Where the value of current is kept in a register, that register can be marked
such that the pointer value is read only, e.g.:
register struct task_struct *const current asm("e2");
This prevents inadvertent assignment outside of assembly code.
This has been available on the MN10300 arch for a while now, and I've also
tested it on the FRV arch.
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
---
arch/frv/include/asm/current.h | 2 +-
arch/microblaze/include/asm/current.h | 2 +-
arch/powerpc/include/asm/current.h | 2 +-
arch/sparc/include/asm/current.h | 2 +-
4 files changed, 4 insertions(+), 4 deletions(-)
diff --git a/arch/frv/include/asm/current.h b/arch/frv/include/asm/current.h
index 86b0274..51bdaf2 100644
--- a/arch/frv/include/asm/current.h
+++ b/arch/frv/include/asm/current.h
@@ -17,7 +17,7 @@
/*
* dedicate GR29 to keeping the current task pointer
*/
-register struct task_struct *current asm("gr29");
+register struct task_struct *const current asm("gr29");
#define get_current() current
diff --git a/arch/microblaze/include/asm/current.h b/arch/microblaze/include/asm/current.h
index 29303ed..b824847 100644
--- a/arch/microblaze/include/asm/current.h
+++ b/arch/microblaze/include/asm/current.h
@@ -21,7 +21,7 @@
/*
* Dedicate r31 to keeping the current task pointer
*/
-register struct task_struct *current asm("r31");
+register struct task_struct *const current asm("r31");
# define get_current() current
# endif /* __ASSEMBLY__ */
diff --git a/arch/powerpc/include/asm/current.h b/arch/powerpc/include/asm/current.h
index e2c7f06..4ca5126 100644
--- a/arch/powerpc/include/asm/current.h
+++ b/arch/powerpc/include/asm/current.h
@@ -32,7 +32,7 @@ static inline struct task_struct *get_current(void)
/*
* We keep `current' in r2 for speed.
*/
-register struct task_struct *current asm ("r2");
+register struct task_struct *const current asm ("r2");
#endif
diff --git a/arch/sparc/include/asm/current.h b/arch/sparc/include/asm/current.h
index f04fd6c..9ae8826 100644
--- a/arch/sparc/include/asm/current.h
+++ b/arch/sparc/include/asm/current.h
@@ -14,7 +14,7 @@
#include <linux/thread_info.h>
#ifdef CONFIG_SPARC64
-register struct task_struct *current asm("g4");
+register struct task_struct *const current asm("g4");
#endif
#ifdef CONFIG_SPARC32
--
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