From 9e8e865bbe294a69666a1996bda3e87825b258c0 Mon Sep 17 00:00:00 2001 From: Mark Rutland Date: Mon, 25 Jan 2016 11:44:58 +0000 Subject: arm64: unify idmap removal We currently open-code the removal of the idmap and restoration of the current task's MMU state in a few places. Before introducing yet more copies of this sequence, unify these to call a new helper, cpu_uninstall_idmap. Signed-off-by: Mark Rutland Reviewed-by: Catalin Marinas Tested-by: Ard Biesheuvel Reviewed-by: Ard Biesheuvel Tested-by: Jeremy Linton Cc: Laura Abbott Cc: Lorenzo Pieralisi Cc: Will Deacon Signed-off-by: Catalin Marinas --- arch/arm64/include/asm/mmu_context.h | 25 +++++++++++++++++++++++++ arch/arm64/kernel/setup.c | 1 + arch/arm64/kernel/smp.c | 4 +--- arch/arm64/kernel/suspend.c | 20 ++++---------------- arch/arm64/mm/mmu.c | 4 +--- 5 files changed, 32 insertions(+), 22 deletions(-) (limited to 'arch') diff --git a/arch/arm64/include/asm/mmu_context.h b/arch/arm64/include/asm/mmu_context.h index 600eacb..b1b2514 100644 --- a/arch/arm64/include/asm/mmu_context.h +++ b/arch/arm64/include/asm/mmu_context.h @@ -27,6 +27,7 @@ #include #include #include +#include #ifdef CONFIG_PID_IN_CONTEXTIDR static inline void contextidr_thread_switch(struct task_struct *next) @@ -90,6 +91,30 @@ static inline void cpu_set_default_tcr_t0sz(void) } /* + * Remove the idmap from TTBR0_EL1 and install the pgd of the active mm. + * + * The idmap lives in the same VA range as userspace, but uses global entries + * and may use a different TCR_EL1.T0SZ. To avoid issues resulting from + * speculative TLB fetches, we must temporarily install the reserved page + * tables while we invalidate the TLBs and set up the correct TCR_EL1.T0SZ. + * + * If current is a not a user task, the mm covers the TTBR1_EL1 page tables, + * which should not be installed in TTBR0_EL1. In this case we can leave the + * reserved page tables in place. + */ +static inline void cpu_uninstall_idmap(void) +{ + struct mm_struct *mm = current->active_mm; + + cpu_set_reserved_ttbr0(); + local_flush_tlb_all(); + cpu_set_default_tcr_t0sz(); + + if (mm != &init_mm) + cpu_switch_mm(mm->pgd, mm); +} + +/* * It would be nice to return ASIDs back to the allocator, but unfortunately * that introduces a race with a generation rollover where we could erroneously * free an ASID allocated in a future generation. We could workaround this by diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c index 8119479..f6621ba 100644 --- a/arch/arm64/kernel/setup.c +++ b/arch/arm64/kernel/setup.c @@ -62,6 +62,7 @@ #include #include #include +#include phys_addr_t __fdt_pointer __initdata; diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c index b1adc51..68e7f79 100644 --- a/arch/arm64/kernel/smp.c +++ b/arch/arm64/kernel/smp.c @@ -149,9 +149,7 @@ asmlinkage void secondary_start_kernel(void) * TTBR0 is only used for the identity mapping at this stage. Make it * point to zero page to avoid speculatively fetching new entries. */ - cpu_set_reserved_ttbr0(); - local_flush_tlb_all(); - cpu_set_default_tcr_t0sz(); + cpu_uninstall_idmap(); preempt_disable(); trace_hardirqs_off(); diff --git a/arch/arm64/kernel/suspend.c b/arch/arm64/kernel/suspend.c index 1095aa4..6605539 100644 --- a/arch/arm64/kernel/suspend.c +++ b/arch/arm64/kernel/suspend.c @@ -60,7 +60,6 @@ void __init cpu_suspend_set_dbg_restorer(void (*hw_bp_restore)(void *)) */ int cpu_suspend(unsigned long arg, int (*fn)(unsigned long)) { - struct mm_struct *mm = current->active_mm; int ret; unsigned long flags; @@ -87,22 +86,11 @@ int cpu_suspend(unsigned long arg, int (*fn)(unsigned long)) ret = __cpu_suspend_enter(arg, fn); if (ret == 0) { /* - * We are resuming from reset with TTBR0_EL1 set to the - * idmap to enable the MMU; set the TTBR0 to the reserved - * page tables to prevent speculative TLB allocations, flush - * the local tlb and set the default tcr_el1.t0sz so that - * the TTBR0 address space set-up is properly restored. - * If the current active_mm != &init_mm we entered cpu_suspend - * with mappings in TTBR0 that must be restored, so we switch - * them back to complete the address space configuration - * restoration before returning. + * We are resuming from reset with the idmap active in TTBR0_EL1. + * We must uninstall the idmap and restore the expected MMU + * state before we can possibly return to userspace. */ - cpu_set_reserved_ttbr0(); - local_flush_tlb_all(); - cpu_set_default_tcr_t0sz(); - - if (mm != &init_mm) - cpu_switch_mm(mm->pgd, mm); + cpu_uninstall_idmap(); /* * Restore per-cpu offset before any kernel diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index cdbf055..e85a719 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -468,9 +468,7 @@ void __init paging_init(void) * TTBR0 is only used for the identity mapping at this stage. Make it * point to zero page to avoid speculatively fetching new entries. */ - cpu_set_reserved_ttbr0(); - local_flush_tlb_all(); - cpu_set_default_tcr_t0sz(); + cpu_uninstall_idmap(); } /* -- cgit v1.1