[rfc/rft] ppc gdbserver: autodetect AltiVec and SPE

Ulrich Weigand uweigand@de.ibm.com
Wed Mar 26 20:21:00 GMT 2008


Daniel Jacobowitz wrote:
> On Thu, Feb 28, 2008 at 05:57:06PM +0100, Ulrich Weigand wrote:
> > What you do think about this patch?
> 
> It looks great to me.  It may be a little while before I can test
> it, though.  Thanks again for working on this!

Did you get around to testing this?

I've found a problem in --multi mode; it did not reset ppc_hwcap
in ppc_arch_setup before accessing the register cache, causing
gdbserver to crash with "unknown register vr0" on a second attach.

Fixed in the version below.

Bye,
Ulrich


ChangeLog:

	* configure.srv [powerpc64-*-linux*]: Remove powerpc-e500.o from
	srv_regobj.  Remove rs6000/powerpc-e500.xml and rs6000/power-spe.xml	
	from reg_xmlfiles.
	* linux-ppc-low.c: Include <elf.h>.
	(PPC_FEATURE_HAS_ALTIVEC, PPC_FEATURE_HAS_SPE): Define.
	(ppc_hwcap): New global variable.
	(ppc_regmap): Remove __SPE__ #ifdef sections.
	(ppc_regmap_e500): New global variable.
	(ppc_cannot_store_register): Remove __SPE__ special case.
	(ppc_get_hwcap): New function.
	(ppc_arch_setup): Use it to determine whether inferior supports
	AltiVec or SPE registers.  Set the_low_target.regmap if appropriate.
	(ppc_fill_vrregset, ppc_store_vrregset): Define unconditionally.
	Do not access registers if target does not support AltiVec.
	(ppc_fill_evrregset, ppc_store_evrregset): Define unconditionally.
	Do not access registers if target does not support SPE.
	(target_regsets): Unconditionally include AltiVec and SPE regsets.

diff -urNp gdb-orig/gdb/gdbserver/configure.srv gdb-head/gdb/gdbserver/configure.srv
--- gdb-orig/gdb/gdbserver/configure.srv	2008-03-26 20:08:19.614861467 +0100
+++ gdb-head/gdb/gdbserver/configure.srv	2008-03-26 16:44:37.000000000 +0100
@@ -106,15 +106,13 @@ case "${target}" in
 			srv_linux_usrregs=yes
 			srv_linux_thread_db=yes
 			;;
-  powerpc64-*-linux*)	srv_regobj="reg-ppc.o powerpc-32.o powerpc-e500.o"
+  powerpc64-*-linux*)	srv_regobj="reg-ppc.o powerpc-32.o"
 			srv_regobj="${srv_regobj} reg-ppc64.o powerpc-64.o"
 			srv_tgtobj="linux-low.o linux-ppc-low.o"
 			srv_xmlfiles="rs6000/powerpc-32.xml"
 			srv_xmlfiles="${srv_xmlfiles} rs6000/power-altivec.xml"
 			srv_xmlfiles="${srv_xmlfiles} rs6000/power-core.xml"
 			srv_xmlfiles="${srv_xmlfiles} rs6000/power-fpu.xml"
-			srv_xmlfiles="${srv_xmlfiles} rs6000/powerpc-e500.xml"
-			srv_xmlfiles="${srv_xmlfiles} rs6000/power-spe.xml"
 			srv_xmlfiles="${srv_xmlfiles} rs6000/powerpc-64.xml"
 			srv_xmlfiles="${srv_xmlfiles} rs6000/power64-core.xml"
 			srv_linux_usrregs=yes
diff -urNp gdb-orig/gdb/gdbserver/linux-ppc-low.c gdb-head/gdb/gdbserver/linux-ppc-low.c
--- gdb-orig/gdb/gdbserver/linux-ppc-low.c	2008-03-26 20:08:19.622860321 +0100
+++ gdb-head/gdb/gdbserver/linux-ppc-low.c	2008-03-26 20:06:45.447120208 +0100
@@ -21,8 +21,16 @@
 #include "server.h"
 #include "linux-low.h"
 
