[rfa:amd64] Fetch 32-bit thread area

[rfa:amd64] Fetch 32-bit thread area

[Andrew Cagney]

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Hello,

This modifies the amd64 code so that, when 32-bit, it fetches the 32-bit 
thread area register (I think this has been posted before?).

ok?
Andrew

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        * amd64-linux-nat.c (ps_get_thread_area): When architecture is
	i386 use PTRACE_GET_THREAD_AREA.  Suggested by Roland McGrath.

Index: amd64-linux-nat.c
===================================================================
RCS file: /cvs/src/src/gdb/amd64-linux-nat.c,v
retrieving revision 1.1
diff -u -r1.1 amd64-linux-nat.c
--- amd64-linux-nat.c	25 Feb 2004 20:45:30 -0000	1.1
+++ amd64-linux-nat.c	27 Feb 2004 01:22:36 -0000
@@ -350,10 +350,14 @@
 }
 \f
 
+/* This function is called by libthread_db as part of its handling of
+   a request for a thread's local storage address.  */
+
 ps_err_e
 ps_get_thread_area (const struct ps_prochandle *ph,
                     lwpid_t lwpid, int idx, void **base)
 {
+#if 0
 /* This definition comes from prctl.h, but some kernels may not have it.  */
 #ifndef PTRACE_ARCH_PRCTL
 #define PTRACE_ARCH_PRCTL      30
@@ -377,6 +381,67 @@
       return PS_BADADDR;
     }
   return PS_ERR;               /* ptrace failed.  */
+#else
+  switch (TARGET_ARCHITECTURE->mach)
+    {
+    case bfd_mach_i386_i386:
+    case bfd_mach_i386_i386_intel_syntax:
+      {
+	/* The full structure is found in <asm-i386/ldt.h>.  The
+	   second integer is the LDT's base_address and that is used
+	   to locate the thread's local storage.  See i386-linux-nat.c
+	   more info.  */
+	unsigned int desc[4];
+
+	/* This code assumes that "int" is 32 bits and that
+           GET_THREAD_AREA returns no more than 4 int values.  */
+	gdb_assert (sizeof (int) == 4);	
+#ifndef PTRACE_GET_THREAD_AREA
+#define PTRACE_GET_THREAD_AREA 25
+#endif
+	if  (ptrace (PTRACE_GET_THREAD_AREA, 
+		     lwpid, (void *) (long) idx, (unsigned long) &desc) < 0)
+	  return PS_ERR;
+      
+	/* Extend the value to 64 bits.  Here it's assumed that a
+           "long" and a "void *" are the same.  */
+	(*base) = (void *) (long) desc[1];
+	return PS_OK;
+      }
+
+    case bfd_mach_x86_64:
+    case bfd_mach_x86_64_intel_syntax:
+
+      /* This definition comes from prctl.h, but some kernels may not
+         have it.  */
+#ifndef PTRACE_ARCH_PRCTL
+#define PTRACE_ARCH_PRCTL      30
+#endif
+      /* FIXME: ezannoni-2003-07-09 see comment above about include
+	 file order.  We could be getting bogus values for these two.  */
+      gdb_assert (FS < ELF_NGREG);
+      gdb_assert (GS < ELF_NGREG);
+      switch (idx)
+	{
+	case FS:
+	  if (ptrace (PTRACE_ARCH_PRCTL, lwpid, base, ARCH_GET_FS) == 0)
+	    return PS_OK;
+	  break;
+	case GS:
+	  if (ptrace (PTRACE_ARCH_PRCTL, lwpid, base, ARCH_GET_GS) == 0)
+	    return PS_OK;
+	  break;
+	default:                   /* Should not happen.  */
+	  return PS_BADADDR;
+	}
+      return PS_ERR;               /* ptrace failed.  */
+      
+    case bfd_mach_i386_i8086:
+      internal_error (__FILE__, __LINE__, "bad i8086 machine");
+    default:
+      internal_error (__FILE__, __LINE__, "bad_switch");
+    }
+#endif
 }
 \f
 

Re: [rfa:amd64] Fetch 32-bit thread area

[Mark Kettenis]

   Date: Thu, 26 Feb 2004 20:24:47 -0500
   From: Andrew Cagney <ac131313@redhat.com>

   Hello,

   This modifies the amd64 code so that, when 32-bit, it fetches the 32-bit 
   thread area register (I think this has been posted before?).

