *STATE.  */
+
+static void
+aarch64_linux_set_debug_regs (const struct aarch64_debug_reg_state *state,
+			      int tid, int watchpoint)
+{
+  int i, count;
+  struct iovec iov;
+  struct user_hwdebug_state regs;
+  const CORE_ADDR *addr;
+  const unsigned int *ctrl;
+
+  iov.iov_base = &regs;
+  iov.iov_len = sizeof (regs);
+  count = watchpoint ? aarch64_num_wp_regs : aarch64_num_bp_regs;
+  addr = watchpoint ? state->dr_addr_wp : state->dr_addr_bp;
+  ctrl = watchpoint ? state->dr_ctrl_wp : state->dr_ctrl_bp;
+
+  for (i = 0; i < count; i++)
+    {
+      regs.dbg_regs[i].addr = addr[i];
+      regs.dbg_regs[i].ctrl = ctrl[i];
+    }
+
+  if (ptrace (PTRACE_SETREGSET, tid,
+	      watchpoint ? NT_ARM_HW_WATCH : NT_ARM_HW_BREAK,
+	      (void *)&iov))
+    error (_("Unexpected error setting hardware debug registers"));
+}
+
+struct aarch64_dr_update_callback_param
+{
+  int pid;
+  int is_watchpoint;
+  unsigned int idx;
+};
+
+/* Callback function which records the information about the change of
+   one hardware breakpoint/watchpoint setting for the thread ENTRY.
+   The information is passed in via PTR.
+   N.B.  The actual updating of hardware debug registers is not
+   carried out until the moment the thread is resumed.  */
+
+static int
+debug_reg_change_callback (struct inferior_list_entry *entry, void *ptr)
+{
+  struct lwp_info *lwp = (struct lwp_info *) entry;
+  struct aarch64_dr_update_callback_param *param_p
+    = (struct aarch64_dr_update_callback_param *) ptr;
+  int pid = param_p->pid;
+  int idx = param_p->idx;
+  int is_watchpoint = param_p->is_watchpoint;
+  struct arch_lwp_info *info = lwp->arch_private;
+  dr_changed_t *dr_changed_ptr;
+  dr_changed_t dr_changed;
+
+  if (debug_hw_points)
+    {
+      fprintf (stderr, "debug_reg_change_callback: \n\tOn entry:\n");
+      fprintf (stderr, "\tpid%d, tid: %ld, dr_changed_bp=0x%llx, "
+	       "dr_changed_wp=0x%llx\n",
+	       pid, lwpid_of (lwp), info->dr_changed_bp,
+	       info->dr_changed_wp);
+    }
+
+  dr_changed_ptr = is_watchpoint ? &info->dr_changed_wp
+    : &info->dr_changed_bp;
+  dr_changed = *dr_changed_ptr;
+
+  /* Only update the threads of this process.  */
+  if (pid_of (lwp) == pid)
+    {
+      gdb_assert (idx >= 0
+		  && (idx <= (is_watchpoint ? aarch64_num_wp_regs
+			      : aarch64_num_bp_regs)));
+
+      /* The following assertion is not right, as there can be changes
+	 that have not been made to the hardware debug registers
+	 before new changes overwrite the old ones.  This can happen,
+	 for instance, when the breakpoint/watchpoint hit one of the
+	 threads and the user enters continue; then what happens is:
+	 1) all breakpoints/watchpoints are removed for all threads;
+	 2) a single step is carried out for the thread that was hit;
+	 3) all of the points are inserted again for all threads;
+	 4) all threads are resumed.
+	 The 2nd step will only affect the one thread in which the
+	 bp/wp was hit, which means only that one thread is resumed;
+	 remember that the actual updating only happen in
+	 aarch64_linux_prepare_to_resume, so other threads remain
+	 stopped during the removal and insertion of bp/wp.  Therefore
+	 for those threads, the change of insertion of the bp/wp
+	 overwrites that of the earlier removals.  (The situation may
+	 be different when bp/wp is steppable, or in the non-stop
+	 mode.)  */
+      /* gdb_assert (DR_N_HAS_CHANGED (dr_changed, idx) == 0);  */
+
+      /* The actual update is done later just before resuming the lwp,
+         we just mark that one register pair needs updating.  */
+      DR_MARK_N_CHANGED (dr_changed, idx);
+      *dr_changed_ptr = dr_changed;
+
+      /* If the lwp isn't stopped, force it to momentarily pause, so
+         we can update its debug registers.  */
+      if (!lwp->stopped)
+	linux_stop_lwp (lwp);
+    }
+
+  if (debug_hw_points)
+    {
+      fprintf (stderr, "\tOn exit:\n\tpid%d, tid: %ld, dr_changed_bp=0x%llx, "
+	       "dr_changed_wp=0x%llx\n",
+	       pid, lwpid_of (lwp), info->dr_changed_bp, info->dr_changed_wp);
+    }
+
+  return 0;
+}
+
+/* Notify each thread that their IDXth breakpoint/watchpoint register
+   pair needs to be updated.  The message will be recorded in each
+   thread's arch-specific data area, the actual updating will be done
+   when the thread is resumed.  */
+
+void
+aarch64_notify_debug_reg_change (const struct aarch64_debug_reg_state *state,
+				 int is_watchpoint, unsigned int idx)
+{
+  struct aarch64_dr_update_callback_param param;
+
+  /* Only update the threads of this process.  */
+  param.pid = pid_of (get_thread_lwp (current_inferior));
+
+  param.is_watchpoint = is_watchpoint;
+  param.idx = idx;
+
+  find_inferior (&all_lwps, debug_reg_change_callback, (void *) &param);
+}
+
+
+/* Return the pointer to the debug register state structure in the
+   current process' arch-specific data area.  */
+
+static struct aarch64_debug_reg_state *
+aarch64_get_debug_reg_state ()
+{
+  int pid;
+  struct lwp_info *thread;
+  struct process_info *proc;
+
+  thread = get_thread_lwp (current_inferior);
+  pid = pid_of (thread);
