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Message-ID: <CAMj1kXH=PgUeU7xMNq5EcW=ivYtXhd7nnFqH=TOFS6mpfu-isg@mail.gmail.com>
Date: Tue, 20 Jul 2021 14:33:04 +0200
From: Ard Biesheuvel <ardb@...nel.org>
To: Jonathan Marek <jonathan@...ek.ca>
Cc: Linux ARM <linux-arm-kernel@...ts.infradead.org>,
Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will@...nel.org>,
Dave Hansen <dave.hansen@...ux.intel.com>,
Andy Lutomirski <luto@...nel.org>,
Peter Zijlstra <peterz@...radead.org>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
"maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@...nel.org>,
"H. Peter Anvin" <hpa@...or.com>,
Anshuman Khandual <anshuman.khandual@....com>,
Andrew Morton <akpm@...ux-foundation.org>,
Mike Rapoport <rppt@...nel.org>,
Nicholas Piggin <npiggin@...il.com>,
Pavel Tatashin <pasha.tatashin@...een.com>,
Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
"Aneesh Kumar K.V" <aneesh.kumar@...ux.ibm.com>,
Pekka Enberg <penberg@...nel.org>,
Steven Price <steven.price@....com>,
Christophe Leroy <christophe.leroy@...roup.eu>,
Daniel Axtens <dja@...ens.net>,
Huang Pei <huangpei@...ngson.cn>,
Randy Dunlap <rdunlap@...radead.org>,
Bhaskar Chowdhury <unixbhaskar@...il.com>,
open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] Revert "mm/pgtable: add stubs for {pmd/pub}_{set/clear}_huge"
On Sat, 17 Jul 2021 at 18:06, Jonathan Marek <jonathan@...ek.ca> wrote:
>
> c742199a breaks arm64 for some configs because it stubs out functions which
> should not have been stubbed out.
>
> With 4K pages and ARM64_VA_BITS_39=y, the kernel crashes early on unmapped
> 1G pages in the linear map caused by pud_set_huge() in alloc_init_pud()
> being stubbed out. Reverting c742199a fixes the crash.
>
> Fixes: c742199a ("mm/pgtable: add stubs for {pmd/pub}_{set/clear}_huge")
> Signed-off-by: Jonathan Marek <jonathan@...ek.ca>
(replying here because some cc'ees were dropped from Christophe's
reply and the thread that followed it - unfortunately, lore does not
seem to have captured any of that discussion either)
Acked-by: Ard Biesheuvel <ardb@...nel.org>
> ---
> arch/arm64/mm/mmu.c | 20 ++++++++------------
> arch/x86/mm/pgtable.c | 34 +++++++++++++++-------------------
> include/linux/pgtable.h | 26 +-------------------------
> 3 files changed, 24 insertions(+), 56 deletions(-)
>
> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> index d745865084488..9ff0de1b2b93c 100644
> --- a/arch/arm64/mm/mmu.c
> +++ b/arch/arm64/mm/mmu.c
> @@ -1339,7 +1339,6 @@ void *__init fixmap_remap_fdt(phys_addr_t dt_phys, int *size, pgprot_t prot)
> return dt_virt;
> }
>
> -#if CONFIG_PGTABLE_LEVELS > 3
> int pud_set_huge(pud_t *pudp, phys_addr_t phys, pgprot_t prot)
> {
> pud_t new_pud = pfn_pud(__phys_to_pfn(phys), mk_pud_sect_prot(prot));
> @@ -1354,16 +1353,6 @@ int pud_set_huge(pud_t *pudp, phys_addr_t phys, pgprot_t prot)
> return 1;
> }
>
> -int pud_clear_huge(pud_t *pudp)
> -{
> - if (!pud_sect(READ_ONCE(*pudp)))
> - return 0;
> - pud_clear(pudp);
> - return 1;
> -}
> -#endif
> -
> -#if CONFIG_PGTABLE_LEVELS > 2
> int pmd_set_huge(pmd_t *pmdp, phys_addr_t phys, pgprot_t prot)
> {
