[PATCH AUTOSEL 6.1 10/60] cacheinfo: Fix shared_cpu_map to handle shared caches at different levels

Sasha Levin
2023-03-03T22:41:05Z

From: Yong-Xuan Wang <yongxuan.wang@sifive.com>

[ Upstream commit 198102c9103fc78d8478495971947af77edb05c1 ]

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.

Reviewed-by: Pierre Gondois <pierre.gondois@arm.com>
Signed-off-by: Yong-Xuan Wang <yongxuan.wang@sifive.com>
Link: https://lore.kernel.org/r/20230117105133.4445-2-yongxuan.wang@sifive.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/base/cacheinfo.c | 27 +++++++++++++++++----------
1 file changed, 17 insertions(+), 10 deletions(-)

diff --git a/drivers/base/cacheinfo.c b/drivers/base/cacheinfo.c
index 4b5cd08c5a657..f30256a524be6 100644
--- a/drivers/base/cacheinfo.c
+++ b/drivers/base/cacheinfo.c
@@ -251,7 +251,7 @@ 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)
@@ -279,11 +279,13 @@ 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);
+ break;
+ }
}
}
/* record the maximum cache line size */
@@ -297,7 +299,7 @@ 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);
@@ -308,9 +310,14 @@ 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);
+ break;
+ }
+ }
}
if (of_have_populated_dt())
of_node_put(this_leaf->fw_token);
--
2.39.2