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Commit aa042141 authored by Borislav Petkov's avatar Borislav Petkov Committed by Ingo Molnar
Browse files

x86/boot: Hide local labels in verify_cpu() 



... from the final ELF image's symbol table as they're not
really needed there.

Before:

$ readelf -a vmlinux | grep verify_cpu
    43: ffffffff810001a9     0 NOTYPE  LOCAL  DEFAULT    1 verify_cpu
    45: ffffffff8100028f     0 NOTYPE  LOCAL  DEFAULT    1 verify_cpu_no_longmode
    46: ffffffff810001de     0 NOTYPE  LOCAL  DEFAULT    1 verify_cpu_noamd
    47: ffffffff8100022b     0 NOTYPE  LOCAL  DEFAULT    1 verify_cpu_check
    48: ffffffff8100021c     0 NOTYPE  LOCAL  DEFAULT    1 verify_cpu_clear_xd
    49: ffffffff81000263     0 NOTYPE  LOCAL  DEFAULT    1 verify_cpu_sse_test
    50: ffffffff81000296     0 NOTYPE  LOCAL  DEFAULT    1 verify_cpu_sse_ok

After:

$ readelf -a vmlinux | grep verify_cpu
    43: ffffffff810001a9     0 NOTYPE  LOCAL  DEFAULT    1 verify_cpu

No functionality change.

Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1451860733-21163-1-git-send-email-bp@alien8.de


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 394db20c

arch/x86/kernel/verify_cpu.S

+25 −25
Original line number Diff line number Diff line
@@ -48,31 +48,31 @@ verify_cpu: 
	pushfl

	popl	%eax

	cmpl	%eax,%ebx

	jz	verify_cpu_no_longmode	# cpu has no cpuid

	jz	.Lverify_cpu_no_longmode	# cpu has no cpuid

#endif



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

	cpuid

	cmpl	$0x1,%eax

	jb	verify_cpu_no_longmode	# no cpuid 1

	jb	.Lverify_cpu_no_longmode	# no cpuid 1



	xor	%di,%di

	cmpl	$0x68747541,%ebx	# AuthenticAMD

	jnz	verify_cpu_noamd

	jnz	.Lverify_cpu_noamd

	cmpl	$0x69746e65,%edx

	jnz	verify_cpu_noamd

	jnz	.Lverify_cpu_noamd

	cmpl	$0x444d4163,%ecx

	jnz	verify_cpu_noamd

	jnz	.Lverify_cpu_noamd

	mov	$1,%di			# cpu is from AMD

	jmp	verify_cpu_check

	jmp	.Lverify_cpu_check



verify_cpu_noamd:

.Lverify_cpu_noamd:

	cmpl	$0x756e6547,%ebx        # GenuineIntel?

	jnz	verify_cpu_check

	jnz	.Lverify_cpu_check

	cmpl	$0x49656e69,%edx

	jnz	verify_cpu_check

	jnz	.Lverify_cpu_check

	cmpl	$0x6c65746e,%ecx

	jnz	verify_cpu_check

	jnz	.Lverify_cpu_check



	# only call IA32_MISC_ENABLE when:

	# family > 6 || (family == 6 && model >= 0xd)
@@ -83,59 +83,59 @@ verify_cpu_noamd: 
	andl	$0x0ff00f00, %eax	# mask family and extended family

	shrl	$8, %eax

	cmpl	$6, %eax

	ja	verify_cpu_clear_xd	# family > 6, ok

	jb	verify_cpu_check	# family < 6, skip

	ja	.Lverify_cpu_clear_xd	# family > 6, ok

	jb	.Lverify_cpu_check	# family < 6, skip



	andl	$0x000f00f0, %ecx	# mask model and extended model

	shrl	$4, %ecx

	cmpl	$0xd, %ecx

	jb	verify_cpu_check	# family == 6, model < 0xd, skip

	jb	.Lverify_cpu_check	# family == 6, model < 0xd, skip



verify_cpu_clear_xd:

.Lverify_cpu_clear_xd:

	movl	$MSR_IA32_MISC_ENABLE, %ecx

	rdmsr

	btrl	$2, %edx		# clear MSR_IA32_MISC_ENABLE_XD_DISABLE

	jnc	verify_cpu_check	# only write MSR if bit was changed

	jnc	.Lverify_cpu_check	# only write MSR if bit was changed

	wrmsr



verify_cpu_check:

.Lverify_cpu_check:

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

	cpuid

	andl	$REQUIRED_MASK0,%edx

	xorl	$REQUIRED_MASK0,%edx

	jnz	verify_cpu_no_longmode

	jnz	.Lverify_cpu_no_longmode



	movl    $0x80000000,%eax	# See if extended cpuid is implemented

	cpuid

	cmpl    $0x80000001,%eax

	jb      verify_cpu_no_longmode	# no extended cpuid

	jb      .Lverify_cpu_no_longmode	# no extended cpuid



	movl    $0x80000001,%eax	# Does the cpu have what it takes

	cpuid

	andl    $REQUIRED_MASK1,%edx

	xorl    $REQUIRED_MASK1,%edx

	jnz     verify_cpu_no_longmode

	jnz     .Lverify_cpu_no_longmode



verify_cpu_sse_test:

.Lverify_cpu_sse_test:

	movl	$1,%eax

	cpuid

	andl	$SSE_MASK,%edx

	cmpl	$SSE_MASK,%edx

	je	verify_cpu_sse_ok

	je	.Lverify_cpu_sse_ok

	test	%di,%di

	jz	verify_cpu_no_longmode	# only try to force SSE on AMD

	jz	.Lverify_cpu_no_longmode	# only try to force SSE on AMD

	movl	$MSR_K7_HWCR,%ecx

	rdmsr

	btr	$15,%eax		# enable SSE

	wrmsr

	xor	%di,%di			# don't loop

	jmp	verify_cpu_sse_test	# try again

	jmp	.Lverify_cpu_sse_test	# try again



verify_cpu_no_longmode:

.Lverify_cpu_no_longmode:

	popf				# Restore caller passed flags

	movl $1,%eax

	ret

verify_cpu_sse_ok:

.Lverify_cpu_sse_ok:

	popf				# Restore caller passed flags

	xorl %eax, %eax

	ret