+  proc = find_process_pid (pid);
+
+  return &proc->private->arch_private->debug_reg_state;
+}
+
+/* Record the insertion of one breakpoint/watchpoint, as represented
+   by ADDR and CTRL, in the process' arch-specific data area *STATE.  */
+
+static int
+aarch64_dr_state_insert_one_point (struct aarch64_debug_reg_state *state,
+				   enum target_point_type type,
+				   CORE_ADDR addr, int len)
+{
+  int i, idx, num_regs, is_watchpoint;
+  unsigned int ctrl, *dr_ctrl_p, *dr_ref_count;
+  CORE_ADDR *dr_addr_p;
+
+  /* Set up state pointers.  */
+  is_watchpoint = (type != hw_execute);
+  gdb_assert (aarch64_point_is_aligned (is_watchpoint, addr, len));
+  if (is_watchpoint)
+    {
+      num_regs = aarch64_num_wp_regs;
+      dr_addr_p = state->dr_addr_wp;
+      dr_ctrl_p = state->dr_ctrl_wp;
+      dr_ref_count = state->dr_ref_count_wp;
+    }
+  else
+    {
+      num_regs = aarch64_num_bp_regs;
+      dr_addr_p = state->dr_addr_bp;
+      dr_ctrl_p = state->dr_ctrl_bp;
+      dr_ref_count = state->dr_ref_count_bp;
+    }
+
+  ctrl = aarch64_point_encode_ctrl_reg (type, len);
+
+  /* Find an existing or free register in our cache.  */
+  idx = -1;
+  for (i = 0; i < num_regs; ++i)
+    {
+      if ((dr_ctrl_p[i] & 1) == 0)
+	{
+	  gdb_assert (dr_ref_count[i] == 0);
+	  idx = i;
+	  /* no break; continue hunting for an exising one.  */
+	}
+      else if (dr_addr_p[i] == addr && dr_ctrl_p[i] == ctrl)
+	{
+	  gdb_assert (dr_ref_count[i] != 0);
+	  idx = i;
+	  break;
+	}
+    }
+
+  /* No space.  */
+  if (idx == -1)
+    return -1;
+
+  /* Update our cache.  */
+  if ((dr_ctrl_p[idx] & 1) == 0)
+    {
+      /* new entry */
+      dr_addr_p[idx] = addr;
+      dr_ctrl_p[idx] = ctrl;
+      dr_ref_count[idx] = 1;
+      /* Notify the change.  */
+      aarch64_notify_debug_reg_change (state, is_watchpoint, idx);
+    }
+  else
+    {
+      /* existing entry */
+      dr_ref_count[idx]++;
+    }
+
+  return 0;
+}
+
+/* Record the removal of one breakpoint/watchpoint, as represented by
+   ADDR and CTRL, in the process' arch-specific data area *STATE.  */
+
+static int
+aarch64_dr_state_remove_one_point (struct aarch64_debug_reg_state *state,
+				   enum target_point_type type,
+				   CORE_ADDR addr, int len)
+{
+  int i, num_regs, is_watchpoint;
+  unsigned int ctrl, *dr_ctrl_p, *dr_ref_count;
+  CORE_ADDR *dr_addr_p;
+
+  /* Set up state pointers.  */
+  is_watchpoint = (type != hw_execute);
+  gdb_assert (aarch64_point_is_aligned (is_watchpoint, addr, len));
+  if (is_watchpoint)
+    {
+      num_regs = aarch64_num_wp_regs;
+      dr_addr_p = state->dr_addr_wp;
+      dr_ctrl_p = state->dr_ctrl_wp;
+      dr_ref_count = state->dr_ref_count_wp;
+    }
+  else
+    {
+      num_regs = aarch64_num_bp_regs;
+      dr_addr_p = state->dr_addr_bp;
+      dr_ctrl_p = state->dr_ctrl_bp;
+      dr_ref_count = state->dr_ref_count_bp;
+    }
+
+  ctrl = aarch64_point_encode_ctrl_reg (type, len);
+
+  /* Find the entry that matches the ADDR and CTRL.  */
+  for (i = 0; i < num_regs; ++i)
+    if (dr_addr_p[i] == addr && dr_ctrl_p[i] == ctrl)
+      {
+	gdb_assert (dr_ref_count[i] != 0);
+	break;
+      }
+
+  /* Not found.  */
+  if (i == num_regs)
+    return -1;
+
+  /* Clear our cache.  */
+  if (--dr_ref_count[i] == 0)
+    {
+      /* Clear the enable bit.  */
+      ctrl &= ~1;
+      dr_addr_p[i] = 0;
+      dr_ctrl_p[i] = ctrl;
+      /* Notify the change.  */
+      aarch64_notify_debug_reg_change (state, is_watchpoint, i);
+    }
+
+  return 0;
+}
+
+static int
+aarch64_handle_breakpoint (enum target_point_type type, CORE_ADDR addr,
+			   int len, int is_insert)
+{
+  struct aarch64_debug_reg_state *state;
+
+  /* The hardware breakpoint on AArch64 should always be 4-byte
+     aligned.  */
+  if (!aarch64_point_is_aligned (0 /* is_watchpoint */ , addr, len))
+    {
+      gdb_assert (0);
+      return -1;
+    }
+
+  state = aarch64_get_debug_reg_state ();
+
+  if (is_insert)
+    return aarch64_dr_state_insert_one_point (state, type, addr, len);
+  else
+    return aarch64_dr_state_remove_one_point (state, type, addr, len);
+}
+
+/* This is essentially the same as aarch64_handle_breakpoint, apart
+   from that it is an aligned watchpoint to be handled.  */
+
+static int
+aarch64_handle_aligned_watchpoint (enum target_point_type type,
+				   CORE_ADDR addr, int len, int is_insert)
+{
+  struct aarch64_debug_reg_state *state;
+
+  state = aarch64_get_debug_reg_state ();
+
+  if (is_insert)
+    return aarch64_dr_state_insert_one_point (state, type, addr, len);
+  else
+    return aarch64_dr_state_remove_one_point (state, type, addr, len);
+}
+
+/* Insert/remove unaligned watchpoint by calling
+   aarch64_align_watchpoint repeatedly until the whole watched region,
+   as represented by ADDR and LEN, has been properly aligned and ready
+   to be written to one or more hardware watchpoint registers.
+   IS_INSERT indicates whether this is an insertion or a deletion.
+   Return 0 if succeed.  */
+
+static int
+aarch64_handle_unaligned_watchpoint (enum target_point_type type,
+				     CORE_ADDR addr, int len, int is_insert)
+{
