x32 ABI Support (was Re: Three weeks to branching (gdb 7.5 release))

[Mark Kettenis <mark.kettenis@xs4all.nl>]

> Date: Sun, 20 May 2012 15:48:54 -0700
> From: "H.J. Lu" <hjl.tools@gmail.com>
> 
> Does this one look OK.  I extracted x32_init_abi from amd64_x32_init_abi
> since amd64_x32_linux_init_abi can't call amd64_init_abi after
> calling amd64_linux_init_abi.

I guess multiple-inheritance is a bad idea, even when implemented in C ;)

I really do think that amd64_x32_linux_init_abi() should call
amd64_x32_init_abi().  That way it is immediately obvious that the OS-specific ABI inherits everything from the generic ABI.

In order too avoid too much code duplication, the common bits should
be split out from amd64_linux_init_abi() into a seperate function that
gets called from both amd64_linux_init_abi() and
amd64_x32_linux_init_abi().  As I wrote earlier, it isn't entirely
obvious that everything in amd64_linix_init_abi() applies to the x32
ABI.  So we should be conservative in moving stuff into the common
function.  In fact it might be a good idea to start out with something
like the attached diff, and gradually move things over.

Cheers,

Mark

Index: amd64-linux-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/amd64-linux-tdep.c,v
retrieving revision 1.50
diff -u -p -r1.50 amd64-linux-tdep.c
--- amd64-linux-tdep.c	12 May 2012 08:54:03 -0000	1.50
+++ amd64-linux-tdep.c	28 May 2012 20:24:28 -0000
@@ -1298,8 +1298,6 @@ amd64_linux_init_abi (struct gdbarch_inf
 
   gdb_assert (tdesc_data);
 
-  linux_init_abi (info, gdbarch);
-
   tdep->gregset_reg_offset = amd64_linux_gregset_reg_offset;
   tdep->gregset_num_regs = ARRAY_SIZE (amd64_linux_gregset_reg_offset);
   tdep->sizeof_gregset = 27 * 8;
@@ -1323,6 +1321,8 @@ amd64_linux_init_abi (struct gdbarch_inf
   if (!valid_p)
     return;
 
+  linux_init_abi (info, gdbarch);
+
   tdep->sigtramp_p = amd64_linux_sigtramp_p;
   tdep->sigcontext_addr = amd64_linux_sigcontext_addr;
   tdep->sc_reg_offset = amd64_linux_sc_reg_offset;
@@ -1543,6 +1543,44 @@ amd64_linux_init_abi (struct gdbarch_inf
 
   tdep->i386_syscall_record = amd64_linux_syscall_record;
 }
+
+static void
+amd64_x32_linux_init_abi(struct gdbarch_info info, struct gdbarch *gdbarch)
+{
+  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+  const struct target_desc *tdesc = info.target_desc;
+
+  gdb_assert (tdesc_data);
+
+  tdep->gregset_reg_offset = amd64_linux_gregset_reg_offset;
+  tdep->gregset_num_regs = ARRAY_SIZE (amd64_linux_gregset_reg_offset);
+  tdep->sizeof_gregset = 27 * 8;
+
+  amd64_x32_init_abi (info, gdbarch);
+
+  /* Reserve a number for orig_rax.  */
+  set_gdbarch_num_regs (gdbarch, AMD64_LINUX_NUM_REGS);
+
+  if (! tdesc_has_registers (tdesc))
+    tdesc = tdesc_x32_linux;
+  tdep->tdesc = tdesc;
+
+  feature = tdesc_find_feature (tdesc, "org.gnu.gdb.i386.linux");
+  if (feature == NULL)
+    return;
+
+  valid_p = tdesc_numbered_register (feature, tdesc_data,
+				     AMD64_LINUX_ORIG_RAX_REGNUM,
+				     "orig_rax");
+  if (!valid_p)
+    return;
+
+  linux_init_abi (info, gdbarch);
+
+  /* GNU/Linux uses SVR4-style shared libraries.  */
+  set_solib_svr4_fetch_link_map_offsets
+    (gdbarch, svr4_ilp32_fetch_link_map_offsets);
+}
 \f
 
