Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

torvalds · torvalds · commit 4d5ac4b8ca1e · 2018-08-13T17:01:03.000-07:00
Pull misc x86 fixes from Thomas Gleixner:
 "Two fixes for x86:

   - Provide a declaration for native_save_fl() which unbreaks the
     wreckage caused by making it 'extern inline'.

   - Fix the failing paravirt patching which is supposed to replace
     indirect with direct calls. The wreckage is caused by an incorrect
     clobber test"

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/paravirt: Fix spectre-v2 mitigations for paravirt guests
  x86/irqflags: Provide a declaration for native_save_fl
diff --git a/arch/x86/include/asm/irqflags.h b/arch/x86/include/asm/irqflags.h
@@ -13,6 +13,8 @@
  * Interrupt control:
  */
 
+/* Declaration required for gcc < 4.9 to prevent -Werror=missing-prototypes */
+extern inline unsigned long native_save_fl(void);
 extern inline unsigned long native_save_fl(void)
 {
 	unsigned long flags;
diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
@@ -88,10 +88,12 @@ unsigned paravirt_patch_call(void *insnbuf,
 	struct branch *b = insnbuf;
 	unsigned long delta = (unsigned long)target - (addr+5);
 
-	if (tgt_clobbers & ~site_clobbers)
-		return len;	/* target would clobber too much for this site */
-	if (len < 5)
+	if (len < 5) {
+#ifdef CONFIG_RETPOLINE
+		WARN_ONCE("Failing to patch indirect CALL in %ps\n", (void *)addr);
+#endif
 		return len;	/* call too long for patch site */
+	}
 
 	b->opcode = 0xe8; /* call */
 	b->delta = delta;
@@ -106,8 +108,12 @@ unsigned paravirt_patch_jmp(void *insnbuf, const void *target,
 	struct branch *b = insnbuf;
 	unsigned long delta = (unsigned long)target - (addr+5);
 
-	if (len < 5)
+	if (len < 5) {
+#ifdef CONFIG_RETPOLINE
+		WARN_ONCE("Failing to patch indirect JMP in %ps\n", (void *)addr);
+#endif
 		return len;	/* call too long for patch site */
+	}
 
 	b->opcode = 0xe9;	/* jmp */
 	b->delta = delta;

Original file line number	Diff line number	Diff line change
`@@ -13,6 +13,8 @@`
`13`	`13`	`* Interrupt control:`
`14`	`14`	`*/`
`15`	`15`
	`16`	`+/* Declaration required for gcc < 4.9 to prevent -Werror=missing-prototypes */`
	`17`	`+extern inline unsigned long native_save_fl(void);`
`16`	`18`	`extern inline unsigned long native_save_fl(void)`
`17`	`19`	`{`
`18`	`20`	`unsigned long flags;`