Why #if 0 ... #else ... #endif?

Anyway, I'm not really happy with the 

   switch (TARGET_ARCHITECTURE->mach)

construction.  The other AMD64 native code uses an

   if (gdbarch_ptr_bit (current_gdbarch) == 32)

to distinguish between 32-bit and 64-bit code.  While this may not be
completely correct (someone might come up with a native AMD64 ABI with
32-bit pointers), I'd rather not use multiple variations of the
32-bit/64-bit check in the code.

Mark

Re: [rfa:amd64] Fetch 32-bit thread area

[Andrew Cagney]

>    Date: Thu, 26 Feb 2004 20:24:47 -0500
>    From: Andrew Cagney <ac131313@redhat.com>
> 
>    Hello,
> 
>    This modifies the amd64 code so that, when 32-bit, it fetches the 32-bit 
>    thread area register (I think this has been posted before?).
> 
> Why #if 0 ... #else ... #endif?

Tipo from testing.

> Anyway, I'm not really happy with the 
> 
>    switch (TARGET_ARCHITECTURE->mach)
> 
> construction.  The other AMD64 native code uses an
> 
>    if (gdbarch_ptr_bit (current_gdbarch) == 32)
> 
> to distinguish between 32-bit and 64-bit code.  While this may not be
> completely correct (someone might come up with a native AMD64 ABI with
> 32-bit pointers), I'd rather not use multiple variations of the
> 32-bit/64-bit check in the code.

Is it ok with that change?

Andrew

Re: [rfa:amd64] Fetch 32-bit thread area

[Mark Kettenis]

   Date: Sat, 28 Feb 2004 10:22:29 -0500
   From: Andrew Cagney <cagney@gnu.org>

   >    Date: Thu, 26 Feb 2004 20:24:47 -0500
   >    From: Andrew Cagney <ac131313@redhat.com>
   > 
   >    Hello,
   > 
   >    This modifies the amd64 code so that, when 32-bit, it fetches the 32-bit 
   >    thread area register (I think this has been posted before?).
   > 
   > Why #if 0 ... #else ... #endif?

   Tipo from testing.

Typo?  You mean that you intended to remove the #if 0 block before
submitting the patch?  Or what?

   > Anyway, I'm not really happy with the 
   > 
   >    switch (TARGET_ARCHITECTURE->mach)
   > 
   > construction.  The other AMD64 native code uses an
   > 
   >    if (gdbarch_ptr_bit (current_gdbarch) == 32)
   > 
   > to distinguish between 32-bit and 64-bit code.  While this may not be
   > completely correct (someone might come up with a native AMD64 ABI with
   > 32-bit pointers), I'd rather not use multiple variations of the
   > 32-bit/64-bit check in the code.

   Is it ok with that change?

If you remove the #if 0 block and re-indent the #else block.  Yes.

Mark

Re: [rfa:amd64] Fetch 32-bit thread area

[Andrew Cagney]

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>    Date: Sat, 28 Feb 2004 10:22:29 -0500
>    From: Andrew Cagney <cagney@gnu.org>
> 
>    >    Date: Thu, 26 Feb 2004 20:24:47 -0500
>    >    From: Andrew Cagney <ac131313@redhat.com>
>    > 
>    >    Hello,
>    > 
>    >    This modifies the amd64 code so that, when 32-bit, it fetches the 32-bit 
>    >    thread area register (I think this has been posted before?).
>    > 
>    > Why #if 0 ... #else ... #endif?
> 
>    Tipo from testing.
> 
> Typo?  You mean that you intended to remove the #if 0 block before
> submitting the patch?  Or what?

Yes, "tipo".  As Stan Shebs where the word comes from.

>    > Anyway, I'm not really happy with the 
>    > 
>    >    switch (TARGET_ARCHITECTURE->mach)
>    > 
>    > construction.  The other AMD64 native code uses an
>    > 
>    >    if (gdbarch_ptr_bit (current_gdbarch) == 32)
>    > 
>    > to distinguish between 32-bit and 64-bit code.  While this may not be
>    > completely correct (someone might come up with a native AMD64 ABI with
>    > 32-bit pointers), I'd rather not use multiple variations of the
>    > 32-bit/64-bit check in the code.
> 
>    Is it ok with that change?
> 
> If you remove the #if 0 block and re-indent the #else block.  Yes.

