Messages in this thread Patch in this message | | | Date | Sat, 7 Nov 2015 12:20:59 +0100 (CET) | From | Thomas Gleixner <> | Subject | Re: [PATCH 3/4] x86/asm: Add asm macros for static keys/jump labels |
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On Fri, 6 Nov 2015, Andy Lutomirski wrote:
> Unfortunately, these only work if HAVE_JUMP_LABEL. In principle, we > could do some serious surgery on the core jump label infrastructure > to keep the patch infrastructure available on x86 on all builds, but > that's probably not worth it.
No, but we can be smarter about it. There is nothing which that asm entry code needs from linux/jump_label.h and asm/jump_label.h execpt STATIC_KEY_INIT_NOP. Something like the patch below should do the trick.
Thanks,
tglx
Index: tip/arch/x86/entry/calling.h =================================================================== --- tip.orig/arch/x86/entry/calling.h +++ tip/arch/x86/entry/calling.h @@ -232,3 +232,22 @@ For 32-bit we have the following convent #endif /* CONFIG_X86_64 */ +/* ASM jump label support */ +#if defined(CC_HAVE_ASM_GOTO) && defined(CONFIG_JUMP_LABEL) +#include <asm/jump_label.h> + + .macro STATIC_CALL_IF_ENABLED fun, key + 1: + jmp.d32 2f + call fun + .pushsection __jump_table, "aw" + _ASM_ALIGN + _ASM_PTR 1b, 2f, \key + .popsection + 2: + .endm +#else + .macro STATIC_CALL_IF_ENABLED fun, key + call fun + .endm +#endif Index: tip/arch/x86/entry/entry_64.S =================================================================== --- tip.orig/arch/x86/entry/entry_64.S +++ tip/arch/x86/entry/entry_64.S @@ -510,7 +510,7 @@ END(irq_entries_start) */ SWAPGS #ifdef CONFIG_CONTEXT_TRACKING - call enter_from_user_mode + STATIC_CALL_IF_ENABLED enter_from_user_mode, context_tracking_enabled #endif 1: @@ -1050,7 +1050,7 @@ ENTRY(error_entry) .Lerror_entry_from_usermode_after_swapgs: #ifdef CONFIG_CONTEXT_TRACKING - call enter_from_user_mode + STATIC_CALL_IF_ENABLED enter_from_user_mode, context_tracking_enabled #endif .Lerror_entry_done: Index: tip/arch/x86/include/asm/jump_label.h =================================================================== --- tip.orig/arch/x86/include/asm/jump_label.h +++ tip/arch/x86/include/asm/jump_label.h @@ -1,10 +1,6 @@ #ifndef _ASM_X86_JUMP_LABEL_H #define _ASM_X86_JUMP_LABEL_H -#ifndef __ASSEMBLY__ - -#include <linux/stringify.h> -#include <linux/types.h> #include <asm/nops.h> #include <asm/asm.h> @@ -16,6 +12,11 @@ # define STATIC_KEY_INIT_NOP GENERIC_NOP5_ATOMIC #endif +#ifndef __ASSEMBLY__ + +#include <linux/stringify.h> +#include <linux/types.h> + static __always_inline bool arch_static_branch(struct static_key *key, bool branch) { asm_volatile_goto("1:"
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