linux-stable/arch/x86/lib/putuser.S
Josh Poimboeuf 82e844a653 x86/uaccess: Remove redundant CLACs in getuser/putuser error paths
The same getuser/putuser error paths are used regardless of whether AC
is set.  In non-exception failure cases, this results in an unnecessary
CLAC.

Fixes the following warnings:

  arch/x86/lib/getuser.o: warning: objtool: .altinstr_replacement+0x18: redundant UACCESS disable
  arch/x86/lib/putuser.o: warning: objtool: .altinstr_replacement+0x18: redundant UACCESS disable

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/bc14ded2755ae75bd9010c446079e113dbddb74b.1563413318.git.jpoimboe@redhat.com
2019-07-18 21:01:06 +02:00

106 lines
2 KiB
ArmAsm

/* SPDX-License-Identifier: GPL-2.0 */
/*
* __put_user functions.
*
* (C) Copyright 2005 Linus Torvalds
* (C) Copyright 2005 Andi Kleen
* (C) Copyright 2008 Glauber Costa
*
* These functions have a non-standard call interface
* to make them more efficient, especially as they
* return an error value in addition to the "real"
* return value.
*/
#include <linux/linkage.h>
#include <asm/thread_info.h>
#include <asm/errno.h>
#include <asm/asm.h>
#include <asm/smap.h>
#include <asm/export.h>
/*
* __put_user_X
*
* Inputs: %eax[:%edx] contains the data
* %ecx contains the address
*
* Outputs: %eax is error code (0 or -EFAULT)
*
* These functions should not modify any other registers,
* as they get called from within inline assembly.
*/
#define ENTER mov PER_CPU_VAR(current_task), %_ASM_BX
.text
ENTRY(__put_user_1)
ENTER
cmp TASK_addr_limit(%_ASM_BX),%_ASM_CX
jae bad_put_user
ASM_STAC
1: movb %al,(%_ASM_CX)
xor %eax,%eax
ASM_CLAC
ret
ENDPROC(__put_user_1)
EXPORT_SYMBOL(__put_user_1)
ENTRY(__put_user_2)
ENTER
mov TASK_addr_limit(%_ASM_BX),%_ASM_BX
sub $1,%_ASM_BX
cmp %_ASM_BX,%_ASM_CX
jae bad_put_user
ASM_STAC
2: movw %ax,(%_ASM_CX)
xor %eax,%eax
ASM_CLAC
ret
ENDPROC(__put_user_2)
EXPORT_SYMBOL(__put_user_2)
ENTRY(__put_user_4)
ENTER
mov TASK_addr_limit(%_ASM_BX),%_ASM_BX
sub $3,%_ASM_BX
cmp %_ASM_BX,%_ASM_CX
jae bad_put_user
ASM_STAC
3: movl %eax,(%_ASM_CX)
xor %eax,%eax
ASM_CLAC
ret
ENDPROC(__put_user_4)
EXPORT_SYMBOL(__put_user_4)
ENTRY(__put_user_8)
ENTER
mov TASK_addr_limit(%_ASM_BX),%_ASM_BX
sub $7,%_ASM_BX
cmp %_ASM_BX,%_ASM_CX
jae bad_put_user
ASM_STAC
4: mov %_ASM_AX,(%_ASM_CX)
#ifdef CONFIG_X86_32
5: movl %edx,4(%_ASM_CX)
#endif
xor %eax,%eax
ASM_CLAC
RET
ENDPROC(__put_user_8)
EXPORT_SYMBOL(__put_user_8)
bad_put_user_clac:
ASM_CLAC
bad_put_user:
movl $-EFAULT,%eax
RET
_ASM_EXTABLE_UA(1b, bad_put_user_clac)
_ASM_EXTABLE_UA(2b, bad_put_user_clac)
_ASM_EXTABLE_UA(3b, bad_put_user_clac)
_ASM_EXTABLE_UA(4b, bad_put_user_clac)
#ifdef CONFIG_X86_32
_ASM_EXTABLE_UA(5b, bad_put_user_clac)
#endif