gdb: Add native GDB support for ARC

This adds support of so-called "native" GDB for ARC processors.
It was submitted upstream a bit late for inclusion in v10.x,
but already in the upstream "master" branch and will be an essential part
of v11.1 whenever it happens.

These are the changes from upstream "master":
 * https://sourceware.org/git?p=binutils-gdb.git;a=commit;h=b4e3cd0440109d0a5552d3313ccbd35c8103335b
 * https://sourceware.org/git?p=binutils-gdb.git;a=commit;h=d4af727286e3a9f177ba11677fbd3a012d36558a
 * https://sourceware.org/git?p=binutils-gdb.git;a=commit;h=46023bbe81355230b4e7b76d3084337823d02362
 * https://sourceware.org/git?p=binutils-gdb.git;a=commit;h=04c9f85efcd8df5fc482ce97c0104cc7dd5d19e6

Thanks a bunch to Anton & Shahab who made it possible!

(From OE-Core rev: 3429acea0f4a0b59f233947defecdf919c7b1799)

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

1 files changed, 414 insertions, 0 deletions

diff --git a/meta/recipes-devtools/gdb/gdb/0015-gdb-Add-native-support-for-ARC-in-GNU-Linux.patch b/meta/recipes-devtools/gdb/gdb/0015-gdb-Add-native-support-for-ARC-in-GNU-Linux.patch
new file mode 100644
index 0000000000..31cf0b0be2
--- /dev/null
+++ b/meta/recipes-devtools/gdb/gdb/0015-gdb-Add-native-support-for-ARC-in-GNU-Linux.patch
@@ -0,0 +1,414 @@
+From 32b366249fd42d74cbc4a91039431554ebadcfd0 Mon Sep 17 00:00:00 2001
+From: Anton Kolesov <anton.kolesov@synopsys.com>
+Date: Fri, 14 Feb 2014 11:56:23 +0400
+Subject: [PATCH 4/4] gdb: Add native support for ARC in GNU/Linux
+
+With this patch in place it is possible to build a GDB that
+can run on ARC (GNU/Linux) hosts for debugging ARC targets.
+
+The "arc-linux-nat.c" is a rather small one that mostly deals
+with registers and a few thread related hooks.
+
+v2 [1]:
+- Remove "void" from the input of "_initialize_arc_linux_nat ()"
+
+[1] Tom's remark after the first patch
+https://sourceware.org/pipermail/gdb-patches/2020-November/173223.html
+
+gdb/ChangeLog:
+
+        * Makefile.in (ALLDEPFILES): Add arc-linux-nat.c.
+        * configure.host (host to gdb names): Add arc*-*-linux*.
+        * configure.nat (gdb_host_cpu): Add arc.
+        * arc-linux-nat.c: New.
+
+Upstream-Status: Backport [https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=04c9f85efcd8df5fc482ce97c0104cc7dd5d19e6]
+
+Signed-off-by: Anton Kolesov <Anton.Kolesov@synopsys.com>
+Signed-off-by: Shahab Vahedi <shahab@synopsys.com>
+Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
+---
+ gdb/Makefile.in     |   1 +
+ gdb/arc-linux-nat.c | 320 ++++++++++++++++++++++++++++++++++++++++++++++++++++
+ gdb/configure.host  |   3 +
+ gdb/configure.nat   |   4 +
+ 4 files changed, 328 insertions(+)
+ create mode 100644 gdb/arc-linux-nat.c
+
+diff --git a/gdb/Makefile.in b/gdb/Makefile.in
+index ec371fc7e52..c76136907ae 100644
+--- a/gdb/Makefile.in
++++ b/gdb/Makefile.in
+@@ -2136,6 +2136,7 @@ ALLDEPFILES = \
+        amd64-obsd-tdep.c \
+        amd64-sol2-tdep.c \
+        amd64-tdep.c \
++       arc-linux-nat.c \
+        arc-tdep.c \
+        arm.c \
+        arm-bsd-tdep.c \
+diff --git a/gdb/arc-linux-nat.c b/gdb/arc-linux-nat.c
+new file mode 100644
+index 00000000000..41301fd4fed
+--- /dev/null
++++ b/gdb/arc-linux-nat.c
+@@ -0,0 +1,320 @@
++/* Native-dependent code for GNU/Linux ARC.
++
++   Copyright 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 "defs.h"
++#include "frame.h"
++#include "inferior.h"
++#include "gdbcore.h"
++#include "regcache.h"
++#include "gdbsupport/gdb_assert.h"
++#include "target.h"
++#include "linux-nat.h"