+  struct aarch64_debug_reg_state *state
+    = aarch64_get_debug_reg_state ();
+
+  while (len > 0)
+    {
+      CORE_ADDR aligned_addr;
+      int aligned_len, ret;
+
+      aarch64_align_watchpoint (addr, len, &aligned_addr, &aligned_len,
+				&addr, &len);
+
+      if (is_insert)
+	ret = aarch64_dr_state_insert_one_point (state, type, aligned_addr,
+						 aligned_len);
+      else
+	ret = aarch64_dr_state_remove_one_point (state, type, aligned_addr,
+						 aligned_len);
+
+      if (debug_hw_points)
+	fprintf (stderr,
+ "handle_unaligned_watchpoint: is_insert: %d\n"
+ "                             aligned_addr: 0x%llx, aligned_len: %d\n"
+ "                                next_addr: 0x%llx,    next_len: %d\n",
+		 is_insert, aligned_addr, aligned_len, addr, len);
+
+      if (ret != 0)
+	return ret;
+    }
+
+  return 0;
+}
+
+static int
+aarch64_handle_watchpoint (enum target_point_type type, CORE_ADDR addr,
+			   int len, int is_insert)
+{
+  if (aarch64_point_is_aligned (1 /* is_watchpoint */ , addr, len))
+    return aarch64_handle_aligned_watchpoint (type, addr, len, is_insert);
+  else
+    return aarch64_handle_unaligned_watchpoint (type, addr, len, is_insert);
+}
+
+/* Insert a hardware breakpoint/watchpoint.
+   It actually only records the info of the to-be-inserted bp/wp;
+   the actual insertion will happen when threads are resumed.
+
+   Return 0 if succeed;
+   Return 1 if TYPE is unsupported type;
+   Return -1 if an error occurs.  */
+
+static int
+aarch64_insert_point (char type, CORE_ADDR addr, int len)
+{
+  int ret;
+  enum target_point_type targ_type;
+
+  if (debug_hw_points)
+    fprintf (stderr, "insert_point on entry (addr=0x%08lx, len=%d)\n",
+	     (unsigned long) addr, len);
+
+  /* Determine the type from the packet.  */
+  targ_type = Z_packet_to_point_type (type);
+  if (targ_type == point_type_unsupported)
+    return 1;
+
+  if (targ_type != hw_execute)
+    ret =
+      aarch64_handle_watchpoint (targ_type, addr, len, 1 /* is_insert */);
+  else
+    ret =
+      aarch64_handle_breakpoint (targ_type, addr, len, 1 /* is_insert */);
+
+  if (debug_hw_points > 1)
+    aarch64_show_debug_reg_state (aarch64_get_debug_reg_state (),
+				  "insert_point", addr, len, targ_type);
+
+  return ret;
+}
+
+/* Remove a hardware breakpoint/watchpoint.
+   It actually only records the info of the to-be-removed bp/wp,
+   the actual removal will be done when threads are resumed.
+
+   Return 0 if succeed;
+   Return 1 if TYPE is an unsupported type;
+   Return -1 if an error occurs.  */
+
+static int
+aarch64_remove_point (char type, CORE_ADDR addr, int len)
+{
+  int ret;
+  enum target_point_type targ_type;
+
+  if (debug_hw_points)
+    fprintf (stderr, "remove_point on entry (addr=0x%08lx, len=%d)\n",
+	     (unsigned long) addr, len);
+
+  /* Determine the type from the packet.  */
+  targ_type = Z_packet_to_point_type (type);
+  if (targ_type == point_type_unsupported)
+    return 1;
+
+  /* Set up state pointers.  */
+  if (targ_type != hw_execute)
+    ret =
+      aarch64_handle_watchpoint (targ_type, addr, len, 0 /* is_insert */);
+  else
+    ret =
+      aarch64_handle_breakpoint (targ_type, addr, len, 0 /* is_insert */);
+
+  if (debug_hw_points > 1)
+    aarch64_show_debug_reg_state (aarch64_get_debug_reg_state (),
+				  "remove_point", addr, len, targ_type);
+
+  return ret;
+}
+
+/* Returns the address associated with the watchpoint that hit, if
+   any; returns 0 otherwise.  */
+
+static CORE_ADDR
+aarch64_stopped_data_address (void)
+{
+  siginfo_t siginfo;
+  int pid, i;
+  struct aarch64_debug_reg_state *state;
+
+  pid = lwpid_of (get_thread_lwp (current_inferior));
+
+  /* Get the siginfo.  */
+  if (ptrace (PTRACE_GETSIGINFO, pid, NULL, &siginfo) != 0)
+    return (CORE_ADDR) 0;
+
+  /* Need to be a hardware breakpoint/watchpoint trap.  */
+  if (siginfo.si_signo != SIGTRAP
+      || (siginfo.si_code & 0xffff) != TRAP_HWBKPT)
+    return (CORE_ADDR) 0;
+
+  /* Check if the address matches any watched address.  */
+  state = aarch64_get_debug_reg_state ();
+  for (i = aarch64_num_wp_regs - 1; i >= 0; --i)
+    {
+      const unsigned int len = aarch64_watchpoint_length (state->dr_ctrl_wp[i]);
+      const CORE_ADDR addr_trap = (CORE_ADDR) siginfo.si_addr;
+      const CORE_ADDR addr_watch = state->dr_addr_wp[i];
+      if (state->dr_ref_count_wp[i]
+	  && DR_CONTROL_ENABLED (state->dr_ctrl_wp[i])
+	  && addr_trap >= addr_watch
+	  && addr_trap < addr_watch + len)
+	return addr_trap;
+    }
+
+  return (CORE_ADDR) 0;
+}
+
+/* Returns 1 if target was stopped due to a watchpoint hit, 0
+   otherwise.  */
+
+static int
+aarch64_stopped_by_watchpoint (void)
+{
+  if (aarch64_stopped_data_address () != 0)
+    return 1;
+  else
+    return 0;
+}
+
+/* Fetch the thread-local storage pointer for libthread_db.  */
+
+ps_err_e
+ps_get_thread_area (const struct ps_prochandle * ph,
+		    lwpid_t lwpid, int idx, void **base)
+{
+  if (ptrace (PTRACE_GET_THREAD_AREA, lwpid, NULL, base) != 0)
+    return PS_ERR;
+
+  /* IDX is the bias from the thread pointer to the beginning of the
