On Tue, Dec 1, 2020 at 1:01 AM <vitaly.w...@konsulko.com> wrote: > > From: Vitaly Wool <vitaly.w...@konsulko.com> > > Cuurently mmu_enabled flag is set to true way later than the actual > MMU enablement takes place. This leads to hard-to-track races in > e. g. SBI earlycon initialization taking wrong path configuring > fixmap. >
This code path is significantly changed in 5.10-rcX with UEFI series. https://patchwork.kernel.org/project/linux-riscv/patch/20200917223716.2300238-4-atish.pa...@wdc.com/ Can you check if you can still reproduce the issue you were seeing with the latest upstream kernel ? If yes, please share the steps to reproduce the issue. > To fix that, move mmu_enabled toggling to head.S and rename it to > _mmu_enabled to avoid possible name clashes since it's not a static > variable any more. > > Signed-off-by: Vitaly Wool <vitaly.w...@konsulko.com> > --- > arch/riscv/kernel/head.S | 9 +++++++++ > arch/riscv/mm/init.c | 13 +++++-------- > 2 files changed, 14 insertions(+), 8 deletions(-) > > diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S > index 0a4e81b8dc79..33cd57285be3 100644 > --- a/arch/riscv/kernel/head.S > +++ b/arch/riscv/kernel/head.S > @@ -248,6 +248,10 @@ clear_bss_done: > call relocate > #endif /* CONFIG_MMU */ > > + la a0, _mmu_enabled > + li a1, 1 > + sw a1, (a0) > + > call setup_trap_vector > /* Restore C environment */ > la tp, init_task > @@ -370,6 +374,11 @@ ENTRY(reset_regs) > END(reset_regs) > #endif /* CONFIG_RISCV_M_MODE */ > > +.section ".data" > + .global _mmu_enabled > +_mmu_enabled: > + .word 0 > + > __PAGE_ALIGNED_BSS > /* Empty zero page */ > .balign PAGE_SIZE > diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c > index 787c75f751a5..4038be635e25 100644 > --- a/arch/riscv/mm/init.c > +++ b/arch/riscv/mm/init.c > @@ -211,7 +211,7 @@ EXPORT_SYMBOL(pfn_base); > pgd_t swapper_pg_dir[PTRS_PER_PGD] __page_aligned_bss; > pgd_t trampoline_pg_dir[PTRS_PER_PGD] __page_aligned_bss; > pte_t fixmap_pte[PTRS_PER_PTE] __page_aligned_bss; > -static bool mmu_enabled; > +extern bool _mmu_enabled; > > #define MAX_EARLY_MAPPING_SIZE SZ_128M > > @@ -236,7 +236,7 @@ void __set_fixmap(enum fixed_addresses idx, phys_addr_t > phys, pgprot_t prot) > > static pte_t *__init get_pte_virt(phys_addr_t pa) > { > - if (mmu_enabled) { > + if (_mmu_enabled) { > clear_fixmap(FIX_PTE); > return (pte_t *)set_fixmap_offset(FIX_PTE, pa); > } else { > @@ -250,7 +250,7 @@ static phys_addr_t __init alloc_pte(uintptr_t va) > * We only create PMD or PGD early mappings so we > * should never reach here with MMU disabled. > */ > - BUG_ON(!mmu_enabled); > + BUG_ON(!_mmu_enabled); > > return memblock_phys_alloc(PAGE_SIZE, PAGE_SIZE); > } > @@ -281,7 +281,7 @@ pmd_t early_pmd[PTRS_PER_PMD * NUM_EARLY_PMDS] __initdata > __aligned(PAGE_SIZE); > > static pmd_t *__init get_pmd_virt(phys_addr_t pa) > { > - if (mmu_enabled) { > + if (_mmu_enabled) { > clear_fixmap(FIX_PMD); > return (pmd_t *)set_fixmap_offset(FIX_PMD, pa); > } else { > @@ -293,7 +293,7 @@ static phys_addr_t __init alloc_pmd(uintptr_t va) > { > uintptr_t pmd_num; > > - if (mmu_enabled) > + if (_mmu_enabled) > return memblock_phys_alloc(PAGE_SIZE, PAGE_SIZE); > > pmd_num = (va - PAGE_OFFSET) >> PGDIR_SHIFT; > @@ -467,9 +467,6 @@ static void __init setup_vm_final(void) > phys_addr_t pa, start, end; > struct memblock_region *reg; > > - /* Set mmu_enabled flag */ > - mmu_enabled = true; > - > /* Setup swapper PGD for fixmap */ > create_pgd_mapping(swapper_pg_dir, FIXADDR_START, > __pa_symbol(fixmap_pgd_next), > -- > 2.20.1 > > > _______________________________________________ > linux-riscv mailing list > linux-ri...@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-riscv -- Regards, Atish
