linux-kernel - [PATCH 4/5] x86, microcode, AMD: Exit early on success

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

Message-Id: <1323454135-16777-5-git-send-email-bp@amd64.org>
Date:	Fri,  9 Dec 2011 19:08:54 +0100
From:	Borislav Petkov <bp@...64.org>
To:	X86-ML <x86@...nel.org>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Borislav Petkov <borislav.petkov@....com>
Subject: [PATCH 4/5] x86, microcode, AMD: Exit early on success

From: Borislav Petkov <borislav.petkov@....com>

Once we've found and validated the ucode patch for the current CPU,
there's no need to iterate over the remaining patches in the binary
image. Exit then and save us a bunch of cycles.

Signed-off-by: Borislav Petkov <borislav.petkov@....com>
---
 arch/x86/kernel/microcode_amd.c |   22 +++++++++-------------
 1 files changed, 9 insertions(+), 13 deletions(-)

diff --git a/arch/x86/kernel/microcode_amd.c b/arch/x86/kernel/microcode_amd.c
index 384990d..d80e943 100644
--- a/arch/x86/kernel/microcode_amd.c
+++ b/arch/x86/kernel/microcode_amd.c
@@ -282,11 +282,11 @@ generic_load_microcode(int cpu, const u8 *data, size_t size)
 			mc_hdr  = patch;
 			new_mc  = patch;
 			new_rev = mc_hdr->patch_id;
-			leftover -= mc_size;
-		} else {
-			ucode_ptr += current_size;
-			leftover  -= current_size;
+			goto out_ok;
 		}
+
+		ucode_ptr += current_size;
+		leftover  -= current_size;
 	}
 
 	if (!new_mc) {
@@ -294,15 +294,11 @@ generic_load_microcode(int cpu, const u8 *data, size_t size)
 		goto free_table;
 	}
 
-	if (!leftover) {
-		uci->mc = new_mc;
-		state = UCODE_OK;
-		pr_debug("CPU%d update ucode (0x%08x -> 0x%08x)\n",
-			 cpu, uci->cpu_sig.rev, new_rev);
-	} else {
-		new_mc = NULL;
-		state = UCODE_ERROR;
-	}
+out_ok:
+	uci->mc = new_mc;
+	state = UCODE_OK;
+	pr_debug("CPU%d update ucode (0x%08x -> 0x%08x)\n",
+		 cpu, uci->cpu_sig.rev, new_rev);
 
 free_table:
 	free_equiv_cpu_table();
-- 
1.7.8.rc0

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/