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[92.247.61.126]) by smtp.gmail.com with ESMTPSA id l8sm1959654wro.46.2020.12.01.01.00.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 01 Dec 2020 01:00:56 -0800 (PST) From: vitaly.wool@konsulko.com To: linux-riscv@lists.infradead.org Cc: linux-kernel@vger.kernel.org, Bin Meng , Anup Patel , Alistair Francis , Palmer Dabbelt , Vitaly Wool Subject: [PATCH] riscv: toggle mmu_enabled flag in a precise manner Date: Tue, 1 Dec 2020 11:00:24 +0200 Message-Id: <20201201090023.2852-1-vitaly.wool@konsulko.com> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Vitaly Wool 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. 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 --- 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