linux-kernel - [PATCH bpf-next 2/3] bpf: selftests: Add bpf_assert_if() and bpf_assert_with

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Date: Thu, 14 Dec 2023 15:56:26 -0700
From: Daniel Xu <dxu@...uu.xyz>
To: ast@...nel.org,
	daniel@...earbox.net,
	andrii@...nel.org,
	shuah@...nel.org,
	memxor@...il.com
Cc: martin.lau@...ux.dev,
	song@...nel.org,
	yonghong.song@...ux.dev,
	john.fastabend@...il.com,
	kpsingh@...nel.org,
	sdf@...gle.com,
	haoluo@...gle.com,
	jolsa@...nel.org,
	mykolal@...com,
	bpf@...r.kernel.org,
	linux-kselftest@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH bpf-next 2/3] bpf: selftests: Add bpf_assert_if() and bpf_assert_with_if() macros

These macros are a temporary stop-gap until bpf exceptions support
unwinding acquired entities. Basically these macros act as if they take
a callback which only get executed if the assertion fails.

Signed-off-by: Daniel Xu <dxu@...uu.xyz>
---
 .../testing/selftests/bpf/bpf_experimental.h  | 22 +++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/tools/testing/selftests/bpf/bpf_experimental.h b/tools/testing/selftests/bpf/bpf_experimental.h
index 1386baf9ae4a..d63f415bef26 100644
--- a/tools/testing/selftests/bpf/bpf_experimental.h
+++ b/tools/testing/selftests/bpf/bpf_experimental.h
@@ -263,6 +263,17 @@ extern void bpf_throw(u64 cookie) __ksym;
  */
 #define bpf_assert(cond) if (!(cond)) bpf_throw(0);
 
+/* Description
+ *	Assert that a conditional expression is true. If false, runs code in the
+ *	body before throwing.
+ * Returns
+ *	Void.
+ * Throws
+ *	An exception with the value zero when the assertion fails.
+ */
+#define bpf_assert_if(cond) \
+	for (int ___i = 0, ___j = !!(cond); !(___j) && !___i; bpf_throw(0), ___i++)
+
 /* Description
  *	Assert that a conditional expression is true.
  * Returns
@@ -272,6 +283,17 @@ extern void bpf_throw(u64 cookie) __ksym;
  */
 #define bpf_assert_with(cond, value) if (!(cond)) bpf_throw(value);
 
+/* Description
+ *	Assert that a conditional expression is true. If false, runs code in the
+ *	body before throwing.
+ * Returns
+ *	Void.
+ * Throws
+ *	An exception with the given value when the assertion fails.
+ */
+#define bpf_assert_with_if(cond, value) \
+	for (int ___i = 0, ___j = !!(cond); !(___j) && !___i; bpf_throw(value), ___i++)
+
 /* Description
  *	Assert that LHS is equal to RHS. This statement updates the known value
  *	of LHS during verification. Note that RHS must be a constant value, and
-- 
2.42.1