[Qemu-devel] [PATCH v3 12/12] decodetree: Properly diagnose fields overflowing an insn

[Richard Henderson]

Previously this would result in an exception for shifting
the field mask by a negative number.

Signed-off-by: Richard Henderson <address@hidden>
---
 scripts/decodetree.py          | 2 ++
 tests/decode/err_width1.decode | 5 +++++
 tests/decode/err_width2.decode | 5 +++++
 tests/decode/err_width3.decode | 5 +++++
 tests/decode/err_width4.decode | 5 +++++
 5 files changed, 22 insertions(+)
 create mode 100644 tests/decode/err_width1.decode
 create mode 100644 tests/decode/err_width2.decode
 create mode 100644 tests/decode/err_width3.decode
 create mode 100644 tests/decode/err_width4.decode

diff --git a/scripts/decodetree.py b/scripts/decodetree.py
index f8df89e072..7e890ecf1a 100755
--- a/scripts/decodetree.py
+++ b/scripts/decodetree.py
@@ -622,6 +622,8 @@ def parse_generic(lineno, is_format, name, toks):
                 sign = True
                 flen = flen[1:]
             shift = int(flen, 10)
+            if shift + width > insnwidth:
+                error(lineno, 'field {0} exceeds insnwidth'.format(fname))
             f = Field(sign, insnwidth - width - shift, shift)
             flds = add_field(lineno, flds, fname, f)
             fixedbits <<= shift
diff --git a/tests/decode/err_width1.decode b/tests/decode/err_width1.decode
new file mode 100644
index 0000000000..0c14f6d73b
--- /dev/null
+++ b/tests/decode/err_width1.decode
@@ -0,0 +1,5 @@
+# This work is licensed under the terms of the GNU LGPL, version 2 or later.
+# See the COPYING.LIB file in the top-level directory.
+
+# Diagnose too many bits (33 of 32)
+one    000000000000000000000000000000000
diff --git a/tests/decode/err_width2.decode b/tests/decode/err_width2.decode
new file mode 100644
index 0000000000..47f0acf322
--- /dev/null
+++ b/tests/decode/err_width2.decode
@@ -0,0 +1,5 @@
+# This work is licensed under the terms of the GNU LGPL, version 2 or later.
+# See the COPYING.LIB file in the top-level directory.
+
+# Diagnose too few bits (31 of 32)
+one    0000000000000000000000000000000
diff --git a/tests/decode/err_width3.decode b/tests/decode/err_width3.decode
new file mode 100644
index 0000000000..c5fb6b3699
--- /dev/null
+++ b/tests/decode/err_width3.decode
@@ -0,0 +1,5 @@
+# This work is licensed under the terms of the GNU LGPL, version 2 or later.
+# See the COPYING.LIB file in the top-level directory.
+
+# Diagnose too many bits (33 of 32)
+one    0 s:32
diff --git a/tests/decode/err_width4.decode b/tests/decode/err_width4.decode
new file mode 100644
index 0000000000..1588a63698
--- /dev/null
+++ b/tests/decode/err_width4.decode
@@ -0,0 +1,5 @@
+# This work is licensed under the terms of the GNU LGPL, version 2 or later.
+# See the COPYING.LIB file in the top-level directory.
+
+# Diagnose too few bits (31 of 32)
+one    0 s:30
-- 
2.17.2