* [PATCH -tip] x86: kvm/paging_tmpl.h intialize the variable before using it
@ 2009-05-20 4:29 Jaswinder Singh Rajput
2009-05-24 12:21 ` Avi Kivity
0 siblings, 1 reply; 8+ messages in thread
From: Jaswinder Singh Rajput @ 2009-05-20 4:29 UTC (permalink / raw
To: Ingo Molnar, Avi Kivity, x86 maintainers, LKML
May be in some cases paging64_fetch() and paging32_fetch() will return sptep
without initialization.
Also fixes compilation warning:
CC arch/x86/kernel/io_delay.o
arch/x86/kvm/paging_tmpl.h: In function ‘paging64_fetch’:
arch/x86/kvm/paging_tmpl.h:279: warning: ‘sptep’ may be used uninitialized in this function
arch/x86/kvm/paging_tmpl.h: In function ‘paging32_fetch’:
arch/x86/kvm/paging_tmpl.h:279: warning: ‘sptep’ may be used uninitialized in this function
Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
---
arch/x86/kvm/paging_tmpl.h | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
index 6bd7020..99cb10d 100644
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -276,7 +276,7 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
{
unsigned access = gw->pt_access;
struct kvm_mmu_page *shadow_page;
- u64 spte, *sptep;
+ u64 spte, *sptep = NULL;
int direct;
gfn_t table_gfn;
int r;
--
1.6.1.1
^ permalink raw reply related [flat|nested] 8+ messages in thread* Re: [PATCH -tip] x86: kvm/paging_tmpl.h intialize the variable before using it
2009-05-20 4:29 [PATCH -tip] x86: kvm/paging_tmpl.h intialize the variable before using it Jaswinder Singh Rajput
@ 2009-05-24 12:21 ` Avi Kivity
2009-05-25 5:17 ` Jaswinder Singh Rajput
2009-05-25 6:05 ` Ingo Molnar
0 siblings, 2 replies; 8+ messages in thread
From: Avi Kivity @ 2009-05-24 12:21 UTC (permalink / raw
To: Jaswinder Singh Rajput; +Cc: Ingo Molnar, x86 maintainers, LKML
Jaswinder Singh Rajput wrote:
> May be in some cases paging64_fetch() and paging32_fetch() will return sptep
> without initialization.
>
> Also fixes compilation warning:
> CC arch/x86/kernel/io_delay.o
> arch/x86/kvm/paging_tmpl.h: In function ‘paging64_fetch’:
> arch/x86/kvm/paging_tmpl.h:279: warning: ‘sptep’ may be used uninitialized in this function
> arch/x86/kvm/paging_tmpl.h: In function ‘paging32_fetch’:
> arch/x86/kvm/paging_tmpl.h:279: warning: ‘sptep’ may be used uninitialized in this function
>
> Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
> ---
> arch/x86/kvm/paging_tmpl.h | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
> index 6bd7020..99cb10d 100644
> --- a/arch/x86/kvm/paging_tmpl.h
> +++ b/arch/x86/kvm/paging_tmpl.h
> @@ -276,7 +276,7 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
> {
> unsigned access = gw->pt_access;
> struct kvm_mmu_page *shadow_page;
> - u64 spte, *sptep;
> + u64 spte, *sptep = NULL;
> int direct;
> gfn_t table_gfn;
> int r;
>
It's a false alarm. Isn't there a macro to shut up the warning?
--
error compiling committee.c: too many arguments to function
^ permalink raw reply [flat|nested] 8+ messages in thread* Re: [PATCH -tip] x86: kvm/paging_tmpl.h intialize the variable before using it
2009-05-24 12:21 ` Avi Kivity
@ 2009-05-25 5:17 ` Jaswinder Singh Rajput
2009-05-25 5:21 ` Avi Kivity
2009-05-25 6:05 ` Ingo Molnar
1 sibling, 1 reply; 8+ messages in thread
From: Jaswinder Singh Rajput @ 2009-05-25 5:17 UTC (permalink / raw
To: Avi Kivity; +Cc: Ingo Molnar, x86 maintainers, LKML
Hello Avi,
On Sun, 2009-05-24 at 15:21 +0300, Avi Kivity wrote:
> Jaswinder Singh Rajput wrote:
> > May be in some cases paging64_fetch() and paging32_fetch() will return sptep
> > without initialization.
