linux-kernel - [PATCH] x86/microcode/intel: Use 64-bit arithmetic instead of 32-bit

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Message-ID: <20180213164404.GA11664@embeddedor.com>
Date:   Tue, 13 Feb 2018 10:44:04 -0600
From:   "Gustavo A. R. Silva" <garsilva@...eddedor.com>
To:     Borislav Petkov <bp@...en8.de>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org
Cc:     linux-kernel@...r.kernel.org,
        "Gustavo A. R. Silva" <garsilva@...eddedor.com>
Subject: [PATCH] x86/microcode/intel: Use 64-bit arithmetic instead of 32-bit

Add suffix ULL to constant 1024 in order to give the compiler complete
information about the proper arithmetic to use. Notice that this
constant is used in a context that expects an expression of type
u64 (64 bits, unsigned).

The expression c->x86_cache_size * 1024 is currently being evaluated
using 32-bit arithmetic.

Addresses-Coverity-ID: 1464429
Signed-off-by: Gustavo A. R. Silva <garsilva@...eddedor.com>
---
 arch/x86/kernel/cpu/microcode/intel.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c
index f7c55b0..e5edb92 100644
--- a/arch/x86/kernel/cpu/microcode/intel.c
+++ b/arch/x86/kernel/cpu/microcode/intel.c
@@ -982,7 +982,7 @@ static struct microcode_ops microcode_intel_ops = {
 
 static int __init calc_llc_size_per_core(struct cpuinfo_x86 *c)
 {
-	u64 llc_size = c->x86_cache_size * 1024;
+	u64 llc_size = c->x86_cache_size * 1024ULL;
 
 	do_div(llc_size, c->x86_max_cores);
 
-- 
2.7.4