[PATCH] i386: paravirt unhandled fallthrough

The current code simply calls "start_kernel" directly if we're under a
hypervisor and no paravirt_ops backend wants us, because paravirt.c
registers that as a backend.

This was always a vain hope; start_kernel won't get far without setup.
It's also impossible for paravirt_ops backends which don't sit in the
arch/i386/kernel directory: they can't link before paravirt.o anyway.

Keep it simple: if we pass all the registered paravirt probes, BUG().

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andi Kleen <ak@suse.de>

1 files changed, 6 insertions, 1 deletions

diff --git a/arch/i386/kernel/head.S b/arch/i386/kernel/head.S
index 734be5572eb9..b322f72ffaad 100644
--- a/arch/i386/kernel/head.S
+++ b/arch/i386/kernel/head.S
@@ -513,10 +513,11 @@ startup_paravirt:
         pushl   %ecx
         pushl   %eax
 
-        /* paravirt.o is last in link, and that probe fn never returns */
         pushl   $__start_paravirtprobe
 1:
         movl    0(%esp), %eax
+        cmpl    $__stop_paravirtprobe, %eax
+        je      unhandled_paravirt
         pushl   (%eax)
         movl    8(%esp), %eax
         call    *(%esp)
@@ -528,6 +529,10 @@ startup_paravirt:
 
         addl    $4, (%esp)
         jmp     1b
+
+unhandled_paravirt:
+        /* Nothing wanted us: we're screwed. */
+        ud2
 #endif
 
 /*