From 20a004e7b017cce282a46ac5d02c2b9c6b9bb1fa Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Thu, 15 Feb 2018 11:14:56 +0000 Subject: arm64: mm: Use READ_ONCE/WRITE_ONCE when accessing page tables In many cases, page tables can be accessed concurrently by either another CPU (due to things like fast gup) or by the hardware page table walker itself, which may set access/dirty bits. In such cases, it is important to use READ_ONCE/WRITE_ONCE when accessing page table entries so that entries cannot be torn, merged or subject to apparent loss of coherence due to compiler transformations. Whilst there are some scenarios where this cannot happen (e.g. pinned kernel mappings for the linear region), the overhead of using READ_ONCE /WRITE_ONCE everywhere is minimal and makes the code an awful lot easier to reason about. This patch consistently uses these macros in the arch code, as well as explicitly namespacing pointers to page table entries from the entries themselves by using adopting a 'p' suffix for the former (as is sometimes used elsewhere in the kernel source). Tested-by: Yury Norov Tested-by: Richard Ruigrok Reviewed-by: Marc Zyngier Signed-off-by: Will Deacon Signed-off-by: Catalin Marinas --- arch/arm64/include/asm/mmu_context.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'arch/arm64/include/asm/mmu_context.h') diff --git a/arch/arm64/include/asm/mmu_context.h b/arch/arm64/include/asm/mmu_context.h index 8d3331985d2e..39ec0b8a689e 100644 --- a/arch/arm64/include/asm/mmu_context.h +++ b/arch/arm64/include/asm/mmu_context.h @@ -141,13 +141,13 @@ static inline void cpu_install_idmap(void) * Atomically replaces the active TTBR1_EL1 PGD with a new VA-compatible PGD, * avoiding the possibility of conflicting TLB entries being allocated. */ -static inline void cpu_replace_ttbr1(pgd_t *pgd) +static inline void cpu_replace_ttbr1(pgd_t *pgdp) { typedef void (ttbr_replace_func)(phys_addr_t); extern ttbr_replace_func idmap_cpu_replace_ttbr1; ttbr_replace_func *replace_phys; - phys_addr_t pgd_phys = virt_to_phys(pgd); + phys_addr_t pgd_phys = virt_to_phys(pgdp); replace_phys = (void *)__pa_symbol(idmap_cpu_replace_ttbr1); -- cgit v1.2.3