+     thread descriptor.  It has to be subtracted due to implementation
+     quirks in libthread_db.  */
+  *base = (void *) ((char *) *base - idx);
+
+  return PS_OK;
+}
+
+/* Called when a new process is created.  */
+
+static struct arch_process_info *
+aarch64_linux_new_process (void)
+{
+  struct arch_process_info *info = xcalloc (1, sizeof (*info));
+
+  aarch64_init_debug_reg_state (&info->debug_reg_state);
+
+  return info;
+}
+
+/* Called when a new thread is detected.  */
+
+static struct arch_lwp_info *
+aarch64_linux_new_thread (void)
+{
+  struct arch_lwp_info *info = xcalloc (1, sizeof (*info));
+
+  /* Mark that all the hardware breakpoint/watchpoint register pairs
+     for this thread need to be initialized (with data from
+     aarch_process_info.debug_reg_state).  */
+  DR_MARK_ALL_CHANGED (info->dr_changed_bp, aarch64_num_bp_regs);
+  DR_MARK_ALL_CHANGED (info->dr_changed_wp, aarch64_num_wp_regs);
+
+  return info;
+}
+
+/* Called when resuming a thread.
+   If the debug regs have changed, update the thread's copies.  */
+
+static void
+aarch64_linux_prepare_to_resume (struct lwp_info *lwp)
+{
+  ptid_t ptid = ptid_of (lwp);
+  struct arch_lwp_info *info = lwp->arch_private;
+
+  if (DR_HAS_CHANGED (info->dr_changed_bp)
+      || DR_HAS_CHANGED (info->dr_changed_wp))
+    {
+      int tid = ptid_get_lwp (ptid);
+      struct process_info *proc = find_process_pid (ptid_get_pid (ptid));
+      struct aarch64_debug_reg_state *state
+	= &proc->private->arch_private->debug_reg_state;
+
+      if (debug_hw_points)
+	fprintf (stderr, "prepare_to_resume thread %ld\n", lwpid_of (lwp));
+
+      /* Watchpoints.  */
+      if (DR_HAS_CHANGED (info->dr_changed_wp))
+	{
+	  aarch64_linux_set_debug_regs (state, tid, 1);
+	  DR_CLEAR_CHANGED (info->dr_changed_wp);
+	}
+
+      /* Breakpoints.  */
+      if (DR_HAS_CHANGED (info->dr_changed_bp))
+	{
+	  aarch64_linux_set_debug_regs (state, tid, 0);
+	  DR_CLEAR_CHANGED (info->dr_changed_bp);
+	}
+    }
+}
+
+/* ptrace hardware breakpoint resource info is formatted as follows:
+
+   31             24             16               8              0
+   +---------------+--------------+---------------+---------------+
+   |   RESERVED    |   RESERVED   |   DEBUG_ARCH  |  NUM_SLOTS    |
+   +---------------+--------------+---------------+---------------+  */
+
+#define AARCH64_DEBUG_NUM_SLOTS(x) ((x) & 0xff)
+#define AARCH64_DEBUG_ARCH(x) (((x) >> 8) & 0xff)
+#define AARCH64_DEBUG_ARCH_V8 0x6
+
+static void
+aarch64_arch_setup (void)
+{
+  int pid;
+  struct iovec iov;
+  struct user_hwdebug_state dreg_state;
+
+  init_registers_aarch64 ();
+
+  pid = lwpid_of (get_thread_lwp (current_inferior));
+  iov.iov_base = &dreg_state;
+  iov.iov_len = sizeof (dreg_state);
+
+  /* Get hardware watchpoint register info.  */
+  if (ptrace (PTRACE_GETREGSET, pid, NT_ARM_HW_WATCH, &iov) == 0
+      && AARCH64_DEBUG_ARCH (dreg_state.dbg_info) == AARCH64_DEBUG_ARCH_V8)
+    {
+      aarch64_num_wp_regs = AARCH64_DEBUG_NUM_SLOTS (dreg_state.dbg_info);
+      if (aarch64_num_wp_regs > AARCH64_HBP_MAX_NUM)
+	error ("arch_setup fails: num_wp_regs (%d) exceeds the maximum (%d)",
+	       aarch64_num_wp_regs, AARCH64_HBP_MAX_NUM);
+    }
+  else
+    error ("arch_setup fails: unable to get debug register resource info");
+
+  /* Get hardware breakpoint register info.  */
+  if (ptrace (PTRACE_GETREGSET, pid, NT_ARM_HW_BREAK, &iov) == 0
+      && AARCH64_DEBUG_ARCH (dreg_state.dbg_info) == AARCH64_DEBUG_ARCH_V8)
+    {
+      aarch64_num_bp_regs = AARCH64_DEBUG_NUM_SLOTS (dreg_state.dbg_info);
+      if (aarch64_num_bp_regs > AARCH64_HBP_MAX_NUM)
+	error ("arch_setup fails: num_bp_regs (%d) exceeds the maximum (%d)",
+	       aarch64_num_bp_regs, AARCH64_HBP_MAX_NUM);
+    }
+  else
+    error ("arch_setup fails: unable to get debug register resource info");
+}
+
+struct regset_info target_regsets[] = {
+  { PTRACE_GETREGSET, PTRACE_SETREGSET, NT_PRSTATUS,
+    sizeof (struct user_pt_regs), GENERAL_REGS,
+    aarch64_fill_gregset, aarch64_store_gregset },
+  { PTRACE_GETREGSET, PTRACE_SETREGSET, NT_FPREGSET,
+    sizeof (struct user_fpsimd_state), FP_REGS,
+    aarch64_fill_fpregset, aarch64_store_fpregset
+  },
+  { 0, 0, 0, -1, -1, NULL, NULL }
+};
+
+struct linux_target_ops the_low_target = {
+  aarch64_arch_setup,
+  AARCH64_NUM_REGS,
+  aarch64_regmap,
+  NULL,
+  aarch64_cannot_fetch_register,
+  aarch64_cannot_store_register,
+  NULL,
+  aarch64_get_pc,
+  aarch64_set_pc,
+  (const unsigned char *) &aarch64_breakpoint,
+  aarch64_breakpoint_len,
+  NULL,
+  0,
+  aarch64_breakpoint_at,
+  aarch64_insert_point,
+  aarch64_remove_point,
+  aarch64_stopped_by_watchpoint,
+  aarch64_stopped_data_address,
+  NULL,
+  NULL,
+  NULL,
+  aarch64_linux_new_process,
+  aarch64_linux_new_thread,
+  aarch64_linux_prepare_to_resume,
+};
diff --git a/gdb/gdbserver/linux-low.c b/gdb/gdbserver/linux-low.c
index 89988eb..4002918 100644
--- a/gdb/gdbserver/linux-low.c
+++ b/gdb/gdbserver/linux-low.c
@@ -445,7 +445,8 @@ handle_extended_wait (struct lwp_info *event_child, int wstat)
       unsigned long new_pid;
       int ret, status;
 