> pmd_t new_pmd = pfn_pmd(__phys_to_pfn(phys), mk_pmd_sect_prot(prot));
> @@ -1378,6 +1367,14 @@ int pmd_set_huge(pmd_t *pmdp, phys_addr_t phys, pgprot_t prot)
> return 1;
> }
>
> +int pud_clear_huge(pud_t *pudp)
> +{
> + if (!pud_sect(READ_ONCE(*pudp)))
> + return 0;
> + pud_clear(pudp);
> + return 1;
> +}
> +
> int pmd_clear_huge(pmd_t *pmdp)
> {
> if (!pmd_sect(READ_ONCE(*pmdp)))
> @@ -1385,7 +1382,6 @@ int pmd_clear_huge(pmd_t *pmdp)
> pmd_clear(pmdp);
> return 1;
> }
> -#endif
>
> int pmd_free_pte_page(pmd_t *pmdp, unsigned long addr)
> {
> diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
> index 3364fe62b9037..3481b35cb4ec7 100644
> --- a/arch/x86/mm/pgtable.c
> +++ b/arch/x86/mm/pgtable.c
> @@ -682,7 +682,6 @@ int p4d_clear_huge(p4d_t *p4d)
> }
> #endif
>
> -#if CONFIG_PGTABLE_LEVELS > 3
> /**
> * pud_set_huge - setup kernel PUD mapping
> *
> @@ -721,23 +720,6 @@ int pud_set_huge(pud_t *pud, phys_addr_t addr, pgprot_t prot)
> return 1;
> }
>
> -/**
> - * pud_clear_huge - clear kernel PUD mapping when it is set
> - *
> - * Returns 1 on success and 0 on failure (no PUD map is found).
> - */
> -int pud_clear_huge(pud_t *pud)
> -{
> - if (pud_large(*pud)) {
> - pud_clear(pud);
> - return 1;
> - }
> -
> - return 0;
> -}
> -#endif
> -
> -#if CONFIG_PGTABLE_LEVELS > 2
> /**
> * pmd_set_huge - setup kernel PMD mapping
> *
> @@ -768,6 +750,21 @@ int pmd_set_huge(pmd_t *pmd, phys_addr_t addr, pgprot_t prot)
> return 1;
> }
>
> +/**
> + * pud_clear_huge - clear kernel PUD mapping when it is set
> + *
> + * Returns 1 on success and 0 on failure (no PUD map is found).
> + */
> +int pud_clear_huge(pud_t *pud)
> +{
> + if (pud_large(*pud)) {
> + pud_clear(pud);
> + return 1;
> + }
> +
> + return 0;
> +}
> +
> /**
> * pmd_clear_huge - clear kernel PMD mapping when it is set
> *
> @@ -782,7 +779,6 @@ int pmd_clear_huge(pmd_t *pmd)
>
> return 0;
> }
> -#endif
>
> #ifdef CONFIG_X86_64
> /**
> diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
> index d147480cdefc7..e24d2c992b112 100644
> --- a/include/linux/pgtable.h
> +++ b/include/linux/pgtable.h
> @@ -1397,34 +1397,10 @@ static inline int p4d_clear_huge(p4d_t *p4d)
> }
> #endif /* !__PAGETABLE_P4D_FOLDED */
>
> -#ifndef __PAGETABLE_PUD_FOLDED
> int pud_set_huge(pud_t *pud, phys_addr_t addr, pgprot_t prot);
> -int pud_clear_huge(pud_t *pud);
> -#else
> -static inline int pud_set_huge(pud_t *pud, phys_addr_t addr, pgprot_t prot)
> -{
> - return 0;
> -}
> -static inline int pud_clear_huge(pud_t *pud)
> -{
> - return 0;
> -}
> -#endif /* !__PAGETABLE_PUD_FOLDED */
> -
> -#ifndef __PAGETABLE_PMD_FOLDED
> int pmd_set_huge(pmd_t *pmd, phys_addr_t addr, pgprot_t prot);
> +int pud_clear_huge(pud_t *pud);
> int pmd_clear_huge(pmd_t *pmd);
> -#else
> -static inline int pmd_set_huge(pmd_t *pmd, phys_addr_t addr, pgprot_t prot)
> -{
> - return 0;
> -}
> -static inline int pmd_clear_huge(pmd_t *pmd)
> -{
> - return 0;
> -}
> -#endif /* !__PAGETABLE_PMD_FOLDED */
> -
> int p4d_free_pud_page(p4d_t *p4d, unsigned long addr);
> int pud_free_pmd_page(pud_t *pud, unsigned long addr);
> int pmd_free_pte_page(pmd_t *pmd, unsigned long addr);
> --
> 2.26.1
>
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