diff mbox

GICv3: Fixing 32 bit compatibility

Message ID 1410185480-5153-1-git-send-email-rric@kernel.org (mailing list archive)
State New, archived
Headers show

Commit Message

Robert Richter Sept. 8, 2014, 2:11 p.m. UTC
From: Robert Richter <rrichter@cavium.com>

Fixing 32 bit compatibility by using ULL for u64 constants.

Signed-off-by: Robert Richter <rrichter@cavium.com>
---
 drivers/irqchip/irq-gic-v3.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Comments

Marc Zyngier Sept. 8, 2014, 2:24 p.m. UTC | #1
Hi Robert,

On 08/09/14 15:11, Robert Richter wrote:
> From: Robert Richter <rrichter@cavium.com>
> 
> Fixing 32 bit compatibility by using ULL for u64 constants.
> 
> Signed-off-by: Robert Richter <rrichter@cavium.com>
> ---
>  drivers/irqchip/irq-gic-v3.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
> index 57eaa5a0b1e3..9e13c87c7dfe 100644
> --- a/drivers/irqchip/irq-gic-v3.c
> +++ b/drivers/irqchip/irq-gic-v3.c
> @@ -441,7 +441,7 @@ static u16 gic_compute_target_list(int *base_cpu, const struct cpumask *mask,
>  
>  		mpidr = cpu_logical_map(cpu);
>  
> -		if (cluster_id != (mpidr & ~0xffUL)) {
> +		if (cluster_id != (mpidr & ~0xffULL)) {
>  			cpu--;
>  			goto out;
>  		}
> @@ -479,7 +479,7 @@ static void gic_raise_softirq(const struct cpumask *mask, unsigned int irq)
>  	smp_wmb();
>  
>  	for_each_cpu_mask(cpu, *mask) {
> -		u64 cluster_id = cpu_logical_map(cpu) & ~0xffUL;
> +		u64 cluster_id = cpu_logical_map(cpu) & ~0xffULL;
>  		u16 tlist;
>  
>  		tlist = gic_compute_target_list(&cpu, mask, cluster_id);
> 

Yeah, and there are many more. I'm currently sitting on a rather long
queue of GICv3-related 32bit patches. I'll try to get that posted shortly.

Thanks,

	M.
Uwe Kleine-König Sept. 9, 2014, 8 a.m. UTC | #2
Hello Robert,

On Mon, Sep 08, 2014 at 04:11:19PM +0200, Robert Richter wrote:
> From: Robert Richter <rrichter@cavium.com>
> 
> Fixing 32 bit compatibility by using ULL for u64 constants.
> 
> Signed-off-by: Robert Richter <rrichter@cavium.com>
> ---
>  drivers/irqchip/irq-gic-v3.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
> index 57eaa5a0b1e3..9e13c87c7dfe 100644
> --- a/drivers/irqchip/irq-gic-v3.c
> +++ b/drivers/irqchip/irq-gic-v3.c
> @@ -441,7 +441,7 @@ static u16 gic_compute_target_list(int *base_cpu, const struct cpumask *mask,
>  
>  		mpidr = cpu_logical_map(cpu);
>  
> -		if (cluster_id != (mpidr & ~0xffUL)) {
> +		if (cluster_id != (mpidr & ~0xffULL)) {
>  			cpu--;
>  			goto out;
>  		}
> @@ -479,7 +479,7 @@ static void gic_raise_softirq(const struct cpumask *mask, unsigned int irq)
>  	smp_wmb();
>  
>  	for_each_cpu_mask(cpu, *mask) {
> -		u64 cluster_id = cpu_logical_map(cpu) & ~0xffUL;
> +		u64 cluster_id = cpu_logical_map(cpu) & ~0xffULL;
This doesn't change anything, does it?

I wonder if it would be cleaner to use (u64)0xff here. Or still better
put the determination of the current cluster id(?) into a static inline
function?

Further, apart from arm and arm64 all other arch defining
cpu_logical_map (m32r, mips, mn10300, parisc, sh, sparc, um,
xtensa) return an int. (Three of them return just the cpu parameter
which at least for irq-gic-v3 is an int, too.)

