5 files changed, 277 insertions, 168 deletions

diff --git a/gdbserver/linux-amd64-ipa.cc b/gdbserver/linux-amd64-ipa.cc
index f97b0d6..42de7d2 100644
--- a/gdbserver/linux-amd64-ipa.cc
+++ b/gdbserver/linux-amd64-ipa.cc
@@ -169,47 +169,21 @@ supply_static_tracepoint_registers (struct regcache *regcache,
 
 #endif /* HAVE_UST */
 
-#if !defined __ILP32__
-/* Map the tdesc index to xcr0 mask.  */
-static uint64_t idx2mask[X86_TDESC_LAST] = {
-  X86_XSTATE_X87_MASK,
-  X86_XSTATE_SSE_MASK,
-  X86_XSTATE_AVX_MASK,
-  X86_XSTATE_MPX_MASK,
-  X86_XSTATE_AVX_MPX_MASK,
-  X86_XSTATE_AVX_AVX512_MASK,
-  X86_XSTATE_AVX_MPX_AVX512_PKU_MASK,
-};
-#endif
-
 /* Return target_desc to use for IPA, given the tdesc index passed by
    gdbserver.  */
 
 const struct target_desc *
 get_ipa_tdesc (int idx)
 {
-  if (idx >= X86_TDESC_LAST)
-    {
-      internal_error ("unknown ipa tdesc index: %d", idx);
-    }
+  uint64_t xcr0 = x86_linux_tdesc_idx_to_xcr0 (idx);
 
 #if defined __ILP32__
-  switch (idx)
-    {
-    case X86_TDESC_SSE:
-      return amd64_linux_read_description (X86_XSTATE_SSE_MASK, true);
-    case X86_TDESC_AVX:
-      return amd64_linux_read_description (X86_XSTATE_AVX_MASK, true);
-    case X86_TDESC_AVX_AVX512:
-      return amd64_linux_read_description (X86_XSTATE_AVX_AVX512_MASK, true);
-    default:
-      break;
-    }
+  bool is_x32 = true;
 #else
-  return amd64_linux_read_description (idx2mask[idx], false);
+  bool is_x32 = false;
 #endif
 
-  internal_error ("unknown ipa tdesc index: %d", idx);
+  return amd64_linux_read_description (xcr0, is_x32);
 }
 
 /* Allocate buffer for the jump pads.  The branch instruction has a
@@ -277,11 +251,10 @@ void
 initialize_low_tracepoint (void)
 {
 #if defined __ILP32__
-  amd64_linux_read_description (X86_XSTATE_SSE_MASK, true);
-  amd64_linux_read_description (X86_XSTATE_AVX_MASK, true);
-  amd64_linux_read_description (X86_XSTATE_AVX_AVX512_MASK, true);
+  for (auto i = 0; i < x86_linux_x32_ipa_tdesc_count (); i++)
+    amd64_linux_read_description (x86_linux_tdesc_idx_to_xcr0 (i), true);
 #else
-  for (auto i = 0; i < X86_TDESC_LAST; i++)
-    amd64_linux_read_description (idx2mask[i], false);
+  for (auto i = 0; i < x86_linux_amd64_ipa_tdesc_count (); i++)
+    amd64_linux_read_description (x86_linux_tdesc_idx_to_xcr0 (i), false);
 #endif
 }
diff --git a/gdbserver/linux-i386-ipa.cc b/gdbserver/linux-i386-ipa.cc
index 459b805..246bcb9 100644
--- a/gdbserver/linux-i386-ipa.cc
+++ b/gdbserver/linux-i386-ipa.cc
@@ -246,28 +246,15 @@ initialize_fast_tracepoint_trampoline_buffer (void)
     }
 }
 
-/* Map the tdesc index to xcr0 mask.  */
-static uint64_t idx2mask[X86_TDESC_LAST] = {
-  X86_XSTATE_X87_MASK,
-  X86_XSTATE_SSE_MASK,
-  X86_XSTATE_AVX_MASK,
-  X86_XSTATE_MPX_MASK,
-  X86_XSTATE_AVX_MPX_MASK,
-  X86_XSTATE_AVX_AVX512_MASK,
-  X86_XSTATE_AVX_MPX_AVX512_PKU_MASK,
-};
-
 /* Return target_desc to use for IPA, given the tdesc index passed by
    gdbserver.  */
 
 const struct target_desc *
 get_ipa_tdesc (int idx)
 {
-  if (idx >= X86_TDESC_LAST)
-    {
-      internal_error ("unknown ipa tdesc index: %d", idx);
-    }
-  return i386_linux_read_description (idx2mask[idx]);
+  uint64_t xcr0 = x86_linux_tdesc_idx_to_xcr0 (idx);
+
+  return i386_linux_read_description (xcr0);
 }
 
