Re: [PATCH 3/3] LoongArch: mm: Add unified function populate_kernel_pte

bibo mao
2023-08-01T01:22:31Z

在 2023/7/31 22:15, Huacai Chen 写道:
> On Wed, Jul 12, 2023 at 11:16 AM Bibo Mao <maobibo@loongson.cn> wrote:
>>
>> Function pcpu_populate_pte and fixmap_pte are similar, they populate
>> one page from kernel address space. And there is confusion between
>> pgd and p4d in function fixmap_pte, such as pgd_none always returns
>> zero. This patch adds unified function populate_kernel_pte and replaces
>> pcpu_populate_pte and fixmap_pte.
>>
>> Signed-off-by: Bibo Mao <maobibo@loongson.cn>
>> ---
>> arch/loongarch/include/asm/pgalloc.h | 1 +
>> arch/loongarch/kernel/numa.c | 40 +--------------------
>> arch/loongarch/mm/init.c | 52 ++++++++++++++++------------
>> 3 files changed, 32 insertions(+), 61 deletions(-)
>>
>> diff --git a/arch/loongarch/include/asm/pgalloc.h b/arch/loongarch/include/asm/pgalloc.h
>> index af1d1e4a6965..ca17b573dba6 100644
>> --- a/arch/loongarch/include/asm/pgalloc.h
>> +++ b/arch/loongarch/include/asm/pgalloc.h
>> @@ -91,4 +91,5 @@ static inline pud_t *pud_alloc_one(struct mm_struct *mm, unsigned long address)
>>
>> #endif /* __PAGETABLE_PUD_FOLDED */
>>
>> +extern pte_t * __init populate_kernel_pte(unsigned long addr);
>> #endif /* _ASM_PGALLOC_H */
>> diff --git a/arch/loongarch/kernel/numa.c b/arch/loongarch/kernel/numa.c
>> index 778e1c20bfb0..24a693b76873 100644
>> --- a/arch/loongarch/kernel/numa.c
>> +++ b/arch/loongarch/kernel/numa.c
>> @@ -67,46 +67,8 @@ static int __init pcpu_cpu_distance(unsigned int from, unsigned int to)
>>
>> void __init pcpu_populate_pte(unsigned long addr)
>> {
>> - pgd_t *pgd = pgd_offset_k(addr);
>> - p4d_t *p4d = p4d_offset(pgd, addr);
>> - pud_t *pud;
>> - pmd_t *pmd;
>> -
>> - if (p4d_none(*p4d)) {
>> - pud = memblock_alloc_raw(PAGE_SIZE, PAGE_SIZE);
>> - if (!pud)
>> - goto err_alloc;
>> - p4d_populate(&init_mm, p4d, pud);
>> -#ifndef __PAGETABLE_PUD_FOLDED
>> - pud_init(pud);
>> -#endif
>> - }
>> -
>> - pud = pud_offset(p4d, addr);
>> - if (pud_none(*pud)) {
>> - pmd = memblock_alloc_raw(PAGE_SIZE, PAGE_SIZE);
>> - if (!pmd)
>> - goto err_alloc;
>> - pud_populate(&init_mm, pud, pmd);
>> -#ifndef __PAGETABLE_PMD_FOLDED
>> - pmd_init(pmd);
>> -#endif
>> - }
>> -
>> - pmd = pmd_offset(pud, addr);
>> - if (!pmd_present(*pmd)) {
>> - pte_t *pte;
>> -
>> - pte = memblock_alloc(PAGE_SIZE, PAGE_SIZE);
>> - if (!pte)
>> - goto err_alloc;
>> - pmd_populate_kernel(&init_mm, pmd, pte);
>> - }
>> -
>> + populate_kernel_pte(addr);
>> return;
>> -
>> -err_alloc:
>> - panic("%s: Failed to allocate memory\n", __func__);
>> }
>>
>> void __init setup_per_cpu_areas(void)
>> diff --git a/arch/loongarch/mm/init.c b/arch/loongarch/mm/init.c
