drivers: dwc_otg: stop GCC from patching FIQ functions

Configuring GCC to use task stack protector canaries means it will
insert calls to check functions in FIQ code. This is bad, as a) the
FIQ's stack is banked and b) the failure invokes __stack_chk_fail which
eventually tries to call printk(). Printing to the console inside the
FIQ is generally fatal.

Add CFLAGS to stop this happening in FIQ code.

Also catch one function where notrace wasn't specified.

Signed-off-by: Jonathan Bell <[email protected]>

Author: P33M

drivers/usb/host/dwc_otg/Makefile

@@ -28,6 +28,7 @@ ccflags-y   	+= -DDWC_LINUX
 ccflags-y   	+= $(CFI)
 ccflags-y	+= $(BUS_INTERFACE)
 #ccflags-y	+= -DDWC_DEV_SRPCAP
+CFLAGS_dwc_otg_fiq_fsm.o += -fno-stack-protector
 
 obj-$(CONFIG_USB_DWCOTG) += dwc_otg.o
 

drivers/usb/host/dwc_otg/dwc_otg_fiq_fsm.c

@@ -142,7 +142,7 @@ inline void fiq_fsm_spin_unlock(fiq_lock_t *lock) { }
  * fiq_fsm_restart_channel() - Poke channel enable bit for a split transaction
  * @channel: channel to re-enable
  */
-static void fiq_fsm_restart_channel(struct fiq_state *st, int n, int force)
+static void notrace fiq_fsm_restart_channel(struct fiq_state *st, int n, int force)
 {
 	hcchar_data_t hcchar = { .d32 = FIQ_READ(st->dwc_regs_base + HC_START + (HC_OFFSET * n) + HCCHAR) };