linux-kernel - [PATCH v2 1/2] x86/cpu: Use correct macros for Cyrix calls

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]

Date:   Fri, 21 Sep 2018 17:20:40 -0400
From:   Matthew Whitehead <tedheadster@...il.com>
To:     linux-kernel@...r.kernel.org
Cc:     mingo@...nel.org, tglx@...utronix.de, peterz@...radead.org,
        luto@...capital.net, bp@...en8.de, hpa@...or.com,
        Matthew Whitehead <tedheadster@...il.com>
Subject: [PATCH v2 1/2] x86/cpu: Use correct macros for Cyrix calls

There are comments in processor-cyrix.h advising you to _not_ make calls
using the deprecated macros in this style:

  setCx86_old(CX86_CCR4, getCx86_old(CX86_CCR4) | 0x80);

This is because it expands the macro into a non-functioning calling
sequence. The calling order must be:

  outb(CX86_CCR2, 0x22);
  inb(0x23);

>From the comments:

 * When using the old macros a line like
 *   setCx86(CX86_CCR2, getCx86(CX86_CCR2) | 0x88);
 * gets expanded to:
 *  do {
 *    outb((CX86_CCR2), 0x22);
 *    outb((({
 *        outb((CX86_CCR2), 0x22);
 *        inb(0x23);
 *    }) | 0x88), 0x23);
 *  } while (0);

The new macros fix this problem, so we use them instead.

Reviewed-by: Andy Lutomirski <luto@...capital.net>
Signed-off-by: Matthew Whitehead <tedheadster@...il.com>
---
 arch/x86/kernel/cpu/cyrix.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/cyrix.c b/arch/x86/kernel/cpu/cyrix.c
index 8949b7ae6d92..d12226f60168 100644
--- a/arch/x86/kernel/cpu/cyrix.c
+++ b/arch/x86/kernel/cpu/cyrix.c
@@ -437,7 +437,7 @@ static void cyrix_identify(struct cpuinfo_x86 *c)
 			/* enable MAPEN  */
 			setCx86(CX86_CCR3, (ccr3 & 0x0f) | 0x10);
 			/* enable cpuid  */
-			setCx86_old(CX86_CCR4, getCx86_old(CX86_CCR4) | 0x80);
+			setCx86(CX86_CCR4, getCx86(CX86_CCR4) | 0x80);
 			/* disable MAPEN */
 			setCx86(CX86_CCR3, ccr3);
 			local_irq_restore(flags);
-- 
2.16.4