 /* Allocate buffer for the jump pads.  On i386, we can reach an arbitrary
@@ -289,6 +276,6 @@ void
 initialize_low_tracepoint (void)
 {
   initialize_fast_tracepoint_trampoline_buffer ();
-  for (auto i = 0; i < X86_TDESC_LAST; i++)
-    i386_linux_read_description (idx2mask[i]);
+  for (auto i = 0; i < x86_linux_i386_ipa_tdesc_count (); i++)
+    i386_linux_read_description (x86_linux_tdesc_idx_to_xcr0 (i));
 }
diff --git a/gdbserver/linux-x86-low.cc b/gdbserver/linux-x86-low.cc
index 9bf369f..6dbefdb 100644
--- a/gdbserver/linux-x86-low.cc
+++ b/gdbserver/linux-x86-low.cc
@@ -2892,14 +2892,17 @@ x86_target::get_ipa_tdesc_idx ()
   struct regcache *regcache = get_thread_regcache (current_thread, 0);
   const struct target_desc *tdesc = regcache->tdesc;
 
+  if (!use_xml)
+    {
+      if (tdesc == tdesc_i386_linux_no_xml.get ()
 #ifdef __x86_64__
-  return amd64_get_ipa_tdesc_idx (tdesc);
-#endif
-
-  if (tdesc == tdesc_i386_linux_no_xml.get ())
-    return X86_TDESC_SSE;
+	  || tdesc == tdesc_amd64_linux_no_xml.get ()
+#endif /* __x86_64__ */
+	  )
+	return x86_linux_xcr0_to_tdesc_idx (X86_XSTATE_SSE_MASK);
+    }
 
-  return i386_get_ipa_tdesc_idx (tdesc);
+  return x86_linux_xcr0_to_tdesc_idx (xcr0_storage);
 }
 
 /* The linux target ops object.  */
diff --git a/gdbserver/linux-x86-tdesc.cc b/gdbserver/linux-x86-tdesc.cc
index 9fd64d8..87cf368 100644
--- a/gdbserver/linux-x86-tdesc.cc
+++ b/gdbserver/linux-x86-tdesc.cc
@@ -28,96 +28,277 @@
 #include "x86-tdesc.h"
 #include "nat/x86-linux-tdesc.h"
 
-/* Return the right x86_linux_tdesc index for a given XCR0.  Return
-   X86_TDESC_LAST if can't find a match.  */
+/* A structure used to describe a single cpu feature that might, or might
+   not, be checked for when creating a target description for one of i386,
+   amd64, or x32.  */
 
