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Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
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linux
x86/lib/copy_user_64.S: Convert to ALTERNATIVE_2
Use the asm macro and drop the locally grown version.
Signed-off-by: Borislav Petkov <bp@suse.de>
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arch/x86/lib/copy_user_64.S
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arch/x86/lib/copy_user_64.S
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#include <asm/asm.h>
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#include <asm/smap.h>
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/*
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* By placing feature2 after feature1 in altinstructions section, we logically
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* implement:
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* If CPU has feature2, jmp to alt2 is used
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* else if CPU has feature1, jmp to alt1 is used
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* else jmp to orig is used.
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*/
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.macro ALTERNATIVE_JUMP feature1,feature2,orig,alt1,alt2
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0:
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jmp \orig
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1:
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.section .altinstr_replacement,"ax"
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jmp \alt1
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jmp \alt2
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.previous
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.section .altinstructions,"a"
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altinstruction_entry 0b,2b,\feature1,5,5,0
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altinstruction_entry 0b,3b,\feature2,5,5,0
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.previous
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.endm
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.macro ALIGN_DESTINATION
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/* check for bad alignment of destination */
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movl %edi,%ecx
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jc bad_to_user
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cmpq TI_addr_limit(%rax),%rcx
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ja bad_to_user
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ALTERNATIVE_JUMP X86_FEATURE_REP_GOOD,X86_FEATURE_ERMS, \
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copy_user_generic_unrolled,copy_user_generic_string, \
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copy_user_enhanced_fast_string
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ALTERNATIVE_2 "jmp copy_user_generic_unrolled", \
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"jmp copy_user_generic_string", \
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X86_FEATURE_REP_GOOD, \
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"jmp copy_user_enhanced_fast_string", \
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X86_FEATURE_ERMS
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CFI_ENDPROC
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ENDPROC(_copy_to_user)
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···
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jc bad_from_user
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cmpq TI_addr_limit(%rax),%rcx
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ja bad_from_user
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ALTERNATIVE_JUMP X86_FEATURE_REP_GOOD,X86_FEATURE_ERMS, \
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copy_user_generic_unrolled,copy_user_generic_string, \
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copy_user_enhanced_fast_string
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ALTERNATIVE_2 "jmp copy_user_generic_unrolled", \
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"jmp copy_user_generic_string", \
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X86_FEATURE_REP_GOOD, \
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"jmp copy_user_enhanced_fast_string", \
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X86_FEATURE_ERMS
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CFI_ENDPROC
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ENDPROC(_copy_from_user)
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