++#include "nat/gdb_ptrace.h"
++
++#include <stdint.h>
++#include <sys/types.h>
++#include <sys/param.h>
++#include <signal.h>
++#include <sys/user.h>
++#include <sys/ioctl.h>
++#include "gdbsupport/gdb_wait.h"
++#include <fcntl.h>
++#include <sys/procfs.h>
++#include <linux/elf.h>
++
++#include "gregset.h"
++#include "arc-tdep.h"
++#include "arc-linux-tdep.h"
++#include "arch/arc.h"
++
++/* Defines ps_err_e, struct ps_prochandle.  */
++#include "gdb_proc_service.h"
++
++/* Linux starting with 4.12 supports NT_ARC_V2 note type, which adds R30,
++   R58 and R59 registers, which are specific to ARC HS and aren't
++   available in ARC 700.  */
++#if defined (NT_ARC_V2) && defined (__ARCHS__)
++#define ARC_HAS_V2_REGSET
++#endif
++
++class arc_linux_nat_target final : public linux_nat_target
++{
++public:
++  /* Add ARC register access methods.  */
++  void fetch_registers (struct regcache *, int) override;
++  void store_registers (struct regcache *, int) override;
++
++  const struct target_desc *read_description () override;
++
++  /* Handle threads  */
++  void low_prepare_to_resume (struct lwp_info *lp) override;
++};
++
++static arc_linux_nat_target the_arc_linux_nat_target;
++
++/* Read general registers from target process/thread (via ptrace)
++   into REGCACHE.  */
++
++static void
++fetch_gregs (struct regcache *regcache, int regnum)
++{
++  const int tid = get_ptrace_pid (regcache->ptid ());
++  struct iovec iov;
++  gdb_gregset_t regs;
++
++  iov.iov_base = &regs;
++  iov.iov_len = sizeof (gdb_gregset_t);
++
++  if (ptrace (PTRACE_GETREGSET, tid, NT_PRSTATUS, (void *) &iov) < 0)
++    perror_with_name (_("Couldn't get general registers"));
++  else
++    arc_linux_supply_gregset (NULL, regcache, regnum, &regs, 0);
++}
++
++#ifdef ARC_HAS_V2_REGSET
++/* Read ARC v2 registers from target process/thread (via ptrace)
++   into REGCACHE.  */
++
++static void
++fetch_v2_regs (struct regcache *regcache, int regnum)
++{
++  const int tid = get_ptrace_pid (regcache->ptid ());
++  struct iovec iov;
++  bfd_byte v2_buffer[ARC_LINUX_SIZEOF_V2_REGSET];
++
++  iov.iov_base = &v2_buffer;
++  iov.iov_len = ARC_LINUX_SIZEOF_V2_REGSET;
++
++  if (ptrace (PTRACE_GETREGSET, tid, NT_ARC_V2, (void *) &iov) < 0)
++    perror_with_name (_("Couldn't get ARC HS registers"));
++  else
++    arc_linux_supply_v2_regset (NULL, regcache, regnum, v2_buffer, 0);
++}
++#endif
++
++/* Store general registers from REGCACHE into the target process/thread.  */
++
++static void
++store_gregs (const struct regcache *regcache, int regnum)
++{
++  const int tid = get_ptrace_pid (regcache->ptid ());
++  struct iovec iov;
++  gdb_gregset_t regs;
++
++  iov.iov_base = &regs;
++  iov.iov_len = sizeof (gdb_gregset_t);
++
++  if (ptrace (PTRACE_GETREGSET, tid, NT_PRSTATUS, (void *) &iov) < 0)
++    perror_with_name (_("Couldn't get general registers"));
++  else
++    {
++      arc_linux_collect_gregset (NULL, regcache, regnum, regs, 0);
++
++      if (ptrace (PTRACE_SETREGSET, tid, NT_PRSTATUS, (void *) &iov) < 0)
++       perror_with_name (_("Couldn't write general registers"));
++    }
++}
++
++#ifdef ARC_HAS_V2_REGSET
++/* Store ARC v2 registers from REGCACHE into the target process/thread.  */
++
++static void
++store_v2_regs (const struct regcache *regcache, int regnum)
++{
++  const int tid = get_ptrace_pid (regcache->ptid ());
++  struct iovec iov;
++  bfd_byte v2_buffer[ARC_LINUX_SIZEOF_V2_REGSET];
++
++  iov.iov_base = &v2_buffer;
++  iov.iov_len = ARC_LINUX_SIZEOF_V2_REGSET;
++