-static enum x86_linux_tdesc
-xcr0_to_tdesc_idx (uint64_t xcr0, bool is_x32)
+struct x86_tdesc_feature {
+  /* The cpu feature mask.  This is a mask against an xcr0 value.  */
+  uint64_t feature;
+
+  /* Is this feature checked when creating an i386 target description.  */
+  bool is_i386;
+
+  /* Is this feature checked when creating an amd64 target description.  */
+  bool is_amd64;
+
+  /* Is this feature checked when creating an x32 target description.  */
+  bool is_x32;
+};
+
+/* A constant table that describes all of the cpu features that are
+   checked when building a target description for i386, amd64, or x32.  */
+
+static constexpr x86_tdesc_feature x86_linux_all_tdesc_features[] = {
+  /* Feature,           i386,	amd64,	x32.  */
+  { X86_XSTATE_PKRU,	true,	true, 	true },
+  { X86_XSTATE_AVX512,	true,	true, 	true },
+  { X86_XSTATE_AVX,	true,	true, 	true },
+  { X86_XSTATE_MPX,	true,	true, 	false },
+  { X86_XSTATE_SSE,	true,	false, 	false },
+  { X86_XSTATE_X87,	true,	false, 	false }
+};
+
+/* Return a compile time constant which is a mask of all the cpu features
+   that are checked for when building an i386 target description.  */
+
+static constexpr uint64_t
+x86_linux_i386_tdesc_feature_mask ()
 {
-  if (xcr0 & X86_XSTATE_PKRU)
-    {
-      if (is_x32)
-	{
-	  /* No x32 MPX and PKU, fall back to avx_avx512.  */
-	  return X86_TDESC_AVX_AVX512;
-	}
-      else
-	return X86_TDESC_AVX_MPX_AVX512_PKU;
-    }
-  else if (xcr0 & X86_XSTATE_AVX512)
-    return X86_TDESC_AVX_AVX512;
-  else if ((xcr0 & X86_XSTATE_AVX_MPX_MASK) == X86_XSTATE_AVX_MPX_MASK)
+  uint64_t mask = 0;
+
+  for (const auto &entry : x86_linux_all_tdesc_features)
+    if (entry.is_i386)
+      mask |= entry.feature;
+
+  return mask;
+}
+
+/* Return a compile time constant which is a mask of all the cpu features
+   that are checked for when building an amd64 target description.  */
+
+static constexpr uint64_t
+x86_linux_amd64_tdesc_feature_mask ()
+{
+  uint64_t mask = 0;
+
+  for (const auto &entry : x86_linux_all_tdesc_features)
+    if (entry.is_amd64)
+      mask |= entry.feature;
+
+  return mask;
+}
+
+/* Return a compile time constant which is a mask of all the cpu features
+   that are checked for when building an x32 target description.  */
+
+static constexpr uint64_t
+x86_linux_x32_tdesc_feature_mask ()
+{
+  uint64_t mask = 0;
+
+  for (const auto &entry : x86_linux_all_tdesc_features)
+    if (entry.is_x32)
+      mask |= entry.feature;
+
+  return mask;
+}
+
+/* Return a compile time constant which is a count of the number of cpu
+   features that are checked for when building an i386 target description.  */
+
+static constexpr int
+x86_linux_i386_tdesc_count ()
+{
+  uint64_t count = 0;
+
+  for (const auto &entry : x86_linux_all_tdesc_features)
+    if (entry.is_i386)
+      ++count;
+
+  gdb_assert (count > 0);
+
+  return (1 << count);
+}
+
+/* Return a compile time constant which is a count of the number of cpu
+   features that are checked for when building an amd64 target description.  */
+
+static constexpr int
+x86_linux_amd64_tdesc_count ()
+{
+  uint64_t count = 0;
+
+  for (const auto &entry : x86_linux_all_tdesc_features)
+    if (entry.is_amd64)
+      ++count;
+
+  gdb_assert (count > 0);
+
+  return (1 << count);
+}
+
+/* Return a compile time constant which is a count of the number of cpu
+   features that are checked for when building an x32 target description.  */
+
+static constexpr int
+x86_linux_x32_tdesc_count ()
+{
+  uint64_t count = 0;
+
+  for (const auto &entry : x86_linux_all_tdesc_features)
+    if (entry.is_x32)
+      ++count;
+
+  gdb_assert (count > 0);
+
+  return (1 << count);
+}
+
+#ifdef IN_PROCESS_AGENT
+
+/* See linux-x86-tdesc.h.  */
+
+int
+x86_linux_amd64_ipa_tdesc_count ()
+{
+  return x86_linux_amd64_tdesc_count ();
+}
+
+/* See linux-x86-tdesc.h.  */
+
+int
+x86_linux_x32_ipa_tdesc_count ()
+{
+  return x86_linux_x32_tdesc_count ();
+}
+
+/* See linux-x86-tdesc.h.  */
+
+int
+x86_linux_i386_ipa_tdesc_count ()
+{
+  return x86_linux_i386_tdesc_count ();
+}
+
+#endif /* IN_PROCESS_AGENT */
+
+/* Convert an xcr0 value into an integer.  The integer will be passed to
+   the in-process-agent where it will then be passed to
+   x86_linux_tdesc_idx_to_xcr0 to get back the xcr0 value.  */
+
+int
+x86_linux_xcr0_to_tdesc_idx (uint64_t xcr0)
+{
+  /* The following table shows which features are checked for when creating
+     the target descriptions (see nat/x86-linux-tdesc.c), the feature order
+     represents the bit order within the generated index number.
+
+     i386  | x87 sse mpx avx avx512 pkru
+     amd64 |         mpx avx avx512 pkru
+     i32   |             avx avx512 pkru
+
+     The features are ordered so that for each mode (i386, amd64, i32) the
+     generated index will form a continuous range.  */
+
+  int idx = 0;
+
+  for (int i = 0; i < ARRAY_SIZE (x86_linux_all_tdesc_features); ++i)
     {
-      if (is_x32) /* No MPX on x32.  */
-	return X86_TDESC_AVX;
-      else
-	return X86_TDESC_AVX_MPX;
+      if ((xcr0 & x86_linux_all_tdesc_features[i].feature) != 0)
+	idx |= (1 << i);
     }
-  else if (xcr0 & X86_XSTATE_MPX)
+
+  return idx;
+}
+
+
+#ifdef IN_PROCESS_AGENT
+
+/* Convert an index number (as returned from x86_linux_xcr0_to_tdesc_idx)
+   into an xcr0 value which can then be used to create a target
+   description.  */
+
+uint64_t
+x86_linux_tdesc_idx_to_xcr0 (int idx)
+{
+  uint64_t xcr0 = 0;
+
+  for (int i = 0; i < ARRAY_SIZE (x86_linux_all_tdesc_features); ++i)
     {
-      if (is_x32) /* No MPX on x32.  */
-	return X86_TDESC_AVX;
-      else
-	return X86_TDESC_MPX;
+      if ((idx & (1 << i)) != 0)
+	xcr0 |= x86_linux_all_tdesc_features[i].feature;
     }
-  else if (xcr0 & X86_XSTATE_AVX)
-    return X86_TDESC_AVX;
-  else if (xcr0 & X86_XSTATE_SSE)
-    return X86_TDESC_SSE;
-  else if (xcr0 & X86_XSTATE_X87)
-    return X86_TDESC_MMX;
-  else
-    return X86_TDESC_LAST;
+
+  return xcr0;
 }
 
