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Commit aea49029 authored by Jon Medhurst's avatar Jon Medhurst Committed by Tixy
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ARM: kprobes: Make str_pc_offset a constant on ARMv7 



The str_pc_offset value is architecturally defined on ARMv7 onwards so
we can make it a compile time constant. This means on Thumb kernels the
runtime checking code isn't needed, which saves us from having to fix it
to work for Thumb.

Signed-off-by: default avatarJon Medhurst <tixy@yxit.co.uk>
Acked-by: default avatarNicolas Pitre <nicolas.pitre@linaro.org>
parent 6c8df330

arch/arm/kernel/kprobes-common.c

+4 −0
Original line number Diff line number Diff line
@@ -17,6 +17,8 @@ 
#include "kprobes.h"





#ifndef find_str_pc_offset



/*

 * For STR and STM instructions, an ARM core may choose to use either

 * a +8 or a +12 displacement from the current instruction's address.
@@ -40,6 +42,8 @@ void __init find_str_pc_offset(void) 
	str_pc_offset = ret;

}



#endif /* !find_str_pc_offset */





void __init arm_kprobe_decode_init(void)

{

arch/arm/kernel/kprobes.h

+14 −0
Original line number Diff line number Diff line
@@ -36,7 +36,21 @@ void __init arm_kprobe_decode_init(void); 


extern kprobe_check_cc * const kprobe_condition_checks[16];





#if __LINUX_ARM_ARCH__ >= 7



/* str_pc_offset is architecturally defined from ARMv7 onwards */

#define str_pc_offset 8

#define find_str_pc_offset()



#else /* __LINUX_ARM_ARCH__ < 7 */



/* We need a run-time check to determine str_pc_offset */

extern int str_pc_offset;

void __init find_str_pc_offset(void);



#endif





/*

 * Test if load/store instructions writeback the address register.