[PATCH 2/3] powerpc: Define swapper_pg_dir[] in C
Daniel Axtens
dja at axtens.net
Wed Jun 23 21:53:05 AEST 2021
Hi Christophe,
This breaks booting a radix KVM guest with 4k pages for me:
make pseries_le_defconfig
scripts/config -d CONFIG_PPC_64K_PAGES
scripts/config -e CONFIG_PPC_4K_PAGES
make vmlinux
sudo qemu-system-ppc64 -enable-kvm -M pseries -m 1G -nographic -vga none -smp 4 -cpu host -kernel vmlinux
Boot hangs after printing 'Booting Linux via __start()' and qemu's 'info
registers' reports that it's stuck at the instruction fetch exception.
My host is Power9, 64k page size radix, and
gcc (Ubuntu 9.3.0-17ubuntu1~20.04) 9.3.0, GNU ld (GNU Binutils for Ubuntu) 2.34
Kind regards,
Daniel
> Don't duplicate swapper_pg_dir[] in each platform's head.S
>
> Define it in mm/pgtable.c
>
> Define MAX_PTRS_PER_PGD because on book3s/64 PTRS_PER_PGD is
> not a constant.
>
> Signed-off-by: Christophe Leroy <christophe.leroy at csgroup.eu>
> ---
> arch/powerpc/include/asm/book3s/64/pgtable.h | 3 +++
> arch/powerpc/include/asm/pgtable.h | 4 ++++
> arch/powerpc/kernel/asm-offsets.c | 5 -----
> arch/powerpc/kernel/head_40x.S | 11 -----------
> arch/powerpc/kernel/head_44x.S | 17 +----------------
> arch/powerpc/kernel/head_64.S | 15 ---------------
> arch/powerpc/kernel/head_8xx.S | 12 ------------
> arch/powerpc/kernel/head_book3s_32.S | 11 -----------
> arch/powerpc/kernel/head_fsl_booke.S | 12 ------------
> arch/powerpc/mm/pgtable.c | 2 ++
> 10 files changed, 10 insertions(+), 82 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h
> index a666d561b44d..4d9941b2fe51 100644
> --- a/arch/powerpc/include/asm/book3s/64/pgtable.h
> +++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
> @@ -232,6 +232,9 @@ extern unsigned long __pmd_frag_size_shift;
> #define PTRS_PER_PUD (1 << PUD_INDEX_SIZE)
> #define PTRS_PER_PGD (1 << PGD_INDEX_SIZE)
>
> +#define MAX_PTRS_PER_PGD (1 << (H_PGD_INDEX_SIZE > RADIX_PGD_INDEX_SIZE ? \
> + H_PGD_INDEX_SIZE : RADIX_PGD_INDEX_SIZE))
> +
> /* PMD_SHIFT determines what a second-level page table entry can map */
> #define PMD_SHIFT (PAGE_SHIFT + PTE_INDEX_SIZE)
> #define PMD_SIZE (1UL << PMD_SHIFT)
> diff --git a/arch/powerpc/include/asm/pgtable.h b/arch/powerpc/include/asm/pgtable.h
> index c6a676714f04..b9c8641654f4 100644
> --- a/arch/powerpc/include/asm/pgtable.h
> +++ b/arch/powerpc/include/asm/pgtable.h
> @@ -41,6 +41,10 @@ struct mm_struct;
>
> #ifndef __ASSEMBLY__
>
> +#ifndef MAX_PTRS_PER_PGD
> +#define MAX_PTRS_PER_PGD PTRS_PER_PGD
> +#endif
> +
> /* Keep these as a macros to avoid include dependency mess */
> #define pte_page(x) pfn_to_page(pte_pfn(x))
> #define mk_pte(page, pgprot) pfn_pte(page_to_pfn(page), (pgprot))
> diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
> index 0480f4006e0c..f1b6ff14c8a0 100644
> --- a/arch/powerpc/kernel/asm-offsets.c
> +++ b/arch/powerpc/kernel/asm-offsets.c
> @@ -361,11 +361,6 @@ int main(void)
> DEFINE(BUG_ENTRY_SIZE, sizeof(struct bug_entry));
> #endif
>
> -#ifdef CONFIG_PPC_BOOK3S_64
> - DEFINE(PGD_TABLE_SIZE, (sizeof(pgd_t) << max(RADIX_PGD_INDEX_SIZE, H_PGD_INDEX_SIZE)));
> -#else
> - DEFINE(PGD_TABLE_SIZE, PGD_TABLE_SIZE);
> -#endif
> DEFINE(PTE_SIZE, sizeof(pte_t));
>
> #ifdef CONFIG_KVM
> diff --git a/arch/powerpc/kernel/head_40x.S b/arch/powerpc/kernel/head_40x.S
> index 92b6c7356161..7d72ee5ab387 100644
> --- a/arch/powerpc/kernel/head_40x.S
> +++ b/arch/powerpc/kernel/head_40x.S
> @@ -701,14 +701,3 @@ _GLOBAL(abort)
> mfspr r13,SPRN_DBCR0
> oris r13,r13,DBCR0_RST_SYSTEM at h
> mtspr SPRN_DBCR0,r13
> -
> -/* We put a few things here that have to be page-aligned. This stuff
> - * goes at the beginning of the data segment, which is page-aligned.
