arm64: Move do_notify_resume() to entry-common.c

Currently do_notify_resume() lives in arch/arm64/kernel/signal.c, but it would
make more sense for it to live in entry-common.c as it handles more than
signals, and is coupled with the rest of the return-to-userspace sequence (e.g.
with unusual DAIF masking that matches the exception return requirements).

Move do_notify_resume() to entry-common.c.

There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Will Deacon <will@kernel.org>
Reviewed-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20240206123848.1696480-3-mark.rutland@arm.comSigned-off-by: Catalin Marinas <catalin.marinas@arm.com>
Tested-by: Itaru Kitayama <itaru.kitayama@linux.dev>

arch/arm64/include/asm/exception.h

@@ -74,7 +74,7 @@ void do_el0_fpac(struct pt_regs *regs, unsigned long esr);
 void do_el1_fpac(struct pt_regs *regs, unsigned long esr);
 void do_el0_mops(struct pt_regs *regs, unsigned long esr);
 void do_serror(struct pt_regs *regs, unsigned long esr);
-void do_notify_resume(struct pt_regs *regs, unsigned long thread_flags);
+void do_signal(struct pt_regs *regs);
 
 void __noreturn panic_bad_stack(struct pt_regs *regs, unsigned long esr, unsigned long far);
 #endif	/* __ASM_EXCEPTION_H */

arch/arm64/kernel/entry-common.c

@@ -10,6 +10,7 @@
 #include <linux/linkage.h>
 #include <linux/lockdep.h>
 #include <linux/ptrace.h>
+#include <linux/resume_user_mode.h>
 #include <linux/sched.h>
 #include <linux/sched/debug.h>
 #include <linux/thread_info.h>
@@ -126,6 +127,37 @@ static __always_inline void __exit_to_user_mode(void)
 	lockdep_hardirqs_on(CALLER_ADDR0);
 }
 
+static void do_notify_resume(struct pt_regs *regs, unsigned long thread_flags)
+{
+	do {
+		local_daif_restore(DAIF_PROCCTX);
+
+		if (thread_flags & _TIF_NEED_RESCHED)
+			schedule();
+
+		if (thread_flags & _TIF_UPROBE)
+			uprobe_notify_resume(regs);
+
+		if (thread_flags & _TIF_MTE_ASYNC_FAULT) {
+			clear_thread_flag(TIF_MTE_ASYNC_FAULT);
+			send_sig_fault(SIGSEGV, SEGV_MTEAERR,
+				       (void __user *)NULL, current);
+		}
+
+		if (thread_flags & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL))
+			do_signal(regs);
+
+		if (thread_flags & _TIF_NOTIFY_RESUME)
+			resume_user_mode_work(regs);
+
+		if (thread_flags & _TIF_FOREIGN_FPSTATE)
+			fpsimd_restore_current_state();
+
+		local_daif_mask();
+		thread_flags = read_thread_flags();
+	} while (thread_flags & _TIF_WORK_MASK);
+}
+
 static __always_inline void exit_to_user_mode_prepare(struct pt_regs *regs)
 {
 	unsigned long flags;

arch/arm64/kernel/signal.c

@@ -16,8 +16,8 @@
 #include <linux/uaccess.h>
 #include <linux/sizes.h>
 #include <linux/string.h>
-#include <linux/resume_user_mode.h>
 #include <linux/ratelimit.h>
+#include <linux/rseq.h>
 #include <linux/syscalls.h>
 
 #include <asm/daifflags.h>
@@ -1207,7 +1207,7 @@ static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
  * the kernel can handle, and then we build all the user-level signal handling
  * stack-frames in one go after that.
  */
-static void do_signal(struct pt_regs *regs)
+void do_signal(struct pt_regs *regs)
 {
 	unsigned long continue_addr = 0, restart_addr = 0;
 	int retval = 0;
@@ -1278,37 +1278,6 @@ static void do_signal(struct pt_regs *regs)
 	restore_saved_sigmask();
 }
 
-void do_notify_resume(struct pt_regs *regs, unsigned long thread_flags)
-{
-	do {
-		local_daif_restore(DAIF_PROCCTX);
-
-		if (thread_flags & _TIF_NEED_RESCHED)
-			schedule();
-
-		if (thread_flags & _TIF_UPROBE)
-			uprobe_notify_resume(regs);
-
-		if (thread_flags & _TIF_MTE_ASYNC_FAULT) {
-			clear_thread_flag(TIF_MTE_ASYNC_FAULT);
-			send_sig_fault(SIGSEGV, SEGV_MTEAERR,
-				       (void __user *)NULL, current);
-		}
-
-		if (thread_flags & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL))
-			do_signal(regs);
-
-		if (thread_flags & _TIF_NOTIFY_RESUME)
-			resume_user_mode_work(regs);
-
-		if (thread_flags & _TIF_FOREIGN_FPSTATE)
-			fpsimd_restore_current_state();
-
-		local_daif_mask();
-		thread_flags = read_thread_flags();
-	} while (thread_flags & _TIF_WORK_MASK);
-}
-
 unsigned long __ro_after_init signal_minsigstksz;
 
 /*