The patch titled Subject: Revert "MIPS: make userspace mapping young by default" has been added to the -mm tree. Its filename is revert-mips-make-userspace-mapping-young-by-default.patch

This patch should soon appear at https://ozlabs.org/~akpm/mmots/broken-out/revert-mips-make-userspace-mapping... and later at https://ozlabs.org/~akpm/mmotm/broken-out/revert-mips-make-userspace-mapping...

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------------------------------------------------------ From: Thomas Bogendoerfer tsbogend@alpha.franken.de Subject: Revert "MIPS: make userspace mapping young by default"

This reverts commit f685a533a7fab35c5d069dcd663f59c8e4171a75.

MIPS cache flush logic needs to know whether the mapping was already established to decide how to flush caches. This is done by checking the valid bit in the PTE. The commit above breaks this logic by setting the valid in the PTE in new mappings, which causes kernel crashes.

Link: https://lkml.kernel.org/r/20210526094335.92948-1-tsbogend@alpha.franken.de Fixes: f685a533a7f ("MIPS: make userspace mapping young by default") Reported-by: Zhou Yanjie zhouyanjie@wanyeetech.com Signed-off-by: Thomas Bogendoerfer tsbogend@alpha.franken.de Cc: Huang Pei huangpei@loongson.cn Cc: Nicholas Piggin npiggin@gmail.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

arch/mips/mm/cache.c | 30 ++++++++++++++---------------- include/linux/pgtable.h | 8 ++++++++ mm/memory.c | 4 ++++ 3 files changed, 26 insertions(+), 16 deletions(-)

--- a/arch/mips/mm/cache.c~revert-mips-make-userspace-mapping-young-by-default +++ a/arch/mips/mm/cache.c @@ -158,31 +158,29 @@ unsigned long _page_cachable_default; EXPORT_SYMBOL(_page_cachable_default);

#define PM(p) __pgprot(_page_cachable_default | (p)) -#define PVA(p) PM(_PAGE_VALID | _PAGE_ACCESSED | (p))

static inline void setup_protection_map(void) { protection_map[0] = PM(_PAGE_PRESENT | _PAGE_NO_EXEC | _PAGE_NO_READ); - protection_map[1] = PVA(_PAGE_PRESENT | _PAGE_NO_EXEC); - protection_map[2] = PVA(_PAGE_PRESENT | _PAGE_NO_EXEC | _PAGE_NO_READ); - protection_map[3] = PVA(_PAGE_PRESENT | _PAGE_NO_EXEC); - protection_map[4] = PVA(_PAGE_PRESENT); - protection_map[5] = PVA(_PAGE_PRESENT); - protection_map[6] = PVA(_PAGE_PRESENT); - protection_map[7] = PVA(_PAGE_PRESENT); + protection_map[1] = PM(_PAGE_PRESENT | _PAGE_NO_EXEC); + protection_map[2] = PM(_PAGE_PRESENT | _PAGE_NO_EXEC | _PAGE_NO_READ); + protection_map[3] = PM(_PAGE_PRESENT | _PAGE_NO_EXEC); + protection_map[4] = PM(_PAGE_PRESENT); + protection_map[5] = PM(_PAGE_PRESENT); + protection_map[6] = PM(_PAGE_PRESENT); + protection_map[7] = PM(_PAGE_PRESENT);

protection_map[8] = PM(_PAGE_PRESENT | _PAGE_NO_EXEC | _PAGE_NO_READ); - protection_map[9] = PVA(_PAGE_PRESENT | _PAGE_NO_EXEC); - protection_map[10] = PVA(_PAGE_PRESENT | _PAGE_NO_EXEC | _PAGE_WRITE | + protection_map[9] = PM(_PAGE_PRESENT | _PAGE_NO_EXEC); + protection_map[10] = PM(_PAGE_PRESENT | _PAGE_NO_EXEC | _PAGE_WRITE | _PAGE_NO_READ); - protection_map[11] = PVA(_PAGE_PRESENT | _PAGE_NO_EXEC | _PAGE_WRITE); - protection_map[12] = PVA(_PAGE_PRESENT); - protection_map[13] = PVA(_PAGE_PRESENT); - protection_map[14] = PVA(_PAGE_PRESENT); - protection_map[15] = PVA(_PAGE_PRESENT); + protection_map[11] = PM(_PAGE_PRESENT | _PAGE_NO_EXEC | _PAGE_WRITE); + protection_map[12] = PM(_PAGE_PRESENT); + protection_map[13] = PM(_PAGE_PRESENT); + protection_map[14] = PM(_PAGE_PRESENT | _PAGE_WRITE); + protection_map[15] = PM(_PAGE_PRESENT | _PAGE_WRITE); }

-#undef _PVA #undef PM

void cpu_cache_init(void) --- a/include/linux/pgtable.h~revert-mips-make-userspace-mapping-young-by-default +++ a/include/linux/pgtable.h @@ -432,6 +432,14 @@ static inline void ptep_set_wrprotect(st * To be differentiate with macro pte_mkyoung, this macro is used on platforms * where software maintains page access bit. */ +#ifndef pte_sw_mkyoung +static inline pte_t pte_sw_mkyoung(pte_t pte) +{ + return pte; +} +#define pte_sw_mkyoung pte_sw_mkyoung +#endif + #ifndef pte_savedwrite #define pte_savedwrite pte_write #endif --- a/mm/memory.c~revert-mips-make-userspace-mapping-young-by-default +++ a/mm/memory.c @@ -2939,6 +2939,7 @@ static vm_fault_t wp_page_copy(struct vm } flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte)); entry = mk_pte(new_page, vma->vm_page_prot); + entry = pte_sw_mkyoung(entry); entry = maybe_mkwrite(pte_mkdirty(entry), vma);

/* @@ -3602,6 +3603,7 @@ static vm_fault_t do_anonymous_page(stru __SetPageUptodate(page);

entry = mk_pte(page, vma->vm_page_prot); + entry = pte_sw_mkyoung(entry); if (vma->vm_flags & VM_WRITE) entry = pte_mkwrite(pte_mkdirty(entry));

@@ -3786,6 +3788,8 @@ void do_set_pte(struct vm_fault *vmf, st

if (prefault && arch_wants_old_prefaulted_pte()) entry = pte_mkold(entry); + else + entry = pte_sw_mkyoung(entry);

if (write) entry = maybe_mkwrite(pte_mkdirty(entry), vma); _

Patches currently in -mm which might be from tsbogend@alpha.franken.de are

revert-mips-make-userspace-mapping-young-by-default.patch