> - */
> - .data
> - .align 12
> - .globl sdata
> -sdata:
> - .globl swapper_pg_dir
> -swapper_pg_dir:
> - .space PGD_TABLE_SIZE
> diff --git a/arch/powerpc/kernel/head_44x.S b/arch/powerpc/kernel/head_44x.S
> index e037eb615757..ddc978a2d381 100644
> --- a/arch/powerpc/kernel/head_44x.S
> +++ b/arch/powerpc/kernel/head_44x.S
> @@ -1233,23 +1233,8 @@ head_start_common:
> isync
> blr
>
> -/*
> - * We put a few things here that have to be page-aligned. This stuff
> - * goes at the beginning of the data segment, which is page-aligned.
> - */
> - .data
> - .align PAGE_SHIFT
> - .globl sdata
> -sdata:
> -
> -/*
> - * To support >32-bit physical addresses, we use an 8KB pgdir.
> - */
> - .globl swapper_pg_dir
> -swapper_pg_dir:
> - .space PGD_TABLE_SIZE
> -
> #ifdef CONFIG_SMP
> + .data
> .align 12
> temp_boot_stack:
> .space 1024
> diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S
> index 730838c7ca39..79f2d1e61abd 100644
> --- a/arch/powerpc/kernel/head_64.S
> +++ b/arch/powerpc/kernel/head_64.S
> @@ -997,18 +997,3 @@ start_here_common:
> 0: trap
> EMIT_BUG_ENTRY 0b, __FILE__, __LINE__, 0
> .previous
> -
> -/*
> - * We put a few things here that have to be page-aligned.
> - * This stuff goes at the beginning of the bss, which is page-aligned.
> - */
> - .section ".bss"
> -/*
> - * pgd dir should be aligned to PGD_TABLE_SIZE which is 64K.
> - * We will need to find a better way to fix this
> - */
> - .align 16
> -
> - .globl swapper_pg_dir
> -swapper_pg_dir:
> - .space PGD_TABLE_SIZE
> diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
> index 5ce42dfac061..9bdb95f5694f 100644
> --- a/arch/powerpc/kernel/head_8xx.S
> +++ b/arch/powerpc/kernel/head_8xx.S
> @@ -786,15 +786,3 @@ _GLOBAL(mmu_pin_tlb)
> mtspr SPRN_SRR1, r10
> mtspr SPRN_SRR0, r11
> rfi
> -
> -/*
> - * We put a few things here that have to be page-aligned.
> - * This stuff goes at the beginning of the data segment,
> - * which is page-aligned.
> - */
> - .data
> - .globl sdata
> -sdata:
> - .globl swapper_pg_dir
> -swapper_pg_dir:
> - .space PGD_TABLE_SIZE
> diff --git a/arch/powerpc/kernel/head_book3s_32.S b/arch/powerpc/kernel/head_book3s_32.S
> index 79c744afc6b6..689c9d37f193 100644
> --- a/arch/powerpc/kernel/head_book3s_32.S
> +++ b/arch/powerpc/kernel/head_book3s_32.S
> @@ -1266,18 +1266,7 @@ setup_usbgecko_bat:
> blr
> #endif
>
> -/*
> - * We put a few things here that have to be page-aligned.
> - * This stuff goes at the beginning of the data segment,
> - * which is page-aligned.
> - */
> .data
> - .globl sdata
> -sdata:
> - .globl swapper_pg_dir
> -swapper_pg_dir:
> - .space PGD_TABLE_SIZE
> -
> /* Room for two PTE pointers, usually the kernel and current user pointers
> * to their respective root page table.
> */
> diff --git a/arch/powerpc/kernel/head_fsl_booke.S b/arch/powerpc/kernel/head_fsl_booke.S
> index f33bc5a8e73e..0f9642f36b49 100644
> --- a/arch/powerpc/kernel/head_fsl_booke.S
> +++ b/arch/powerpc/kernel/head_fsl_booke.S
> @@ -1212,15 +1212,3 @@ _GLOBAL(restore_to_as0)
> */
> 3: mr r3,r5
> bl _start
> -
> -/*
> - * We put a few things here that have to be page-aligned. This stuff
> - * goes at the beginning of the data segment, which is page-aligned.
> - */
> - .data
> - .align 12
> - .globl sdata
> -sdata:
> - .globl swapper_pg_dir
> -swapper_pg_dir:
> - .space PGD_TABLE_SIZE
> diff --git a/arch/powerpc/mm/pgtable.c b/arch/powerpc/mm/pgtable.c
> index 354611940118..1707ab580ee2 100644
> --- a/arch/powerpc/mm/pgtable.c
> +++ b/arch/powerpc/mm/pgtable.c
> @@ -28,6 +28,8 @@
> #include <asm/hugetlb.h>
> #include <asm/pte-walk.h>
>
> +pgd_t swapper_pg_dir[MAX_PTRS_PER_PGD] __page_aligned_bss;
> +
> static inline int is_exec_fault(void)
> {
> return current->thread.regs && TRAP(current->thread.regs) == 0x400;
> --
> 2.25.0
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