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Commit c7f81c94 authored by Andi Kleen's avatar Andi Kleen Committed by Andi Kleen
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[PATCH] i386: Verify important CPUID bits in real mode 



Check some CPUID bits that are needed for compiler generated early in boot.
When the system is still in real mode before changing the VESA BIOS mode
it is possible to still display an visible error message on the screen.

Similar to x86-64.

Includes cleanups from Eric Biederman

Signed-off-by: default avatarAndi Kleen <ak@suse.de>
parent 484ad393

arch/i386/Kconfig.cpu

+20 −2
Original line number Diff line number Diff line
@@ -240,14 +240,19 @@ config X86_L1_CACHE_SHIFT 
	default "5" if MWINCHIP3D || MWINCHIP2 || MWINCHIPC6 || MCRUSOE || MEFFICEON || MCYRIXIII || MK6 || MPENTIUMIII || MPENTIUMII || M686 || M586MMX || M586TSC || M586 || MVIAC3_2 || MGEODE_LX

	default "6" if MK7 || MK8 || MPENTIUMM || MCORE2 || MVIAC7



config X86_XADD

	bool

	depends on !M386

	default y



config RWSEM_GENERIC_SPINLOCK

	bool

	depends on M386

	depends on !X86_XADD

	default y



config RWSEM_XCHGADD_ALGORITHM

	bool

	depends on !M386

	depends on X86_XADD

	default y



config ARCH_HAS_ILOG2_U32
@@ -331,3 +336,16 @@ config X86_TSC 
	bool

	depends on (MWINCHIP3D || MWINCHIP2 || MCRUSOE || MEFFICEON || MCYRIXIII || MK7 || MK6 || MPENTIUM4 || MPENTIUMM || MPENTIUMIII || MPENTIUMII || M686 || M586MMX || M586TSC || MK8 || MVIAC3_2 || MVIAC7 || MGEODEGX1 || MGEODE_LX || MCORE2) && !X86_NUMAQ

	default y



# this should be set for all -march=.. options where the compiler

# generates cmov.

config X86_CMOV

	bool

	depends on (MK7 || MPENTIUM4 || MPENTIUMM || MPENTIUMIII || MPENTIUMII || M686 || MVIAC3_2 || MVIAC7)

	default y



config X86_MINIMUM_CPU_MODEL

	int

	default "4" if X86_XADD || X86_CMPXCHG || X86_BSWAP

	default "0"

arch/i386/boot/setup.S

+17 −0
Original line number Diff line number Diff line
@@ -302,7 +302,24 @@ good_sig: 


loader_panic_mess: .string "Wrong loader, giving up..."



# check minimum cpuid

# we do this here because it is the last place we can actually

# show a user visible error message. Later the video modus

# might be already messed up.

loader_ok:

	call verify_cpu

	testl  %eax,%eax

	jz	cpu_ok

	lea	cpu_panic_mess,%si

	call	prtstr

1:	jmp	1b



cpu_panic_mess:

	.asciz  "PANIC: CPU too old for this kernel."



#include "../kernel/verify_cpu.S"



cpu_ok:

# Get memory size (extended mem, kB)



	xorl	%eax, %eax

arch/i386/kernel/verify_cpu.S

0 → 100644
+65 −0
Original line number Diff line number Diff line 
/* Check if CPU has some minimum CPUID bits

   This runs in 16bit mode so that the caller can still use the BIOS

   to output errors on the screen */

#include <asm/cpufeature.h>



verify_cpu:

	pushfl				# Save caller passed flags

	pushl	$0			# Kill any dangerous flags

	popfl



#if CONFIG_X86_MINIMUM_CPU_MODEL >= 4

	pushfl

	orl	$(1<<18),(%esp)		# try setting AC

	popfl

	pushfl

	popl    %eax

	testl	$(1<<18),%eax

	jz	bad

#endif

#if REQUIRED_MASK1 != 0

	pushfl				# standard way to check for cpuid

	popl	%eax

	movl	%eax,%ebx

	xorl	$0x200000,%eax

	pushl	%eax

	popfl

	pushfl

	popl	%eax

	cmpl	%eax,%ebx

	pushfl				# standard way to check for cpuid

	popl	%eax

	movl	%eax,%ebx

	xorl	$0x200000,%eax

	pushl	%eax

	popfl

	pushfl

	popl	%eax

	cmpl	%eax,%ebx

	jz	bad			# REQUIRED_MASK1 != 0 requires CPUID



	movl	$0x0,%eax		# See if cpuid 1 is implemented

	cpuid

	cmpl	$0x1,%eax

	jb	bad			# no cpuid 1



	movl    $0x1,%eax		# Does the cpu have what it takes

	cpuid



#if CONFIG_X86_MINIMUM_CPU_MODEL > 4

#error	add proper model checking here

#endif



	andl	$REQUIRED_MASK1,%edx

	xorl	$REQUIRED_MASK1,%edx

	jnz	bad

#endif /* REQUIRED_MASK1 */



	popfl

	xor	%eax,%eax

	ret



bad:

	popfl

	movl	$1,%eax

	ret

include/asm-i386/cpufeature.h

+3 −0
Original line number Diff line number Diff line
@@ -7,7 +7,10 @@ 
#ifndef __ASM_I386_CPUFEATURE_H

#define __ASM_I386_CPUFEATURE_H



#ifndef __ASSEMBLY__

#include <linux/bitops.h>

#endif

#include <asm/required-features.h>



#define NCAPINTS	7	/* N 32-bit words worth of info */

include/asm-i386/required-features.h

0 → 100644
+34 −0
Original line number Diff line number Diff line 
#ifndef _ASM_REQUIRED_FEATURES_H

#define _ASM_REQUIRED_FEATURES_H 1



/* Define minimum CPUID feature set for kernel These bits are checked

   really early to actually display a visible error message before the

   kernel dies.  Only add word 0 bits here



   Some requirements that are not in CPUID yet are also in the

   CONFIG_X86_MINIMUM_CPU mode which is checked too.



   The real information is in arch/i386/Kconfig.cpu, this just converts

   the CONFIGs into a bitmask */



#ifdef CONFIG_X86_PAE

#define NEED_PAE	(1<<X86_FEATURE_PAE)

#else

#define NEED_PAE	0

#endif



#ifdef CONFIG_X86_CMOV

#define NEED_CMOV	(1<<X86_FEATURE_CMOV)

#else

#define NEED_CMOV	0

#endif



#ifdef CONFIG_X86_CMPXCHG64

#define NEED_CMPXCHG64  (1<<X86_FEATURE_CX8)

#else

#define NEED_CMPXCHG64  0

#endif



#define REQUIRED_MASK1	(NEED_PAE|NEED_CMOV|NEED_CMPXCHG64)



#endif