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From: Rusty Russell <rusty@rustcorp.com.au>
To: lkml - Kernel Mailing List <linux-kernel@vger.kernel.org>
Cc: Andrew Morton <akpm@osdl.org>, Andi Kleen <ak@muc.de>,
	virtualization <virtualization@lists.osdl.org>
Subject: [PATCH 1/10] lguest: Don't rely on last-linked fallthru when no paravirt handler
Date: Fri, 09 Feb 2007 20:14:18 +1100	[thread overview]
Message-ID: <1171012458.2718.30.camel@localhost.localdomain> (raw)
In-Reply-To: <1171012296.2718.26.camel@localhost.localdomain>

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 and it's linked last.

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.

This implements a real fallthrough if we pass all the registered
paravirt probes.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

===================================================================
--- a/arch/i386/kernel/Makefile
+++ b/arch/i386/kernel/Makefile
@@ -39,8 +39,6 @@ obj-$(CONFIG_EARLY_PRINTK)	+= early_prin
 obj-$(CONFIG_EARLY_PRINTK)	+= early_printk.o
 obj-$(CONFIG_HPET_TIMER) 	+= hpet.o
 obj-$(CONFIG_K8_NB)		+= k8.o
-
-# Make sure this is linked after any other paravirt_ops structs: see head.S
 obj-$(CONFIG_PARAVIRT)		+= paravirt.o
 
 EXTRA_AFLAGS   := -traditional
===================================================================
--- a/arch/i386/kernel/head.S
+++ b/arch/i386/kernel/head.S
@@ -502,10 +502,11 @@ 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)
@@ -517,6 +518,12 @@ 1:
 
 	addl	$4, (%esp)
 	jmp	1b
+
+unhandled_paravirt:
+	/* Nothing wanted us: try to die with dignity (impossible trap). */ 
+	movl	$0x1F, %edx
+	pushl	$0
+	jmp	early_fault
 #endif
 
 /*
===================================================================
--- a/arch/i386/kernel/paravirt.c
+++ b/arch/i386/kernel/paravirt.c
@@ -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:[~2007-02-09  9:15 UTC|newest]

Thread overview: 53+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-02-09  9:11 [PATCH 0/10] lguest Rusty Russell
2007-02-09  9:14 ` Rusty Russell [this message]
2007-02-09  9:15   ` [PATCH 2/10] lguest: Export symbols for lguest as a module Rusty Russell
2007-02-09  9:32     ` Andi Kleen
2007-02-09 12:06       ` Rusty Russell
2007-02-09 13:58         ` Andi Kleen
2007-02-10 11:39           ` Rusty Russell
2007-02-09  9:17   ` [PATCH 3/10] lguest: Expose get_futex_key, get_key_refs and drop_key_refs Rusty Russell
2007-02-09  9:18   ` [PATCH 4/10] lguest: Initialize esp0 properly all the time Rusty Russell
2007-02-09  9:19     ` [PATCH 5/10] Make hvc_console.c compile on non-PowerPC Rusty Russell
     [not found]       ` <1171012827.2718.42.camel@localhost.localdomain>
2007-02-09  9:22         ` [PATCH 7/10] lguest: Simple lguest network driver Rusty Russell
2007-02-09  9:23           ` [PATCH 8/10] lguest: console driver Rusty Russell
2007-02-09  9:24             ` [PATCH 9/10] lguest: block driver Rusty Russell
2007-02-09  9:25               ` [PATCH 10/10] lguest: documentatation including example launcher Rusty Russell
2007-02-09  9:35         ` [PATCH 6/10] lguest code: the little linux hypervisor Andrew Morton
2007-02-09 11:00           ` Rusty Russell
2007-02-09 11:13             ` Zachary Amsden
2007-02-09 11:50               ` Andi Kleen
2007-02-09 11:54                 ` Zachary Amsden
2007-02-09 11:57                   ` Andi Kleen
2007-02-09 12:08                     ` Zachary Amsden
2007-02-09 22:29                 ` David Miller
2007-02-09 10:09         ` Andi Kleen
2007-02-09 12:39           ` Rusty Russell
2007-02-09 13:57             ` Andi Kleen
2007-02-09 15:01               ` Rusty Russell
2007-02-09 14:17             ` Sam Ravnborg
2007-02-09 15:23               ` Rusty Russell
2007-02-12 13:34                 ` [q] kbuild for private asm-offsets (Re: [PATCH 6/10] lguest code: the little linux hypervisor.) Oleg Verych
2007-02-12 17:24                   ` Andi Kleen
2007-02-12 21:41                   ` Sam Ravnborg
2007-02-12 23:41                   ` Rusty Russell
2007-02-13  3:10                     ` Oleg Verych
2007-02-16 15:55                       ` [pp] kbuild: lguest with private asm-offsets (and some bloat) Oleg Verych
2007-02-16 15:59                         ` [pp] kbuild: asm-offsets generalized Oleg Verych
2007-02-16 18:56                           ` Sam Ravnborg
2007-02-16 21:56                             ` Oleg Verych
2007-02-17  4:43                               ` Rusty Russell
2007-02-17  5:33                                 ` Oleg Verych
2007-04-01 20:42                           ` Sam Ravnborg
2007-04-01 21:08                             ` Oleg Verych
2007-04-01 21:03                               ` Sam Ravnborg
2007-02-09 10:55       ` [PATCH 6a/10] lguest: Config and headers Rusty Russell
2007-02-09 10:56         ` [PATCH 6b/10] lguest: the host code (lg.ko) Rusty Russell
2007-02-09 10:57           ` [PATCH 6c/10] lguest: the guest code Rusty Russell
2007-02-09 10:58             ` [PATCH 6d/10] lguest: the Makefiles Rusty Russell
2007-02-09 17:06             ` [PATCH 6c/10] lguest: the guest code Len Brown
2007-02-09 17:14               ` James Morris
2007-02-09 17:49                 ` Len Brown
2007-02-09 23:48                   ` [PATCH 11/10] lguest: use disable_acpi() Rusty Russell
2007-02-09  9:31   ` [PATCH 1/10] lguest: Don't rely on last-linked fallthru when no paravirt handler Andi Kleen
2007-02-09 11:52     ` Rusty Russell
2007-02-09 20:49       ` Jeremy Fitzhardinge

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