63bcff2a30
When Supervisor Mode Access Prevention (SMAP) is enabled, access to userspace from the kernel is controlled by the AC flag. To make the performance of manipulating that flag acceptable, there are two new instructions, STAC and CLAC, to set and clear it. This patch adds those instructions, via alternative(), when the SMAP feature is enabled. It also adds X86_EFLAGS_AC unconditionally to the SYSCALL entry mask; there is simply no reason to make that one conditional. Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> Link: http://lkml.kernel.org/r/1348256595-29119-9-git-send-email-hpa@linux.intel.com
136 lines
2.6 KiB
ArmAsm
136 lines
2.6 KiB
ArmAsm
/*
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* Copyright 2008 Vitaly Mayatskikh <vmayatsk@redhat.com>
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* Copyright 2002 Andi Kleen, SuSE Labs.
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* Subject to the GNU Public License v2.
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*
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* Functions to copy from and to user space.
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*/
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#include <linux/linkage.h>
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#include <asm/dwarf2.h>
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#define FIX_ALIGNMENT 1
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#include <asm/current.h>
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#include <asm/asm-offsets.h>
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#include <asm/thread_info.h>
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#include <asm/asm.h>
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#include <asm/smap.h>
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.macro ALIGN_DESTINATION
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#ifdef FIX_ALIGNMENT
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/* check for bad alignment of destination */
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movl %edi,%ecx
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andl $7,%ecx
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jz 102f /* already aligned */
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subl $8,%ecx
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negl %ecx
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subl %ecx,%edx
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100: movb (%rsi),%al
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101: movb %al,(%rdi)
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incq %rsi
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incq %rdi
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decl %ecx
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jnz 100b
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102:
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.section .fixup,"ax"
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103: addl %ecx,%edx /* ecx is zerorest also */
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jmp copy_user_handle_tail
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.previous
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_ASM_EXTABLE(100b,103b)
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_ASM_EXTABLE(101b,103b)
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#endif
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.endm
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/*
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* copy_user_nocache - Uncached memory copy with exception handling
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* This will force destination/source out of cache for more performance.
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*/
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ENTRY(__copy_user_nocache)
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CFI_STARTPROC
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ASM_STAC
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cmpl $8,%edx
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jb 20f /* less then 8 bytes, go to byte copy loop */
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ALIGN_DESTINATION
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movl %edx,%ecx
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andl $63,%edx
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shrl $6,%ecx
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jz 17f
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1: movq (%rsi),%r8
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2: movq 1*8(%rsi),%r9
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3: movq 2*8(%rsi),%r10
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4: movq 3*8(%rsi),%r11
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5: movnti %r8,(%rdi)
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6: movnti %r9,1*8(%rdi)
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7: movnti %r10,2*8(%rdi)
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8: movnti %r11,3*8(%rdi)
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9: movq 4*8(%rsi),%r8
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10: movq 5*8(%rsi),%r9
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11: movq 6*8(%rsi),%r10
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12: movq 7*8(%rsi),%r11
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13: movnti %r8,4*8(%rdi)
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14: movnti %r9,5*8(%rdi)
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15: movnti %r10,6*8(%rdi)
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16: movnti %r11,7*8(%rdi)
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leaq 64(%rsi),%rsi
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leaq 64(%rdi),%rdi
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decl %ecx
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jnz 1b
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17: movl %edx,%ecx
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andl $7,%edx
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shrl $3,%ecx
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jz 20f
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18: movq (%rsi),%r8
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19: movnti %r8,(%rdi)
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leaq 8(%rsi),%rsi
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leaq 8(%rdi),%rdi
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decl %ecx
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jnz 18b
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20: andl %edx,%edx
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jz 23f
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movl %edx,%ecx
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21: movb (%rsi),%al
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22: movb %al,(%rdi)
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incq %rsi
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incq %rdi
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decl %ecx
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jnz 21b
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23: xorl %eax,%eax
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ASM_CLAC
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sfence
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ret
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.section .fixup,"ax"
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30: shll $6,%ecx
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addl %ecx,%edx
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jmp 60f
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40: lea (%rdx,%rcx,8),%rdx
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jmp 60f
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50: movl %ecx,%edx
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60: sfence
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jmp copy_user_handle_tail
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.previous
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_ASM_EXTABLE(1b,30b)
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_ASM_EXTABLE(2b,30b)
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_ASM_EXTABLE(3b,30b)
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_ASM_EXTABLE(4b,30b)
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_ASM_EXTABLE(5b,30b)
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_ASM_EXTABLE(6b,30b)
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_ASM_EXTABLE(7b,30b)
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_ASM_EXTABLE(8b,30b)
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_ASM_EXTABLE(9b,30b)
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_ASM_EXTABLE(10b,30b)
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_ASM_EXTABLE(11b,30b)
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_ASM_EXTABLE(12b,30b)
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_ASM_EXTABLE(13b,30b)
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_ASM_EXTABLE(14b,30b)
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_ASM_EXTABLE(15b,30b)
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_ASM_EXTABLE(16b,30b)
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_ASM_EXTABLE(18b,40b)
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_ASM_EXTABLE(19b,40b)
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_ASM_EXTABLE(21b,50b)
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_ASM_EXTABLE(22b,50b)
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CFI_ENDPROC
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ENDPROC(__copy_user_nocache)
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