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Subject[PATCH 1/4] x86, head_32: Remove i386 pieces
Date
From: Borislav Petkov <bp@suse.de>

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>
---
arch/x86/kernel/head_32.S | 22 +++++-----------------
1 file changed, 5 insertions(+), 17 deletions(-)

diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S
index c8932c79e78b..a9c5cc851285 100644
--- a/arch/x86/kernel/head_32.S
+++ b/arch/x86/kernel/head_32.S
@@ -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
--
1.8.1.2.422.g08c0e7f


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