powerpc: Put exception configuration in a common place

The various calls to establish exception endianness and AIL are
now done from a single point using already established CPU and FW
feature bits to decide what to do.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/platforms/pseries/setup.c

@@ -319,15 +319,23 @@ static void pseries_lpar_idle(void)
  * to ever be a problem in practice we can move this into a kernel thread to
  * finish off the process later in boot.
  */
-long pSeries_enable_reloc_on_exc(void)
+void pseries_enable_reloc_on_exc(void)
 {
 	long rc;
 	unsigned int delay, total_delay = 0;
 
 	while (1) {
 		rc = enable_reloc_on_exceptions();
-		if (!H_IS_LONG_BUSY(rc))
-			return rc;
+		if (!H_IS_LONG_BUSY(rc)) {
+			if (rc == H_P2) {
+				pr_info("Relocation on exceptions not"
+					" supported\n");
+			} else if (rc != H_SUCCESS) {
+				pr_warn("Unable to enable relocation"
+					" on exceptions: %ld\n", rc);
+			}
+			break;
+		}
 
 		delay = get_longbusy_msecs(rc);
 		total_delay += delay;
@@ -335,66 +343,81 @@ long pSeries_enable_reloc_on_exc(void)
 			pr_warn("Warning: Giving up waiting to enable "
 				"relocation on exceptions (%u msec)!\n",
 				total_delay);
-			return rc;
+			return;
 		}
 
 		mdelay(delay);
 	}
 }
-EXPORT_SYMBOL(pSeries_enable_reloc_on_exc);
+EXPORT_SYMBOL(pseries_enable_reloc_on_exc);
 
-long pSeries_disable_reloc_on_exc(void)
+void pseries_disable_reloc_on_exc(void)
 {
 	long rc;
 
 	while (1) {
 		rc = disable_reloc_on_exceptions();
 		if (!H_IS_LONG_BUSY(rc))
-			return rc;
+			break;
 		mdelay(get_longbusy_msecs(rc));
 	}
+	if (rc != H_SUCCESS)
+		pr_warning("Warning: Failed to disable relocation on "
+			   "exceptions: %ld\n", rc);
 }
-EXPORT_SYMBOL(pSeries_disable_reloc_on_exc);
+EXPORT_SYMBOL(pseries_disable_reloc_on_exc);
 
 #ifdef CONFIG_KEXEC
 static void pSeries_machine_kexec(struct kimage *image)
 {
-	long rc;
-
-	if (firmware_has_feature(FW_FEATURE_SET_MODE)) {
-		rc = pSeries_disable_reloc_on_exc();
-		if (rc != H_SUCCESS)
-			pr_warning("Warning: Failed to disable relocation on "
-				   "exceptions: %ld\n", rc);
-	}
+	if (firmware_has_feature(FW_FEATURE_SET_MODE))
+		pseries_disable_reloc_on_exc();
 
 	default_machine_kexec(image);
 }
 #endif
 
 #ifdef __LITTLE_ENDIAN__
-long pseries_big_endian_exceptions(void)
+void pseries_big_endian_exceptions(void)
 {
 	long rc;
 
 	while (1) {
 		rc = enable_big_endian_exceptions();
 		if (!H_IS_LONG_BUSY(rc))
-			return rc;
+			break;
 		mdelay(get_longbusy_msecs(rc));
 	}
+
+	/*
+	 * At this point it is unlikely panic() will get anything
+	 * out to the user, since this is called very late in kexec
+	 * but at least this will stop us from continuing on further
+	 * and creating an even more difficult to debug situation.
+	 *
+	 * There is a known problem when kdump'ing, if cpus are offline
+	 * the above call will fail. Rather than panicking again, keep
+	 * going and hope the kdump kernel is also little endian, which
+	 * it usually is.
+	 */
+	if (rc && !kdump_in_progress())
+		panic("Could not enable big endian exceptions");
 }
 
-static long pseries_little_endian_exceptions(void)
+void pseries_little_endian_exceptions(void)
 {
 	long rc;
 
 	while (1) {
 		rc = enable_little_endian_exceptions();
 		if (!H_IS_LONG_BUSY(rc))
-			return rc;
+			break;
 		mdelay(get_longbusy_msecs(rc));
 	}
+	if (rc) {
+		ppc_md.progress("H_SET_MODE LE exception fail", 0);
+		panic("Could not enable little endian exceptions");
+	}
 }
 #endif
 
@@ -464,18 +487,6 @@ static void __init pSeries_setup_arch(void)
 	}
 
 	ppc_md.pcibios_root_bridge_prepare = pseries_root_bridge_prepare;
-
-	if (firmware_has_feature(FW_FEATURE_SET_MODE)) {
-		long rc;
-
-		rc = pSeries_enable_reloc_on_exc();
-		if (rc == H_P2) {
-			pr_info("Relocation on exceptions not supported\n");
-		} else if (rc != H_SUCCESS) {
-			pr_warn("Unable to enable relocation on exceptions: "
-				"%ld\n", rc);
-		}
-	}
 }
 
 static int __init pSeries_init_panel(void)
@@ -678,23 +689,6 @@ static int __init pSeries_probe(void)
 
 	pr_debug("pSeries detected, looking for LPAR capability...\n");
 
-
-#ifdef __LITTLE_ENDIAN__
-	if (firmware_has_feature(FW_FEATURE_SET_MODE)) {
-		long rc;
-		/*
-		 * Tell the hypervisor that we want our exceptions to
-		 * be taken in little endian mode. If this fails we don't
-		 * want to use BUG() because it will trigger an exception.
-		 */
-		rc = pseries_little_endian_exceptions();
-		if (rc) {
-			ppc_md.progress("H_SET_MODE LE exception fail", 0);
-			panic("Could not enable little endian exceptions");
-		}
-	}
-#endif
-
 	if (firmware_has_feature(FW_FEATURE_LPAR))
 		hpte_init_lpar();
 	else