Messages in this thread | ![/](/images/icornerl.gif) | | From | Yong Xuan Wang <> | Date | Tue, 17 Jan 2023 18:02:56 +0800 | Subject | Re: [PATCH -next v3] drivers: base: cacheinfo: fix shared_cpu_map |
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Hi Sudeep,
> On Wed, Jan 4, 2023 at 6:59 PM Sudeep Holla <sudeep.holla@arm.com> wrote: > > On Wed, Dec 28, 2022 at 03:24:19AM +0000, 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. > > > > Just curious to know if this is just Qemu config or a real platform. > I had intentionally not supported this to just to get to know when such > h/w appears in the real world 😁. >
We are trying to build such kind of config in QEMU.
> > Reviewed-by: Pierre Gondois <pierre.gondois@arm.com> > > Signed-off-by: Yong-Xuan Wang <yongxuan.wang@sifive.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..dfa804bcf3cc 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); > > + 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); > > Does it make sense to break here once we match as it is unlikely to match > with any other indices ? >
Yeah. We can break here once we find the shared instance. I'll send a new version to fix it. Thank you!
> > + } > > } > > } > > /* record the maximum cache line size */ > > @@ -302,7 +303,7 @@ static int cache_shared_cpu_map_setup(unsigned int cpu) > > static void cache_shared_cpu_map_remove(unsigned int cpu) > > { > > struct cacheinfo *this_leaf, *sib_leaf; > > - unsigned int sibling, index; > > + unsigned int sibling, index, sib_index; > > > > for (index = 0; index < cache_leaves(cpu); index++) { > > this_leaf = per_cpu_cacheinfo_idx(cpu, index); > > @@ -313,9 +314,13 @@ static void cache_shared_cpu_map_remove(unsigned int cpu) > > if (sibling == cpu || !sib_cpu_ci->info_list) > > continue;/* skip if itself or no cacheinfo */ > > > > - sib_leaf = per_cpu_cacheinfo_idx(sibling, index); > > - cpumask_clear_cpu(cpu, &sib_leaf->shared_cpu_map); > > - cpumask_clear_cpu(sibling, &this_leaf->shared_cpu_map); > > + for (sib_index = 0; sib_index < cache_leaves(sibling); sib_index++) { > > + sib_leaf = per_cpu_cacheinfo_idx(sibling, sib_index); > > + if (cache_leaves_are_shared(this_leaf, sib_leaf)) { > > + cpumask_clear_cpu(cpu, &sib_leaf->shared_cpu_map); > > + cpumask_clear_cpu(sibling, &this_leaf->shared_cpu_map); > > Same comment as above. > > -- > Regards, > Sudeep
Regards, Yong-Xuan
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