linux-kernel - Re: [kvm-devel] [PATCH] KVM: Avoid using vmx instruction directly

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <45532EE3.4000104@qumranet.com>
Date:	Thu, 09 Nov 2006 15:36:35 +0200
From:	Avi Kivity <avi@...ranet.com>
To:	Arnd Bergmann <arnd@...db.de>
CC:	kvm-devel@...ts.sourceforge.net, akpm@...l.org,
	linux-kernel@...r.kernel.org
Subject: Re: [kvm-devel] [PATCH] KVM: Avoid using vmx instruction directly

Arnd Bergmann wrote:
> On Thursday 09 November 2006 12:08, Avi Kivity wrote:
>   
>> Index: linux-2.6/drivers/kvm/kvm_main.c
>> ===================================================================
>> --- linux-2.6.orig/drivers/kvm/kvm_main.c
>> +++ linux-2.6/drivers/kvm/kvm_main.c
>> @@ -369,8 +369,8 @@ static void vmcs_clear(struct vmcs *vmcs
>>         u64 phys_addr = __pa(vmcs);
>>         u8 error;
>>  
>> -       asm volatile ("vmclear %1; setna %0"
>> -                      : "=m"(error) : "m"(phys_addr) : "cc", "memory" );
>> +       asm volatile (ASM_VMX_VMCLEAR_RAX "; setna %0"
>> +                      : "=g"(error) : "a"(&phys_addr) : "cc", "memory" );
>>         if (error)
>>                 printk(KERN_ERR "kvm: vmclear fail: %p/%llx\n",
>>                        vmcs, phys_addr);
>>     
>
> I'm not an expert on inline assembly, but don't you need an extra
> '"m" (phys_addr)' to make sure that gcc actually puts the variable
> on the stack instead of passing a NULL pointer as '"a"(&phys_addr)'?
>
>   

Taking a variable's address should force its contents into memory (like 
calling an uninlined function with &var).


-- 
error compiling committee.c: too many arguments to function

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/