+#endif /* IN_PROCESS_AGENT */
+
 #if defined __i386__ || !defined IN_PROCESS_AGENT
 
-static struct target_desc *i386_tdescs[X86_TDESC_LAST] = { };
+/* A cache of all possible i386 target descriptions.  */
 
-/* Return the target description according to XCR0.  */
+static struct target_desc *i386_tdescs[x86_linux_i386_tdesc_count ()] = { };
+
+/* See nat/x86-linux-tdesc.h.  */
 
 const struct target_desc *
 i386_linux_read_description (uint64_t xcr0)
 {
-  enum x86_linux_tdesc idx = xcr0_to_tdesc_idx (xcr0, false);
+  xcr0 &= x86_linux_i386_tdesc_feature_mask ();
+  int idx = x86_linux_xcr0_to_tdesc_idx (xcr0);
 
-  if (idx == X86_TDESC_LAST)
-    return NULL;
+  gdb_assert (idx >= 0 && idx < x86_linux_i386_tdesc_count ());
 
-  struct target_desc **tdesc = &i386_tdescs[idx];
+  target_desc **tdesc = &i386_tdescs[idx];
 
-  if (*tdesc == NULL)
+  if (*tdesc == nullptr)
     {
       *tdesc = i386_create_target_description (xcr0, true, false);
 
       init_target_desc (*tdesc, i386_expedite_regs);
     }
 
-  return *tdesc;;
+  return *tdesc;
 }
 #endif
 
 #ifdef __x86_64__
 
-static target_desc *amd64_tdescs[X86_TDESC_LAST] = { };
-static target_desc *x32_tdescs[X86_TDESC_LAST] = { };
+/* A cache of all possible amd64 target descriptions.  */
+
+static target_desc *amd64_tdescs[x86_linux_amd64_tdesc_count ()] = { };
+
+/* A cache of all possible x32 target descriptions.  */
+
+static target_desc *x32_tdescs[x86_linux_x32_tdesc_count ()] = { };
+
+/* See nat/x86-linux-tdesc.h.  */
 
 const struct target_desc *
 amd64_linux_read_description (uint64_t xcr0, bool is_x32)
 {
-  enum x86_linux_tdesc idx = xcr0_to_tdesc_idx (xcr0, is_x32);
+  if (is_x32)
+    xcr0 &= x86_linux_x32_tdesc_feature_mask ();
+  else
+    xcr0 &= x86_linux_amd64_tdesc_feature_mask ();
+
+  int idx = x86_linux_xcr0_to_tdesc_idx (xcr0);
 
