>
> 3. For speculative execution, if it is user address, there is eret from
> syscall. eret will rollback all speculative execution instruction. So it
> is only problem for speculative execution. And how to verify whether it
> is the problem of speculative execution or it is the problem of clause 2?
As described above, if spurious page faults still exist after adding
dbar to set_pte(), it may be a problem of clause 2 (case 3 in my
description), otherwise it is not a problem of clause 2.
At last, this patch itself is attempting to solve the concurrent
problem about _PAGE_GLOBAL, so adding pte_alloc_one_kernel() and
removing the buddy stuff in set_pte() are what it needs. However it
shouldn't touch the logic of dbar in set_pte(), whether "LoongArch:
Improve hardware page table walker" is right or wrong.
Huacai
>
> Regards
> Bibo Mao
>
>
> >
> > Huacai
> >
> >>
> >> Bibo Mao
> >>>
> >>> Huacai
> >>>
> >>>>
> >>>> Obvious you do not it and you write wrong patch.
> >>>>
> >>>>>
> >>>>> Huacai
> >>>>>
> >>>>>>
> >>>>>> Regards
> >>>>>> Bibo Mao
> >>>>>>> Huacai
> >>>>>>>
> >>>>>>> On Mon, Oct 14, 2024 at 11:59â?¯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
> >>>>>>>>
> >>>>>>
> >>>>>>
> >>>>
> >>>>
> >>
> >>
>