Best regards
Uwe
Robert Richter Sept. 9, 2014, 9:12 a.m. UTC | #3
On 09.09.14 10:00:42, Uwe Kleine-König wrote:
> On Mon, Sep 08, 2014 at 04:11:19PM +0200, Robert Richter wrote:

> > @@ -479,7 +479,7 @@ static void gic_raise_softirq(const struct cpumask *mask, unsigned int irq)
> >     smp_wmb();
> >  
> >     for_each_cpu_mask(cpu, *mask) {
> > -           u64 cluster_id = cpu_logical_map(cpu) & ~0xffUL;
> > +           u64 cluster_id = cpu_logical_map(cpu) & ~0xffULL;
> This doesn't change anything, does it?

It does, not in 64 bit but in 32 bit there unsigned long is 32
bit. So, bit masks are broken if you compile a 32 bit kernel.

> I wonder if it would be cleaner to use (u64)0xff here.

No, that's ULL for. This is commonly used in x86 too.

-Robert
Uwe Kleine-König Sept. 9, 2014, 9:19 a.m. UTC | #4
On Tue, Sep 09, 2014 at 11:12:01AM +0200, Robert Richter wrote:
> On 09.09.14 10:00:42, Uwe Kleine-König wrote:
> > On Mon, Sep 08, 2014 at 04:11:19PM +0200, Robert Richter wrote:
> 
> > > @@ -479,7 +479,7 @@ static void gic_raise_softirq(const struct cpumask *mask, unsigned int irq)
> > >     smp_wmb();
> > >  
> > >     for_each_cpu_mask(cpu, *mask) {
> > > -           u64 cluster_id = cpu_logical_map(cpu) & ~0xffUL;
> > > +           u64 cluster_id = cpu_logical_map(cpu) & ~0xffULL;
> > This doesn't change anything, does it?
> 
> It does, not in 64 bit but in 32 bit there unsigned long is 32
> bit. So, bit masks are broken if you compile a 32 bit kernel.
Can you make an example where the result actually changes?

> > I wonder if it would be cleaner to use (u64)0xff here.
> 
> No, that's ULL for. This is commonly used in x86 too.
I don't care much here, but I'd say ULL is to force an unsigned long
long. If you want to make it obvious that you want a 64bit value, a cast
to u64 makes this more clear.

Best regards
Uwe
Robert Richter Sept. 9, 2014, 9:26 a.m. UTC | #5
On 09.09.14 11:19:12, Uwe Kleine-König wrote:
> On Tue, Sep 09, 2014 at 11:12:01AM +0200, Robert Richter wrote:
> > On 09.09.14 10:00:42, Uwe Kleine-König wrote:
> > > On Mon, Sep 08, 2014 at 04:11:19PM +0200, Robert Richter wrote:
> > 
> > > > @@ -479,7 +479,7 @@ static void gic_raise_softirq(const struct cpumask *mask, unsigned int irq)
> > > >     smp_wmb();
> > > >  
> > > >     for_each_cpu_mask(cpu, *mask) {
> > > > -           u64 cluster_id = cpu_logical_map(cpu) & ~0xffUL;
> > > > +           u64 cluster_id = cpu_logical_map(cpu) & ~0xffULL;
> > > This doesn't change anything, does it?
> > 
> > It does, not in 64 bit but in 32 bit there unsigned long is 32
> > bit. So, bit masks are broken if you compile a 32 bit kernel.
> Can you make an example where the result actually changes?

Upper 32 bits will be cleared above.

> > > I wonder if it would be cleaner to use (u64)0xff here.
> > 
> > No, that's ULL for. This is commonly used in x86 too.
> I don't care much here, but I'd say ULL is to force an unsigned long
> long. If you want to make it obvious that you want a 64bit value, a cast
> to u64 makes this more clear.

ULL is no cast at all.

-Robert
Uwe Kleine-König Sept. 9, 2014, 9:43 a.m. UTC | #6
On Tue, Sep 09, 2014 at 11:26:53AM +0200, Robert Richter wrote:
> On 09.09.14 11:19:12, Uwe Kleine-König wrote:
> > On Tue, Sep 09, 2014 at 11:12:01AM +0200, Robert Richter wrote:
> > > On 09.09.14 10:00:42, Uwe Kleine-König wrote:
> > > > On Mon, Sep 08, 2014 at 04:11:19PM +0200, Robert Richter wrote:
> > > 
> > > > > @@ -479,7 +479,7 @@ static void gic_raise_softirq(const struct cpumask *mask, unsigned int irq)
> > > > >     smp_wmb();
> > > > >  
> > > > >     for_each_cpu_mask(cpu, *mask) {
> > > > > -           u64 cluster_id = cpu_logical_map(cpu) & ~0xffUL;
> > > > > +           u64 cluster_id = cpu_logical_map(cpu) & ~0xffULL;
> > > > This doesn't change anything, does it?
> > > 
> > > It does, not in 64 bit but in 32 bit there unsigned long is 32
> > > bit. So, bit masks are broken if you compile a 32 bit kernel.
> > Can you make an example where the result actually changes?
> 
> Upper 32 bits will be cleared above.
ah, I missed the ~ while thinking about the difference.

