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-rw-r--r--arch/arm64/include/asm/mmu_context.h285
1 files changed, 285 insertions, 0 deletions
diff --git a/arch/arm64/include/asm/mmu_context.h b/arch/arm64/include/asm/mmu_context.h
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index 000000000..d3f8b5df0
--- /dev/null
+++ b/arch/arm64/include/asm/mmu_context.h
@@ -0,0 +1,285 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Based on arch/arm/include/asm/mmu_context.h
+ *
+ * Copyright (C) 1996 Russell King.
+ * Copyright (C) 2012 ARM Ltd.
+ */
+#ifndef __ASM_MMU_CONTEXT_H
+#define __ASM_MMU_CONTEXT_H
+
+#ifndef __ASSEMBLY__
+
+#include <linux/compiler.h>
+#include <linux/sched.h>
+#include <linux/sched/hotplug.h>
+#include <linux/mm_types.h>
+#include <linux/pgtable.h>
+
+#include <asm/cacheflush.h>
+#include <asm/cpufeature.h>
+#include <asm/proc-fns.h>
+#include <asm-generic/mm_hooks.h>
+#include <asm/cputype.h>
+#include <asm/sysreg.h>
+#include <asm/tlbflush.h>
+
+extern bool rodata_full;
+
+static inline void contextidr_thread_switch(struct task_struct *next)
+{
+ if (!IS_ENABLED(CONFIG_PID_IN_CONTEXTIDR))
+ return;
+
+ write_sysreg(task_pid_nr(next), contextidr_el1);
+ isb();
+}
+
+/*
+ * Set TTBR0 to reserved_pg_dir. No translations will be possible via TTBR0.
+ */
+static inline void cpu_set_reserved_ttbr0(void)
+{
+ unsigned long ttbr = phys_to_ttbr(__pa_symbol(reserved_pg_dir));
+
+ write_sysreg(ttbr, ttbr0_el1);
+ isb();
+}
+
+void cpu_do_switch_mm(phys_addr_t pgd_phys, struct mm_struct *mm);
+
+static inline void cpu_switch_mm(pgd_t *pgd, struct mm_struct *mm)
+{
+ BUG_ON(pgd == swapper_pg_dir);
+ cpu_set_reserved_ttbr0();
+ cpu_do_switch_mm(virt_to_phys(pgd),mm);
+}
+
+/*
+ * TCR.T0SZ value to use when the ID map is active. Usually equals
+ * TCR_T0SZ(VA_BITS), unless system RAM is positioned very high in
+ * physical memory, in which case it will be smaller.
+ */
+extern int idmap_t0sz;
+
+/*
+ * Ensure TCR.T0SZ is set to the provided value.
+ */
+static inline void __cpu_set_tcr_t0sz(unsigned long t0sz)
+{
+ unsigned long tcr = read_sysreg(tcr_el1);
+
+ if ((tcr & TCR_T0SZ_MASK) >> TCR_T0SZ_OFFSET == t0sz)
+ return;
+
+ tcr &= ~TCR_T0SZ_MASK;
+ tcr |= t0sz << TCR_T0SZ_OFFSET;
+ write_sysreg(tcr, tcr_el1);
+ isb();
+}
+
+#define cpu_set_default_tcr_t0sz() __cpu_set_tcr_t0sz(TCR_T0SZ(vabits_actual))
+#define cpu_set_idmap_tcr_t0sz() __cpu_set_tcr_t0sz(idmap_t0sz)
+
+/*
+ * 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 && !system_uses_ttbr0_pan())
+ cpu_switch_mm(mm->pgd, mm);
+}
+
+static inline void __cpu_install_idmap(pgd_t *idmap)
+{
+ cpu_set_reserved_ttbr0();
+ local_flush_tlb_all();
+ cpu_set_idmap_tcr_t0sz();
+
+ cpu_switch_mm(lm_alias(idmap), &init_mm);
+}
+
+static inline void cpu_install_idmap(void)
+{
+ __cpu_install_idmap(idmap_pg_dir);
+}
+
+/*
+ * Load our new page tables. A strict BBM approach requires that we ensure that
+ * TLBs are free of any entries that may overlap with the global mappings we are
+ * about to install.
