powerpc/kasan: Mark more real-mode code as not to be instrumented

This marks more files and functions that can possibly be called in
real mode as not to be instrumented by KASAN. Most were found by
inspection, except for get_pseries_errorlog() which was reported as
causing a crash in testing.

Reported-by: Nageswara R Sastry <[e-mail]>
Signed-off-by: Paul Mackerras <[e-mail]>
Signed-off-by: Michael Ellerman <[e-mail]>
Link: https://lore.kernel.org/r/YoX1kZPnmUX4RZEK@cleo

arch/powerpc/kernel/Makefile

···
 KASAN_SANITIZE_setup_64.o := n
 KASAN_SANITIZE_mce.o := n
 KASAN_SANITIZE_mce_power.o := n
+KASAN_SANITIZE_udbg.o := n
+KASAN_SANITIZE_udbg_16550.o := n
 
 # we have to be particularly careful in ppc64 to exclude code that
 # runs with translations off, as we cannot access the shadow with

arch/powerpc/kernel/rtas.c

···
  *
  * Return: A pointer to the specified errorlog or NULL if not found.
  */
-struct pseries_errorlog *get_pseries_errorlog(struct rtas_error_log *log,
-					      uint16_t section_id)
+noinstr struct pseries_errorlog *get_pseries_errorlog(struct rtas_error_log *log,
+						      uint16_t section_id)
 {
 	struct rtas_ext_event_log_v6 *ext_log =
 		(struct rtas_ext_event_log_v6 *)log->buffer;

arch/powerpc/kexec/crash.c

···
 
 /* wait for all the CPUs to hit real mode but timeout if they don't come in */
 #if defined(CONFIG_SMP) && defined(CONFIG_PPC64)
-static void __maybe_unused crash_kexec_wait_realmode(int cpu)
+noinstr static void __maybe_unused crash_kexec_wait_realmode(int cpu)
 {
 	unsigned int msecs;
 	int i;

arch/powerpc/platforms/powernv/Makefile

···
 # in particular, idle code runs a bunch of things in real mode
 KASAN_SANITIZE_idle.o := n
 KASAN_SANITIZE_pci-ioda.o := n
+KASAN_SANITIZE_pci-ioda-tce.o := n
 # pnv_machine_check_early
 KASAN_SANITIZE_setup.o := n