linux-kernel - Re: [BUGFIX/x86] Fix initialization of wakeup

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Date:	Tue, 10 Feb 2009 14:00:40 -0800
From:	Alok Kataria <akataria@...are.com>
To:	Yinghai Lu <yinghai@...nel.org>
Cc:	Ingo Molnar <mingo@...e.hu>,
	the arch/x86 maintainers <x86@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [BUGFIX/x86] Fix initialization of wakeup_cpu.

On Tue, 2009-02-10 at 13:03 -0800, Yinghai Lu wrote:
> On Tue, Feb 10, 2009 at 12:28 PM, Alok Kataria <akataria@...are.com> wrote:
> > Was originally reported in the..
> > "Re: [PARAVIRT/x86] BUGFIX: Put a missing paravirt_release_pmd in pgd_dtor" thread
> >
> > --
> > With the patches for refactoring of wake_cpu macros, the 32bit code
> > in tip doesn't execute generic_apic_probe if CONFIG_X86_32_NON_STANDARD
> > is not set.
> >
> > Even on a x86 STANDARD cpu we need to execute the generic_apic_probe
> > function, as we rely on this function to execute the update_genapic
> > quirk which initilizes apic->wakeup_cpu.
> >
> > Failing to do so results in we making a call to a null function in do_boot_cpu.
> >
> > The stack trace without the patch goes like this.
> >
> > Booting processor 1 APIC 0x1 ip 0x6000
> > BUG: unable to handle kernel NULL pointer dereference at (null)
> > IP: [<(null)>] (null)
> > *pdpt = 0000000000839001 *pde = 0000000000c97067 *pte = 0000000000000163
> > Oops: 0000 [#1] SMP
> > last sysfs file:
> > Modules linked in:
> >
> > Pid: 1, comm: swapper Not tainted (2.6.29-rc4-tip #18) VMware Virtual Platform
> > EIP: 0062:[<00000000>] EFLAGS: 00010293 CPU: 0
> > EIP is at 0x0
> > EAX: 00000001 EBX: 00006000 ECX: c077ed00 EDX: 00006000
> > ESI: 00000001 EDI: 00000001 EBP: ef04cf40 ESP: ef04cf1c
> >  DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 006a
> > Process swapper (pid: 1, ti=ef04c000 task=ef050000 task.ti=ef04c000)
> > Stack:
> >  c0644e52 00000000 ef04cf24 ef04cf24 c064468d c0886dc0 00000000 c0702aea
> >  ef055480 00000001 00000101 dead4ead ffffffff ffffffff c08af530 00000000
> >  c0709715 ef04cf60 ef04cf60 00000001 00000000 00000000 dead4ead ffffffff
> > Call Trace:
> >  [<c0644e52>] ? native_cpu_up+0x2de/0x45b
> >  [<c064468d>] ? do_fork_idle+0x0/0x19
> >  [<c0645c5e>] ? _cpu_up+0x88/0xe8
> >  [<c0645d20>] ? cpu_up+0x42/0x4e
> >  [<c07e7462>] ? kernel_init+0x99/0x14b
> >  [<c07e73c9>] ? kernel_init+0x0/0x14b
> >  [<c040375f>] ? kernel_thread_helper+0x7/0x10
> > Code:  Bad EIP value.
> > EIP: [<00000000>] 0x0 SS:ESP 006a:ef04cf1c
> >
> > I think we should call generic_apic_probe unconditionally now.
> >
> > Signed-off-by: Alok N Kataria <akataria@...are.com>
> >
> > Index: linux-tip-master/arch/x86/kernel/setup.c
> > ===================================================================
> > --- linux-tip-master.orig/arch/x86/kernel/setup.c       2009-02-10 11:37:31.000000000 -0800
> > +++ linux-tip-master/arch/x86/kernel/setup.c    2009-02-10 11:50:37.000000000 -0800
> > @@ -936,9 +936,7 @@
> >        map_vsyscall();
> >  #endif
> >
> > -#if defined(CONFIG_X86_32_NON_STANDARD) || defined(CONFIG_X86_BIGSMP)
> >        generic_apic_probe();
> > -#endif
> >
> >        early_quirks();
> >
> 
> 1. only es7000 and numaq has update_genapic() ==> they need
> X86_32_NON_STANDARD..


There is one here too 

static struct x86_quirks default_x86_quirks __initdata = {
        .update_genapic         = default_update_genapic,
}

> 2. also will break 64 bit....
isn't the default_x86_quirks defined for 64 bit too ? 

--
Alok

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