+#include <elf.h>
 #include <asm/ptrace.h>
 
+/* These are in <asm/cputable.h> in current kernels.  */
+#define PPC_FEATURE_HAS_ALTIVEC         0x10000000
+#define PPC_FEATURE_HAS_SPE             0x00800000
+
+static unsigned long ppc_hwcap;
+
+
 /* Defined in auto-generated file reg-ppc.c.  */
 void init_registers_ppc (void);
 /* Defined in auto-generated file powerpc-32.c.  */
@@ -69,16 +77,6 @@ static int ppc_regmap[] =
   PT_R20 * 4,    PT_R21 * 4,    PT_R22 * 4,    PT_R23 * 4,
   PT_R24 * 4,    PT_R25 * 4,    PT_R26 * 4,    PT_R27 * 4,
   PT_R28 * 4,    PT_R29 * 4,    PT_R30 * 4,    PT_R31 * 4,
-#ifdef __SPE__
-  -1,            -1,            -1,            -1,
-  -1,            -1,            -1,            -1,
-  -1,            -1,            -1,            -1,
-  -1,            -1,            -1,            -1,
-  -1,            -1,            -1,            -1,
-  -1,            -1,            -1,            -1,
-  -1,            -1,            -1,            -1,
-  -1,            -1,            -1,            -1,
-#else
   PT_FPR0*4,     PT_FPR0*4 + 8, PT_FPR0*4+16,  PT_FPR0*4+24,
   PT_FPR0*4+32,  PT_FPR0*4+40,  PT_FPR0*4+48,  PT_FPR0*4+56,
   PT_FPR0*4+64,  PT_FPR0*4+72,  PT_FPR0*4+80,  PT_FPR0*4+88,
@@ -87,20 +85,36 @@ static int ppc_regmap[] =
   PT_FPR0*4+160,  PT_FPR0*4+168,  PT_FPR0*4+176,  PT_FPR0*4+184,
   PT_FPR0*4+192,  PT_FPR0*4+200,  PT_FPR0*4+208,  PT_FPR0*4+216,
   PT_FPR0*4+224,  PT_FPR0*4+232,  PT_FPR0*4+240,  PT_FPR0*4+248,
-#endif
   PT_NIP * 4,    PT_MSR * 4,    PT_CCR * 4,    PT_LNK * 4,
-#ifdef __SPE__
-  PT_CTR * 4,    PT_XER * 4,    -1
-#else
   PT_CTR * 4,    PT_XER * 4,    PT_FPSCR * 4
-#endif
+ };
+
+static int ppc_regmap_e500[] =
+ {PT_R0 * 4,     PT_R1 * 4,     PT_R2 * 4,     PT_R3 * 4,
+  PT_R4 * 4,     PT_R5 * 4,     PT_R6 * 4,     PT_R7 * 4,
+  PT_R8 * 4,     PT_R9 * 4,     PT_R10 * 4,    PT_R11 * 4,
+  PT_R12 * 4,    PT_R13 * 4,    PT_R14 * 4,    PT_R15 * 4,
+  PT_R16 * 4,    PT_R17 * 4,    PT_R18 * 4,    PT_R19 * 4,
+  PT_R20 * 4,    PT_R21 * 4,    PT_R22 * 4,    PT_R23 * 4,
+  PT_R24 * 4,    PT_R25 * 4,    PT_R26 * 4,    PT_R27 * 4,
+  PT_R28 * 4,    PT_R29 * 4,    PT_R30 * 4,    PT_R31 * 4,
+  -1,            -1,            -1,            -1,
+  -1,            -1,            -1,            -1,
+  -1,            -1,            -1,            -1,
+  -1,            -1,            -1,            -1,
+  -1,            -1,            -1,            -1,
+  -1,            -1,            -1,            -1,
+  -1,            -1,            -1,            -1,
+  -1,            -1,            -1,            -1,
+  PT_NIP * 4,    PT_MSR * 4,    PT_CCR * 4,    PT_LNK * 4,
+  PT_CTR * 4,    PT_XER * 4,    -1
  };
 #endif
 
 static int
 ppc_cannot_store_register (int regno)
 {
-#if !defined (__powerpc64__) && !defined (__SPE__)
+#ifndef __powerpc64__
   /* Some kernels do not allow us to store fpscr.  */
   if (regno == find_regno ("fpscr"))
     return 2;
@@ -167,35 +181,83 @@ ppc_set_pc (CORE_ADDR pc)
     }
 }
 
+
+static int
+ppc_get_hwcap (unsigned long *valp)
+{
+  int wordsize = register_size (0);
+  unsigned char *data = alloca (2 * wordsize);
+  int offset = 0;
+
+  while ((*the_target->read_auxv) (offset, data, 2 * wordsize) == 2 * wordsize)
+    {
+      if (wordsize == 4)
+	{
+	  unsigned int *data_p = (unsigned int *)data;
+	  if (data_p[0] == AT_HWCAP)
+	    {
+	      *valp = data_p[1];
+	      return 1;
+	    }
+	}
+      else
+	{
+	  unsigned long *data_p = (unsigned long *)data;
+	  if (data_p[0] == AT_HWCAP)
+	    {
+	      *valp = data_p[1];
+	      return 1;
+	    }
+	}
+
+      offset += 2 * wordsize;
+    }
+
+  *valp = 0;
+  return 0;
+}
+
 static void
 ppc_arch_setup (void)
 {
 #ifdef __powerpc64__
   long msr;
 
-  /* On a 64-bit host, assume 64-bit inferior process.  */
-#ifdef __ALTIVEC__
-  init_registers_powerpc_64 ();
-#else
+  /* On a 64-bit host, assume 64-bit inferior process with no
+     AltiVec registers.  This is required to make sure the
+     collect_register call below does not fail.  */
   init_registers_ppc64 ();
-#endif
+  ppc_hwcap = 0;
 
