On Fri, Oct 18, 2024 at 11:44 AM maobibo <maobibo@xxxxxxxxxxx> wrote: > > > > On 2024/10/18 上午11:14, Huacai Chen wrote: > > Hi, Bibo, > > > > I applied this patch but drop the part of arch/loongarch/mm/kasan_init.c: > > https://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson.git/commit/?h=loongarch-next&id=15832255e84494853f543b4c70ced50afc403067 > > > > Because kernel_pte_init() should operate on page-table pages, not on > > data pages. You have already handle page-table page in > > mm/kasan/init.c, and if we don't drop the modification on data pages > > in arch/loongarch/mm/kasan_init.c, the kernel fail to boot if KASAN is > > enabled. > > > static inline void set_pte(pte_t *ptep, pte_t pteval) > { > WRITE_ONCE(*ptep, pteval); > - > - if (pte_val(pteval) & _PAGE_GLOBAL) { > - pte_t *buddy = ptep_buddy(ptep); > - /* > - * Make sure the buddy is global too (if it's !none, > - * it better already be global) > - */ > - if (pte_none(ptep_get(buddy))) { > -#ifdef CONFIG_SMP > - /* > - * For SMP, multiple CPUs can race, so we need > - * to do this atomically. > - */ > - __asm__ __volatile__( > - __AMOR "$zero, %[global], %[buddy] \n" > - : [buddy] "+ZB" (buddy->pte) > - : [global] "r" (_PAGE_GLOBAL) > - : "memory"); > - > - DBAR(0b11000); /* o_wrw = 0b11000 */ > -#else /* !CONFIG_SMP */ > - WRITE_ONCE(*buddy, __pte(pte_val(ptep_get(buddy)) | _PAGE_GLOBAL)); > -#endif /* CONFIG_SMP */ > - } > - } > + DBAR(0b11000); /* o_wrw = 0b11000 */ > } > > No, please hold on. This issue exists about twenty years, Do we need be > in such a hurry now? > > why is DBAR(0b11000) added in set_pte()? It exists before, not added by this patch. The reason is explained in https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?h=v6.12-rc3&id=f93f67d06b1023313ef1662eac490e29c025c030 Huacai > > Regards > Bibo Mao > > Huacai > > > > On Mon, Oct 14, 2024 at 11:59 AM Bibo Mao <maobibo@xxxxxxxxxxx> wrote: > >> > >> Unlike general architectures, there are two pages in one TLB entry > >> on LoongArch system. For kernel space, it requires both two pte > >> entries with PAGE_GLOBAL bit set, else HW treats it as non-global > >> tlb, there will be potential problems if tlb entry for kernel space > >> is not global. Such as fail to flush kernel tlb with function > >> local_flush_tlb_kernel_range() which only flush tlb with global bit. > >> > >> With function kernel_pte_init() added, it can be used to init pte > >> table when it is created for kernel address space, and the default > >> initial pte value is PAGE_GLOBAL rather than zero at beginning. > >> > >> Kernel address space areas includes fixmap, percpu, vmalloc, kasan > >> and vmemmap areas set default pte entry with PAGE_GLOBAL set. > >> > >> Signed-off-by: Bibo Mao <maobibo@xxxxxxxxxxx> > >> --- > >> arch/loongarch/include/asm/pgalloc.h | 13 +++++++++++++ > >> arch/loongarch/include/asm/pgtable.h | 1 + > >> arch/loongarch/mm/init.c | 4 +++- > >> arch/loongarch/mm/kasan_init.c | 4 +++- > >> arch/loongarch/mm/pgtable.c | 22 ++++++++++++++++++++++ > >> include/linux/mm.h | 1 + > >> mm/kasan/init.c | 8 +++++++- > >> mm/sparse-vmemmap.c | 5 +++++ > >> 8 files changed, 55 insertions(+), 3 deletions(-) > >> > >> diff --git a/arch/loongarch/include/asm/pgalloc.h b/arch/loongarch/include/asm/pgalloc.h > >> index 4e2d6b7ca2ee..b2698c03dc2c 100644 > >> --- a/arch/loongarch/include/asm/pgalloc.h > >> +++ b/arch/loongarch/include/asm/pgalloc.h > >> @@ -10,8 +10,21 @@ > >> > >> #define __HAVE_ARCH_PMD_ALLOC_ONE > >> #define __HAVE_ARCH_PUD_ALLOC_ONE > >> +#define __HAVE_ARCH_PTE_ALLOC_ONE_KERNEL > >> #include <asm-generic/pgalloc.h> > >> > >> +static inline pte_t *pte_alloc_one_kernel(struct mm_struct *mm) > >> +{ > >> + pte_t *pte; > >> + > >> + pte = (pte_t *) __get_free_page(GFP_KERNEL); > >> + if (!pte) > >> + return NULL; > >> + > >> + kernel_pte_init(pte); > >> + return pte; > >> +} > >> + > >> static inline void pmd_populate_kernel(struct mm_struct *mm, > >> pmd_t *pmd, pte_t *pte) > >> { > >> diff --git a/arch/loongarch/include/asm/pgtable.h b/arch/loongarch/include/asm/pgtable.h > >> index 9965f52ef65b..22e3a8f96213 100644 > >> --- a/arch/loongarch/include/asm/pgtable.h > >> +++ b/arch/loongarch/include/asm/pgtable.h > >> @@ -269,6 +269,7 @@ extern void set_pmd_at(struct mm_struct *mm, unsigned long addr, pmd_t *pmdp, pm > >> extern void pgd_init(void *addr); > >> extern void pud_init(void *addr); > >> extern void pmd_init(void *addr); > >> +extern void kernel_pte_init(void *addr); > >> > >> /* > >> * Encode/decode swap entries and swap PTEs. Swap PTEs are all PTEs that > >> diff --git a/arch/loongarch/mm/init.c b/arch/loongarch/mm/init.c > >> index 8a87a482c8f4..9f26e933a8a3 100644 > >> --- a/arch/loongarch/mm/init.c > >> +++ b/arch/loongarch/mm/init.c > >> @@ -198,9 +198,11 @@ pte_t * __init populate_kernel_pte(unsigned long addr) > >> if (!pmd_present(pmdp_get(pmd))) { > >> pte_t *pte; > >> > >> - pte = memblock_alloc(PAGE_SIZE, PAGE_SIZE); > >> + pte = memblock_alloc_raw(PAGE_SIZE, PAGE_SIZE); > >> if (!pte) > >> panic("%s: Failed to allocate memory\n", __func__); > >> + > >> + kernel_pte_init(pte); > >> pmd_populate_kernel(&init_mm, pmd, pte); > >> } > >> > >> diff --git a/arch/loongarch/mm/kasan_init.c b/arch/loongarch/mm/kasan_init.c > >> index 427d6b1aec09..34988573b0d5 100644 > >> --- a/arch/loongarch/mm/kasan_init.c > >> +++ b/arch/loongarch/mm/kasan_init.c > >> @@ -152,6 +152,8 @@ static void __init kasan_pte_populate(pmd_t *pmdp, unsigned long addr, > >> phys_addr_t page_phys = early ? > >> __pa_symbol(kasan_early_shadow_page) > >> : kasan_alloc_zeroed_page(node); > >> + if (!early) > >> + kernel_pte_init(__va(page_phys)); > >> next = addr + PAGE_SIZE; > >> set_pte(ptep, pfn_pte(__phys_to_pfn(page_phys), PAGE_KERNEL)); > >> } while (ptep++, addr = next, addr != end && __pte_none(early, ptep_get(ptep))); > >> @@ -287,7 +289,7 @@ void __init kasan_init(void) > >> set_pte(&kasan_early_shadow_pte[i], > >> pfn_pte(__phys_to_pfn(__pa_symbol(kasan_early_shadow_page)), PAGE_KERNEL_RO)); > >> > >> - memset(kasan_early_shadow_page, 0, PAGE_SIZE); > >> + kernel_pte_init(kasan_early_shadow_page); > >> csr_write64(__pa_symbol(swapper_pg_dir), LOONGARCH_CSR_PGDH); > >> local_flush_tlb_all(); > >> > >> diff --git a/arch/loongarch/mm/pgtable.c b/arch/loongarch/mm/pgtable.c > >> index eb6a29b491a7..228ffc1db0a3 100644 > >> --- a/arch/loongarch/mm/pgtable.c > >> +++ b/arch/loongarch/mm/pgtable.c > >> @@ -38,6 +38,28 @@ pgd_t *pgd_alloc(struct mm_struct *mm) > >> } > >> EXPORT_SYMBOL_GPL(pgd_alloc); > >> > >> +void kernel_pte_init(void *addr) > >> +{ > >> + unsigned long *p, *end; > >> + unsigned long entry; > >> + > >> + entry = (unsigned long)_PAGE_GLOBAL; > >> + p = (unsigned long *)addr; > >> + end = p + PTRS_PER_PTE; > >> + > >> + do { > >> + p[0] = entry; > >> + p[1] = entry; > >> + p[2] = entry; > >> + p[3] = entry; > >> + p[4] = entry; > >> + p += 8; > >> + p[-3] = entry; > >> + p[-2] = entry; > >> + p[-1] = entry; > >> + } while (p != end); > >> +} > >> + > >> void pgd_init(void *addr) > >> { > >> unsigned long *p, *end; > >> diff --git a/include/linux/mm.h b/include/linux/mm.h > >> index ecf63d2b0582..6909fe059a2c 100644 > >> --- a/include/linux/mm.h > >> +++ b/include/linux/mm.h > >> @@ -3818,6 +3818,7 @@ void *sparse_buffer_alloc(unsigned long size); > >> struct page * __populate_section_memmap(unsigned long pfn, > >> unsigned long nr_pages, int nid, struct vmem_altmap *altmap, > >> struct dev_pagemap *pgmap); > >> +void kernel_pte_init(void *addr); > >> void pmd_init(void *addr); > >> void pud_init(void *addr); > >> pgd_t *vmemmap_pgd_populate(unsigned long addr, int node); > >> diff --git a/mm/kasan/init.c b/mm/kasan/init.c > >> index 89895f38f722..ac607c306292 100644 > >> --- a/mm/kasan/init.c > >> +++ b/mm/kasan/init.c > >> @@ -106,6 +106,10 @@ static void __ref zero_pte_populate(pmd_t *pmd, unsigned long addr, > >> } > >> } > >> > >> +void __weak __meminit kernel_pte_init(void *addr) > >> +{ > >> +} > >> + > >> static int __ref zero_pmd_populate(pud_t *pud, unsigned long addr, > >> unsigned long end) > >> { > >> @@ -126,8 +130,10 @@ static int __ref zero_pmd_populate(pud_t *pud, unsigned long addr, > >> > >> if (slab_is_available()) > >> p = pte_alloc_one_kernel(&init_mm); > >> - else > >> + else { > >> p = early_alloc(PAGE_SIZE, NUMA_NO_NODE); > >> + kernel_pte_init(p); > >> + } > >> if (!p) > >> return -ENOMEM; > >> > >> diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c > >> index edcc7a6b0f6f..c0388b2e959d 100644 > >> --- a/mm/sparse-vmemmap.c > >> +++ b/mm/sparse-vmemmap.c > >> @@ -184,6 +184,10 @@ static void * __meminit vmemmap_alloc_block_zero(unsigned long size, int node) > >> return p; > >> } > >> > >> +void __weak __meminit kernel_pte_init(void *addr) > >> +{ > >> +} > >> + > >> pmd_t * __meminit vmemmap_pmd_populate(pud_t *pud, unsigned long addr, int node) > >> { > >> pmd_t *pmd = pmd_offset(pud, addr); > >> @@ -191,6 +195,7 @@ pmd_t * __meminit vmemmap_pmd_populate(pud_t *pud, unsigned long addr, int node) > >> void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node); > >> if (!p) > >> return NULL; > >> + kernel_pte_init(p); > >> pmd_populate_kernel(&init_mm, pmd, p); > >> } > >> return pmd; > >> -- > >> 2.39.3 > >> > >
