From aea490299f7f0412f884a4895bc96211d8d8dbaf Mon Sep 17 00:00:00 2001 From: Jon Medhurst Date: Thu, 7 Jul 2011 19:58:29 +0100 Subject: [PATCH] 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: Jon Medhurst Acked-by: Nicolas Pitre --- arch/arm/kernel/kprobes-common.c | 4 ++++ arch/arm/kernel/kprobes.h | 14 ++++++++++++++ 2 files changed, 18 insertions(+) diff --git a/arch/arm/kernel/kprobes-common.c b/arch/arm/kernel/kprobes-common.c index e18576cca6cf..87e91ce4d495 100644 --- a/arch/arm/kernel/kprobes-common.c +++ b/arch/arm/kernel/kprobes-common.c @@ -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) { diff --git a/arch/arm/kernel/kprobes.h b/arch/arm/kernel/kprobes.h index 43f630d7f03d..406bb2da7fea 100644 --- a/arch/arm/kernel/kprobes.h +++ b/arch/arm/kernel/kprobes.h @@ -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.