From ac053946f5c40ce90ca7ccb75ed687612d9eccf9 Mon Sep 17 00:00:00 2001
From: Uros Bizjak <ubizjak@gmail.com>
Date: Mon, 27 Jan 2025 17:05:06 +0100
Subject: [PATCH] compiler.h: introduce TYPEOF_UNQUAL() macro

Define TYPEOF_UNQUAL() to use __typeof_unqual__() as typeof operator when
available, to return unqualified type of the expression.

Current version of sparse doesn't know anything about __typeof_unqual__()
operator.  Avoid the usage of __typeof_unqual__() when sparse checking is
active to prevent sparse errors with unknowing keyword.

Link: https://lkml.kernel.org/r/20250127160709.80604-3-ubizjak@gmail.com
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 include/linux/compiler-clang.h |  8 ++++++++
 include/linux/compiler-gcc.h   |  8 ++++++++
 include/linux/compiler.h       | 20 ++++++++++++++++++++
 3 files changed, 36 insertions(+)

diff --git a/include/linux/compiler-clang.h b/include/linux/compiler-clang.h
index 2e7c2c282f3a..4fc8e26914ad 100644
--- a/include/linux/compiler-clang.h
+++ b/include/linux/compiler-clang.h
@@ -128,3 +128,11 @@
  */
 #define ASM_INPUT_G "ir"
 #define ASM_INPUT_RM "r"
+
+/*
+ * Declare compiler support for __typeof_unqual__() operator.
+ *
+ * Bindgen uses LLVM even if our C compiler is GCC, so we cannot
+ * rely on the auto-detected CONFIG_CC_HAS_TYPEOF_UNQUAL.
+ */
+#define CC_HAS_TYPEOF_UNQUAL (__clang_major__ >= 19)
diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h
index c9b58188ec61..32048052c64a 100644
--- a/include/linux/compiler-gcc.h
+++ b/include/linux/compiler-gcc.h
@@ -137,3 +137,11 @@
 #if GCC_VERSION < 90100
 #undef __alloc_size__
 #endif
+
+/*
+ * Declare compiler support for __typeof_unqual__() operator.
+ *
+ * Bindgen uses LLVM even if our C compiler is GCC, so we cannot
+ * rely on the auto-detected CONFIG_CC_HAS_TYPEOF_UNQUAL.
+ */
+#define CC_HAS_TYPEOF_UNQUAL (__GNUC__ >= 14)
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index 155385754824..3a7a537e13a3 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -210,6 +210,26 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
 #define __must_be_cstr(p) \
 	__BUILD_BUG_ON_ZERO_MSG(__annotated(p, nonstring), "must be cstr (NUL-terminated)")
 
+/*
+ * Use __typeof_unqual__() when available.
+ *
+ * XXX: Remove test for __CHECKER__ once
+ * sparse learns about __typeof_unqual__().
+ */
+#if CC_HAS_TYPEOF_UNQUAL && !defined(__CHECKER__)
+# define USE_TYPEOF_UNQUAL 1
+#endif
+
+/*
+ * Define TYPEOF_UNQUAL() to use __typeof_unqual__() as typeof
+ * operator when available, to return an unqualified type of the exp.
+ */
+#if defined(USE_TYPEOF_UNQUAL)
+# define TYPEOF_UNQUAL(exp) __typeof_unqual__(exp)
+#else
+# define TYPEOF_UNQUAL(exp) __typeof__(exp)
+#endif
+
 #endif /* __KERNEL__ */
 
 /**
-- 
2.25.1