tty: synclink_gt: Fix namespace collision and startup() section placement with -ffunction-sections

When compiled with -ffunction-sections (e.g., for LTO, livepatch, dead
code elimination, AutoFDO, or Propeller), the startup() function gets
compiled into the .text.startup section (or in some cases
.text.startup.constprop.0 or .text.startup.isra.0).

However, the .text.startup and .text.startup.* sections are also used by
the compiler for __attribute__((constructor)) code.

This naming conflict causes the vmlinux linker script to wrongly place
startup() function code in .init.text, which gets freed during boot.

Some builds have a mix of objects, both with and without
-ffunctions-sections, so it's not possible for the linker script to
disambiguate with #ifdef CONFIG_FUNCTION_SECTIONS or similar.  This
means that "startup" unfortunately needs to be prohibited as a function
name.

Rename startup() to startup_hw().  For consistency, also rename its
shutdown() counterpart to shutdown_hw().

Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://patch.msgid.link/f0ee750f35c878172cc09916a0724b74e62eadc2.1763669451.git.jpoimboe@kernel.org

Author: jpoimboe

drivers/tty/synclink_gt.c

@@ -407,9 +407,9 @@ static void  wr_reg32(struct slgt_info *info, unsigned int addr, __u32 value);
 
 static void  msc_set_vcr(struct slgt_info *info);
 
-static int  startup(struct slgt_info *info);
+static int  startup_hw(struct slgt_info *info);
 static int  block_til_ready(struct tty_struct *tty, struct file * filp,struct slgt_info *info);
-static void shutdown(struct slgt_info *info);
+static void shutdown_hw(struct slgt_info *info);
 static void program_hw(struct slgt_info *info);
 static void change_params(struct slgt_info *info);
 
@@ -622,7 +622,7 @@ static int open(struct tty_struct *tty, struct file *filp)
 
 	if (info->port.count == 1) {
 		/* 1st open on this device, init hardware */
-		retval = startup(info);
+		retval = startup_hw(info);
 		if (retval < 0) {
 			mutex_unlock(&info->port.mutex);
 			goto cleanup;
@@ -666,7 +666,7 @@ static void close(struct tty_struct *tty, struct file *filp)
 	flush_buffer(tty);
 	tty_ldisc_flush(tty);
 
-	shutdown(info);
+	shutdown_hw(info);
 	mutex_unlock(&info->port.mutex);
 
 	tty_port_close_end(&info->port, tty);
@@ -687,7 +687,7 @@ static void hangup(struct tty_struct *tty)
 	flush_buffer(tty);
 
 	mutex_lock(&info->port.mutex);
-	shutdown(info);
+	shutdown_hw(info);
 
 	spin_lock_irqsave(&info->port.lock, flags);
 	info->port.count = 0;
@@ -1445,7 +1445,7 @@ static int hdlcdev_open(struct net_device *dev)
 	spin_unlock_irqrestore(&info->netlock, flags);
 
 	/* claim resources and init adapter */
-	if ((rc = startup(info)) != 0) {
+	if ((rc = startup_hw(info)) != 0) {
 		spin_lock_irqsave(&info->netlock, flags);
 		info->netcount=0;
 		spin_unlock_irqrestore(&info->netlock, flags);
@@ -1455,7 +1455,7 @@ static int hdlcdev_open(struct net_device *dev)
 	/* generic HDLC layer open processing */
 	rc = hdlc_open(dev);
 	if (rc) {
-		shutdown(info);
+		shutdown_hw(info);
 		spin_lock_irqsave(&info->netlock, flags);
 		info->netcount = 0;
 		spin_unlock_irqrestore(&info->netlock, flags);
@@ -1499,7 +1499,7 @@ static int hdlcdev_close(struct net_device *dev)
 	netif_stop_queue(dev);
 
 	/* shutdown adapter and release resources */
-	shutdown(info);
+	shutdown_hw(info);
 
 	hdlc_close(dev);
 
@@ -2328,7 +2328,7 @@ static irqreturn_t slgt_interrupt(int dummy, void *dev_id)
 	return IRQ_HANDLED;
 }
 
-static int startup(struct slgt_info *info)
+static int startup_hw(struct slgt_info *info)
 {
 	DBGINFO(("%s startup\n", info->device_name));
 
@@ -2361,7 +2361,7 @@ static int startup(struct slgt_info *info)
 /*
  *  called by close() and hangup() to shutdown hardware
  */
-static void shutdown(struct slgt_info *info)
+static void shutdown_hw(struct slgt_info *info)
 {
 	unsigned long flags;