Done.  Committed the attached.

Andrew


[-- Attachment #2: diffs --]
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2004-02-28  Andrew Cagney  <cagney@redhat.com>

        * amd64-linux-nat.c (ps_get_thread_area): When architecture is
	i386 use PTRACE_GET_THREAD_AREA.  Suggested by Roland McGrath.

Index: amd64-linux-nat.c
===================================================================
RCS file: /cvs/src/src/gdb/amd64-linux-nat.c,v
retrieving revision 1.3
diff -u -r1.3 amd64-linux-nat.c
--- amd64-linux-nat.c	28 Feb 2004 18:54:31 -0000	1.3
+++ amd64-linux-nat.c	28 Feb 2004 19:28:56 -0000
@@ -350,31 +350,60 @@
 }
 \f
 
+/* This function is called by libthread_db as part of its handling of
+   a request for a thread's local storage address.  */
+
 ps_err_e
 ps_get_thread_area (const struct ps_prochandle *ph,
                     lwpid_t lwpid, int idx, void **base)
 {
-/* This definition comes from prctl.h, but some kernels may not have it.  */
+  if (gdbarch_ptr_bit (current_gdbarch) == 32)
+    {
+      /* The full structure is found in <asm-i386/ldt.h>.  The second
+	 integer is the LDT's base_address and that is used to locate
+	 the thread's local storage.  See i386-linux-nat.c more
+	 info.  */
+      unsigned int desc[4];
+
+      /* This code assumes that "int" is 32 bits and that
+	 GET_THREAD_AREA returns no more than 4 int values.  */
+      gdb_assert (sizeof (int) == 4);	
+#ifndef PTRACE_GET_THREAD_AREA
+#define PTRACE_GET_THREAD_AREA 25
+#endif
+      if  (ptrace (PTRACE_GET_THREAD_AREA, 
+		   lwpid, (void *) (long) idx, (unsigned long) &desc) < 0)
+	return PS_ERR;
+      
+      /* Extend the value to 64 bits.  Here it's assumed that a "long"
+	 and a "void *" are the same.  */
+      (*base) = (void *) (long) desc[1];
+      return PS_OK;
+    }
+  else
+    {
+      /* This definition comes from prctl.h, but some kernels may not
+         have it.  */
 #ifndef PTRACE_ARCH_PRCTL
 #define PTRACE_ARCH_PRCTL      30
 #endif
-
-  /* FIXME: ezannoni-2003-07-09 see comment above about include file order.
-     We could be getting bogus values for these two.  */
-  gdb_assert (FS < ELF_NGREG);
-  gdb_assert (GS < ELF_NGREG);
-  switch (idx)
-    {
-    case FS:
-      if (ptrace (PTRACE_ARCH_PRCTL, lwpid, base, ARCH_GET_FS) == 0)
-	return PS_OK;
-      break;
-    case GS:
-      if (ptrace (PTRACE_ARCH_PRCTL, lwpid, base, ARCH_GET_GS) == 0)
-	return PS_OK;
-      break;
-    default:                   /* Should not happen.  */
-      return PS_BADADDR;
+      /* FIXME: ezannoni-2003-07-09 see comment above about include
+	 file order.  We could be getting bogus values for these two.  */
+      gdb_assert (FS < ELF_NGREG);
+      gdb_assert (GS < ELF_NGREG);
+      switch (idx)
+	{
+	case FS:
+	  if (ptrace (PTRACE_ARCH_PRCTL, lwpid, base, ARCH_GET_FS) == 0)
+	    return PS_OK;
+	  break;
+	case GS:
+	  if (ptrace (PTRACE_ARCH_PRCTL, lwpid, base, ARCH_GET_GS) == 0)
+	    return PS_OK;
+	  break;
+	default:                   /* Should not happen.  */
+	  return PS_BADADDR;
+	}
     }
   return PS_ERR;               /* ptrace failed.  */
 }