3.16.68-rc1 review patch. If anyone has any objections, please let me know.
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From: Andy Lutomirski luto@kernel.org
commit 2671c3e4fe2a34bd9bf2eecdf5d1149d4b55dbdf upstream.
Unfortunately, we can only do this 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.
Implementing the macros using a conditional branch as a fallback seems like a bad idea: we'd have to clobber flags.
This limitation can't cause silent failures -- trying to include asm/jump_label.h at all on a non-HAVE_JUMP_LABEL kernel will error out. The macro's users are responsible for handling this issue themselves.
Signed-off-by: Andy Lutomirski luto@kernel.org Reviewed-by: Thomas Gleixner tglx@linutronix.de Cc: Andy Lutomirski luto@amacapital.net Cc: Borislav Petkov bp@alien8.de Cc: Brian Gerst brgerst@gmail.com Cc: Denys Vlasenko dvlasenk@redhat.com Cc: Frederic Weisbecker fweisbec@gmail.com Cc: H. Peter Anvin hpa@zytor.com Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Peter Zijlstra peterz@infradead.org Link: http://lkml.kernel.org/r/63aa45c4b692e8469e1876d6ccbb5da707972990.1447361906... Signed-off-by: Ingo Molnar mingo@kernel.org Signed-off-by: Ben Hutchings ben@decadent.org.uk --- arch/x86/include/asm/jump_label.h | 52 ++++++++++++++++++++++++++----- 1 file changed, 44 insertions(+), 8 deletions(-)
--- a/arch/x86/include/asm/jump_label.h +++ b/arch/x86/include/asm/jump_label.h @@ -14,13 +14,6 @@ #error asm/jump_label.h included on a non-jump-label kernel #endif
-#ifndef __ASSEMBLY__ - -#include <linux/stringify.h> -#include <linux/types.h> -#include <asm/nops.h> -#include <asm/asm.h> - #define JUMP_LABEL_NOP_SIZE 5
#ifdef CONFIG_X86_64 @@ -29,6 +22,14 @@ # define STATIC_KEY_INIT_NOP GENERIC_NOP5_ATOMIC #endif
+#include <asm/asm.h> +#include <asm/nops.h> + +#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:" @@ -72,5 +73,40 @@ struct jump_entry { jump_label_t key; };
-#endif /* __ASSEMBLY__ */ +#else /* __ASSEMBLY__ */ + +.macro STATIC_JUMP_IF_TRUE target, key, def +.Lstatic_jump_@: + .if \def + /* Equivalent to "jmp.d32 \target" */ + .byte 0xe9 + .long \target - .Lstatic_jump_after_@ +.Lstatic_jump_after_@: + .else + .byte STATIC_KEY_INIT_NOP + .endif + .pushsection __jump_table, "aw" + _ASM_ALIGN + _ASM_PTR .Lstatic_jump_@, \target, \key + .popsection +.endm + +.macro STATIC_JUMP_IF_FALSE target, key, def +.Lstatic_jump_@: + .if \def + .byte STATIC_KEY_INIT_NOP + .else + /* Equivalent to "jmp.d32 \target" */ + .byte 0xe9 + .long \target - .Lstatic_jump_after_@ +.Lstatic_jump_after_@: + .endif + .pushsection __jump_table, "aw" + _ASM_ALIGN + _ASM_PTR .Lstatic_jump_@, \target, \key + 1 + .popsection +.endm + +#endif /* __ASSEMBLY__ */ + #endif