Messages in this thread Patch in this message | | | Date | Wed, 4 Jan 2023 10:59:39 +0000 | From | Sudeep Holla <> | Subject | Re: [PATCH -next v3] drivers: base: cacheinfo: fix shared_cpu_map |
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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 😁.
> 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 ?
> + } > } > } > /* 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
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