linux-kernel - [PATCH 7/8] x86, 386 removal: Remove CONFIG_X86_POPAD

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Date:	Wed, 28 Nov 2012 11:50:29 -0800
From:	"H. Peter Anvin" <hpa@...ux.intel.com>
To:	"H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Mario Gzuk <mariogzuk@...hnikz.de>,
	"H. Peter Anvin" <hpa@...ux.intel.com>
Subject: [PATCH 7/8] x86, 386 removal: Remove CONFIG_X86_POPAD_OK

From: "H. Peter Anvin" <hpa@...ux.intel.com>

The check_popad() routine tested for a 386-specific bug, and never
actually did anything useful with it anyway other than print a
message.

Signed-off-by: H. Peter Anvin <hpa@...ux.intel.com>
---
 arch/x86/Kconfig.cpu       |  4 ----
 arch/x86/kernel/cpu/bugs.c | 28 ----------------------------
 2 files changed, 32 deletions(-)

diff --git a/arch/x86/Kconfig.cpu b/arch/x86/Kconfig.cpu
index 159ee9c..423db71 100644
--- a/arch/x86/Kconfig.cpu
+++ b/arch/x86/Kconfig.cpu
@@ -325,10 +325,6 @@ config X86_INVD_BUG
 	def_bool y
 	depends on M486
 
-config X86_POPAD_OK
-	def_bool y
-	depends on X86_32
-
 config X86_ALIGNMENT_16
 	def_bool y
 	depends on MWINCHIP3D || MWINCHIPC6 || MCYRIXIII || MELAN || MK6 || M586MMX || M586TSC || M586 || M486 || MVIAC3_2 || MGEODEGX1
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 0cd07cc..92dfec9 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -107,33 +107,6 @@ static void __init check_hlt(void)
 }
 
 /*
- *	Most 386 processors have a bug where a POPAD can lock the
- *	machine even from user space.
- */
-
-static void __init check_popad(void)
-{
-#ifndef CONFIG_X86_POPAD_OK
-	int res, inp = (int) &res;
-
-	pr_info("Checking for popad bug... ");
-	__asm__ __volatile__(
-	  "movl $12345678,%%eax; movl $0,%%edi; pusha; popa; movl (%%edx,%%edi),%%ecx "
-	  : "=&a" (res)
-	  : "d" (inp)
-	  : "ecx", "edi");
-	/*
-	 * If this fails, it means that any user program may lock the
-	 * CPU hard. Too bad.
-	 */
-	if (res != 12345678)
-		pr_cont("Buggy\n");
-	else
-		pr_cont("OK\n");
-#endif
-}
-
-/*
  * Check whether we are able to run this kernel safely on SMP.
  *
  * - i386 is no longer supported.
@@ -157,7 +130,6 @@ void __init check_bugs(void)
 #endif
 	check_config();
 	check_hlt();
-	check_popad();
 	init_utsname()->machine[1] =
 		'0' + (boot_cpu_data.x86 > 6 ? 6 : boot_cpu_data.x86);
 	alternative_instructions();
-- 
1.7.11.7

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