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SubjectRe: [PATCH v2 1/1] drivers: base: cacheinfo: fix shared_cpu_map
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@arm.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@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..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).

> + 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);
> + }
> }
> }
> /* 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);
> + }
> + }
> }
> }
> }

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