From e67b37c368b7cc24b8c0fe5ab6c44422312eab37 Mon Sep 17 00:00:00 2001
From: Hugh Dickins <hughd@google.com>
Date: Thu, 8 Jun 2023 12:15:16 -0700
Subject: 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/795f6a7-bcca-cdf-ad2a-fbdaa232998c@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexandre Ghiti <alexghiti@rivosinc.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Greg Ungerer <gerg@linux-m68k.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: John David Anglin <dave.anglin@bell.net>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 arch/m68k/mm/mcfmmu.c | 52 +++++++++++++++++++++------------------------------
 1 file changed, 21 insertions(+), 31 deletions(-)

(limited to 'arch/m68k/mm')

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)
-- 
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