-      ptrace (PTRACE_GETEVENTMSG, lwpid_of (event_child), 0, &new_pid);
+      ptrace (PTRACE_GETEVENTMSG, lwpid_of (event_child), (PTRACE_ARG3_TYPE) 0,
+	      &new_pid);
 
       /* If we haven't already seen the new PID stop, wait for it now.  */
       if (!pull_pid_from_list (&stopped_pids, new_pid, &status))
@@ -641,7 +642,7 @@ linux_create_inferior (char *program, char **allargs)
 
   if (pid == 0)
     {
-      ptrace (PTRACE_TRACEME, 0, 0, 0);
+      ptrace (PTRACE_TRACEME, 0, (PTRACE_ARG3_TYPE) 0, (PTRACE_ARG4_TYPE) 0);
 
 #ifndef __ANDROID__ /* Bionic doesn't use SIGRTMIN the way glibc does.  */
       signal (__SIGRTMIN + 1, SIG_DFL);
@@ -703,7 +704,8 @@ linux_attach_lwp_1 (unsigned long lwpid, int initial)
   ptid_t ptid;
   struct lwp_info *new_lwp;
 
-  if (ptrace (PTRACE_ATTACH, lwpid, 0, 0) != 0)
+  if (ptrace (PTRACE_ATTACH, lwpid, (PTRACE_ARG3_TYPE) 0, (PTRACE_ARG4_TYPE) 0)
+      != 0)
     {
       struct buffer buffer;
 
@@ -769,7 +771,7 @@ linux_attach_lwp_1 (unsigned long lwpid, int initial)
       /* Finally, resume the stopped process.  This will deliver the
 	 SIGSTOP (or a higher priority signal, just like normal
 	 PTRACE_ATTACH), which we'll catch later on.  */
-      ptrace (PTRACE_CONT, lwpid, 0, 0);
+      ptrace (PTRACE_CONT, lwpid, (PTRACE_ARG3_TYPE) 0, (PTRACE_ARG4_TYPE) 0);
     }
 
