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Date:   Tue,  8 Aug 2023 12:17:26 +0200
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Subject: [PATCH v3 2/3] list_debug: Introduce inline wrappers for debug checks
From:   Marco Elver <elver@google.com>
To:     elver@google.com, Andrew Morton <akpm@linux-foundation.org>,
        Kees Cook <keescook@chromium.org>
Cc:     Guenter Roeck <linux@roeck-us.net>,
        Peter Zijlstra <peterz@infradead.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Marc Zyngier <maz@kernel.org>,
        Oliver Upton <oliver.upton@linux.dev>,
        James Morse <james.morse@arm.com>,
        Suzuki K Poulose <suzuki.poulose@arm.com>,
        Zenghui Yu <yuzenghui@huawei.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>,
        Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Tom Rix <trix@redhat.com>, Miguel Ojeda <ojeda@kernel.org>,
        Sami Tolvanen <samitolvanen@google.com>,
        linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev,
        linux-kernel@vger.kernel.org, llvm@lists.linux.dev,
        Dmitry Vyukov <dvyukov@google.com>,
        Alexander Potapenko <glider@google.com>,
        kasan-dev@googlegroups.com, linux-toolchains@vger.kernel.org
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Turn the list debug checking functions __list_*_valid() into inline
functions that wrap the out-of-line functions. Care is taken to ensure
the inline wrappers are always inlined, so that additional compiler
instrumentation (such as sanitizers) does not result in redundant
outlining.

This change is preparation for performing checks in the inline wrappers.

No functional change intended.

Signed-off-by: Marco Elver <elver@google.com>
---
v3:
* Rename ___list_*_valid() to __list_*_valid_or_report().
* Some documentation.
---
 arch/arm64/kvm/hyp/nvhe/list_debug.c |  6 ++---
 include/linux/list.h                 | 37 +++++++++++++++++++++++++---
 lib/list_debug.c                     | 11 ++++-----
 3 files changed, 41 insertions(+), 13 deletions(-)

diff --git a/arch/arm64/kvm/hyp/nvhe/list_debug.c b/arch/arm64/kvm/hyp/nvhe/list_debug.c
index d68abd7ea124..16266a939a4c 100644
--- a/arch/arm64/kvm/hyp/nvhe/list_debug.c
+++ b/arch/arm64/kvm/hyp/nvhe/list_debug.c
@@ -26,8 +26,8 @@ static inline __must_check bool nvhe_check_data_corruption(bool v)
 
 /* The predicates checked here are taken from lib/list_debug.c. */
 
-bool __list_add_valid(struct list_head *new, struct list_head *prev,
-		      struct list_head *next)
+bool __list_add_valid_or_report(struct list_head *new, struct list_head *prev,
+				struct list_head *next)
 {
 	if (NVHE_CHECK_DATA_CORRUPTION(next->prev != prev) ||
 	    NVHE_CHECK_DATA_CORRUPTION(prev->next != next) ||
@@ -37,7 +37,7 @@ bool __list_add_valid(struct list_head *new, struct list_head *prev,
 	return true;
 }
 
-bool __list_del_entry_valid(struct list_head *entry)
+bool __list_del_entry_valid_or_report(struct list_head *entry)
 {
 	struct list_head *prev, *next;
 
diff --git a/include/linux/list.h b/include/linux/list.h
index f10344dbad4d..130c6a1bb45c 100644
--- a/include/linux/list.h
+++ b/include/linux/list.h
@@ -39,10 +39,39 @@ static inline void INIT_LIST_HEAD(struct list_head *list)
 }
 
 #ifdef CONFIG_DEBUG_LIST
-extern bool __list_add_valid(struct list_head *new,
-			      struct list_head *prev,
-			      struct list_head *next);
-extern bool __list_del_entry_valid(struct list_head *entry);
+/*
+ * Performs the full set of list corruption checks before __list_add().
+ * On list corruption reports a warning, and returns false.
+ */
+extern bool __list_add_valid_or_report(struct list_head *new,
+				       struct list_head *prev,
+				       struct list_head *next);
+
+/*
+ * Performs list corruption checks before __list_add(). Returns false if a
+ * corruption is detected, true otherwise.
+ */
+static __always_inline bool __list_add_valid(struct list_head *new,
+					     struct list_head *prev,
+					     struct list_head *next)
+{
+	return __list_add_valid_or_report(new, prev, next);
+}
+
+/*
+ * Performs the full set of list corruption checks before __list_del_entry().
+ * On list corruption reports a warning, and returns false.
+ */
+extern bool __list_del_entry_valid_or_report(struct list_head *entry);
+
+/*
+ * Performs list corruption checks before __list_del_entry(). Returns false if a
+ * corruption is detected, true otherwise.
+ */
+static __always_inline bool __list_del_entry_valid(struct list_head *entry)
+{
+	return __list_del_entry_valid_or_report(entry);
+}
 #else
 static inline bool __list_add_valid(struct list_head *new,
 				struct list_head *prev,
diff --git a/lib/list_debug.c b/lib/list_debug.c
index d98d43f80958..2def33b1491f 100644
--- a/lib/list_debug.c
+++ b/lib/list_debug.c
@@ -17,8 +17,8 @@
  * attempt).
  */
 
-bool __list_add_valid(struct list_head *new, struct list_head *prev,
-		      struct list_head *next)
+bool __list_add_valid_or_report(struct list_head *new, struct list_head *prev,
+				struct list_head *next)
 {
 	if (CHECK_DATA_CORRUPTION(prev == NULL,
 			"list_add corruption. prev is NULL.\n") ||
@@ -37,9 +37,9 @@ bool __list_add_valid(struct list_head *new, struct list_head *prev,
 
 	return true;
 }
-EXPORT_SYMBOL(__list_add_valid);
+EXPORT_SYMBOL(__list_add_valid_or_report);
 
-bool __list_del_entry_valid(struct list_head *entry)
+bool __list_del_entry_valid_or_report(struct list_head *entry)
 {
 	struct list_head *prev, *next;
 
@@ -65,6 +65,5 @@ bool __list_del_entry_valid(struct list_head *entry)
 		return false;
 
 	return true;
-
 }
-EXPORT_SYMBOL(__list_del_entry_valid);
+EXPORT_SYMBOL(__list_del_entry_valid_or_report);
-- 
2.41.0.640.ga95def55d0-goog