>> index 3b7d8129570b..6cd2948373ae 100644
>> --- a/arch/loongarch/mm/init.c
>> +++ b/arch/loongarch/mm/init.c
>> @@ -191,46 +191,49 @@ void vmemmap_free(unsigned long start, unsigned long end, struct vmem_altmap *al
>> #endif
>> #endif
>>
>> -static pte_t *fixmap_pte(unsigned long addr)
>> +pte_t * __init populate_kernel_pte(unsigned long addr)
>> {
>> - pgd_t *pgd;
>> - p4d_t *p4d;
>> + pgd_t *pgd = pgd_offset_k(addr);
>> + p4d_t *p4d = p4d_offset(pgd, addr);
>> pud_t *pud;
>> pmd_t *pmd;
>>
>> - pgd = pgd_offset_k(addr);
>> - p4d = p4d_offset(pgd, addr);
>> -
>> - if (pgd_none(*pgd)) {
>> - pud_t *new __maybe_unused;
>> -
>> - new = memblock_alloc_low(PAGE_SIZE, PAGE_SIZE);
>> - pgd_populate(&init_mm, pgd, new);
>> + if (p4d_none(*p4d)) {
>> + pud = memblock_alloc_raw(PAGE_SIZE, PAGE_SIZE);
>> + if (!pud)
>> + goto err_alloc;
>> + p4d_populate(&init_mm, p4d, pud);
>> #ifndef __PAGETABLE_PUD_FOLDED
>> - pud_init(new);
>> + pud_init(pud);
>> #endif
>> }
>>
>> pud = pud_offset(p4d, addr);
>> if (pud_none(*pud)) {
>> - pmd_t *new __maybe_unused;
>> -
>> - new = memblock_alloc_low(PAGE_SIZE, PAGE_SIZE);
>> - pud_populate(&init_mm, pud, new);
>> + pmd = memblock_alloc_raw(PAGE_SIZE, PAGE_SIZE);
>> + if (!pmd)
>> + goto err_alloc;
>> + pud_populate(&init_mm, pud, pmd);
>> #ifndef __PAGETABLE_PMD_FOLDED
>> - pmd_init(new);
>> + pmd_init(pmd);
>> #endif
>> }
>>
>> pmd = pmd_offset(pud, addr);
>> - if (pmd_none(*pmd)) {
>> - pte_t *new __maybe_unused;
>> + if (!pmd_present(*pmd)) {
>> + pte_t *pte;
>>
>> - new = memblock_alloc_low(PAGE_SIZE, PAGE_SIZE);
>> - pmd_populate_kernel(&init_mm, pmd, new);
>> + pte = memblock_alloc(PAGE_SIZE, PAGE_SIZE);
> I don't think memblock_alloc_low() here can be replaced by memblock_alloc().
Can you share me the points that pte table must be allocated with memblock_alloc_low
in this place?

Regards
Bibo Mao
>
>
> Huacai
>> + if (!pte)
>> + goto err_alloc;
>> + pmd_populate_kernel(&init_mm, pmd, pte);
>> }
>>
>> return pte_offset_kernel(pmd, addr);
>> +
>> +err_alloc:
>> + panic("%s: Failed to allocate memory\n", __func__);
>> + return NULL;
>> }
>>
>> void __init __set_fixmap(enum fixed_addresses idx,
>> @@ -241,7 +244,12 @@ void __init __set_fixmap(enum fixed_addresses idx,
>>
>> BUG_ON(idx <= FIX_HOLE || idx >= __end_of_fixed_addresses);
>>
>> - ptep = fixmap_pte(addr);
>> + /*
>> + * Now only FIX_EARLYCON_MEM_BASE fixed map is used
>> + * __set_fixmap must be called before mem_init since function
>> + * populate_kernel_pte allocates memory with memblock_alloc method.
>> + */
>> + ptep = populate_kernel_pte(addr);
>> if (!pte_none(*ptep)) {
>> pte_ERROR(*ptep);
>> return;
>> --
>> 2.27.0
>>