From: Michael Ellerman <mpe@ellerman.id.au>
Date: Thu, 13 Jun 2019 05:00:34 +0000 (+1000)
Subject: Merge branch 'context-id-fix' into fixes
X-Git-Tag: v5.2-rc7~28^2
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=65565a68c582fec2f2a8f5aaa399118ab1209103;p=users%2Fjedix%2Flinux-maple.git

Merge branch 'context-id-fix' into fixes

This merges a fix for a bug in our context id handling on 64-bit hash
CPUs.

The fix was written against v5.1 to ease backporting to stable
releases. Here we are merging it up to a v5.2-rc2 base, which involves
a bit of manual resolution.

It also adds a test case for the bug.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
---

65565a68c582fec2f2a8f5aaa399118ab1209103
diff --cc arch/powerpc/mm/book3s64/mmu_context.c
index cb2b08635508,8751ae2e2d04..6d8f06b04022
--- a/arch/powerpc/mm/book3s64/mmu_context.c
+++ b/arch/powerpc/mm/book3s64/mmu_context.c
@@@ -59,17 -97,6 +97,11 @@@ static int hash__init_new_context(struc
  {
  	int index;
  
- 	index = hash__alloc_context_id();
- 	if (index < 0)
- 		return index;
- 
 +	mm->context.hash_context = kmalloc(sizeof(struct hash_mm_context),
 +					   GFP_KERNEL);
- 	if (!mm->context.hash_context) {
- 		ida_free(&mmu_context_ida, index);
++	if (!mm->context.hash_context)
 +		return -ENOMEM;
- 	}
 +
  	/*
  	 * The old code would re-promote on fork, we don't do that when using
  	 * slices as it could cause problem promoting slices that have been
@@@ -84,26 -111,14 +116,33 @@@
  	 * We should not be calling init_new_context() on init_mm. Hence a
  	 * check against 0 is OK.
  	 */
 -	if (mm->context.id == 0)
 +	if (mm->context.id == 0) {
 +		memset(mm->context.hash_context, 0, sizeof(struct hash_mm_context));
  		slice_init_new_context_exec(mm);
 +	} else {
 +		/* This is fork. Copy hash_context details from current->mm */
 +		memcpy(mm->context.hash_context, current->mm->context.hash_context, sizeof(struct hash_mm_context));
 +#ifdef CONFIG_PPC_SUBPAGE_PROT
 +		/* inherit subpage prot detalis if we have one. */
 +		if (current->mm->context.hash_context->spt) {
 +			mm->context.hash_context->spt = kmalloc(sizeof(struct subpage_prot_table),
 +								GFP_KERNEL);
 +			if (!mm->context.hash_context->spt) {
- 				ida_free(&mmu_context_ida, index);
 +				kfree(mm->context.hash_context);
 +				return -ENOMEM;
 +			}
 +		}
 +#endif
++	}
  
+ 	index = realloc_context_ids(&mm->context);
 -	if (index < 0)
++	if (index < 0) {
++#ifdef CONFIG_PPC_SUBPAGE_PROT
++		kfree(mm->context.hash_context->spt);
++#endif
++		kfree(mm->context.hash_context);
+ 		return index;
 -
 -	subpage_prot_init_new_context(mm);
 +	}
  
  	pkey_mm_init(mm);
  	return index;