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Date:   Tue, 29 Sep 2020 12:22:04 -0700
Message-Id: <20200929192204.499006-1-ndesaulniers@google.com>
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Subject: [PATCH] srcu: avoid escaped section names
From:   Nick Desaulniers <ndesaulniers@google.com>
To:     "Paul E . McKenney" <paulmck@kernel.org>
Cc:     Steven Rostedt <rostedt@goodmis.org>,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        Lai Jiangshan <jiangshanlai@gmail.com>,
        Josh Triplett <josh@joshtriplett.org>,
        Kees Cook <keescook@chromium.org>,
        linux-kernel@vger.kernel.org, rcu@vger.kernel.org,
        clang-built-linux@googlegroups.com,
        Nick Desaulniers <ndesaulniers@google.com>
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Precedence: bulk

The stringification operator, `#`, in the preprocessor escapes strings.
For example, `# "foo"` becomes `"\"foo\""`.  GCC and Clang differ in how
they treat section names that contain \".

The portable solution is to not use a string literal with the
preprocessor stringification operator.

Link: https://bugs.llvm.org/show_bug.cgi?id=42950
Fixes: commit fe15b50cdeee ("srcu: Allocate per-CPU data for DEFINE_SRCU() in modules")
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
---
 arch/arm/Kconfig         |  1 +
 arch/arm/mm/Kconfig      | 11 +++++++++++
 include/linux/srcutree.h |  2 +-
 3 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index fe2f17eb2b50..51200e371faf 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -358,6 +358,7 @@ config ARCH_EBSA110
 
 config ARCH_EP93XX
 	bool "EP93xx-based"
+	depends on !LD_IS_LLD
 	select ARCH_SPARSEMEM_ENABLE
 	select ARM_AMBA
 	imply ARM_PATCH_PHYS_VIRT
diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig
index 65e4482e3849..c06787c9bb48 100644
--- a/arch/arm/mm/Kconfig
+++ b/arch/arm/mm/Kconfig
@@ -9,6 +9,7 @@ comment "Processor Type"
 config CPU_ARM7TDMI
 	bool
 	depends on !MMU
+	depends on !LD_IS_LLD
 	select CPU_32v4T
 	select CPU_ABRT_LV4T
 	select CPU_CACHE_V4
@@ -23,6 +24,7 @@ config CPU_ARM7TDMI
 # ARM720T
 config CPU_ARM720T
 	bool
+	depends on !LD_IS_LLD
 	select CPU_32v4T
 	select CPU_ABRT_LV4T
 	select CPU_CACHE_V4
@@ -43,6 +45,7 @@ config CPU_ARM720T
 config CPU_ARM740T
 	bool
 	depends on !MMU
+	depends on !LD_IS_LLD
 	select CPU_32v4T
 	select CPU_ABRT_LV4T
 	select CPU_CACHE_V4
@@ -61,6 +64,7 @@ config CPU_ARM740T
 config CPU_ARM9TDMI
 	bool
 	depends on !MMU
+	depends on !LD_IS_LLD
 	select CPU_32v4T
 	select CPU_ABRT_NOMMU
 	select CPU_CACHE_V4
@@ -75,6 +79,7 @@ config CPU_ARM9TDMI
 # ARM920T
 config CPU_ARM920T
 	bool
+	depends on !LD_IS_LLD
 	select CPU_32v4T
 	select CPU_ABRT_EV4T
 	select CPU_CACHE_V4WT
@@ -94,6 +99,7 @@ config CPU_ARM920T
 # ARM922T
 config CPU_ARM922T
 	bool
+	depends on !LD_IS_LLD
 	select CPU_32v4T
 	select CPU_ABRT_EV4T
 	select CPU_CACHE_V4WT
@@ -114,6 +120,7 @@ config CPU_ARM922T
 # ARM925T
 config CPU_ARM925T
 	bool
+	depends on !LD_IS_LLD
 	select CPU_32v4T
 	select CPU_ABRT_EV4T
 	select CPU_CACHE_V4WT
@@ -153,6 +160,7 @@ config CPU_ARM926T
 # FA526
 config CPU_FA526
 	bool
+	depends on !LD_IS_LLD
 	select CPU_32v4
 	select CPU_ABRT_EV4
 	select CPU_CACHE_FA
@@ -172,6 +180,7 @@ config CPU_FA526
 config CPU_ARM940T
 	bool
 	depends on !MMU
+	depends on !LD_IS_LLD
 	select CPU_32v4T
 	select CPU_ABRT_NOMMU
 	select CPU_CACHE_VIVT
@@ -278,6 +287,7 @@ config CPU_ARM1026
 # SA110
 config CPU_SA110
 	bool
+	depends on !LD_IS_LLD
 	select CPU_32v3 if ARCH_RPC
 	select CPU_32v4 if !ARCH_RPC
 	select CPU_ABRT_EV4
@@ -299,6 +309,7 @@ config CPU_SA110
 # SA1100
 config CPU_SA1100
 	bool
+	depends on !LD_IS_LLD
 	select CPU_32v4
 	select CPU_ABRT_EV4
 	select CPU_CACHE_V4WB
diff --git a/include/linux/srcutree.h b/include/linux/srcutree.h
index 9cfcc8a756ae..9de652f4e1bd 100644
--- a/include/linux/srcutree.h
+++ b/include/linux/srcutree.h
@@ -124,7 +124,7 @@ struct srcu_struct {
 # define __DEFINE_SRCU(name, is_static)					\
 	is_static struct srcu_struct name;				\
 	struct srcu_struct * const __srcu_struct_##name			\
-		__section("___srcu_struct_ptrs") = &name
+		__section(___srcu_struct_ptrs) = &name
 #else
 # define __DEFINE_SRCU(name, is_static)					\
 	static DEFINE_PER_CPU(struct srcu_data, name##_srcu_data);	\
-- 
2.28.0.709.gb0816b6eb0-goog