powerpc fixes for 6.10 #4

- Fix unnecessary copy to 0 when kernel is booted at address 0.
 
  - Fix usercopy crash when dumping dtl via debugfs.
 
  - Avoid possible crash when PCI hotplug races with error handling.
 
  - Fix kexec crash caused by scv being disabled before other CPUs call-in.
 
  - Fix powerpc selftests build with USERCFLAGS set.
 
 Thanks to: Anjali K, Ganesh Goudar, Gautam Menghani, Jinglin Wen, Nicholas
 Piggin, Sourabh Jain, Srikar Dronamraju, Vishal Chourasia.
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Merge tag 'powerpc-6.10-4' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux

Pull powerpc fixes from Michael Ellerman:

 - Fix unnecessary copy to 0 when kernel is booted at address 0

 - Fix usercopy crash when dumping dtl via debugfs

 - Avoid possible crash when PCI hotplug races with error handling

 - Fix kexec crash caused by scv being disabled before other CPUs
   call-in

 - Fix powerpc selftests build with USERCFLAGS set

Thanks to Anjali K, Ganesh Goudar, Gautam Menghani, Jinglin Wen,
Nicholas Piggin, Sourabh Jain, Srikar Dronamraju, and Vishal Chourasia.

* tag 'powerpc-6.10-4' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  selftests/powerpc: Fix build with USERCFLAGS set
  powerpc/pseries: Fix scv instruction crash with kexec
  powerpc/eeh: avoid possible crash when edev->pdev changes
  powerpc/pseries: Whitelist dtl slub object for copying to userspace
  powerpc/64s: Fix unnecessary copy to 0 when kernel is booted at address 0

arch/powerpc/kernel/eeh_pe.c

@@ -849,6 +849,7 @@ struct pci_bus *eeh_pe_bus_get(struct eeh_pe *pe)
 {
 	struct eeh_dev *edev;
 	struct pci_dev *pdev;
+	struct pci_bus *bus = NULL;
 
 	if (pe->type & EEH_PE_PHB)
 		return pe->phb->bus;
@@ -859,9 +860,11 @@ struct pci_bus *eeh_pe_bus_get(struct eeh_pe *pe)
 
 	/* Retrieve the parent PCI bus of first (top) PCI device */
 	edev = list_first_entry_or_null(&pe->edevs, struct eeh_dev, entry);
+	pci_lock_rescan_remove();
 	pdev = eeh_dev_to_pci_dev(edev);
 	if (pdev)
-		return pdev->bus;
+		bus = pdev->bus;
+	pci_unlock_rescan_remove();
 
-	return NULL;
+	return bus;
 }

arch/powerpc/kernel/head_64.S

@@ -647,8 +647,9 @@ __after_prom_start:
  * Note: This process overwrites the OF exception vectors.
  */
 	LOAD_REG_IMMEDIATE(r3, PAGE_OFFSET)
-	mr.	r4,r26			/* In some cases the loader may  */
-	beq	9f			/* have already put us at zero */
+	mr	r4,r26			/* Load the virtual source address into r4 */
+	cmpld	r3,r4			/* Check if source == dest */
+	beq	9f			/* If so skip the copy  */
 	li	r6,0x100		/* Start offset, the first 0x100 */
 					/* bytes were copied earlier.	 */
 

arch/powerpc/kexec/core_64.c

@@ -27,6 +27,7 @@
 #include <asm/paca.h>
 #include <asm/mmu.h>
 #include <asm/sections.h>	/* _end */
+#include <asm/setup.h>
 #include <asm/smp.h>
 #include <asm/hw_breakpoint.h>
 #include <asm/svm.h>
@@ -317,6 +318,16 @@ void default_machine_kexec(struct kimage *image)
 	if (!kdump_in_progress())
 		kexec_prepare_cpus();
 
+#ifdef CONFIG_PPC_PSERIES
+	/*
+	 * This must be done after other CPUs have shut down, otherwise they
+	 * could execute the 'scv' instruction, which is not supported with
+	 * reloc disabled (see configure_exceptions()).
+	 */
+	if (firmware_has_feature(FW_FEATURE_SET_MODE))
+		pseries_disable_reloc_on_exc();
+#endif
+
 	printk("kexec: Starting switchover sequence.\n");
 
 	/* switch to a staticly allocated stack.  Based on irq stack code.

arch/powerpc/platforms/pseries/kexec.c

@@ -61,11 +61,3 @@ void pseries_kexec_cpu_down(int crash_shutdown, int secondary)
 	} else
 		xics_kexec_teardown_cpu(secondary);
 }
-
-void pseries_machine_kexec(struct kimage *image)
-{
-	if (firmware_has_feature(FW_FEATURE_SET_MODE))
-		pseries_disable_reloc_on_exc();
-
-	default_machine_kexec(image);
-}

arch/powerpc/platforms/pseries/pseries.h

@@ -38,7 +38,6 @@ static inline void smp_init_pseries(void) { }
 #endif
 
 extern void pseries_kexec_cpu_down(int crash_shutdown, int secondary);
-void pseries_machine_kexec(struct kimage *image);
 
 extern void pSeries_final_fixup(void);
 

arch/powerpc/platforms/pseries/setup.c

@@ -343,8 +343,8 @@ static int alloc_dispatch_log_kmem_cache(void)
 {
 	void (*ctor)(void *) = get_dtl_cache_ctor();
 
-	dtl_cache = kmem_cache_create("dtl", DISPATCH_LOG_BYTES,
-						DISPATCH_LOG_BYTES, 0, ctor);
+	dtl_cache = kmem_cache_create_usercopy("dtl", DISPATCH_LOG_BYTES,
+						DISPATCH_LOG_BYTES, 0, 0, DISPATCH_LOG_BYTES, ctor);
 	if (!dtl_cache) {
 		pr_warn("Failed to create dispatch trace log buffer cache\n");
 		pr_warn("Stolen time statistics will be unreliable\n");
@@ -1159,7 +1159,6 @@ define_machine(pseries) {
 	.machine_check_exception = pSeries_machine_check_exception,
 	.machine_check_log_err	= pSeries_machine_check_log_err,
 #ifdef CONFIG_KEXEC_CORE
-	.machine_kexec          = pseries_machine_kexec,
 	.kexec_cpu_down         = pseries_kexec_cpu_down,
 #endif
 #ifdef CONFIG_MEMORY_HOTPLUG

tools/testing/selftests/powerpc/flags.mk

@@ -5,8 +5,5 @@ GIT_VERSION := $(shell git describe --always --long --dirty || echo "unknown")
 export GIT_VERSION
 endif
 
-ifeq ($(CFLAGS),)
-CFLAGS := -std=gnu99 -O2 -Wall -Werror -DGIT_VERSION='"$(GIT_VERSION)"' -I$(selfdir)/powerpc/include $(CFLAGS)
+CFLAGS := -std=gnu99 -O2 -Wall -Werror -DGIT_VERSION='"$(GIT_VERSION)"' -I$(selfdir)/powerpc/include $(USERCFLAGS)
 export CFLAGS
-endif
-