++  if (ptrace (PTRACE_GETREGSET, tid, NT_ARC_V2, (void *) &iov) < 0)
++    perror_with_name (_("Couldn't get ARC HS registers"));
++  else
++    {
++      arc_linux_collect_v2_regset (NULL, regcache, regnum, v2_buffer, 0);
++
++      if (ptrace (PTRACE_SETREGSET, tid, NT_ARC_V2, (void *) &iov) < 0)
++       perror_with_name (_("Couldn't write ARC HS registers"));
++    }
++}
++#endif
++
++/* Target operation: Read REGNUM register (all registers if REGNUM == -1)
++   from target process into REGCACHE.  */
++
++void
++arc_linux_nat_target::fetch_registers (struct regcache *regcache, int regnum)
++{
++
++  if (regnum == -1 || regnum <= ARC_LAST_REGNUM)
++    fetch_gregs (regcache, regnum);
++
++#ifdef ARC_HAS_V2_REGSET
++  if (regnum == -1
++      || regnum == ARC_R30_REGNUM
++      || regnum == ARC_R58_REGNUM
++      || regnum == ARC_R59_REGNUM)
++      fetch_v2_regs (regcache, regnum);
++#endif
++}
++
++/* Target operation: Store REGNUM register (all registers if REGNUM == -1)
++   to the target process from REGCACHE.  */
++
++void
++arc_linux_nat_target::store_registers (struct regcache *regcache, int regnum)
++{
++  if (regnum == -1 || regnum <= ARC_LAST_REGNUM)
++    store_gregs (regcache, regnum);
++
++#ifdef ARC_HAS_V2_REGSET
++  if (regnum == -1
++      || regnum == ARC_R30_REGNUM
++      || regnum == ARC_R58_REGNUM
++      || regnum == ARC_R59_REGNUM)
++    store_v2_regs (regcache, regnum);
++#endif
++}
++
++/* Copy general purpose register(s) from REGCACHE into regset GREGS.
++   This function is exported to proc-service.c  */
++
++void
++fill_gregset (const struct regcache *regcache,
++             gdb_gregset_t *gregs, int regnum)
++{
++  arc_linux_collect_gregset (NULL, regcache, regnum, gregs, 0);
++}
++
++/* Copy all the general purpose registers from regset GREGS into REGCACHE.
++   This function is exported to proc-service.c.  */
++
++void
++supply_gregset (struct regcache *regcache, const gdb_gregset_t *gregs)
++{
++  arc_linux_supply_gregset (NULL, regcache, -1, gregs, 0);
++}
++
++/* ARC doesn't have separate FP registers.  This function is exported
++   to proc-service.c.  */
++
++void
++fill_fpregset (const struct regcache *regcache,
++              gdb_fpregset_t *fpregsetp, int regnum)
++{
++  if (arc_debug)
++    debug_printf ("arc-linux-nat: fill_fpregset called.");
++  return;
++}
++
++/* ARC doesn't have separate FP registers.  This function is exported
++   to proc-service.c.  */
++
++void
++supply_fpregset (struct regcache *regcache, const gdb_fpregset_t *fpregsetp)
++{
++  if (arc_debug)
++    debug_printf ("arc-linux-nat: supply_fpregset called.");
++  return;
++}
++
++/* Implement the "read_description" method of linux_nat_target.  */
++
++const struct target_desc *
++arc_linux_nat_target::read_description ()
++{
++  /* This is a native target, hence description is hardcoded.  */
++#ifdef __ARCHS__
++  arc_arch_features features (4, ARC_ISA_ARCV2);
++#else
++  arc_arch_features features (4, ARC_ISA_ARCV1);
++#endif
++  return arc_lookup_target_description (features);
++}
++
++/* As described in arc_linux_collect_gregset(), we need to write resume-PC
++   to ERET.  However by default GDB for native targets doesn't write
++   registers if they haven't been changed.  This is a callback called by
++   generic GDB, and in this callback we have to rewrite PC value so it
++   would force rewrite of register on target.  It seems that the only
++   other arch that utilizes this hook is x86/x86-64 for HW breakpoint
++   support.  But then, AFAIK no other arch has this stop_pc/eret
