linux-kernel - [PATCH 3/6] tty: amiserial: Fix namespace collision and startup() section placement with -ffunction-sections

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Message-ID: <9e56afff5268b0b12b99a8aa9bf244d6ebdcdf47.1763669451.git.jpoimboe@kernel.org>
Date: Thu, 20 Nov 2025 12:14:18 -0800
From: Josh Poimboeuf <jpoimboe@...nel.org>
To: x86@...nel.org
Cc: linux-kernel@...r.kernel.org,
	Peter Zijlstra <peterz@...radead.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jiri Slaby <jirislaby@...nel.org>,
	Mauro Carvalho Chehab <mchehab@...nel.org>,
	Hans de Goede <hansg@...nel.org>
Subject: [PATCH 3/6] tty: amiserial: 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 rs_startup().  For consistency, also rename its
shutdown() counterpart to rs_shutdown().

Signed-off-by: Josh Poimboeuf <jpoimboe@...nel.org>
---
 drivers/tty/amiserial.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/drivers/tty/amiserial.c b/drivers/tty/amiserial.c
index 5af46442a792..81eaca751541 100644
--- a/drivers/tty/amiserial.c
+++ b/drivers/tty/amiserial.c
@@ -438,7 +438,7 @@ static irqreturn_t ser_tx_int(int irq, void *dev_id)
  * ---------------------------------------------------------------
  */
 
-static int startup(struct tty_struct *tty, struct serial_state *info)
+static int rs_startup(struct tty_struct *tty, struct serial_state *info)
 {
 	struct tty_port *port = &info->tport;
 	unsigned long flags;
@@ -513,7 +513,7 @@ static int startup(struct tty_struct *tty, struct serial_state *info)
  * This routine will shutdown a serial port; interrupts are disabled, and
  * DTR is dropped if the hangup on close termio flag is on.
  */
-static void shutdown(struct tty_struct *tty, struct serial_state *info)
+static void rs_shutdown(struct tty_struct *tty, struct serial_state *info)
 {
 	unsigned long	flags;
 
@@ -975,7 +975,7 @@ static int set_serial_info(struct tty_struct *tty, struct serial_struct *ss)
 			change_speed(tty, state, NULL);
 		}
 	} else
-		retval = startup(tty, state);
+		retval = rs_startup(tty, state);
 	tty_unlock(tty);
 	return retval;
 }
@@ -1251,9 +1251,9 @@ static void rs_close(struct tty_struct *tty, struct file * filp)
 		 */
 		rs_wait_until_sent(tty, state->timeout);
 	}
-	shutdown(tty, state);
+	rs_shutdown(tty, state);
 	rs_flush_buffer(tty);
-		
+
 	tty_ldisc_flush(tty);
 	port->tty = NULL;
 
@@ -1325,7 +1325,7 @@ static void rs_hangup(struct tty_struct *tty)
 	struct serial_state *info = tty->driver_data;
 
 	rs_flush_buffer(tty);
-	shutdown(tty, info);
+	rs_shutdown(tty, info);
 	info->tport.count = 0;
 	tty_port_set_active(&info->tport, false);
 	info->tport.tty = NULL;
@@ -1349,7 +1349,7 @@ static int rs_open(struct tty_struct *tty, struct file * filp)
 	port->tty = tty;
 	tty->driver_data = info;
 
-	retval = startup(tty, info);
+	retval = rs_startup(tty, info);
 	if (retval) {
 		return retval;
 	}
-- 
2.51.1