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

Huacai Chen
2023-08-02T07:25:41Z

On Tue, Aug 1, 2023 at 9:22 AM bibo mao <maobibo@loongson.cn> wrote:
>
>
>
> 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?
I forget the reason now, so if you confirm memblock_alloc() works well
here, you can use it. But please don't use memblock_alloc_raw().

Huacai
>
> 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
> >>
>
>