1 files changed, 22 insertions, 1 deletions

diff --git a/include/asm-x86/alternative.h b/include/asm-x86/alternative.h
index d8bacf3c4b08..d26416b5722c 100644
--- a/include/asm-x86/alternative.h
+++ b/include/asm-x86/alternative.h
@@ -156,6 +156,27 @@ apply_paravirt(struct paravirt_patch_site *start,
 #define __parainstructions_end  NULL
 #endif
 
-extern void text_poke(void *addr, unsigned char *opcode, int len);
+extern void add_nops(void *insns, unsigned int len);
+
+/*
+ * Clear and restore the kernel write-protection flag on the local CPU.
+ * Allows the kernel to edit read-only pages.
+ * Side-effect: any interrupt handler running between save and restore will have
+ * the ability to write to read-only pages.
+ *
+ * Warning:
+ * Code patching in the UP case is safe if NMIs and MCE handlers are stopped and
+ * no thread can be preempted in the instructions being modified (no iret to an
+ * invalid instruction possible) or if the instructions are changed from a
+ * consistent state to another consistent state atomically.
+ * More care must be taken when modifying code in the SMP case because of
+ * Intel's errata.
+ * On the local CPU you need to be protected again NMI or MCE handlers seeing an
+ * inconsistent instruction while you patch.
+ * The _early version expects the memory to already be RW.
+ */
+
+extern void *text_poke(void *addr, const void *opcode, size_t len);
+extern void *text_poke_early(void *addr, const void *opcode, size_t len);
 
 #endif /* _ASM_X86_ALTERNATIVE_H */