From: Dave Vasilevsky Date: Sun, 16 Nov 2025 06:40:46 +0000 (-0500) Subject: powerpc, mm: Fix mprotect on book3s 32-bit X-Git-Tag: v6.19-rc1~106^2~13 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=78fc63ffa7813e33681839bb33826c24195f0eb7;p=thirdparty%2Flinux.git powerpc, mm: Fix mprotect on book3s 32-bit On 32-bit book3s with hash-MMUs, tlb_flush() was a no-op. This was unnoticed because all uses until recently were for unmaps, and thus handled by __tlb_remove_tlb_entry(). After commit 4a18419f71cd ("mm/mprotect: use mmu_gather") in kernel 5.19, tlb_gather_mmu() started being used for mprotect as well. This caused mprotect to simply not work on these machines: int *ptr = mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); *ptr = 1; // force HPTE to be created mprotect(ptr, 4096, PROT_READ); *ptr = 2; // should segfault, but succeeds Fixed by making tlb_flush() actually flush TLB pages. This finally agrees with the behaviour of boot3s64's tlb_flush(). Fixes: 4a18419f71cd ("mm/mprotect: use mmu_gather") Cc: stable@vger.kernel.org Reviewed-by: Christophe Leroy Reviewed-by: Ritesh Harjani (IBM) Signed-off-by: Dave Vasilevsky Signed-off-by: Madhavan Srinivasan Link: https://patch.msgid.link/20251116-vasi-mprotect-g3-v3-1-59a9bd33ba00@vasilevsky.ca --- diff --git a/arch/powerpc/include/asm/book3s/32/tlbflush.h b/arch/powerpc/include/asm/book3s/32/tlbflush.h index e43534da5207a..4be2200a3c7e1 100644 --- a/arch/powerpc/include/asm/book3s/32/tlbflush.h +++ b/arch/powerpc/include/asm/book3s/32/tlbflush.h @@ -11,6 +11,7 @@ void hash__flush_tlb_mm(struct mm_struct *mm); void hash__flush_tlb_page(struct vm_area_struct *vma, unsigned long vmaddr); void hash__flush_range(struct mm_struct *mm, unsigned long start, unsigned long end); +void hash__flush_gather(struct mmu_gather *tlb); #ifdef CONFIG_SMP void _tlbie(unsigned long address); @@ -29,7 +30,9 @@ void _tlbia(void); static inline void tlb_flush(struct mmu_gather *tlb) { /* 603 needs to flush the whole TLB here since it doesn't use a hash table. */ - if (!mmu_has_feature(MMU_FTR_HPTE_TABLE)) + if (mmu_has_feature(MMU_FTR_HPTE_TABLE)) + hash__flush_gather(tlb); + else _tlbia(); } diff --git a/arch/powerpc/mm/book3s32/tlb.c b/arch/powerpc/mm/book3s32/tlb.c index 9ad6b56bfec96..e54a7b0112322 100644 --- a/arch/powerpc/mm/book3s32/tlb.c +++ b/arch/powerpc/mm/book3s32/tlb.c @@ -105,3 +105,12 @@ void hash__flush_tlb_page(struct vm_area_struct *vma, unsigned long vmaddr) flush_hash_pages(mm->context.id, vmaddr, pmd_val(*pmd), 1); } EXPORT_SYMBOL(hash__flush_tlb_page); + +void hash__flush_gather(struct mmu_gather *tlb) +{ + if (tlb->fullmm || tlb->need_flush_all) + hash__flush_tlb_mm(tlb->mm); + else + hash__flush_range(tlb->mm, tlb->start, tlb->end); +} +EXPORT_SYMBOL(hash__flush_gather);