powerpc fixes for 6.3 #4

- Fix a false positive warning in __pte_needs_flush() (with DEBUG_VM=y).
  - Fix oops when a PF_IO_WORKER thread tries to core dump.
  - Don't try to reconfigure VAS when it's disabled.
 
 Thanks to: Benjamin Gray, Haren Myneni, Jens Axboe, Nathan Lynch, Russell Currey.
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Merge tag 'powerpc-6.3-4' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux

Pull powerpc fixes from Michael Ellerman:

 - Fix a false positive warning in __pte_needs_flush() (with DEBUG_VM=y)

 - Fix oops when a PF_IO_WORKER thread tries to core dump

 - Don't try to reconfigure VAS when it's disabled

Thanks to Benjamin Gray, Haren Myneni, Jens Axboe, Nathan Lynch, and
Russell Currey.

* tag 'powerpc-6.3-4' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/pseries/vas: Ignore VAS update for DLPAR if copy/paste is not enabled
  powerpc: Don't try to copy PPR for task with NULL pt_regs
  powerpc/64s: Fix __pte_needs_flush() false positive warning

arch/powerpc/include/asm/book3s/64/tlbflush.h

@@ -148,6 +148,11 @@ static inline void flush_tlb_fix_spurious_fault(struct vm_area_struct *vma,
 	 */
 }
 
+static inline bool __pte_protnone(unsigned long pte)
+{
+	return (pte & (pgprot_val(PAGE_NONE) | _PAGE_RWX)) == pgprot_val(PAGE_NONE);
+}
+
 static inline bool __pte_flags_need_flush(unsigned long oldval,
 					  unsigned long newval)
 {
@@ -164,8 +169,8 @@ static inline bool __pte_flags_need_flush(unsigned long oldval,
 	/*
 	 * We do not expect kernel mappings or non-PTEs or not-present PTEs.
 	 */
-	VM_WARN_ON_ONCE(oldval & _PAGE_PRIVILEGED);
-	VM_WARN_ON_ONCE(newval & _PAGE_PRIVILEGED);
+	VM_WARN_ON_ONCE(!__pte_protnone(oldval) && oldval & _PAGE_PRIVILEGED);
+	VM_WARN_ON_ONCE(!__pte_protnone(newval) && newval & _PAGE_PRIVILEGED);
 	VM_WARN_ON_ONCE(!(oldval & _PAGE_PTE));
 	VM_WARN_ON_ONCE(!(newval & _PAGE_PTE));
 	VM_WARN_ON_ONCE(!(oldval & _PAGE_PRESENT));

arch/powerpc/kernel/ptrace/ptrace-view.c

@@ -290,6 +290,9 @@ static int gpr_set(struct task_struct *target, const struct user_regset *regset,
 static int ppr_get(struct task_struct *target, const struct user_regset *regset,
 		   struct membuf to)
 {
+	if (!target->thread.regs)
+		return -EINVAL;
+
 	return membuf_write(&to, &target->thread.regs->ppr, sizeof(u64));
 }
 
@@ -297,6 +300,9 @@ static int ppr_set(struct task_struct *target, const struct user_regset *regset,
 		   unsigned int pos, unsigned int count, const void *kbuf,
 		   const void __user *ubuf)
 {
+	if (!target->thread.regs)
+		return -EINVAL;
+
 	return user_regset_copyin(&pos, &count, &kbuf, &ubuf,
 				  &target->thread.regs->ppr, 0, sizeof(u64));
 }

arch/powerpc/platforms/pseries/vas.c

@@ -856,6 +856,13 @@ int pseries_vas_dlpar_cpu(void)
 {
 	int new_nr_creds, rc;
 
+	/*
+	 * NX-GZIP is not enabled. Nothing to do for DLPAR event
+	 */
+	if (!copypaste_feat)
+		return 0;
+
+
 	rc = h_query_vas_capabilities(H_QUERY_VAS_CAPABILITIES,
 				      vascaps[VAS_GZIP_DEF_FEAT_TYPE].feat,
 				      (u64)virt_to_phys(&hv_cop_caps));
@@ -1012,6 +1019,7 @@ static int __init pseries_vas_init(void)
 	 * Linux supports user space COPY/PASTE only with Radix
 	 */
 	if (!radix_enabled()) {
+		copypaste_feat = false;
 		pr_err("API is supported only with radix page tables\n");
 		return -ENOTSUPP;
 	}