5 files changed, 8 insertions, 45 deletions

diff --git a/arch/arm64/include/asm/exec.h b/arch/arm64/include/asm/exec.h
index 1aae6f9962fc..9a1c22ce664b 100644
--- a/arch/arm64/include/asm/exec.h
+++ b/arch/arm64/include/asm/exec.h
@@ -10,6 +10,5 @@
 #include <linux/sched.h>
 
 extern unsigned long arch_align_stack(unsigned long sp);
-void uao_thread_switch(struct task_struct *next);
 
 #endif	/* __ASM_EXEC_H */
diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h
index fce8cbecd6bc..724249f37af5 100644
--- a/arch/arm64/include/asm/processor.h
+++ b/arch/arm64/include/asm/processor.h
@@ -8,9 +8,6 @@
 #ifndef __ASM_PROCESSOR_H
 #define __ASM_PROCESSOR_H
 
-#define KERNEL_DS		UL(-1)
-#define USER_DS			((UL(1) << VA_BITS) - 1)
-
 /*
  * On arm64 systems, unaligned accesses by the CPU are cheap, and so there is
  * no point in shifting all network buffers by 2 bytes just to make some IP
@@ -48,6 +45,7 @@
 
 #define DEFAULT_MAP_WINDOW_64	(UL(1) << VA_BITS_MIN)
 #define TASK_SIZE_64		(UL(1) << vabits_actual)
+#define TASK_SIZE_MAX		(UL(1) << VA_BITS)
 
 #ifdef CONFIG_COMPAT
 #if defined(CONFIG_ARM64_64K_PAGES) && defined(CONFIG_KUSER_HELPERS)
diff --git a/arch/arm64/include/asm/ptrace.h b/arch/arm64/include/asm/ptrace.h
index 2547d94634be..2bb53bc3c326 100644
--- a/arch/arm64/include/asm/ptrace.h
+++ b/arch/arm64/include/asm/ptrace.h
@@ -193,8 +193,7 @@ struct pt_regs {
 	s32 syscallno;
 	u32 unused2;
 #endif
-
-	u64 orig_addr_limit;
+	u64 sdei_ttbr1;
 	/* Only valid when ARM64_HAS_IRQ_PRIO_MASKING is enabled. */
 	u64 pmr_save;
 	u64 stackframe[2];
diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h
index 1fbab854a51b..3a88a55de568 100644
--- a/arch/arm64/include/asm/thread_info.h
+++ b/arch/arm64/include/asm/thread_info.h
@@ -18,14 +18,11 @@ struct task_struct;
 #include <asm/stack_pointer.h>
 #include <asm/types.h>
 
-typedef unsigned long mm_segment_t;
-
 /*
  * low level task data that entry.S needs immediate access to.
  */
 struct thread_info {
 	unsigned long		flags;		/* low level flags */
-	mm_segment_t		addr_limit;	/* address limit */
 #ifdef CONFIG_ARM64_SW_TTBR0_PAN
 	u64			ttbr0;		/* saved TTBR0_EL1 */
 #endif
@@ -119,7 +116,6 @@ void arch_release_task_struct(struct task_struct *tsk);
 {									\
 	.flags		= _TIF_FOREIGN_FPSTATE,				\
 	.preempt_count	= INIT_PREEMPT_COUNT,				\
-	.addr_limit	= KERNEL_DS,					\
 	INIT_SCS							\
 }
 
diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
index eb04f02299fe..e639d8b2b38d 100644
--- a/arch/arm64/include/asm/uaccess.h
+++ b/arch/arm64/include/asm/uaccess.h
@@ -26,44 +26,16 @@
 
 #define HAVE_GET_KERNEL_NOFAULT
 
-#define get_fs()	(current_thread_info()->addr_limit)
-
-static inline void set_fs(mm_segment_t fs)
-{
-	current_thread_info()->addr_limit = fs;
-
-	/*
-	 * Prevent a mispredicted conditional call to set_fs from forwarding
-	 * the wrong address limit to access_ok under speculation.
-	 */
-	spec_bar();
-
-	/* On user-mode return, check fs is correct */
-	set_thread_flag(TIF_FSCHECK);
-
-	/*
-	 * Enable/disable UAO so that copy_to_user() etc can access
-	 * kernel memory with the unprivileged instructions.
-	 */
-	if (IS_ENABLED(CONFIG_ARM64_UAO) && fs == KERNEL_DS)
-		asm(ALTERNATIVE("nop", SET_PSTATE_UAO(1), ARM64_HAS_UAO));
-	else
-		asm(ALTERNATIVE("nop", SET_PSTATE_UAO(0), ARM64_HAS_UAO,
-				CONFIG_ARM64_UAO));
-}
-
-#define uaccess_kernel()	(get_fs() == KERNEL_DS)
-
 /*
  * Test whether a block of memory is a valid user space address.
  * Returns 1 if the range is valid, 0 otherwise.
  *
  * This is equivalent to the following test:
- * (u65)addr + (u65)size <= (u65)current->addr_limit + 1
+ * (u65)addr + (u65)size <= (u65)TASK_SIZE_MAX
  */
 static inline unsigned long __range_ok(const void __user *addr, unsigned long size)
 {
-	unsigned long ret, limit = current_thread_info()->addr_limit;
+	unsigned long ret, limit = TASK_SIZE_MAX - 1;
 
 	/*
 	 * Asynchronous I/O running in a kernel thread does not have the
@@ -96,7 +68,6 @@ static inline unsigned long __range_ok(const void __user *addr, unsigned long si
 }
 
 #define access_ok(addr, size)	__range_ok(addr, size)
-#define user_addr_max			get_fs
 
 #define _ASM_EXTABLE(from, to)						\
 	"	.pushsection	__ex_table, \"a\"\n"			\
@@ -226,9 +197,9 @@ static inline void uaccess_enable_not_uao(void)
 }
 
 /*
- * Sanitise a uaccess pointer such that it becomes NULL if above the
- * current addr_limit. In case the pointer is tagged (has the top byte set),
- * untag the pointer before checking.
+ * Sanitise a uaccess pointer such that it becomes NULL if above the maximum
+ * user address. In case the pointer is tagged (has the top byte set), untag
+ * the pointer before checking.
  */
 #define uaccess_mask_ptr(ptr) (__typeof__(ptr))__uaccess_mask_ptr(ptr)
 static inline void __user *__uaccess_mask_ptr(const void __user *ptr)
@@ -239,7 +210,7 @@ static inline void __user *__uaccess_mask_ptr(const void __user *ptr)
 	"	bics	xzr, %3, %2\n"
 	"	csel	%0, %1, xzr, eq\n"
 	: "=&r" (safe_ptr)
-	: "r" (ptr), "r" (current_thread_info()->addr_limit),
+	: "r" (ptr), "r" (TASK_SIZE_MAX - 1),
 	  "r" (untagged_addr(ptr))
 	: "cc");