arm64: uaccess: remove addr_limit_user_check()

Now that set_fs() is gone, addr_limit_user_check() is redundant. Remove
the checks and associated thread flag.

To ensure that _TIF_WORK_MASK can be used as an immediate value in an
AND instruction (as it is in `ret_to_user`), TIF_MTE_ASYNC_FAULT is
renumbered to keep the constituent bits of _TIF_WORK_MASK contiguous.

There should be no functional change as a result of this patch.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: James Morse <james.morse@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20201202131558.39270-11-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h
index 3a88a55..015beaf 100644 (file)
--- a/arch/arm64/include/asm/thread_info.h
+++ b/arch/arm64/include/asm/thread_info.h
@@ -63,8 +63,7 @@ void arch_release_task_struct(struct task_struct *tsk);
 #define TIF_NOTIFY_RESUME      2       /* callback before returning to user */
 #define TIF_FOREIGN_FPSTATE    3       /* CPU's FP state is not current's */
 #define TIF_UPROBE             4       /* uprobe breakpoint or singlestep */
-#define TIF_FSCHECK            5       /* Check FS is USER_DS on return */
-#define TIF_MTE_ASYNC_FAULT    6       /* MTE Asynchronous Tag Check Fault */
+#define TIF_MTE_ASYNC_FAULT    5       /* MTE Asynchronous Tag Check Fault */
 #define TIF_SYSCALL_TRACE      8       /* syscall trace active */
 #define TIF_SYSCALL_AUDIT      9       /* syscall auditing */
 #define TIF_SYSCALL_TRACEPOINT 10      /* syscall tracepoint for ftrace */
@@ -90,7 +89,6 @@ void arch_release_task_struct(struct task_struct *tsk);
 #define _TIF_SECCOMP           (1 << TIF_SECCOMP)
 #define _TIF_SYSCALL_EMU       (1 << TIF_SYSCALL_EMU)
 #define _TIF_UPROBE            (1 << TIF_UPROBE)
-#define _TIF_FSCHECK           (1 << TIF_FSCHECK)
 #define _TIF_SINGLESTEP                (1 << TIF_SINGLESTEP)
 #define _TIF_32BIT             (1 << TIF_32BIT)
 #define _TIF_SVE               (1 << TIF_SVE)
@@ -98,7 +96,7 @@ void arch_release_task_struct(struct task_struct *tsk);
 
 #define _TIF_WORK_MASK         (_TIF_NEED_RESCHED | _TIF_SIGPENDING | \
                                 _TIF_NOTIFY_RESUME | _TIF_FOREIGN_FPSTATE | \
-                                _TIF_UPROBE | _TIF_FSCHECK | _TIF_MTE_ASYNC_FAULT)
+                                _TIF_UPROBE | _TIF_MTE_ASYNC_FAULT)
 
 #define _TIF_SYSCALL_WORK      (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | \
                                 _TIF_SYSCALL_TRACEPOINT | _TIF_SECCOMP | \

diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
index a8184ca..af5c6c6 100644 (file)
--- a/arch/arm64/kernel/signal.c
+++ b/arch/arm64/kernel/signal.c
@@ -922,9 +922,6 @@ asmlinkage void do_notify_resume(struct pt_regs *regs,
        trace_hardirqs_off();
 
        do {
-               /* Check valid user FS if needed */
-               addr_limit_user_check();
-
                if (thread_flags & _TIF_NEED_RESCHED) {
                        /* Unmask Debug and SError for the next task */
                        local_daif_restore(DAIF_PROCCTX_NOIRQ);