linux-kernel - [PATCH] x86/CPU/AMD: Fix LLC ID bit-shift calculation

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:   Wed, 13 Jun 2018 13:43:10 -0500
From:   Suravee Suthikulpanit <suravee.suthikulpanit@....com>
To:     x86@...nel.org, linux-kernel@...r.kernel.org
Cc:     tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, bp@...e.de,
        Suravee Suthikulpanit <suravee.suthikulpanit@....com>
Subject: [PATCH] x86/CPU/AMD: Fix LLC ID bit-shift calculation

The current logic incorrectly calculates the LLC ID from the APIC ID.
Unless specified otherwise, the LLC ID should be calculated from
the count order of the number of threads sharing cache.

Fixes: 68091ee7ac3c ("Calculate last level cache ID from number of sharing threads")
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@....com>
---
 arch/x86/kernel/cpu/cacheinfo.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/cacheinfo.c b/arch/x86/kernel/cpu/cacheinfo.c
index 38354c6..0c5fcbd 100644
--- a/arch/x86/kernel/cpu/cacheinfo.c
+++ b/arch/x86/kernel/cpu/cacheinfo.c
@@ -671,7 +671,7 @@ void cacheinfo_amd_init_llc_id(struct cpuinfo_x86 *c, int cpu, u8 node_id)
 			num_sharing_cache = ((eax >> 14) & 0xfff) + 1;
 
 		if (num_sharing_cache) {
-			int bits = get_count_order(num_sharing_cache) - 1;
+			int bits = get_count_order(num_sharing_cache);
 
 			per_cpu(cpu_llc_id, cpu) = c->apicid >> bits;
 		}
-- 
2.7.4