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[PATCH] xen/check-endbr.sh: Explain the purpose of the script
- To: Xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxxx>
- From: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
- Date: Tue, 26 Jul 2022 15:23:28 +0100
- Authentication-results: esa6.hc3370-68.iphmx.com; dkim=none (message not signed) header.i=none
- Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Jan Beulich <JBeulich@xxxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>, Wei Liu <wl@xxxxxxx>
- Delivery-date: Tue, 26 Jul 2022 14:24:07 +0000
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Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>
CC: Wei Liu <wl@xxxxxxx>
---
xen/tools/check-endbr.sh | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/xen/tools/check-endbr.sh b/xen/tools/check-endbr.sh
index b97684ac25e9..bf153a570db4 100755
--- a/xen/tools/check-endbr.sh
+++ b/xen/tools/check-endbr.sh
@@ -2,6 +2,15 @@
#
# Usage ./$0 xen-syms
#
+# When CET-IBT (Control-flow Enforcement Technology, Indirect Branch Tracking)
+# is active, ENDBR instructions mark legal indirect branch targets in the
+# .text section.
+#
+# However x86 is a variable length instruction set so the same byte pattern
+# can exist embedded in other instructions, or crossing multiple instructions.
+# This script searches .text for any problematic byte patterns which aren't
+# legitimate ENDBR instructions.
+#
set -e
# Pretty-print parameters a little for message
--
2.11.0
|