   /* The next time we wait for this LWP we'll see a SIGSTOP as PTRACE_ATTACH
@@ -960,7 +962,7 @@ linux_kill_one_lwp (struct lwp_info *lwp)
 	     errno ? strerror (errno) : "OK");
 
   errno = 0;
-  ptrace (PTRACE_KILL, pid, 0, 0);
+  ptrace (PTRACE_KILL, pid, (PTRACE_ARG3_TYPE) 0, (PTRACE_ARG4_TYPE) 0);
   if (debug_threads)
     fprintf (stderr,
 	     "LKL:  PTRACE_KILL %s, 0, 0 (%s)\n",
@@ -1174,7 +1176,7 @@ linux_detach_one_lwp (struct inferior_list_entry *entry, void *args)
   /* Finally, let it resume.  */
   if (the_low_target.prepare_to_resume != NULL)
     the_low_target.prepare_to_resume (lwp);
-  if (ptrace (PTRACE_DETACH, lwpid_of (lwp), 0,
+  if (ptrace (PTRACE_DETACH, lwpid_of (lwp), (PTRACE_ARG3_TYPE) 0,
 	      (PTRACE_ARG4_TYPE) (long) sig) < 0)
     error (_("Can't detach %s: %s"),
 	   target_pid_to_str (ptid_of (lwp)),
@@ -1605,13 +1607,15 @@ Checking whether LWP %ld needs to move out of the jump pad...it does\n",
 		   || WSTOPSIG (*wstat) == SIGFPE
 		   || WSTOPSIG (*wstat) == SIGBUS
 		   || WSTOPSIG (*wstat) == SIGSEGV)
-		  && ptrace (PTRACE_GETSIGINFO, lwpid_of (lwp), 0, &info) == 0
+		  && ptrace (PTRACE_GETSIGINFO, lwpid_of (lwp),
+			     (PTRACE_ARG3_TYPE) 0, &info) == 0
 		  /* Final check just to make sure we don't clobber
 		     the siginfo of non-kernel-sent signals.  */
 		  && (uintptr_t) info.si_addr == lwp->stop_pc)
 		{
 		  info.si_addr = (void *) (uintptr_t) status.tpoint_addr;
-		  ptrace (PTRACE_SETSIGINFO, lwpid_of (lwp), 0, &info);
+		  ptrace (PTRACE_SETSIGINFO, lwpid_of (lwp),
+			  (PTRACE_ARG3_TYPE) 0, &info);
 		}
 
 	      regcache = get_thread_regcache (get_lwp_thread (lwp), 1);
@@ -1706,7 +1710,8 @@ Deferring signal %d for LWP %ld.\n", WSTOPSIG (*wstat), lwpid_of (lwp));
   p_sig->prev = lwp->pending_signals_to_report;
   p_sig->signal = WSTOPSIG (*wstat);
   memset (&p_sig->info, 0, sizeof (siginfo_t));
-  ptrace (PTRACE_GETSIGINFO, lwpid_of (lwp), 0, &p_sig->info);
+  ptrace (PTRACE_GETSIGINFO, lwpid_of (lwp), (PTRACE_ARG3_TYPE) 0,
+	  &p_sig->info);
 
   lwp->pending_signals_to_report = p_sig;
 }
@@ -1727,7 +1732,8 @@ dequeue_one_deferred_signal (struct lwp_info *lwp, int *wstat)
 
       *wstat = W_STOPCODE ((*p_sig)->signal);
       if ((*p_sig)->info.si_signo != 0)
-	ptrace (PTRACE_SETSIGINFO, lwpid_of (lwp), 0, &(*p_sig)->info);
+	ptrace (PTRACE_SETSIGINFO, lwpid_of (lwp), (PTRACE_ARG3_TYPE) 0,
+		&(*p_sig)->info);
       free (*p_sig);
       *p_sig = NULL;
 
@@ -2597,7 +2603,8 @@ Check if we're already there.\n",
 	fprintf (stderr, "Ignored signal %d for LWP %ld.\n",
 		 WSTOPSIG (w), lwpid_of (event_child));
 
-      if (ptrace (PTRACE_GETSIGINFO, lwpid_of (event_child), 0, &info) == 0)
+      if (ptrace (PTRACE_GETSIGINFO, lwpid_of (event_child),
+		  (PTRACE_ARG3_TYPE) 0, &info) == 0)
 	info_p = &info;
       else
 	info_p = NULL;
@@ -3277,7 +3284,8 @@ lwp %ld wants to get out of fast tracepoint jump pad single-stepping\n",
 
       signal = (*p_sig)->signal;
       if ((*p_sig)->info.si_signo != 0)
-	ptrace (PTRACE_SETSIGINFO, lwpid_of (lwp), 0, &(*p_sig)->info);
+	ptrace (PTRACE_SETSIGINFO, lwpid_of (lwp), (PTRACE_ARG3_TYPE) 0,
+		&(*p_sig)->info);
 
       free (*p_sig);
       *p_sig = NULL;
@@ -3292,7 +3300,8 @@ lwp %ld wants to get out of fast tracepoint jump pad single-stepping\n",
   lwp->stopped = 0;
   lwp->stopped_by_watchpoint = 0;
   lwp->stepping = step;
-  ptrace (step ? PTRACE_SINGLESTEP : PTRACE_CONT, lwpid_of (lwp), 0,
+  ptrace (step ? PTRACE_SINGLESTEP : PTRACE_CONT, lwpid_of (lwp),
+	  (PTRACE_ARG3_TYPE) 0,
 	  /* Coerce to a uintptr_t first to avoid potential gcc warning
 	     of coercing an 8 byte integer to a 4 byte pointer.  */
 	  (PTRACE_ARG4_TYPE) (uintptr_t) signal);
@@ -3760,7 +3769,8 @@ linux_resume_one_thread (struct inferior_list_entry *entry, void *arg)
 	     PTRACE_SETSIGINFO.  */
 	  if (WIFSTOPPED (lwp->last_status)
 	      && WSTOPSIG (lwp->last_status) == lwp->resume->sig)
-	    ptrace (PTRACE_GETSIGINFO, lwpid_of (lwp), 0, &p_sig->info);
+	    ptrace (PTRACE_GETSIGINFO, lwpid_of (lwp), (PTRACE_ARG3_TYPE) 0,
+		    &p_sig->info);
 
