Messages in this thread Patch in this message | | | From | Michael Ellerman <> | Subject | Re: [PATCH 2/3] powerpc: Define swapper_pg_dir[] in C | Date | Wed, 23 Jun 2021 22:38:58 +1000 |
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Daniel Axtens <dja@axtens.net> writes: > 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 >
... >> 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
This is now 4K aligned whereas it used to be 64K.
This fixes it and is not completely ugly?
diff --git a/arch/powerpc/mm/pgtable.c b/arch/powerpc/mm/pgtable.c index 1707ab580ee2..298469beaa90 100644 --- a/arch/powerpc/mm/pgtable.c +++ b/arch/powerpc/mm/pgtable.c @@ -28,7 +28,13 @@ #include <asm/hugetlb.h> #include <asm/pte-walk.h> -pgd_t swapper_pg_dir[MAX_PTRS_PER_PGD] __page_aligned_bss; +#ifdef CONFIG_PPC64 +#define PGD_ALIGN 0x10000 +#else +#define PGD_ALIGN PAGE_SIZE +#endif + +pgd_t swapper_pg_dir[MAX_PTRS_PER_PGD] __section(".bss..page_aligned") __aligned(PGD_ALIGN); static inline int is_exec_fault(void) {
cheers
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