> >
> > Also fixes compilation warning:
> > CC arch/x86/kernel/io_delay.o
> > arch/x86/kvm/paging_tmpl.h: In function ‘paging64_fetch’:
> > arch/x86/kvm/paging_tmpl.h:279: warning: ‘sptep’ may be used uninitialized in this function
> > arch/x86/kvm/paging_tmpl.h: In function ‘paging32_fetch’:
> > arch/x86/kvm/paging_tmpl.h:279: warning: ‘sptep’ may be used uninitialized in this function
> >
> > Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
> > ---
> > arch/x86/kvm/paging_tmpl.h | 2 +-
> > 1 files changed, 1 insertions(+), 1 deletions(-)
> >
> > diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
> > index 6bd7020..99cb10d 100644
> > --- a/arch/x86/kvm/paging_tmpl.h
> > +++ b/arch/x86/kvm/paging_tmpl.h
> > @@ -276,7 +276,7 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
> > {
> > unsigned access = gw->pt_access;
> > struct kvm_mmu_page *shadow_page;
> > - u64 spte, *sptep;
> > + u64 spte, *sptep = NULL;
> > int direct;
> > gfn_t table_gfn;
> > int r;
> >
>
> It's a false alarm. Isn't there a macro to shut up the warning?
>
In arch/x86/kvm/paging_tmpl.h sptep is initialize only in :
for_each_shadow_entry(vcpu, addr, iterator) {
If we skip this, then we end up with wild sptep and returning it.
Do you still think it is a false alarm ?
--
JSR
^ permalink raw reply [flat|nested] 8+ messages in thread* Re: [PATCH -tip] x86: kvm/paging_tmpl.h intialize the variable before using it
2009-05-25 5:17 ` Jaswinder Singh Rajput
@ 2009-05-25 5:21 ` Avi Kivity
2009-05-25 5:37 ` Jaswinder Singh Rajput
0 siblings, 1 reply; 8+ messages in thread
From: Avi Kivity @ 2009-05-25 5:21 UTC (permalink / raw
To: Jaswinder Singh Rajput; +Cc: Ingo Molnar, x86 maintainers, LKML
Jaswinder Singh Rajput wrote:
>> It's a false alarm. Isn't there a macro to shut up the warning?
>>
>>
>
> In arch/x86/kvm/paging_tmpl.h sptep is initialize only in :
>
> for_each_shadow_entry(vcpu, addr, iterator) {
>
> If we skip this, then we end up with wild sptep and returning it.
>
> Do you still think it is a false alarm ?
>
That loop always has at least one iteration.
--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.
^ permalink raw reply [flat|nested] 8+ messages in thread* Re: [PATCH -tip] x86: kvm/paging_tmpl.h intialize the variable before using it
2009-05-25 5:21 ` Avi Kivity
@ 2009-05-25 5:37 ` Jaswinder Singh Rajput
2009-05-25 6:01 ` Avi Kivity
0 siblings, 1 reply; 8+ messages in thread
From: Jaswinder Singh Rajput @ 2009-05-25 5:37 UTC (permalink / raw
To: Avi Kivity; +Cc: Ingo Molnar, x86 maintainers, LKML
On Mon, 2009-05-25 at 08:21 +0300, Avi Kivity wrote:
> Jaswinder Singh Rajput wrote:
> >> It's a false alarm. Isn't there a macro to shut up the warning?
> >>
> >>
> >
> > In arch/x86/kvm/paging_tmpl.h sptep is initialize only in :
> >
> > for_each_shadow_entry(vcpu, addr, iterator) {
> >
> > If we skip this, then we end up with wild sptep and returning it.
> >
> > Do you still think it is a false alarm ?
> >
>
> That loop always has at least one iteration.
>
hmm, In that case we should use a do-while flavor function so that the
compiler will also happy with it.
--
JSR
^ permalink raw reply [flat|nested] 8+ messages in thread* Re: [PATCH -tip] x86: kvm/paging_tmpl.h intialize the variable before using it
2009-05-25 5:37 ` Jaswinder Singh Rajput
@ 2009-05-25 6:01 ` Avi Kivity
0 siblings, 0 replies; 8+ messages in thread
From: Avi Kivity @ 2009-05-25 6:01 UTC (permalink / raw
To: Jaswinder Singh Rajput; +Cc: Ingo Molnar, x86 maintainers, LKML
Jaswinder Singh Rajput wrote:
>> That loop always has at least one iteration.
