[PATCH AUTOSEL 6.2 11/64] cacheinfo: Fix shared_cpu_map to handle shared caches at different levels

[Sasha Levin]

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

[ 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@xxxxxxx>
Signed-off-by: Yong-Xuan Wang <yongxuan.wang@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230117105133.4445-2-yongxuan.wang@xxxxxxxxxx
Signed-off-by: Sudeep Holla <sudeep.holla@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 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 950b22cdb5f7c..f05acf3c16c6b 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 +284,13 @@ 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 */
@@ -302,7 +304,7 @@ 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 +315,14 @@ 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;
+				}
+			}
 		}
 	}
 }
-- 
2.39.2