openbsd-ports/devel/gdb/patches/patch-gdb_aarch64obsd-tdep_c

$OpenBSD: patch-gdb_aarch64obsd-tdep_c,v 1.2 2019/10/17 17:10:26 kurt Exp $
Index: gdb/aarch64obsd-tdep.c
--- gdb/aarch64obsd-tdep.c.orig
+++ gdb/aarch64obsd-tdep.c
@@ -0,0 +1,299 @@
+/* Target-dependent code for OpenBSD/aarch64.
+
+   Copyright (C) 2006-2017 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-unwind.h"
+#include "osabi.h"
+#include "regset.h"
+#include "trad-frame.h"
+#include "tramp-frame.h"
+
+#include "aarch64-tdep.h"
+#include "obsd-tdep.h"
+#include "solib-svr4.h"
+
+/* Signal trampolines.  */
+
+/* Since OpenBSD 3.2, the sigtramp routine is mapped at a random page
+   in virtual memory.  The randomness makes it somewhat tricky to
+   detect it, but fortunately we can rely on the fact that the start
+   of the sigtramp routine is page-aligned.  We recognize the
+   trampoline by looking for the code that invokes the sigreturn
+   system call.  The offset where we can find that code varies from
+   release to release.
+
+   By the way, the mapping mentioned above is read-only, so you cannot
+   place a breakpoint in the signal trampoline.  */
+
+/* Default page size.  */
+static const CORE_ADDR aarch64obsd_page_size = 4096;
+
+/* Offset for sigreturn(2).  */
+static const int aarch64obsd_sigreturn_offset[] = {
+  0xb4,				/* OpenBSD 6.2 */
+  0x08,				/* OpenBSD 6.1 */
+  -1
+};
+
+static int
+aarch64obsd_sigtramp_frame_sniffer (const struct frame_unwind *self,
+				    struct frame_info *this_frame,
+				    void **this_cache)
+{
+  struct gdbarch *gdbarch = get_frame_arch (this_frame);
+  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
+  CORE_ADDR pc = get_frame_pc (this_frame);
+  CORE_ADDR start_pc = (pc & ~(aarch64obsd_page_size - 1));
+  const int *offset;
+  const char *name;
+
+  find_pc_partial_function (pc, &name, NULL, NULL);
+  if (name)
+    return 0;
+
+  for (offset = aarch64obsd_sigreturn_offset; *offset != -1; offset++)
+    {
+      gdb_byte buf[8];
+      unsigned long insn;
+
+      if (!safe_frame_unwind_memory (this_frame, start_pc + *offset,
+				     buf, sizeof buf))
+	continue;
+
+      /* Check for "mov x8, #SYS_sigreturn".  */
+      insn = extract_unsigned_integer (buf, 4, byte_order);
+      if (insn != 0xd2800ce8)
+	continue;
+
+      /* Check for "svc 0".  */
+      insn = extract_unsigned_integer (buf + 4, 4, byte_order);
+      if (insn != 0xd4000001)
+	continue;
+
+      return 1;
+    }
+
+  return 0;
+}
+
+/*
+   In 6.1 the sp points to the struct sigframe. Since 6.2 the 
+   sigtramp routine saves floating point registers on the stack
+   before the struct sigframe so that needs to be skipped to look
+   at sigframe. A sigframe looks like this:
+
+   struct sigframe {
+           int     sf_signum;
+           struct  sigcontext sf_sc;
+           siginfo_t sf_si;
+   };
+
+   struct  sigcontext {
+           int     __sc_unused;
+           int     sc_mask;
+
