Revert "arm64: fix current_thread_info()->addr_limit setup"

hulk inclusion
category: performance
bugzilla: https://e.gitee.com/open_euler/issues/list?issue=I4SCW7
CVE: NA

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This reverts commit 979046bd.

The macro 'USER_DS' and related assembly code is deleted by
commit 3d2403fd ("arm64: uaccess: remove set_fs()", so the
problem fixed by this patch is disappeared accordingly.
Signed-off-by: NZhen Lei <thunder.leizhen@huawei.com>
Reviewed-by: NJiahao Chen <chenjiahao16@huawei.com>
Reviewed-by: NHanjun Guo <guohanjun@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

arch/arm64/include/asm/processor.h

@@ -9,8 +9,7 @@
 #define __ASM_PROCESSOR_H
 
 #define KERNEL_DS		UL(-1)
-#define USER_DS			(is_compat_task() ? \
-				(UL(0x100000000) - 1) : (TASK_SIZE - 1))
+#define USER_DS			((UL(1) << VA_BITS) - 1)
 
 /*
  * On arm64 systems, unaligned accesses by the CPU are cheap, and so there is

arch/arm64/kernel/entry.S

@@ -221,8 +221,7 @@ alternative_else_nop_endif
 	/* Save the task's original addr_limit and set USER_DS */
 	ldr	x20, [tsk, #TSK_TI_ADDR_LIMIT]
 	str	x20, [sp, #S_ORIG_ADDR_LIMIT]
-	/* expand USER_DS here using its value while is_compat_task() is false */
-	mov	x20, #((UL(1) << VA_BITS) - 1)
+	mov	x20, #USER_DS
 	str	x20, [tsk, #TSK_TI_ADDR_LIMIT]
 	/* No need to reset PSTATE.UAO, hardware's already set it to 0 for us */
 	.endif /* \el == 0 */

arch/arm64/kernel/process.c

@@ -628,13 +628,6 @@ unsigned long arch_align_stack(unsigned long sp)
  */
 void arch_setup_new_exec(void)
 {
-	/*
-	 * set the address limit for the new executable.
-	 * Here we reset the addr_limit only for the scenario
-	 * where is_compat_task() is set in AARCH64 kernel.
-	 */
-	set_fs(USER_DS);
-
 	current->mm->context.flags = is_compat_task() ? MMCF_AARCH32 : 0;
 
 	ptrauth_thread_init_user(current);