 /* Provide a prototype to silence -Wmissing-prototypes.  */
@@ -1553,6 +1591,8 @@ _initialize_amd64_linux_tdep (void)
 {
   gdbarch_register_osabi (bfd_arch_i386, bfd_mach_x86_64,
 			  GDB_OSABI_LINUX, amd64_linux_init_abi);
+  gdbarch_register_osabi (bfd_arch_i386, bfd_mach_x64_32,
+			  GDB_OSABI_LINUX, amd64_x32_linux_init_abi);
 
   /* Initialize the Linux target description.  */
   initialize_tdesc_amd64_linux ();
Index: amd64-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/amd64-tdep.c,v
retrieving revision 1.104
diff -u -p -r1.104 amd64-tdep.c
--- amd64-tdep.c	14 May 2012 18:56:40 -0000	1.104
+++ amd64-tdep.c	28 May 2012 20:24:29 -0000
@@ -258,7 +258,8 @@ static const char *amd64_word_names[] =
 static const char *amd64_dword_names[] =
 {
   "eax", "ebx", "ecx", "edx", "esi", "edi", "ebp", "esp", 
-  "r8d", "r9d", "r10d", "r11d", "r12d", "r13d", "r14d", "r15d"
+  "r8d", "r9d", "r10d", "r11d", "r12d", "r13d", "r14d", "r15d",
+  "eip"
 };
 
 /* Return the name of register REGNUM.  */
@@ -2729,6 +2730,43 @@ amd64_init_abi (struct gdbarch_info info
   set_gdbarch_stap_parse_special_token (gdbarch,
 					i386_stap_parse_special_token);
 }
+\f
+
+static struct type *
+amd64_x32_pseudo_register_type (struct gdbarch *gdbarch, int regnum)
+{
+  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+
+  switch (regnum - tdep->eax_regnum)
+    {
+    case AMD64_RBP_REGNUM:	/* %ebp */
+    case AMD64_RSP_REGNUM:	/* %esp */
+      return builtin_type (gdbarch)->builtin_data_ptr;
+    case AMD64_RIP_REGNUM:	/* %eip */
+      return builtin_type (gdbarch)->builtin_func_ptr;
+    }
+
+  return i386_pseudo_register_type (gdbarch, regnum);
+}
+
+void
+amd64_x32_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
+{
+  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+  const struct target_desc *tdesc = info.target_desc;
+
+  amd64_init_abi (info, gdbarch);
+
+  if (! tdesc_has_registers (tdesc))
+    tdesc = tdesc_x32;
+  tdep->tdesc = tdesc;
+
+  tdep->num_dword_regs = 17;
+  set_tdesc_pseudo_register_type (gdbarch, amd64_x32_pseudo_register_type);
+
+  set_gdbarch_long_bit (gdbarch, 32);
+  set_gdbarch_ptr_bit (gdbarch, 32);
+}
 
 /* Provide a prototype to silence -Wmissing-prototypes.  */
 void _initialize_amd64_tdep (void);
Index: amd64-tdep.h
===================================================================
RCS file: /cvs/src/src/gdb/amd64-tdep.h,v
retrieving revision 1.21
diff -u -p -r1.21 amd64-tdep.h
--- amd64-tdep.h	4 Jan 2012 08:16:56 -0000	1.21
+++ amd64-tdep.h	28 May 2012 20:24:29 -0000
@@ -80,6 +80,8 @@ extern void amd64_displaced_step_fixup (
 					struct regcache *regs);
 
 extern void amd64_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch);
+extern void amd64_x32_init_abi (struct gdbarch_info info,
+				struct gdbarch *gdbarch);
 
 /* Fill register REGNUM in REGCACHE with the appropriate
    floating-point or SSE register value from *FXSAVE.  If REGNUM is