diff mbox

[pushed] Improve target description check for SVE in gdbserver

Message ID 20191120165922.A429328172@gnutoolchain-gerrit.osci.io
State New, archived
Headers

Commit Message

Simon Marchi (Code Review) Nov. 20, 2019, 4:59 p.m. UTC 
  Sourceware to Gerrit sync has submitted this change.

Change URL: https://gnutoolchain-gerrit.osci.io/r/c/binutils-gdb/+/690
......................................................................

Improve target description check for SVE in gdbserver

The current code checks for the presence of a SVE target description by
comparing the number of registers.  This is a bit fragile since the number
of registers can change whenever we add new sets. Like PAC, for example.

If the comparison breaks, then we're left with SVE registers in the
description, but gdbserver doesn't send the registers to GDB, which in
turn displays stale information to the user.

The following patch changes the check to use the SVE feature string instead,
which hopefully should be more stable.

gdb/gdbserver/ChangeLog:

2019-11-20  Luis Machado  <luis.machado@linaro.org>

	* linux-aarch64-low.c (is_sve_tdesc): Check against target feature
	instead of register count.
	* tdesc.c (tdesc_contains_feature): New function.
	* tdesc.h (tdesc_contains_feature): New prototype.

Change-Id: I28b782cb1677560ca9a06a1be442974b25aabae4
---
M gdb/gdbserver/ChangeLog
M gdb/gdbserver/linux-aarch64-low.c
M gdb/gdbserver/tdesc.c
M gdb/gdbserver/tdesc.h
4 files changed, 29 insertions(+), 1 deletion(-)
diff mbox

Patch

diff --git a/gdb/gdbserver/ChangeLog b/gdb/gdbserver/ChangeLog
index fde6abb..a5da6b5 100644
--- a/gdb/gdbserver/ChangeLog
+++ b/gdb/gdbserver/ChangeLog
@@ -1,3 +1,10 @@ 
+2019-11-20  Luis Machado  <luis.machado@linaro.org>
+
+	* linux-aarch64-low.c (is_sve_tdesc): Check against target feature
+	instead of register count.
+	* tdesc.c (tdesc_contains_feature): New function.
+	* tdesc.h (tdesc_contains_feature): New prototype.
+
 2019-11-15  Christian Biesinger  <cbiesinger@google.com>
 
 	* Makefile.in: Add safe-strerror.c.
diff --git a/gdb/gdbserver/linux-aarch64-low.c b/gdb/gdbserver/linux-aarch64-low.c
index 87a21a0..9e234e0 100644
--- a/gdb/gdbserver/linux-aarch64-low.c
+++ b/gdb/gdbserver/linux-aarch64-low.c
@@ -83,7 +83,7 @@ 
 {
   struct regcache *regcache = get_thread_regcache (current_thread, 0);
 
-  return regcache->tdesc->reg_defs.size () == AARCH64_SVE_NUM_REGS;
+  return tdesc_contains_feature (regcache->tdesc, "org.gnu.gdb.aarch64.sve");
 }
 
 static void
diff --git a/gdb/gdbserver/tdesc.c b/gdb/gdbserver/tdesc.c
index 92a0a60..817e69a 100644
--- a/gdb/gdbserver/tdesc.c
+++ b/gdb/gdbserver/tdesc.c
@@ -186,3 +186,19 @@ 
   tdesc->features.emplace_back (new_feature);
   return new_feature;
 }
+
+/* See gdbsupport/tdesc.h.  */
+
+bool
+tdesc_contains_feature (const target_desc *tdesc, const std::string &feature)
+{
+  gdb_assert (tdesc != nullptr);
+
+  for (const tdesc_feature_up &f : tdesc->features)
+    {
+      if (f->name == feature)
+	return true;
+    }
+
+  return false;
+}
diff --git a/gdb/gdbserver/tdesc.h b/gdb/gdbserver/tdesc.h
index b93f53c..da21cda 100644
--- a/gdb/gdbserver/tdesc.h
+++ b/gdb/gdbserver/tdesc.h
@@ -93,4 +93,9 @@ 
 
 const struct target_desc *current_target_desc (void);
 
+/* Return true if TDESC contains the feature described by string FEATURE.
+   Return false otherwise.  */
+bool tdesc_contains_feature (const target_desc *tdesc,
+			     const std::string &feature);
+
 #endif /* GDBSERVER_TDESC_H */