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Diffstat (limited to 'arch/x86/include/asm/jump_label.h')
-rw-r--r--arch/x86/include/asm/jump_label.h63
1 files changed, 56 insertions, 7 deletions
diff --git a/arch/x86/include/asm/jump_label.h b/arch/x86/include/asm/jump_label.h
index 5daeca3d0f9e..adc54c12cbd1 100644
--- a/arch/x86/include/asm/jump_label.h
+++ b/arch/x86/include/asm/jump_label.h
@@ -1,12 +1,18 @@
#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>
+#ifndef HAVE_JUMP_LABEL
+/*
+ * For better or for worse, if jump labels (the gcc extension) are missing,
+ * then the entire static branch patching infrastructure is compiled out.
+ * If that happens, the code in here will malfunction. Raise a compiler
+ * error instead.
+ *
+ * In theory, jump labels and the static branch patching infrastructure
+ * could be decoupled to fix this.
+ */
+#error asm/jump_label.h included on a non-jump-label kernel
+#endif
#define JUMP_LABEL_NOP_SIZE 5
@@ -16,6 +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:"
@@ -59,5 +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