+           unsigned long sc_sp;
+           unsigned long sc_lr;
+           unsigned long sc_elr;
+           unsigned long sc_spsr;
+           unsigned long sc_x[30];
+
+           long    sc_cookie;
+   };
+
+*/
+
+#define AARCH64_SIGCONTEXT_REG_SIZE		8
+#define AARCH64_SIGFRAME_SIGCONTEXT_OFFSET	8
+#define AARCH64_SIGCONTEXT_SP_OFFSET		8
+#define AARCH64_SIGCONTEXT_LR_OFFSET		16
+#define AARCH64_SIGCONTEXT_PC_OFFSET		24
+#define AARCH64_SIGCONTEXT_SPSR_OFFSET		32
+#define AARCH64_SIGCONTEXT_X0_OFFSET		40
+
+static struct trad_frame_cache *
+aarch64obsd_sigtramp_frame_cache (struct frame_info *this_frame, void **this_cache)
+{
+  struct gdbarch *gdbarch = get_frame_arch (this_frame);
+  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
+  struct trad_frame_cache *cache;
+  CORE_ADDR sp, sigcontext_addr, x0_addr, func;
+  gdb_byte buf[4];
+  unsigned long insn, sigframe_offset = 0;
+  int i;
+
+  if (*this_cache)
+    return (struct trad_frame_cache *) *this_cache;
+
+  cache = trad_frame_cache_zalloc (this_frame);
+  *this_cache = cache;
+
+  func = get_frame_pc (this_frame);
+  func &= ~(aarch64obsd_page_size - 1);
+  if (!safe_frame_unwind_memory (this_frame, func, buf, sizeof buf))
+    return cache;
+
+  /* Calculate the offset where we can find `struct sigframe'.  In 6.1
+     no adjustment is needed so we look at the first instruction to see
+     if it matches 6.2+. If it is a 'sub sp, sp, #0xNNN' instruction,
+     use the amount of stack space to skip from it. */
+  insn = extract_unsigned_integer (buf, 4, byte_order);
+  if ((insn & 0xffc003ff) == 0xd10003ff)
+    sigframe_offset += ((insn & 0x003ffc00) >> 10);
+
+  sp = get_frame_register_unsigned (this_frame, AARCH64_SP_REGNUM);
+  sigcontext_addr = sp + sigframe_offset + AARCH64_SIGFRAME_SIGCONTEXT_OFFSET;
+  x0_addr = sigcontext_addr + AARCH64_SIGCONTEXT_X0_OFFSET;
+
+  trad_frame_set_reg_addr (cache, AARCH64_SP_REGNUM,
+			   sigcontext_addr + AARCH64_SIGCONTEXT_SP_OFFSET);
+  trad_frame_set_reg_addr (cache, AARCH64_LR_REGNUM,
+			   sigcontext_addr + AARCH64_SIGCONTEXT_LR_OFFSET);
+  trad_frame_set_reg_addr (cache, AARCH64_PC_REGNUM,
+			   sigcontext_addr + AARCH64_SIGCONTEXT_PC_OFFSET);
+  trad_frame_set_reg_addr (cache, AARCH64_CPSR_REGNUM,
+			   sigcontext_addr + AARCH64_SIGCONTEXT_SPSR_OFFSET);
+  for (i = 0; i < 30; i++)
+    {
+      trad_frame_set_reg_addr (cache, AARCH64_X0_REGNUM + i,
+			       x0_addr + i * AARCH64_SIGCONTEXT_REG_SIZE);
+    }
+
+  trad_frame_set_id (cache, frame_id_build (sp, func));
+
+  return cache;
+}
+
+static void
+aarch64obsd_sigtramp_frame_this_id (struct frame_info *this_frame,
+				    void **this_cache,
+				    struct frame_id *this_id)
+{
+  struct trad_frame_cache *cache =
+    aarch64obsd_sigtramp_frame_cache (this_frame, this_cache);
+
+  trad_frame_get_id (cache, this_id);
+}
+
+static struct value *
+aarch64obsd_sigtramp_frame_prev_register (struct frame_info *this_frame,
