powerpc: Do not call ppc_md.panic in fadump panic notifier

BugLink: https://bugs.launchpad.net/bugs/1736954

If fadump is not registered, and no other crash or debug handlers are
registered, the powerpc panic handler stops the guest before the
generic panic code can push out debug information to the console.

Currently, system reset injection causes the guest to silently stop.

Stop calling ppc_md.panic in the panic notifier. crash_fadump already
does rtas_os_term() to terminate the guest if fadump is registered.

Remove ppc_md.panic. Move fadump panic notifier into fadump code.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
(backported from commit a3b2cb30)
[cascardo: context and setup_panic called from setup_{32,64}.c]
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Colin King <colin.king@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

arch/powerpc/include/asm/machdep.h

@@ -113,7 +113,6 @@ struct machdep_calls {
 
 	void		(*restart)(char *cmd);
 	void		(*halt)(void);
-	void		(*panic)(char *str);
 	void		(*cpu_die)(void);
 
 	long		(*time_init)(void); /* Optional, may be NULL */

arch/powerpc/include/asm/setup.h

@@ -23,7 +23,6 @@ extern void reloc_got2(unsigned long);
 
 void check_for_initrd(void);
 void initmem_init(void);
-void setup_panic(void);
 #define ARCH_PANIC_TIMEOUT 180
 
 void rfi_flush_enable(bool enable);

arch/powerpc/kernel/fadump.c

@@ -1279,6 +1279,25 @@ static void fadump_init_files(void)
 	return;
 }
 
+static int fadump_panic_event(struct notifier_block *this,
+			      unsigned long event, void *ptr)
+{
+	/*
+	 * If firmware-assisted dump has been registered then trigger
+	 * firmware-assisted dump and let firmware handle everything
+	 * else. If this returns, then fadump was not registered, so
+	 * go through the rest of the panic path.
+	 */
+	crash_fadump(NULL, ptr);
+
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block fadump_panic_block = {
+	.notifier_call = fadump_panic_event,
+	.priority = INT_MIN /* may not return; must be done last */
+};
+
 /*
  * Prepare for firmware-assisted dump.
  */
@@ -1311,6 +1330,9 @@ int __init setup_fadump(void)
 		init_fadump_mem_struct(&fdm, fw_dump.reserve_dump_area_start);
 	fadump_init_files();
 
+	atomic_notifier_chain_register(&panic_notifier_list,
+					&fadump_panic_block);
+
 	return 1;
 }
 subsys_initcall(setup_fadump);

arch/powerpc/kernel/setup-common.c

@@ -688,28 +688,6 @@ int check_legacy_ioport(unsigned long base_port)
 }
 EXPORT_SYMBOL(check_legacy_ioport);
 
-static int ppc_panic_event(struct notifier_block *this,
-                             unsigned long event, void *ptr)
-{
-	/*
-	 * If firmware-assisted dump has been registered then trigger
-	 * firmware-assisted dump and let firmware handle everything else.
-	 */
-	crash_fadump(NULL, ptr);
-	ppc_md.panic(ptr);  /* May not return */
-	return NOTIFY_DONE;
-}
-
-static struct notifier_block ppc_panic_block = {
-	.notifier_call = ppc_panic_event,
-	.priority = INT_MIN /* may not return; must be done last */
-};
-
-void __init setup_panic(void)
-{
-	atomic_notifier_chain_register(&panic_notifier_list, &ppc_panic_block);
-}
-
 #ifdef CONFIG_CHECK_CACHE_COHERENCY
 /*
  * For platforms that have configurable cache-coherency.  This function

arch/powerpc/kernel/setup_32.c

@@ -299,9 +299,6 @@ void __init setup_arch(char **cmdline_p)
 	if (cpu_has_feature(CPU_FTR_UNIFIED_ID_CACHE))
 		ucache_bsize = icache_bsize = dcache_bsize;
 
-	if (ppc_md.panic)
-		setup_panic();
-
 	init_mm.start_code = (unsigned long)_stext;
 	init_mm.end_code = (unsigned long) _etext;
 	init_mm.end_data = (unsigned long) _edata;

arch/powerpc/kernel/setup_64.c

@@ -709,9 +709,6 @@ void __init setup_arch(char **cmdline_p)
 	dcache_bsize = ppc64_caches.dline_size;
 	icache_bsize = ppc64_caches.iline_size;
 
-	if (ppc_md.panic)
-		setup_panic();
-
 	init_mm.start_code = (unsigned long)_stext;
 	init_mm.end_code = (unsigned long) _etext;
 	init_mm.end_data = (unsigned long) _edata;

arch/powerpc/platforms/ps3/setup.c

@@ -104,20 +104,6 @@ static void ps3_halt(void)
 	ps3_sys_manager_halt(); /* never returns */
 }
 
-static void ps3_panic(char *str)
-{
-	DBG("%s:%d %s\n", __func__, __LINE__, str);
-
-	smp_send_stop();
-	printk("\n");
-	printk("   System does not reboot automatically.\n");
-	printk("   Please press POWER button.\n");
-	printk("\n");
-
-	while(1)
-		lv1_pause(1);
-}
-
 #if defined(CONFIG_FB_PS3) || defined(CONFIG_FB_PS3_MODULE) || \
     defined(CONFIG_PS3_FLASH) || defined(CONFIG_PS3_FLASH_MODULE)
 static void __init prealloc(struct ps3_prealloc *p)
@@ -268,7 +254,6 @@ define_machine(ps3) {
 	.probe				= ps3_probe,
 	.setup_arch			= ps3_setup_arch,
 	.init_IRQ			= ps3_init_IRQ,
-	.panic				= ps3_panic,
 	.get_boot_time			= ps3_get_boot_time,
 	.set_dabr			= ps3_set_dabr,
 	.calibrate_decr			= ps3_calibrate_decr,

arch/powerpc/platforms/pseries/setup.c

@@ -875,7 +875,6 @@ define_machine(pseries) {
 	.pcibios_fixup		= pSeries_final_fixup,
 	.restart		= rtas_restart,
 	.halt			= rtas_halt,
-	.panic			= rtas_os_term,
 	.get_boot_time		= rtas_get_boot_time,
 	.get_rtc_time		= rtas_get_rtc_time,
 	.set_rtc_time		= rtas_set_rtc_time,