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x86, head_32: Remove i386 pieces

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Remove code fragments detecting a 386 CPU since we don't support those
anymore. Also, do not do alignment checks because they're done only at
CPL3. Also, no need to preserve EFLAGS.

Signed-off-by: Borislav Petkov <bp@suse.de>
Link: http://lkml.kernel.org/r/1360592538-10643-2-git-send-email-bp@alien8.de
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
This commit is contained in:
Borislav Petkov 2013-02-11 15:22:15 +01:00 committed by H. Peter Anvin
parent 8ecba5af94
commit 166df91daf
1 changed files with 5 additions and 17 deletions
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22
arch/x86/kernel/head_32.S
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@ -394,30 +394,21 @@ default_entry:
jz 1f # Did we do this already?
call *%eax
1:
/* check if it is 486 or 386. */
/*
* XXX - this does a lot of unnecessary setup. Alignment checks don't
* apply at our cpl of 0 and the stack ought to be aligned already, and
* we don't need to preserve eflags.
* Check if it is 486
*/
movl $-1,X86_CPUID # -1 for no CPUID initially
movb $3,X86 # at least 386
movb $4,X86 # at least 486
pushfl # push EFLAGS
popl %eax # get EFLAGS
movl %eax,%ecx # save original EFLAGS
xorl $0x240000,%eax # flip AC and ID bits in EFLAGS
xorl $0x200000,%eax # flip ID bit in EFLAGS
pushl %eax # copy to EFLAGS
popfl # set EFLAGS
pushfl # get new EFLAGS
popl %eax # put it in eax
xorl %ecx,%eax # change in flags
pushl %ecx # restore original EFLAGS
popfl
testl $0x40000,%eax # check if AC bit changed
je is386
movb $4,X86 # at least 486
testl $0x200000,%eax # check if ID bit changed
je is486
@ -445,10 +436,7 @@ default_entry:
movl %edx,X86_CAPABILITY
is486: movl $0x50022,%ecx # set AM, WP, NE and MP
jmp 2f
is386: movl $2,%ecx # set MP
2: movl %cr0,%eax
movl %cr0,%eax
andl $0x80000011,%eax # Save PG,PE,ET
orl %ecx,%eax
movl %eax,%cr0