2013-09-06 21:47:56

by Behan Webster

[permalink] [raw]
Subject: [PATCH] arm: LLVMLinux: Use __builtin_frame_address to get thread info

From: Behan Webster <[email protected]>

The LLVMLinux Project is working to be able to build the Linux kernel with
clang/LLVM. With the release of LLVM 3.3 clang is now able to compile the Linux
kernel with a number of small patches (available from the LLVMLinux git repo).

Use the frame pointer to calculate the start of the stack for current_thread_info()
The existing code uses the stack pointer to do this calculation.
Using the frame pointer yeilds the same value in a portable way.
This change supports being able to compile the kernel with gcc and Clang.

Behan Webster (1):
arm: LLVMLinux: Calculate current_thread_info from fp

arch/arm/include/asm/thread_info.h | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

--
1.8.1.2


2013-09-06 21:48:01

by Behan Webster

[permalink] [raw]
Subject: [PATCH] arm: LLVMLinux: Calculate current_thread_info from fp

From: Behan Webster <[email protected]>

Use the frame pointer to calculate the start of the stack for current_thread_info()
The existing code uses the stack pointer to do this calculation.
Using the frame pointer yeilds the same value in a portable way.
This change supports being able to compile the kernel with gcc and Clang.

Signed-off-by: Mark Charlebois <[email protected]>
Signed-off-by: Behan Webster <[email protected]>
Reviewed-by: Jan-Simon Möller <[email protected]>
---
arch/arm/include/asm/thread_info.h | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/arm/include/asm/thread_info.h b/arch/arm/include/asm/thread_info.h
index df5e13d..cb50933 100644
--- a/arch/arm/include/asm/thread_info.h
+++ b/arch/arm/include/asm/thread_info.h
@@ -106,8 +106,9 @@ static inline struct thread_info *current_thread_info(void) __attribute_const__;

static inline struct thread_info *current_thread_info(void)
{
- register unsigned long sp asm ("sp");
- return (struct thread_info *)(sp & ~(THREAD_SIZE - 1));
+ return (struct thread_info *)
+ ((u32)(__builtin_frame_address(0))
+ & ~(THREAD_SIZE - 1));
}

#define thread_saved_pc(tsk) \
--
1.8.1.2