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Subject[PATCH 1/7] cleanup: paravirt unhandled fallthrough
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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>

diff -r 4fb7fc327801 arch/i386/kernel/Makefile
--- a/arch/i386/kernel/Makefile Mon Feb 12 12:37:01 2007 +1100
+++ b/arch/i386/kernel/Makefile Mon Feb 12 12:55:00 2007 +1100
@@ -41,8 +41,6 @@ obj-$(CONFIG_KWATCH) += debugreg.o kwat
obj-$(CONFIG_KWATCH) += debugreg.o kwatch.o

obj-$(CONFIG_VMI) += vmi.o vmitime.o
-
-# Make sure this is linked after any other paravirt_ops structs: see head.S
obj-$(CONFIG_PARAVIRT) += paravirt.o

EXTRA_AFLAGS := -traditional
diff -r 4fb7fc327801 arch/i386/kernel/head.S
--- a/arch/i386/kernel/head.S Mon Feb 12 12:37:01 2007 +1100
+++ b/arch/i386/kernel/head.S Mon Feb 12 12:54:19 2007 +1100
@@ -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 @@ 1:

addl $4, (%esp)
jmp 1b
+
+unhandled_paravirt:
+ /* Nothing wanted us: we're screwed. */
+ ud2
#endif

/*
diff -r 4fb7fc327801 arch/i386/kernel/paravirt.c
--- a/arch/i386/kernel/paravirt.c Mon Feb 12 12:37:01 2007 +1100
+++ b/arch/i386/kernel/paravirt.c Mon Feb 12 12:54:19 2007 +1100
@@ -481,9 +481,6 @@ static int __init print_banner(void)
return 0;
}
core_initcall(print_banner);
-
-/* We simply declare start_kernel to be the paravirt probe of last resort. */
-paravirt_probe(start_kernel);

struct paravirt_ops paravirt_ops = {
.name = "bare hardware",

-
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