 	  lwp->pending_signals = p_sig;
 	}
@@ -3985,7 +3995,6 @@ unstop_all_lwps (int unsuspend, struct lwp_info *except)
     find_inferior (&all_lwps, proceed_one_lwp, except);
 }
 
-
 #ifdef HAVE_LINUX_REGSETS
 
 #define use_linux_regsets 1
@@ -4221,7 +4230,7 @@ fetch_register (struct regcache *regcache, int regno)
 	ptrace (PTRACE_PEEKUSER, pid,
 		/* Coerce to a uintptr_t first to avoid potential gcc warning
 		   of coercing an 8 byte integer to a 4 byte pointer.  */
-		(PTRACE_ARG3_TYPE) (uintptr_t) regaddr, 0);
+		(PTRACE_ARG3_TYPE) (uintptr_t) regaddr, (PTRACE_ARG4_TYPE) 0);
       regaddr += sizeof (PTRACE_XFER_TYPE);
       if (errno != 0)
 	error ("reading register %d: %s", regno, strerror (errno));
@@ -4449,7 +4458,8 @@ linux_read_memory (CORE_ADDR memaddr, unsigned char *myaddr, int len)
       /* Coerce the 3rd arg to a uintptr_t first to avoid potential gcc warning
 	 about coercing an 8 byte integer to a 4 byte pointer.  */
       buffer[i] = ptrace (PTRACE_PEEKTEXT, pid,
-			  (PTRACE_ARG3_TYPE) (uintptr_t) addr, 0);
+			  (PTRACE_ARG3_TYPE) (uintptr_t) addr,
+			  (PTRACE_ARG4_TYPE) 0);
       if (errno)
 	break;
     }
@@ -4492,15 +4502,15 @@ linux_write_memory (CORE_ADDR memaddr, const unsigned char *myaddr, int len)
   if (debug_threads)
     {
       /* Dump up to four bytes.  */
-      unsigned int val = * (unsigned int *) myaddr;
+      unsigned val = * (unsigned *) myaddr;
       if (len == 1)
 	val = val & 0xff;
       else if (len == 2)
 	val = val & 0xffff;
       else if (len == 3)
 	val = val & 0xffffff;
-      fprintf (stderr, "Writing %0*x to 0x%08lx\n", 2 * ((len < 4) ? len : 4),
-	       val, (long)memaddr);
+      fprintf (stderr, "Writing len=%d 0x%0*x to 0x%08lx\n", len,
+	       2 * ((len < 4) ? len : 4), val, (long) memaddr);
     }
 
   /* Fill start and end extra bytes of buffer with existing memory data.  */
@@ -4509,7 +4519,8 @@ linux_write_memory (CORE_ADDR memaddr, const unsigned char *myaddr, int len)
   /* Coerce the 3rd arg to a uintptr_t first to avoid potential gcc warning
      about coercing an 8 byte integer to a 4 byte pointer.  */
   buffer[0] = ptrace (PTRACE_PEEKTEXT, pid,
-		      (PTRACE_ARG3_TYPE) (uintptr_t) addr, 0);
+		      (PTRACE_ARG3_TYPE) (uintptr_t) addr,
+		      (PTRACE_ARG4_TYPE) 0);
   if (errno)
     return errno;
 
@@ -4522,7 +4533,7 @@ linux_write_memory (CORE_ADDR memaddr, const unsigned char *myaddr, int len)
 		     about coercing an 8 byte integer to a 4 byte pointer.  */
 		  (PTRACE_ARG3_TYPE) (uintptr_t) (addr + (count - 1)
 						  * sizeof (PTRACE_XFER_TYPE)),
-		  0);
+		  (PTRACE_ARG4_TYPE) 0);
       if (errno)
 	return errno;
     }
@@ -4558,7 +4569,8 @@ linux_enable_event_reporting (int pid)
   if (!linux_supports_tracefork_flag)
     return;
 
-  ptrace (PTRACE_SETOPTIONS, pid, 0, (PTRACE_ARG4_TYPE) PTRACE_O_TRACECLONE);
+  ptrace (PTRACE_SETOPTIONS, pid, (PTRACE_ARG3_TYPE) 0,
+	  (PTRACE_ARG4_TYPE) PTRACE_O_TRACECLONE);
 }
 
 /* Helper functions for linux_test_for_tracefork, called via clone ().  */
@@ -4574,7 +4586,7 @@ linux_tracefork_grandchild (void *arg)
 static int
 linux_tracefork_child (void *arg)
 {
-  ptrace (PTRACE_TRACEME, 0, 0, 0);
+  ptrace (PTRACE_TRACEME, 0, (PTRACE_ARG3_TYPE) 0, (PTRACE_ARG4_TYPE) 0);
   kill (getpid (), SIGSTOP);
 
 #if !(defined(__UCLIBC__) && defined(HAS_NOMMU))
@@ -4642,28 +4654,33 @@ linux_test_for_tracefork (void)
   if (! WIFSTOPPED (status))
     error ("linux_test_for_tracefork: waitpid: unexpected status %d.", status);
 
