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Message-Id: <20190827204007.201890-13-ndesaulniers@google.com>
Date: Tue, 27 Aug 2019 13:40:05 -0700
From: Nick Desaulniers <ndesaulniers@...gle.com>
To: miguel.ojeda.sandonis@...il.com
Cc: sedat.dilek@...il.com, will@...nel.org, jpoimboe@...hat.com,
naveen.n.rao@...ux.vnet.ibm.com, davem@...emloft.net,
paul.burton@...s.com, clang-built-linux@...glegroups.com,
linux-kernel@...r.kernel.org,
Nick Desaulniers <ndesaulniers@...gle.com>
Subject: [PATCH v2 12/14] include/linux: prefer __section from compiler_attributes.h
GCC unescapes escaped string section names while Clang does not. Because
__section uses the `#` stringification operator for the section name, it
doesn't need to be escaped.
Instead, we should:
1. Prefer __section(.section_name_no_quotes).
2. Only use __attribute__((__section(".section"))) when creating the
section name via C preprocessor (see the definition of __define_initcall
in arch/um/include/shared/init.h).
This antipattern was found with:
$ grep -e __section\(\" -e __section__\(\" -r
See the discussions in:
Link: https://bugs.llvm.org/show_bug.cgi?id=42950
Link: https://marc.info/?l=linux-netdev&m=156412960619946&w=2
Acked-by: Will Deacon <will@...nel.org>
Reported-by: Sedat Dilek <sedat.dilek@...il.com>
Suggested-by: Josh Poimboeuf <jpoimboe@...hat.com>
Tested-by: Sedat Dilek <sedat.dilek@...il.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@...gle.com>
---
include/linux/cache.h | 6 +++---
include/linux/cpu.h | 2 +-
include/linux/export.h | 2 +-
include/linux/init_task.h | 4 ++--
include/linux/interrupt.h | 5 ++---
include/linux/sched/debug.h | 2 +-
include/linux/srcutree.h | 2 +-
7 files changed, 11 insertions(+), 12 deletions(-)
diff --git a/include/linux/cache.h b/include/linux/cache.h
index 750621e41d1c..3f4df9eef1e1 100644
--- a/include/linux/cache.h
+++ b/include/linux/cache.h
@@ -28,7 +28,7 @@
* but may get written to during init, so can't live in .rodata (via "const").
*/
#ifndef __ro_after_init
-#define __ro_after_init __attribute__((__section__(".data..ro_after_init")))
+#define __ro_after_init __section(.data..ro_after_init)
#endif
#ifndef ____cacheline_aligned
@@ -45,8 +45,8 @@
#ifndef __cacheline_aligned
#define __cacheline_aligned \
- __attribute__((__aligned__(SMP_CACHE_BYTES), \
- __section__(".data..cacheline_aligned")))
+ __aligned(SMP_CACHE_BYTES) \
+ __section(.data..cacheline_aligned)
#endif /* __cacheline_aligned */
#ifndef __cacheline_aligned_in_smp
diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index fcb1386bb0d4..186bbd79d6ce 100644
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -166,7 +166,7 @@ void cpu_startup_entry(enum cpuhp_state state);
void cpu_idle_poll_ctrl(bool enable);
/* Attach to any functions which should be considered cpuidle. */
-#define __cpuidle __attribute__((__section__(".cpuidle.text")))
+#define __cpuidle __section(.cpuidle.text)
bool cpu_in_idle(unsigned long pc);
diff --git a/include/linux/export.h b/include/linux/export.h
index fd8711ed9ac4..808c1a0c2ef9 100644
--- a/include/linux/export.h
+++ b/include/linux/export.h
@@ -104,7 +104,7 @@ struct kernel_symbol {
* discarded in the final link stage.
*/
#define __ksym_marker(sym) \
- static int __ksym_marker_##sym[0] __section(".discard.ksym") __used
+ static int __ksym_marker_##sym[0] __section(.discard.ksym) __used
#define __EXPORT_SYMBOL(sym, sec) \
__ksym_marker(sym); \
diff --git a/include/linux/init_task.h b/include/linux/init_task.h
index 6049baa5b8bc..50139505da34 100644
--- a/include/linux/init_task.h
+++ b/include/linux/init_task.h
@@ -51,12 +51,12 @@ extern struct cred init_cred;
/* Attach to the init_task data structure for proper alignment */
#ifdef CONFIG_ARCH_TASK_STRUCT_ON_STACK
-#define __init_task_data __attribute__((__section__(".data..init_task")))
+#define __init_task_data __section(.data..init_task)
#else
#define __init_task_data /**/
#endif
/* Attach to the thread_info data structure for proper alignment */
-#define __init_thread_info __attribute__((__section__(".data..init_thread_info")))
+#define __init_thread_info __section(.data..init_thread_info)
#endif
diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index 5b8328a99b2a..29debfe4dd0f 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -741,8 +741,7 @@ extern int arch_early_irq_init(void);
/*
* We want to know which function is an entrypoint of a hardirq or a softirq.
*/
-#define __irq_entry __attribute__((__section__(".irqentry.text")))
-#define __softirq_entry \
- __attribute__((__section__(".softirqentry.text")))
+#define __irq_entry __section(.irqentry.text)
+#define __softirq_entry __section(.softirqentry.text)
#endif
diff --git a/include/linux/sched/debug.h b/include/linux/sched/debug.h
index 95fb9e025247..e17b66221fdd 100644
--- a/include/linux/sched/debug.h
+++ b/include/linux/sched/debug.h
@@ -42,7 +42,7 @@ extern void proc_sched_set_task(struct task_struct *p);
#endif
/* Attach to any functions which should be ignored in wchan output. */
-#define __sched __attribute__((__section__(".sched.text")))
+#define __sched __section(.sched.text)
/* Linker adds these: start and end of __sched functions */
extern char __sched_text_start[], __sched_text_end[];
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); \
--
2.23.0.187.g17f5b7556c-goog
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