m68k: allow pte_offset_map[_lock]() to fail

In rare transient cases, not yet made possible, pte_offset_map() and
pte_offset_map_lock() may not find a page table: handle appropriately.

Restructure cf_tlb_miss() with a pte_unmap() (previously omitted)
at label out, followed by one local_irq_restore() for all.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Hugh Dickins <[email protected]>
Cc: Alexander Gordeev <[email protected]>
Cc: Alexandre Ghiti <[email protected]>
Cc: Aneesh Kumar K.V <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Christian Borntraeger <[email protected]>
Cc: Chris Zankel <[email protected]>
Cc: Claudio Imbrenda <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: "David S. Miller" <[email protected]>
Cc: Geert Uytterhoeven <[email protected]>
Cc: Greg Ungerer <[email protected]>
Cc: Heiko Carstens <[email protected]>
Cc: Helge Deller <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: John David Anglin <[email protected]>
Cc: John Paul Adrian Glaubitz <[email protected]>
Cc: Kirill A. Shutemov <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Cc: Max Filippov <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Michal Simek <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Mike Rapoport (IBM) <[email protected]>
Cc: Palmer Dabbelt <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Qi Zheng <[email protected]>
Cc: Russell King <[email protected]>
Cc: Suren Baghdasaryan <[email protected]>
Cc: Thomas Bogendoerfer <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Will Deacon <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

1 files changed, 21 insertions, 31 deletions

diff --git a/arch/m68k/mm/mcfmmu.c b/arch/m68k/mm/mcfmmu.c
index 70aa0979e027..42f45abea37a 100644
--- a/arch/m68k/mm/mcfmmu.c
+++ b/arch/m68k/mm/mcfmmu.c
@@ -91,7 +91,8 @@ int cf_tlb_miss(struct pt_regs *regs, int write, int dtlb, int extension_word)
 	p4d_t *p4d;
 	pud_t *pud;
 	pmd_t *pmd;
-	pte_t *pte;
+	pte_t *pte = NULL;
+	int ret = -1;
 	int asid;
 
 	local_irq_save(flags);
@@ -100,47 +101,33 @@ int cf_tlb_miss(struct pt_regs *regs, int write, int dtlb, int extension_word)
 		regs->pc + (extension_word * sizeof(long));
 
 	mm = (!user_mode(regs) && KMAPAREA(mmuar)) ? &init_mm : current->mm;
-	if (!mm) {
-		local_irq_restore(flags);
-		return -1;
-	}
+	if (!mm)
+		goto out;
 
 	pgd = pgd_offset(mm, mmuar);
-	if (pgd_none(*pgd))  {
-		local_irq_restore(flags);
-		return -1;
-	}
+	if (pgd_none(*pgd))
+		goto out;
 
 	p4d = p4d_offset(pgd, mmuar);
-	if (p4d_none(*p4d)) {
-		local_irq_restore(flags);
-		return -1;
-	}
+	if (p4d_none(*p4d))
+		goto out;
 
 	pud = pud_offset(p4d, mmuar);
-	if (pud_none(*pud)) {
-		local_irq_restore(flags);
-		return -1;
-	}
+	if (pud_none(*pud))
+		goto out;
 
 	pmd = pmd_offset(pud, mmuar);
-	if (pmd_none(*pmd)) {
-		local_irq_restore(flags);
-		return -1;
-	}
+	if (pmd_none(*pmd))
+		goto out;
 
 	pte = (KMAPAREA(mmuar)) ? pte_offset_kernel(pmd, mmuar)
 				: pte_offset_map(pmd, mmuar);
-	if (pte_none(*pte) || !pte_present(*pte)) {
-		local_irq_restore(flags);
-		return -1;
-	}
+	if (!pte || pte_none(*pte) || !pte_present(*pte))
+		goto out;
 
 	if (write) {
-		if (!pte_write(*pte)) {
-			local_irq_restore(flags);
-			return -1;
-		}
+		if (!pte_write(*pte))
+			goto out;
 		set_pte(pte, pte_mkdirty(*pte));
 	}
 
@@ -161,9 +148,12 @@ int cf_tlb_miss(struct pt_regs *regs, int write, int dtlb, int extension_word)
 		mmu_write(MMUOR, MMUOR_ACC | MMUOR_UAA);
 	else
 		mmu_write(MMUOR, MMUOR_ITLB | MMUOR_ACC | MMUOR_UAA);
-
+	ret = 0;
+out:
+	if (pte && !KMAPAREA(mmuar))
+		pte_unmap(pte);
 	local_irq_restore(flags);
-	return 0;
+	return ret;
 }
 
 void __init cf_bootmem_alloc(void)