+				      void **this_cache, int regnum)
+{
+  struct trad_frame_cache *cache =
+    aarch64obsd_sigtramp_frame_cache (this_frame, this_cache);
+
+  return trad_frame_get_register (cache, this_frame, regnum);
+}
+
+static const struct frame_unwind aarch64obsd_sigtramp_frame_unwind = {
+  SIGTRAMP_FRAME,
+  default_frame_unwind_stop_reason,
+  aarch64obsd_sigtramp_frame_this_id,
+  aarch64obsd_sigtramp_frame_prev_register,
+  NULL,
+  aarch64obsd_sigtramp_frame_sniffer
+};
+
+/* The general-purpose regset consists of 31 X registers, plus SP, PC,
+   and SPSR and TPIDR registers.  */
+#define AARCH64_OBSD_SIZEOF_GREGSET  (35 * X_REGISTER_SIZE)
+
+/* The fp regset consists of 32 V registers, plus FPSR and FPCR which
+   are 4 bytes wide each, and the whole structure is padded to 128 bit
+   alignment.  */
+#define AARCH64_OBSD_SIZEOF_FPREGSET (33 * V_REGISTER_SIZE)
+
+/* Register maps.  */
+
+static const struct regcache_map_entry aarch64_obsd_gregmap[] =
+  {
+    { 31, AARCH64_X0_REGNUM, 8 }, /* x0 ... x30 */
+    { 1, AARCH64_SP_REGNUM, 8 },
+    { 1, AARCH64_PC_REGNUM, 8 },
+    { 1, AARCH64_CPSR_REGNUM, 8 },
+    { 0 }
+  };
+
+static const struct regcache_map_entry aarch64_obsd_fpregmap[] =
+  {
+    { 32, AARCH64_V0_REGNUM, 16 }, /* v0 ... v31 */
+    { 1, AARCH64_FPSR_REGNUM, 4 },
+    { 1, AARCH64_FPCR_REGNUM, 4 },
+    { 0 }
+  };
+
+/* Register set definitions.  */
+
+const struct regset aarch64_obsd_gregset =
+  {
+    aarch64_obsd_gregmap,
+    regcache_supply_regset, regcache_collect_regset
+  };
+
+const struct regset aarch64_obsd_fpregset =
+  {
+    aarch64_obsd_fpregmap,
+    regcache_supply_regset, regcache_collect_regset
+  };
+
+static void
+aarch64_obsd_iterate_over_regset_sections (struct gdbarch *gdbarch,
+					   iterate_over_regset_sections_cb *cb,
+					   void *cb_data,
+					   const struct regcache *regcache)
+{
+  cb (".reg", AARCH64_OBSD_SIZEOF_GREGSET, &aarch64_obsd_gregset,
+      NULL, cb_data);
+  cb (".reg2", AARCH64_OBSD_SIZEOF_FPREGSET, &aarch64_obsd_fpregset,
+      NULL, cb_data);
+}
+
+
+static void
+aarch64obsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
+{
+  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+
+  obsd_init_abi (info, gdbarch);
+
+  /* OpenBSD/aarch64 uses SVR4-style shared libraries.  */
+  set_solib_svr4_fetch_link_map_offsets
+    (gdbarch, svr4_lp64_fetch_link_map_offsets);
+  set_gdbarch_skip_solib_resolver (gdbarch, obsd_skip_solib_resolver);
+
+  frame_unwind_append_unwinder (gdbarch, &aarch64obsd_sigtramp_frame_unwind);
+
+  /* Enable longjmp. */
+  tdep->jb_pc = 13;
+
+  set_gdbarch_iterate_over_regset_sections
+    (gdbarch, aarch64_obsd_iterate_over_regset_sections);
+}
+
+
+/* Provide a prototype to silence -Wmissing-prototypes.  */
+extern initialize_file_ftype _initialize_aarch64obsd_tdep;
+
+void
+_initialize_aarch64obsd_tdep (void)
+{
+  gdbarch_register_osabi (bfd_arch_aarch64, 0, GDB_OSABI_OPENBSD_ELF,
+			  aarch64obsd_init_abi);
+}