Update Linux to v5.4.148

Sourced from [1]

[1] https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.4.148.tar.gz

Change-Id: Ib3d26c5ba9b022e2e03533005c4fed4d7c30b61b
Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c
index f76d6f7..097ab02 100644
--- a/kernel/debug/debug_core.c
+++ b/kernel/debug/debug_core.c
@@ -96,14 +96,6 @@
 /* Use kdb or gdbserver mode */
 int dbg_kdb_mode = 1;
 
-static int __init opt_kgdb_con(char *str)
-{
-	kgdb_use_con = 1;
-	return 0;
-}
-
-early_param("kgdbcon", opt_kgdb_con);
-
 module_param(kgdb_use_con, int, 0644);
 module_param(kgdbreboot, int, 0644);
 
@@ -501,6 +493,7 @@
 
 	if (exception_level > 1) {
 		dump_stack();
+		kgdb_io_module_registered = false;
 		panic("Recursive entry to debugger");
 	}
 
@@ -545,6 +538,7 @@
 		arch_kgdb_ops.disable_hw_break(regs);
 
 acquirelock:
+	rcu_read_lock();
 	/*
 	 * Interrupts will be restored by the 'trap return' code, except when
 	 * single stepping.
@@ -601,6 +595,7 @@
 			atomic_dec(&slaves_in_kgdb);
 			dbg_touch_watchdogs();
 			local_irq_restore(flags);
+			rcu_read_unlock();
 			return 0;
 		}
 		cpu_relax();
@@ -619,6 +614,7 @@
 		raw_spin_unlock(&dbg_master_lock);
 		dbg_touch_watchdogs();
 		local_irq_restore(flags);
+		rcu_read_unlock();
 
 		goto acquirelock;
 	}
@@ -634,6 +630,8 @@
 	if (kgdb_skipexception(ks->ex_vector, ks->linux_regs))
 		goto kgdb_restore;
 
+	atomic_inc(&ignore_console_lock_warning);
+
 	/* Call the I/O driver's pre_exception routine */
 	if (dbg_io_ops->pre_exception)
 		dbg_io_ops->pre_exception();
@@ -706,6 +704,8 @@
 	if (dbg_io_ops->post_exception)
 		dbg_io_ops->post_exception();
 
+	atomic_dec(&ignore_console_lock_warning);
+
 	if (!kgdb_single_step) {
 		raw_spin_unlock(&dbg_slave_lock);
 		/* Wait till all the CPUs have quit from the debugger. */
@@ -738,6 +738,7 @@
 	raw_spin_unlock(&dbg_master_lock);
 	dbg_touch_watchdogs();
 	local_irq_restore(flags);
+	rcu_read_unlock();
 
 	return kgdb_info[cpu].ret_state;
 }
@@ -867,6 +868,20 @@
 	.index		= -1,
 };
 
+static int __init opt_kgdb_con(char *str)
+{
+	kgdb_use_con = 1;
+
+	if (kgdb_io_module_registered && !kgdb_con_registered) {
+		register_console(&kgdbcons);
+		kgdb_con_registered = 1;
+	}
+
+	return 0;
+}
+
+early_param("kgdbcon", opt_kgdb_con);
+
 #ifdef CONFIG_MAGIC_SYSRQ
 static void sysrq_handle_dbg(int key)
 {
diff --git a/kernel/debug/kdb/kdb_io.c b/kernel/debug/kdb/kdb_io.c
index 3a5184e..4682179 100644
--- a/kernel/debug/kdb/kdb_io.c
+++ b/kernel/debug/kdb/kdb_io.c
@@ -679,12 +679,16 @@
 			size_avail = sizeof(kdb_buffer) - len;
 			goto kdb_print_out;
 		}
-		if (kdb_grepping_flag >= KDB_GREPPING_FLAG_SEARCH)
+		if (kdb_grepping_flag >= KDB_GREPPING_FLAG_SEARCH) {
 			/*
 			 * This was a interactive search (using '/' at more
-			 * prompt) and it has completed. Clear the flag.
+			 * prompt) and it has completed. Replace the \0 with
+			 * its original value to ensure multi-line strings
+			 * are handled properly, and return to normal mode.
 			 */
+			*cphold = replaced_byte;
 			kdb_grepping_flag = 0;
+		}
 		/*
 		 * at this point the string is a full line and
 		 * should be printed, up to the null.
diff --git a/kernel/debug/kdb/kdb_private.h b/kernel/debug/kdb/kdb_private.h
index 2118d82..ad53b19 100644
--- a/kernel/debug/kdb/kdb_private.h
+++ b/kernel/debug/kdb/kdb_private.h
@@ -233,7 +233,7 @@
 #define	kdb_do_each_thread(g, p) do_each_thread(g, p)
 #define	kdb_while_each_thread(g, p) while_each_thread(g, p)
 
-#define GFP_KDB (in_interrupt() ? GFP_ATOMIC : GFP_KERNEL)
+#define GFP_KDB (in_dbg_master() ? GFP_ATOMIC : GFP_KERNEL)
 
 extern void *debug_kmalloc(size_t size, gfp_t flags);
 extern void debug_kfree(void *);