   /* Only if the high bit of the MSR is set, we actually have
      a 64-bit inferior.  */
   collect_register_by_name ("msr", &msr);
   if (msr < 0)
-    return;
+    {
+      ppc_get_hwcap (&ppc_hwcap);
+      if (ppc_hwcap & PPC_FEATURE_HAS_ALTIVEC)
+	init_registers_powerpc_64 ();
+
+      return;
+    }
 #endif
 
   /* OK, we have a 32-bit inferior.  */
-#ifdef __ALTIVEC__
-  init_registers_powerpc_32 ();
-#else
-#ifdef __SPE__
-  init_registers_powerpc_e500 ();
-#else
   init_registers_ppc ();
-#endif
+
+  ppc_get_hwcap (&ppc_hwcap);
+  if (ppc_hwcap & PPC_FEATURE_HAS_ALTIVEC)
+    init_registers_powerpc_32 ();
+
+  /* On 32-bit machines, check for SPE registers.
+     Set the low target's regmap field as appropriately.  */
+#ifndef __powerpc64__
+  the_low_target.regmap = ppc_regmap;
+  if (ppc_hwcap & PPC_FEATURE_HAS_SPE)
+    {
+      init_registers_powerpc_e500 ();
+      the_low_target.regmap = ppc_regmap_e500;
+   }
 #endif
 }
 
@@ -232,8 +294,6 @@ static void ppc_fill_gregset (void *buf)
     ppc_collect_ptrace_register (i, (char *) buf + ppc_regmap[i]);
 }
 
-#ifdef __ALTIVEC__
-
 #ifndef PTRACE_GETVRREGS
 #define PTRACE_GETVRREGS 18
 #define PTRACE_SETVRREGS 19
@@ -247,6 +307,9 @@ ppc_fill_vrregset (void *buf)
   int i, base;
   char *regset = buf;
 
+  if (!(ppc_hwcap & PPC_FEATURE_HAS_ALTIVEC))
+    return;
+
   base = find_regno ("vr0");
   for (i = 0; i < 32; i++)
     collect_register (base + i, &regset[i * 16]);
@@ -261,6 +324,9 @@ ppc_store_vrregset (const void *buf)
   int i, base;
   const char *regset = buf;
 
+  if (!(ppc_hwcap & PPC_FEATURE_HAS_ALTIVEC))
+    return;
+
   base = find_regno ("vr0");
   for (i = 0; i < 32; i++)
     supply_register (base + i, &regset[i * 16]);
@@ -269,10 +335,6 @@ ppc_store_vrregset (const void *buf)
   supply_register_by_name ("vrsave", &regset[33 * 16]);
 }
 
-#endif /* __ALTIVEC__ */
-
-#ifdef __SPE__
-
 #ifndef PTRACE_GETEVRREGS
 #define PTRACE_GETEVRREGS	20
 #define PTRACE_SETEVRREGS	21
@@ -291,6 +353,9 @@ ppc_fill_evrregset (void *buf)
   int i, ev0;
   struct gdb_evrregset_t *regset = buf;
 
+  if (!(ppc_hwcap & PPC_FEATURE_HAS_SPE))
+    return;
+
   ev0 = find_regno ("ev0h");
   for (i = 0; i < 32; i++)
     collect_register (ev0 + i, &regset->evr[i]);
@@ -305,6 +370,9 @@ ppc_store_evrregset (const void *buf)
   int i, ev0;
   const struct gdb_evrregset_t *regset = buf;
 
+  if (!(ppc_hwcap & PPC_FEATURE_HAS_SPE))
+    return;
+
   ev0 = find_regno ("ev0h");
   for (i = 0; i < 32; i++)
     supply_register (ev0 + i, &regset->evr[i]);
@@ -312,21 +380,16 @@ ppc_store_evrregset (const void *buf)
   supply_register_by_name ("acc", &regset->acc);
   supply_register_by_name ("spefscr", &regset->spefscr);
 }
-#endif /* __SPE__ */
 
 struct regset_info target_regsets[] = {
   /* List the extra register sets before GENERAL_REGS.  That way we will
      fetch them every time, but still fall back to PTRACE_PEEKUSER for the
      general registers.  Some kernels support these, but not the newer
      PPC_PTRACE_GETREGS.  */
-#ifdef __ALTIVEC__
   { PTRACE_GETVRREGS, PTRACE_SETVRREGS, SIZEOF_VRREGS, EXTENDED_REGS,
     ppc_fill_vrregset, ppc_store_vrregset },
-#endif
-#ifdef __SPE__
   { PTRACE_GETEVRREGS, PTRACE_SETEVRREGS, 32 * 4 + 8 + 4, EXTENDED_REGS,
     ppc_fill_evrregset, ppc_store_evrregset },
-#endif
   { 0, 0, 0, GENERAL_REGS, ppc_fill_gregset, NULL },
   { 0, 0, -1, -1, NULL, NULL }
 };


-- 
  Dr. Ulrich Weigand
  GNU Toolchain for Linux on System z and Cell BE
  Ulrich.Weigand@de.ibm.com



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