linux-kernel - Re: [PATCH v2 1/1] drivers: base: cacheinfo: fix shared_cpu

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Message-ID: <Y8p6ns/XNrk/CDww@kroah.com>
Date:   Fri, 20 Jan 2023 12:27:26 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Pierre Gondois <pierre.gondois@....com>
Cc:     Yong-Xuan Wang <yongxuan.wang@...ive.com>,
        Sudeep Holla <sudeep.holla@....com>,
        Vincent Chen <vincent.chen@...ive.com>,
        Greentime Hu <greentime.hu@...ive.com>,
        linux-kernel@...r.kernel.org,
        "Rafael J. Wysocki" <rafael@...nel.org>
Subject: Re: [PATCH v2 1/1] drivers: base: cacheinfo: fix shared_cpu_map

On Wed, Dec 21, 2022 at 10:00:39AM +0100, Pierre Gondois wrote:
> Hello Yong-Xuan,
> Except for the nit below, I tried the patch and everything seemed ok, so
> with that:
> Reviewed-by: Pierre Gondois <pierre.gondois@....com>
> 
> Regards,
> Pierre
> 
> On 12/19/22 11:51, Yong-Xuan Wang wrote:
> > The cacheinfo sets up the shared_cpu_map by checking whether the caches
> > with the same index are shared between CPUs. However, this will trigger
> > slab-out-of-bounds access if the CPUs do not have the same cache hierarchy.
> > Another problem is the mismatched shared_cpu_map when the shared cache does
> > not have the same index between CPUs.
> > 
> > CPU0	I	D	L3
> > index	0	1	2	x
> > 	^	^	^	^
> > index	0	1	2	3
> > CPU1	I	D	L2	L3
> > 
> > This patch checks each cache is shared with all caches on other CPUs.
> > 
> > Signed-off-by: Yong-Xuan Wang <yongxuan.wang@...ive.com>
> > ---
> >   drivers/base/cacheinfo.c | 25 +++++++++++++++----------
> >   1 file changed, 15 insertions(+), 10 deletions(-)
> > 
> > diff --git a/drivers/base/cacheinfo.c b/drivers/base/cacheinfo.c
> > index 950b22cdb5f7..d38f80f6fff1 100644
> > --- a/drivers/base/cacheinfo.c
> > +++ b/drivers/base/cacheinfo.c
> > @@ -256,7 +256,7 @@ static int cache_shared_cpu_map_setup(unsigned int cpu)
> >   {
> >   	struct cpu_cacheinfo *this_cpu_ci = get_cpu_cacheinfo(cpu);
> >   	struct cacheinfo *this_leaf, *sib_leaf;
> > -	unsigned int index;
> > +	unsigned int index, sib_index;
> >   	int ret = 0;
> >   	if (this_cpu_ci->cpu_map_populated)
> > @@ -284,11 +284,12 @@ static int cache_shared_cpu_map_setup(unsigned int cpu)
> >   			if (i == cpu || !sib_cpu_ci->info_list)
> >   				continue;/* skip if itself or no cacheinfo */
> > -
> > -			sib_leaf = per_cpu_cacheinfo_idx(i, index);
> > -			if (cache_leaves_are_shared(this_leaf, sib_leaf)) {
> > -				cpumask_set_cpu(cpu, &sib_leaf->shared_cpu_map);
> > -				cpumask_set_cpu(i, &this_leaf->shared_cpu_map);
> > +			for (sib_index = 0; sib_index < cache_leaves(i); sib_index++) {
> > +				sib_leaf = per_cpu_cacheinfo_idx(i, sib_index);;
> 
> It seems there are 2 ';' above (same in the block below).

Yes, the kernel test robot complains about this as well.

It needs to be fixed before this change can be accepted.

thanks,

greg k-h