Commit c7f81c94 authored by Andi Kleen's avatar Andi Kleen Committed by Andi Kleen

[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
......@@ -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"
......@@ -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
......
/* 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
......@@ -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 */
......
#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
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