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From: Rusty Russell <rusty@rustcorp.com.au>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: lkml - Kernel Mailing List <linux-kernel@vger.kernel.org>,
	virtualization <virtualization@lists.osdl.org>,
	Andi Kleen <ak@muc.de>
Subject: [PATCH 1/7] cleanup: paravirt unhandled fallthrough
Date: Mon, 12 Feb 2007 14:32:00 +1100	[thread overview]
Message-ID: <1171251120.10409.2.camel@localhost.localdomain> (raw)

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",



             reply	other threads:[~2007-02-12  3:32 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-02-12  3:32 Rusty Russell [this message]
2007-02-12  3:33 ` [PATCH 2/7] cleanup: Initialize esp0 properly all the time Rusty Russell
2007-02-12  3:34   ` [PATCH 3/7] cleanup: Make hvc_console.c compile on non-PowerPC Rusty Russell
2007-02-12  3:35     ` [PATCH 4/7] cleanup: Move mce_disabled to asm/mce.h Rusty Russell
2007-02-12  3:36       ` [PATCH 5/7] cleanup: Rename cpu_gdt_descr and remove extern declaration from smpboot.c Rusty Russell
2007-02-12  3:37         ` [PATCH 6/7] cleanup: Remove extern declaration from mm/discontig.c, put in header Rusty Russell
2007-02-12  3:39           ` [PATCH 7/7] cleanup: make disable_acpi() valid w/o CONFIG_ACPI Rusty Russell
2007-02-12  3:41             ` [PATCH 1/2] lguest preparation: EXPORT_SYMBOL_GPL 5 functions Rusty Russell
2007-02-12  3:42               ` [PATCH 2/2] lguest preparation: expose futex infrastructure: get_futex_key, get_key_refs and drop_key_refs Rusty Russell
2007-02-12  3:44                 ` [PATCH 1/8] lguest: Kconfig and headers Rusty Russell
2007-02-12  3:46                   ` [PATCH 2/8] lguest: the host code (lg.ko) Rusty Russell
2007-02-12  3:48                     ` [PATCH 3/8] lguest: Guest code Rusty Russell
2007-02-12  3:50                       ` [PATCH 4/8] lguest: Makefile Rusty Russell
2007-02-12  3:52                         ` [PATCH 5/8] lguest: trivial guest network driver Rusty Russell
2007-02-12  3:53                           ` [PATCH 6/8] lguest: trivial guest console driver Rusty Russell
2007-02-12  3:54                             ` [PATCH 7/8] lguest: trivial guest block driver Rusty Russell
2007-02-12  3:55                               ` [PATCH 8/8] lguest: documentatation and example launcher Rusty Russell
2007-02-12  4:43                               ` [PATCH 7/8] lguest: trivial guest block driver Jens Axboe
2007-02-12  5:27                                 ` Rusty Russell
2007-02-12  5:32                                   ` Jens Axboe
2007-02-12  5:33                                     ` Jens Axboe
2007-02-12  7:09                                     ` Rusty Russell
2007-02-12  7:09                                       ` Rusty Russell
2007-02-12 15:01                                       ` Jens Axboe
2007-02-13  0:25                                         ` Rusty Russell
2007-02-13  0:25                                           ` Rusty Russell
2007-02-13  0:44                                           ` Jens Axboe
2007-02-12 15:55                           ` [PATCH 5/8] lguest: trivial guest network driver Herbert Xu
2007-02-13  2:15                             ` Rusty Russell
2007-02-13 14:06                               ` Herbert Xu
2007-02-14  4:47                                 ` Rusty Russell
2007-02-14 13:57                                   ` Herbert Xu
2007-02-14 23:00                                     ` Rusty Russell
2007-02-12 16:02                   ` [PATCH 1/8] lguest: Kconfig and headers James Morris
2007-02-13  5:09             ` [PATCH 7/7] cleanup: make disable_acpi() valid w/o CONFIG_ACPI Len Brown
2007-02-12  9:16         ` [PATCH 5/7] cleanup: Rename cpu_gdt_descr and remove extern declaration from smpboot.c Zachary Amsden

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