The patch titled
trigger a syntax error if percpu macros are incorrectly used
has been added to the -mm tree. Its filename is
trigger-a-syntax-error-if-percpu-macros-are-incorrectly-used.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: trigger a syntax error if percpu macros are incorrectly used
From: Jan Blunck <jblunck@xxxxxxx>
get_cpu_var()/per_cpu()/__get_cpu_var() arguments must be simple
identifiers. Otherwise the arch dependent implementations might break.
This patch enforces the correct usage of the macros by producing a syntax
error if the variable is not a simple identifier.
Signed-off-by: Jan Blunck <jblunck@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
diff -puN include/asm-generic/percpu.h~trigger-a-syntax-error-if-percpu-macros-are-incorrectly-used include/asm-generic/percpu.h
--- a/include/asm-generic/percpu.h~trigger-a-syntax-error-if-percpu-macros-are-incorrectly-used
+++ a/include/asm-generic/percpu.h
@@ -14,7 +14,9 @@ extern unsigned long __per_cpu_offset[NR
__attribute__((__section__(".data.percpu"))) __typeof__(type) per_cpu__##name
/* var is in discarded region: offset to particular copy we want */
-#define per_cpu(var, cpu) (*RELOC_HIDE(&per_cpu__##var, __per_cpu_offset[cpu]))
+#define per_cpu(var, cpu) (*({ \
+ extern int simple_indentifier_##var(void); \
+ RELOC_HIDE(&per_cpu__##var, __per_cpu_offset[cpu]); }))
#define __get_cpu_var(var) per_cpu(var, smp_processor_id())
#define __raw_get_cpu_var(var) per_cpu(var, raw_smp_processor_id())
diff -puN include/asm-s390/percpu.h~trigger-a-syntax-error-if-percpu-macros-are-incorrectly-used include/asm-s390/percpu.h
--- a/include/asm-s390/percpu.h~trigger-a-syntax-error-if-percpu-macros-are-incorrectly-used
+++ a/include/asm-s390/percpu.h
@@ -15,18 +15,20 @@
*/
#if defined(__s390x__) && defined(MODULE)
-#define __reloc_hide(var,offset) \
- (*({ unsigned long *__ptr; \
- asm ( "larl %0,per_cpu__"#var"@GOTENT" \
- : "=a" (__ptr) : "X" (per_cpu__##var) ); \
- (typeof(&per_cpu__##var))((*__ptr) + (offset)); }))
+#define __reloc_hide(var,offset) (*({ \
+ extern int simple_indentifier_##var(void); \
+ unsigned long *__ptr; \
+ asm ( "larl %0,per_cpu__"#var"@GOTENT" \
+ : "=a" (__ptr) : "X" (per_cpu__##var) ); \
+ (typeof(&per_cpu__##var))((*__ptr) + (offset)); }))
#else
-#define __reloc_hide(var, offset) \
- (*({ unsigned long __ptr; \
- asm ( "" : "=a" (__ptr) : "0" (&per_cpu__##var) ); \
- (typeof(&per_cpu__##var)) (__ptr + (offset)); }))
+#define __reloc_hide(var, offset) (*({ \
+ extern int simple_indentifier_##var(void); \
+ unsigned long __ptr; \
+ asm ( "" : "=a" (__ptr) : "0" (&per_cpu__##var) ); \
+ (typeof(&per_cpu__##var)) (__ptr + (offset)); }))
#endif
diff -puN include/asm-x86_64/percpu.h~trigger-a-syntax-error-if-percpu-macros-are-incorrectly-used include/asm-x86_64/percpu.h
--- a/include/asm-x86_64/percpu.h~trigger-a-syntax-error-if-percpu-macros-are-incorrectly-used
+++ a/include/asm-x86_64/percpu.h
@@ -21,9 +21,15 @@
__attribute__((__section__(".data.percpu"))) __typeof__(type) per_cpu__##name
/* var is in discarded region: offset to particular copy we want */
-#define per_cpu(var, cpu) (*RELOC_HIDE(&per_cpu__##var, __per_cpu_offset(cpu)))
-#define __get_cpu_var(var) (*RELOC_HIDE(&per_cpu__##var, __my_cpu_offset()))
-#define __raw_get_cpu_var(var) (*RELOC_HIDE(&per_cpu__##var, __my_cpu_offset()))
+#define per_cpu(var, cpu) (*({ \
+ extern int simple_indentifier_##var(void); \
+ RELOC_HIDE(&per_cpu__##var, __per_cpu_offset(cpu)); }))
+#define __get_cpu_var(var) (*({ \
+ extern int simple_indentifier_##var(void); \
+ RELOC_HIDE(&per_cpu__##var, __my_cpu_offset()); }))
+#define __raw_get_cpu_var(var) (*({ \
+ extern int simple_indentifier_##var(void); \
+ RELOC_HIDE(&per_cpu__##var, __my_cpu_offset()); }))
/* A macro to avoid #include hell... */
#define percpu_modcopy(pcpudst, src, size) \
diff -puN include/linux/percpu.h~trigger-a-syntax-error-if-percpu-macros-are-incorrectly-used include/linux/percpu.h
--- a/include/linux/percpu.h~trigger-a-syntax-error-if-percpu-macros-are-incorrectly-used
+++ a/include/linux/percpu.h
@@ -14,8 +14,14 @@
#define PERCPU_ENOUGH_ROOM 32768
#endif
-/* Must be an lvalue. */
-#define get_cpu_var(var) (*({ preempt_disable(); &__get_cpu_var(var); }))
+/*
+ * Must be an lvalue. Since @var must be a simple identifier,
+ * we force a syntax error here if it isn't.
+ */
+#define get_cpu_var(var) (*({ \
+ extern int simple_indentifier_##var(void); \
+ preempt_disable(); \
+ &__get_cpu_var(var); }))
#define put_cpu_var(var) preempt_enable()
#ifdef CONFIG_SMP
_
Patches currently in -mm which might be from jblunck@xxxxxxx are
trigger-a-syntax-error-if-percpu-macros-are-incorrectly-used.patch
-
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