-  ret = ptrace (PTRACE_SETOPTIONS, child_pid, 0,
+  ret = ptrace (PTRACE_SETOPTIONS, child_pid, (PTRACE_ARG3_TYPE) 0,
 		(PTRACE_ARG4_TYPE) PTRACE_O_TRACEFORK);
   if (ret != 0)
     {
-      ret = ptrace (PTRACE_KILL, child_pid, 0, 0);
+      ret = ptrace (PTRACE_KILL, child_pid, (PTRACE_ARG3_TYPE) 0,
+		    (PTRACE_ARG4_TYPE) 0);
       if (ret != 0)
 	{
 	  warning ("linux_test_for_tracefork: failed to kill child");
 	  return;
 	}
 
+      status = 0;
       ret = my_waitpid (child_pid, &status, 0);
       if (ret != child_pid)
 	warning ("linux_test_for_tracefork: failed to wait for killed child");
       else if (!WIFSIGNALED (status))
-	warning ("linux_test_for_tracefork: unexpected wait status 0x%x from "
-		 "killed child", status);
+	warning ("linux_test_for_tracefork: unexpected wait status "
+		 "0x%x waitint=0x%x x=0x%x x=0x%x from killed child",
+		 status, __WAIT_INT (status), WIFSIGNALED (status),
+		 ((signed char)(((__WAIT_INT (status) & 0x7f) + 1) >> 1)) > 0);
 
       return;
     }
 
-  ret = ptrace (PTRACE_CONT, child_pid, 0, 0);
+  ret = ptrace (PTRACE_CONT, child_pid, (PTRACE_ARG3_TYPE) 0,
+		(PTRACE_ARG4_TYPE) 0);
   if (ret != 0)
     warning ("linux_test_for_tracefork: failed to resume child");
 
@@ -4673,14 +4690,16 @@ linux_test_for_tracefork (void)
       && status >> 16 == PTRACE_EVENT_FORK)
     {
       second_pid = 0;
-      ret = ptrace (PTRACE_GETEVENTMSG, child_pid, 0, &second_pid);
+      ret = ptrace (PTRACE_GETEVENTMSG, child_pid, (PTRACE_ARG3_TYPE) 0,
+		    &second_pid);
       if (ret == 0 && second_pid != 0)
 	{
 	  int second_status;
 
 	  linux_supports_tracefork_flag = 1;
 	  my_waitpid (second_pid, &second_status, 0);
-	  ret = ptrace (PTRACE_KILL, second_pid, 0, 0);
+	  ret = ptrace (PTRACE_KILL, second_pid, (PTRACE_ARG3_TYPE) 0,
+			(PTRACE_ARG4_TYPE) 0);
 	  if (ret != 0)
 	    warning ("linux_test_for_tracefork: failed to kill second child");
 	  my_waitpid (second_pid, &status, 0);
@@ -4692,7 +4711,8 @@ linux_test_for_tracefork (void)
 
   do
     {
-      ret = ptrace (PTRACE_KILL, child_pid, 0, 0);
+      ret = ptrace (PTRACE_KILL, child_pid, (PTRACE_ARG3_TYPE) 0,
+		    (PTRACE_ARG4_TYPE) 0);
       if (ret != 0)
 	warning ("linux_test_for_tracefork: failed to kill child");
       my_waitpid (child_pid, &status, 0);
@@ -4839,9 +4859,12 @@ linux_read_offsets (CORE_ADDR *text_p, CORE_ADDR *data_p)
 
   errno = 0;
 
-  text = ptrace (PTRACE_PEEKUSER, pid, (long)PT_TEXT_ADDR, 0);
-  text_end = ptrace (PTRACE_PEEKUSER, pid, (long)PT_TEXT_END_ADDR, 0);
-  data = ptrace (PTRACE_PEEKUSER, pid, (long)PT_DATA_ADDR, 0);
+  text = ptrace (PTRACE_PEEKUSER, pid, (PTRACE_ARG3_TYPE) PT_TEXT_ADDR,
+		 (PTRACE_ARG4_TYPE) 0);
+  text_end = ptrace (PTRACE_PEEKUSER, pid, (PTRACE_ARG3_TYPE) PT_TEXT_END_ADDR,
+		     (PTRACE_ARG4_TYPE) 0);
+  data = ptrace (PTRACE_PEEKUSER, pid, (PTRACE_ARG3_TYPE) PT_DATA_ADDR,
+		 (PTRACE_ARG4_TYPE) 0);
 
   if (errno == 0)
     {
@@ -4915,7 +4938,7 @@ linux_xfer_siginfo (const char *annex, unsigned char *readbuf,
   if (offset >= sizeof (siginfo))
     return -1;
 
-  if (ptrace (PTRACE_GETSIGINFO, pid, 0, &siginfo) != 0)
+  if (ptrace (PTRACE_GETSIGINFO, pid, (PTRACE_ARG3_TYPE) 0, &siginfo) != 0)
     return -1;
 
   /* When GDBSERVER is built as a 64-bit application, ptrace writes into
@@ -4936,7 +4959,7 @@ linux_xfer_siginfo (const char *annex, unsigned char *readbuf,
       /* Convert back to ptrace layout before flushing it out.  */
       siginfo_fixup (&siginfo, inf_siginfo, 1);
 
-      if (ptrace (PTRACE_SETSIGINFO, pid, 0, &siginfo) != 0)
+      if (ptrace (PTRACE_SETSIGINFO, pid, (PTRACE_ARG3_TYPE) 0, &siginfo) != 0)
 	return -1;
     }
 
-- 
1.7.9.5

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