> > > > I wonder if it would be cleaner to use (u64)0xff here.
> > > 
> > > No, that's ULL for. This is commonly used in x86 too.
> > I don't care much here, but I'd say ULL is to force an unsigned long
> > long. If you want to make it obvious that you want a 64bit value, a cast
> > to u64 makes this more clear.
> 
> ULL is no cast at all.
That's irrelevant here if it's a cast or not. It makes the constant be
an unsigned long long one.

If you want an unsigned long long value, use ULL (or a cast to unsigned
long long if the value permits), if you want an u64 use a cast to u64.

Probably it doesn't make sense to continue to argue here. The type of
cpu_logical_map(cpu) varies per architecture but is always <= 64 bits
wide and IIRC unsigned long long is guaranteed to be >= 64 bits wide so
everything is fine with your patch today.

Best regards
Uwe
Jason Cooper Sept. 14, 2014, 5:55 a.m. UTC | #7
On Mon, Sep 08, 2014 at 03:24:12PM +0100, Marc Zyngier wrote:
> Hi Robert,
> 
> On 08/09/14 15:11, Robert Richter wrote:
> > From: Robert Richter <rrichter@cavium.com>
> > 
> > Fixing 32 bit compatibility by using ULL for u64 constants.
> > 
> > Signed-off-by: Robert Richter <rrichter@cavium.com>
> > ---
> >  drivers/irqchip/irq-gic-v3.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
> > index 57eaa5a0b1e3..9e13c87c7dfe 100644
> > --- a/drivers/irqchip/irq-gic-v3.c
> > +++ b/drivers/irqchip/irq-gic-v3.c
> > @@ -441,7 +441,7 @@ static u16 gic_compute_target_list(int *base_cpu, const struct cpumask *mask,
> >  
> >  		mpidr = cpu_logical_map(cpu);
> >  
> > -		if (cluster_id != (mpidr & ~0xffUL)) {
> > +		if (cluster_id != (mpidr & ~0xffULL)) {
> >  			cpu--;
> >  			goto out;
> >  		}
> > @@ -479,7 +479,7 @@ static void gic_raise_softirq(const struct cpumask *mask, unsigned int irq)
> >  	smp_wmb();
> >  
> >  	for_each_cpu_mask(cpu, *mask) {
> > -		u64 cluster_id = cpu_logical_map(cpu) & ~0xffUL;
> > +		u64 cluster_id = cpu_logical_map(cpu) & ~0xffULL;
> >  		u16 tlist;
> >  
> >  		tlist = gic_compute_target_list(&cpu, mask, cluster_id);
> > 
> 
> Yeah, and there are many more. I'm currently sitting on a rather long
> queue of GICv3-related 32bit patches. I'll try to get that posted shortly.

I'll hold off until you post a complete series then.

thx,

Jason.
diff mbox

Patch

diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
index 57eaa5a0b1e3..9e13c87c7dfe 100644
--- a/drivers/irqchip/irq-gic-v3.c
+++ b/drivers/irqchip/irq-gic-v3.c
@@ -441,7 +441,7 @@  static u16 gic_compute_target_list(int *base_cpu, const struct cpumask *mask,
 
 		mpidr = cpu_logical_map(cpu);
 
-		if (cluster_id != (mpidr & ~0xffUL)) {
+		if (cluster_id != (mpidr & ~0xffULL)) {
 			cpu--;
 			goto out;
 		}
@@ -479,7 +479,7 @@  static void gic_raise_softirq(const struct cpumask *mask, unsigned int irq)
 	smp_wmb();
 
 	for_each_cpu_mask(cpu, *mask) {
-		u64 cluster_id = cpu_logical_map(cpu) & ~0xffUL;
+		u64 cluster_id = cpu_logical_map(cpu) & ~0xffULL;
 		u16 tlist;
 
 		tlist = gic_compute_target_list(&cpu, mask, cluster_id);