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Message-ID: <CAAhV-H5QkULWp6fciR1Lnds0r00fUdrmj86K_wBuxd0D=RkaXQ@mail.gmail.com>
Date: Fri, 18 Oct 2024 11:14:45 +0800
From: Huacai Chen <chenhuacai@...nel.org>
To: Bibo Mao <maobibo@...ngson.cn>
Cc: Andrey Ryabinin <ryabinin.a.a@...il.com>, Andrew Morton <akpm@...ux-foundation.org>,
David Hildenbrand <david@...hat.com>, Barry Song <baohua@...nel.org>, loongarch@...ts.linux.dev,
linux-kernel@...r.kernel.org, kasan-dev@...glegroups.com, linux-mm@...ck.org
Subject: Re: [PATCH v2 1/3] LoongArch: Set initial pte entry with PAGE_GLOBAL
for kernel space
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.
Huacai
On Mon, Oct 14, 2024 at 11:59 AM Bibo Mao <maobibo@...ngson.cn> 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@...ngson.cn>
> ---
> 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
>
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