x86/cacheinfo: Refactor CPUID leaf 0x2 cache descriptor lookup

Extract the cache descriptor lookup logic out of the leaf 0x2 parsing
code and into a dedicated function.  This disentangles such lookup from
the deeply nested leaf 0x2 parsing loop.

Remove the cache table termination entry, as it is no longer needed
after the ARRAY_SIZE()-based lookup.

[ darwi: Move refactoring logic into this separate commit + commit log.
	 Remove the cache table termination entry. ]

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ahmed S. Darwish <darwi@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20250324133324.23458-6-darwi@linutronix.de

diff --git a/arch/x86/kernel/cpu/cacheinfo.c b/arch/x86/kernel/cpu/cacheinfo.c
index 6c610805e3564145d2f1e8ff481adf889d838846..d0bfdb85b96aedd95f1ea450647092ace7bef130 100644 (file)
--- a/arch/x86/kernel/cpu/cacheinfo.c
+++ b/arch/x86/kernel/cpu/cacheinfo.c
@@ -123,7 +123,6 @@ static const struct _cache_table cache_table[] =
        { 0xea, LVL_3,      MB(12) },   /* 24-way set assoc, 64 byte line size */
        { 0xeb, LVL_3,      MB(18) },   /* 24-way set assoc, 64 byte line size */
        { 0xec, LVL_3,      MB(24) },   /* 24-way set assoc, 64 byte line size */
-       { 0x00, 0, 0}
 };
 
 
@@ -728,6 +727,16 @@ void init_hygon_cacheinfo(struct cpuinfo_x86 *c)
        ci->num_leaves = find_num_cache_leaves(c);
 }
 
+static const struct _cache_table *cache_table_get(u8 desc)
+{
+       for (int i = 0; i < ARRAY_SIZE(cache_table); i++) {
+               if (cache_table[i].descriptor == desc)
+                       return &cache_table[i];
+       }
+
+       return NULL;
+}
+
 void init_intel_cacheinfo(struct cpuinfo_x86 *c)
 {
        /* Cache sizes */
@@ -784,34 +793,21 @@ void init_intel_cacheinfo(struct cpuinfo_x86 *c)
 
        /* Don't use CPUID(2) if CPUID(4) is supported. */
        if (!ci->num_leaves && c->cpuid_level > 1) {
+               const struct _cache_table *entry;
                union leaf_0x2_regs regs;
                u8 *desc;
 
                cpuid_get_leaf_0x2_regs(&regs);
                for_each_leaf_0x2_desc(regs, desc) {
-                       u8 k = 0;
-
-                       /* look up this descriptor in the table */
-                       while (cache_table[k].descriptor != 0) {
-                               if (cache_table[k].descriptor == *desc) {
-                                       switch (cache_table[k].cache_type) {
-                                       case LVL_1_INST:
-                                               l1i += cache_table[k].size;
-                                               break;
-                                       case LVL_1_DATA:
-                                               l1d += cache_table[k].size;
-                                               break;
-                                       case LVL_2:
-                                               l2 += cache_table[k].size;
-                                               break;
-                                       case LVL_3:
-                                               l3 += cache_table[k].size;
-                                               break;
-                                       }
-
-                                       break;
-                               }
-                               k++;
+                       entry = cache_table_get(*desc);
+                       if (!entry)
+                               continue;
+
+                       switch (entry->cache_type) {
+                       case LVL_1_INST: l1i += entry->size; break;
+                       case LVL_1_DATA: l1d += entry->size; break;
+                       case LVL_2:      l2  += entry->size; break;
+                       case LVL_3:      l3  += entry->size; break;
                        }
                }
        }