-  if (idx == X86_TDESC_LAST)
-    return NULL;
+  if (is_x32)
+    gdb_assert (idx >= 0 && idx < x86_linux_x32_tdesc_count ());
+  else
+    gdb_assert (idx >= 0 && idx < x86_linux_amd64_tdesc_count ());
 
-  struct target_desc **tdesc = NULL;
+  target_desc **tdesc = nullptr;
 
   if (is_x32)
     tdesc = &x32_tdescs[idx];
   else
     tdesc = &amd64_tdescs[idx];
 
-  if (*tdesc == NULL)
+  if (*tdesc == nullptr)
     {
       *tdesc = amd64_create_target_description (xcr0, is_x32, true, true);
 
@@ -127,39 +308,3 @@ amd64_linux_read_description (uint64_t xcr0, bool is_x32)
 }
 
 #endif
-
-#ifndef IN_PROCESS_AGENT
-
-int
-i386_get_ipa_tdesc_idx (const struct target_desc *tdesc)
-{
-  for (int i = 0; i < X86_TDESC_LAST; i++)
-    {
-      if (tdesc == i386_tdescs[i])
-	return i;
-    }
-
-  /* If none tdesc is found, return the one with minimum features.  */
-  return X86_TDESC_MMX;
-}
-
-#if defined __x86_64__
-int
-amd64_get_ipa_tdesc_idx (const struct target_desc *tdesc)
-{
-  for (int i = 0; i < X86_TDESC_LAST; i++)
-    {
-      if (tdesc == amd64_tdescs[i])
-	return i;
-    }
-  for (int i = 0; i < X86_TDESC_LAST; i++)
-    {
-      if (tdesc == x32_tdescs[i])
-	return i;
-    }
-
-  return X86_TDESC_SSE;
-}
-
-#endif
-#endif
diff --git a/gdbserver/linux-x86-tdesc.h b/gdbserver/linux-x86-tdesc.h
index 576aaf5..70456e4 100644
--- a/gdbserver/linux-x86-tdesc.h
+++ b/gdbserver/linux-x86-tdesc.h
@@ -21,29 +21,30 @@
 #ifndef GDBSERVER_LINUX_X86_TDESC_H
 #define GDBSERVER_LINUX_X86_TDESC_H
 
-/* Note: since IPA obviously knows what ABI it's running on (i386 vs x86_64
-   vs x32), it's sufficient to pass only the register set here.  This,
-   together with the ABI known at IPA compile time, maps to a tdesc.  */
-
-enum x86_linux_tdesc {
-  X86_TDESC_MMX = 0,
-  X86_TDESC_SSE = 1,
-  X86_TDESC_AVX = 2,
-  X86_TDESC_MPX = 3,
-  X86_TDESC_AVX_MPX = 4,
-  X86_TDESC_AVX_AVX512 = 5,
-  X86_TDESC_AVX_MPX_AVX512_PKU = 6,
-  X86_TDESC_LAST = 7,
-};
-
-#if defined __i386__ || !defined IN_PROCESS_AGENT
-int i386_get_ipa_tdesc_idx (const struct target_desc *tdesc);
-#endif
-
-#if defined __x86_64__ && !defined IN_PROCESS_AGENT
-int amd64_get_ipa_tdesc_idx (const struct target_desc *tdesc);
-#endif
-
-const struct target_desc *i386_get_ipa_tdesc (int idx);
+/* Convert an xcr0 value into an integer.  The integer will be passed to
+   the in-process-agent where it will then be passed to
+   x86_linux_tdesc_idx_to_xcr0 to get back the xcr0 value.  */
+
+extern int x86_linux_xcr0_to_tdesc_idx (uint64_t xcr0);
+
+#ifdef IN_PROCESS_AGENT
+
+/* Convert an index number (as returned from x86_linux_xcr0_to_tdesc_idx)
+   into an xcr0 value which can then be used to create a target
+   description.  */
+
+extern uint64_t x86_linux_tdesc_idx_to_xcr0 (int idx);
+
+/* Within the in-process-agent we need to pre-initialise all of the target
+   descriptions, to do this we need to know how many target descriptions
+   there are for each different target type.  These functions return the
+   target description count for the relevant target.  */
+
+extern int x86_linux_amd64_ipa_tdesc_count ();
+extern int x86_linux_x32_ipa_tdesc_count ();
+extern int x86_linux_i386_ipa_tdesc_count ();
+
+
+#endif /* IN_PROCESS_AGENT */
 
 #endif /* GDBSERVER_LINUX_X86_TDESC_H */