[PATCH 12/23] powerpc: allow pte_offset_map[_lock]() to fail

Hugh Dickins
2023-05-10T04:57:57Z

In rare transient cases, not yet made possible, pte_offset_map() and
pte_offset_map_lock() may not find a page table: handle appropriately.
Balance successful pte_offset_map() with pte_unmap() where omitted.

Signed-off-by: Hugh Dickins <hughd@google.com>
---
arch/powerpc/mm/book3s64/hash_tlb.c | 4 ++++
arch/powerpc/mm/book3s64/subpage_prot.c | 2 ++
arch/powerpc/xmon/xmon.c | 5 ++++-
3 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/mm/book3s64/hash_tlb.c b/arch/powerpc/mm/book3s64/hash_tlb.c
index a64ea0a7ef96..21fcad97ae80 100644
--- a/arch/powerpc/mm/book3s64/hash_tlb.c
+++ b/arch/powerpc/mm/book3s64/hash_tlb.c
@@ -239,12 +239,16 @@ void flush_hash_table_pmd_range(struct mm_struct *mm, pmd_t *pmd, unsigned long
local_irq_save(flags);
arch_enter_lazy_mmu_mode();
start_pte = pte_offset_map(pmd, addr);
+ if (!start_pte)
+ goto out;
for (pte = start_pte; pte < start_pte + PTRS_PER_PTE; pte++) {
unsigned long pteval = pte_val(*pte);
if (pteval & H_PAGE_HASHPTE)
hpte_need_flush(mm, addr, pte, pteval, 0);
addr += PAGE_SIZE;
}
+ pte_unmap(start_pte);
+out:
arch_leave_lazy_mmu_mode();
local_irq_restore(flags);
}
diff --git a/arch/powerpc/mm/book3s64/subpage_prot.c b/arch/powerpc/mm/book3s64/subpage_prot.c
index b75a9fb99599..0dc85556dec5 100644
--- a/arch/powerpc/mm/book3s64/subpage_prot.c
+++ b/arch/powerpc/mm/book3s64/subpage_prot.c
@@ -71,6 +71,8 @@ static void hpte_flush_range(struct mm_struct *mm, unsigned long addr,
if (pmd_none(*pmd))
return;
pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
+ if (!pte)
+ return;
arch_enter_lazy_mmu_mode();
for (; npages > 0; --npages) {
pte_update(mm, addr, pte, 0, 0, 0);
diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
index 728d3c257e4a..69447bdf0bcf 100644
--- a/arch/powerpc/xmon/xmon.c
+++ b/arch/powerpc/xmon/xmon.c
@@ -3376,12 +3376,15 @@ static void show_pte(unsigned long addr)
printf("pmdp @ 0x%px = 0x%016lx\n", pmdp, pmd_val(*pmdp));

ptep = pte_offset_map(pmdp, addr);
- if (pte_none(*ptep)) {
+ if (!ptep || pte_none(*ptep)) {
+ if (ptep)
+ pte_unmap(ptep);
printf("no valid PTE\n");
return;
}

format_pte(ptep, pte_val(*ptep));
+ pte_unmap(ptep);

sync();
__delay(200);
--
2.35.3