++   complexity.
++
++   No better way was found, other than this fake write of register value,
++   to force GDB into writing register to target.  Is there any?  */
++
++void
++arc_linux_nat_target::low_prepare_to_resume (struct lwp_info *lwp)
++{
++  /* When new processes and threads are created we do not have the address
++     space for them and calling get_thread_regcache will cause an internal
++     error in GDB.  It looks like that checking for last_resume_kind is the
++     sensible way to determine processes for which we cannot get regcache.
++     Ultimately, a better way would be removing the need for
++     low_prepare_to_resume in the first place.  */
++  if (lwp->last_resume_kind == resume_stop)
++    return;
++
++  struct regcache *regcache = get_thread_regcache (this, lwp->ptid);
++  struct gdbarch *gdbarch = regcache->arch ();
++
++  /* Read current PC value, then write it back.  It is required to call
++     invalidate(), otherwise GDB will note that new value is equal to old
++     value and will skip write.  */
++  ULONGEST new_pc;
++  regcache_cooked_read_unsigned (regcache, gdbarch_pc_regnum (gdbarch),
++                                &new_pc);
++  regcache->invalidate (gdbarch_pc_regnum (gdbarch));
++  regcache_cooked_write_unsigned (regcache, gdbarch_pc_regnum (gdbarch),
++                                 new_pc);
++}
++
++/* Fetch the thread-local storage pointer for libthread_db.  Note that
++   this function is not called from GDB, but is called from libthread_db.
++   This is required to debug multithreaded applications with NPTL.  */
++
++ps_err_e
++ps_get_thread_area (struct ps_prochandle *ph, lwpid_t lwpid, int idx,
++                   void **base)
++{
++  if (arc_debug >= 2)
++    debug_printf ("arc-linux-nat: ps_get_thread_area called");
++
++  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;
++}
++
++/* Suppress warning from -Wmissing-prototypes.  */
++void _initialize_arc_linux_nat ();
++void
++_initialize_arc_linux_nat ()
++{
++  /* Register the target.  */
++  linux_target = &the_arc_linux_nat_target;
++  add_inf_child_target (&the_arc_linux_nat_target);
++}
+diff --git a/gdb/configure.host b/gdb/configure.host
+index ce528237291..e94a19b0332 100644
+--- a/gdb/configure.host
++++ b/gdb/configure.host
+@@ -60,6 +60,7 @@ case "${host_cpu}" in
+ 
+ aarch64*)              gdb_host_cpu=aarch64 ;;
+ alpha*)                        gdb_host_cpu=alpha ;;
++arc*)                  gdb_host_cpu=arc ;;
+ arm*)                  gdb_host_cpu=arm ;;
+ hppa*)                 gdb_host_cpu=pa ;;
+ i[34567]86*)           gdb_host_cpu=i386 ;;
+@@ -91,6 +92,8 @@ alpha*-*-netbsd* | alpha*-*-knetbsd*-gnu)
+                        gdb_host=nbsd ;;
+ alpha*-*-openbsd*)     gdb_host=nbsd ;;
+ 
++arc*-*-linux*)         gdb_host=linux ;;
++
+ arm*-*-freebsd*)       gdb_host=fbsd ;;
+ arm*-*-linux*)         gdb_host=linux ;;
+ arm*-*-netbsdelf* | arm*-*-knetbsd*-gnu)
+diff --git a/gdb/configure.nat b/gdb/configure.nat
+index bb70e303384..cd11bc86dca 100644
+--- a/gdb/configure.nat
++++ b/gdb/configure.nat
+@@ -238,6 +238,10 @@ case ${gdb_host} in
+                nat/aarch64-linux.o \
+                nat/aarch64-sve-linux-ptrace.o"
+                ;;
++           arc)
++               # Host: ARC based machine running GNU/Linux
++               NATDEPFILES="${NATDEPFILES} arc-linux-nat.o"
++               ;;
+            arm)
+                # Host: ARM based machine running GNU/Linux
+                NATDEPFILES="${NATDEPFILES} arm-linux-nat.o \
+-- 
+2.16.2
+