[DTrace-devel] [PATCH] test: Account for pid:::entry ucaller being correct

[eugene.loh at oracle.com]

From: Eugene Loh <eugene.loh at oracle.com>

In commit f38bdf9ea ("test: Account for pid:::entry ustack() being correct")
we accounted for x86-specific heuristics introduced in Linux 6.11 that
dealt with pid:::entry uprobes firing so early in the function preamble
that the frame pointer is not yet set and the caller is not (yet)
correctly identified.

Update a related test to account for the same effect with ucaller.

Signed-off-by: Eugene Loh <eugene.loh at oracle.com>
---
 test/unittest/vars/tst.ucaller.r.p | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)
 create mode 100755 test/unittest/vars/tst.ucaller.r.p

diff --git a/test/unittest/vars/tst.ucaller.r.p b/test/unittest/vars/tst.ucaller.r.p
new file mode 100755
index 000000000..8e03f110d
--- /dev/null
+++ b/test/unittest/vars/tst.ucaller.r.p
@@ -0,0 +1,28 @@
+#!/bin/sh
+
+# A pid entry probe places a uprobe on the first instruction of a function.
+# Unfortunately, this is so early in the function preamble that the function
+# frame pointer has not yet been established and the actual caller of the
+# traced function is missed.
+#
+# In Linux 6.11, x86-specific heuristics are introduced to fix this problem.
+# See commit cfa7f3d
+# ("perf,x86: avoid missing caller address in stack traces captured in uprobe")
+# for both a description of the problem and an explanation of the heuristics.
+#
+# Add post processing to these test results to allow for both cases:
+# caller frame is missing or not missing.
+
+if [ $(uname -m) == "x86_64" ]; then
+        read MAJOR MINOR <<< `uname -r | grep -Eo '^[0-9]+\.[0-9]+' | tr '.' ' '`
+
+        if [ $MAJOR -ge 6 ]; then
+                if [ $MAJOR -gt 6 -o $MINOR -ge 11 ]; then
+                        awk '{ sub("myfunc_w", "myfunc_v"); print; }'
+                        exit 0
+                fi
+        fi
+fi
+
+# Otherwise, just pass the output through.
+cat
-- 
2.43.5