>>
>
> hmm, In that case we should use a do-while flavor function so that the
> compiler will also happy with it.
>
My own happiness requires that the loop not be rewritten.
--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH -tip] x86: kvm/paging_tmpl.h intialize the variable before using it
2009-05-24 12:21 ` Avi Kivity
2009-05-25 5:17 ` Jaswinder Singh Rajput
@ 2009-05-25 6:05 ` Ingo Molnar
2009-05-26 11:44 ` Avi Kivity
1 sibling, 1 reply; 8+ messages in thread
From: Ingo Molnar @ 2009-05-25 6:05 UTC (permalink / raw
To: Avi Kivity; +Cc: Jaswinder Singh Rajput, x86 maintainers, LKML
* Avi Kivity <avi@redhat.com> wrote:
> Jaswinder Singh Rajput wrote:
>> May be in some cases paging64_fetch() and paging32_fetch() will return sptep
>> without initialization.
>>
>> Also fixes compilation warning:
>> CC arch/x86/kernel/io_delay.o
>> arch/x86/kvm/paging_tmpl.h: In function ‘paging64_fetch’:
>> arch/x86/kvm/paging_tmpl.h:279: warning: ‘sptep’ may be used uninitialized in this function
>> arch/x86/kvm/paging_tmpl.h: In function ‘paging32_fetch’:
>> arch/x86/kvm/paging_tmpl.h:279: warning: ‘sptep’ may be used uninitialized in this function
>>
>> Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
>> ---
>> arch/x86/kvm/paging_tmpl.h | 2 +-
>> 1 files changed, 1 insertions(+), 1 deletions(-)
>>
>> diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
>> index 6bd7020..99cb10d 100644
>> --- a/arch/x86/kvm/paging_tmpl.h
>> +++ b/arch/x86/kvm/paging_tmpl.h
>> @@ -276,7 +276,7 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
>> {
>> unsigned access = gw->pt_access;
>> struct kvm_mmu_page *shadow_page;
>> - u64 spte, *sptep;
>> + u64 spte, *sptep = NULL;
>> int direct;
>> gfn_t table_gfn;
>> int r;
>>
>
> It's a false alarm. Isn't there a macro to shut up the warning?
there's uninitialized_var(), but that will shut up the warning and
any _correct_ future warning - so it's dangerous. Initialize it to
NULL and be done with it? We dont want stray warnings in the kernel.
Ingo
^ permalink raw reply [flat|nested] 8+ messages in thread* Re: [PATCH -tip] x86: kvm/paging_tmpl.h intialize the variable before using it
2009-05-25 6:05 ` Ingo Molnar
@ 2009-05-26 11:44 ` Avi Kivity
0 siblings, 0 replies; 8+ messages in thread
From: Avi Kivity @ 2009-05-26 11:44 UTC (permalink / raw
To: Ingo Molnar; +Cc: Jaswinder Singh Rajput, x86 maintainers, LKML
Ingo Molnar wrote:
>> It's a false alarm. Isn't there a macro to shut up the warning?
>>
>
> there's uninitialized_var(), but that will shut up the warning and
> any _correct_ future warning - so it's dangerous. Initialize it to
> NULL and be done with it? We dont want stray warnings in the kernel.
>
Makes sense, so I've applied the patch.
--
error compiling committee.c: too many arguments to function
^ permalink raw reply [flat|nested] 8+ messages in thread
end of thread, other threads:[~2009-05-26 11:45 UTC | newest]
Thread overview: 8+ messages (download: mbox.gz follow: Atom feed
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2009-05-20 4:29 [PATCH -tip] x86: kvm/paging_tmpl.h intialize the variable before using it Jaswinder Singh Rajput
2009-05-24 12:21 ` Avi Kivity
2009-05-25 5:17 ` Jaswinder Singh Rajput
2009-05-25 5:21 ` Avi Kivity
2009-05-25 5:37 ` Jaswinder Singh Rajput
2009-05-25 6:01 ` Avi Kivity
2009-05-25 6:05 ` Ingo Molnar
2009-05-26 11:44 ` Avi Kivity
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