+ *
+ * For a real hibernate/resume/kexec cycle TTBR0 currently points to a zero
+ * page, but TLBs may contain stale ASID-tagged entries (e.g. for EFI runtime
+ * services), while for a userspace-driven test_resume cycle it points to
+ * userspace page tables (and we must point it at a zero page ourselves).
+ *
+ * We change T0SZ as part of installing the idmap. This is undone by
+ * cpu_uninstall_idmap() in __cpu_suspend_exit().
+ */
+static inline void cpu_install_ttbr0(phys_addr_t ttbr0, unsigned long t0sz)
+{
+ cpu_set_reserved_ttbr0();
+ local_flush_tlb_all();
+ __cpu_set_tcr_t0sz(t0sz);
+
+ /* avoid cpu_switch_mm() and its SW-PAN and CNP interactions */
+ write_sysreg(ttbr0, ttbr0_el1);
+ isb();
+}
+
+/*
+ * 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 *pgdp, pgd_t *idmap)
+{
+ typedef void (ttbr_replace_func)(phys_addr_t);
+ extern ttbr_replace_func idmap_cpu_replace_ttbr1;
+ ttbr_replace_func *replace_phys;
+
+ /* phys_to_ttbr() zeros lower 2 bits of ttbr with 52-bit PA */
+ phys_addr_t ttbr1 = phys_to_ttbr(virt_to_phys(pgdp));
+
+ if (system_supports_cnp() && !WARN_ON(pgdp != lm_alias(swapper_pg_dir))) {
+ /*
+ * cpu_replace_ttbr1() is used when there's a boot CPU
+ * up (i.e. cpufeature framework is not up yet) and
+ * latter only when we enable CNP via cpufeature's
+ * enable() callback.
+ * Also we rely on the cpu_hwcap bit being set before
+ * calling the enable() function.
+ */
+ ttbr1 |= TTBR_CNP_BIT;
+ }
+
+ replace_phys = (void *)__pa_symbol(idmap_cpu_replace_ttbr1);
+
+ __cpu_install_idmap(idmap);
+ replace_phys(ttbr1);
+ cpu_uninstall_idmap();
+}
+
+/*
+ * 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
+ * freeing the ASID from the context of the dying mm (e.g. in arch_exit_mmap),
+ * but we'd then need to make sure that we didn't dirty any TLBs afterwards.
+ * Setting a reserved TTBR0 or EPD0 would work, but it all gets ugly when you
+ * take CPU migration into account.
+ */
+void check_and_switch_context(struct mm_struct *mm);
+
+#define init_new_context(tsk, mm) init_new_context(tsk, mm)
+static inline int
+init_new_context(struct task_struct *tsk, struct mm_struct *mm)
+{
+ atomic64_set(&mm->context.id, 0);
+ refcount_set(&mm->context.pinned, 0);
+ return 0;
+}
+
+#ifdef CONFIG_ARM64_SW_TTBR0_PAN
+static inline void update_saved_ttbr0(struct task_struct *tsk,
+ struct mm_struct *mm)
+{
+ u64 ttbr;
+
+ if (!system_uses_ttbr0_pan())
+ return;
+
+ if (mm == &init_mm)
+ ttbr = phys_to_ttbr(__pa_symbol(reserved_pg_dir));
+ else
+ ttbr = phys_to_ttbr(virt_to_phys(mm->pgd)) | ASID(mm) << 48;
+
+ WRITE_ONCE(task_thread_info(tsk)->ttbr0, ttbr);
+}
+#else
+static inline void update_saved_ttbr0(struct task_struct *tsk,
+ struct mm_struct *mm)
+{
+}
+#endif
+
+#define enter_lazy_tlb enter_lazy_tlb
+static inline void
+enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
+{
+ /*
+ * We don't actually care about the ttbr0 mapping, so point it at the
+ * zero page.
+ */
+ update_saved_ttbr0(tsk, &init_mm);
+}
+
+static inline void __switch_mm(struct mm_struct *next)
+{
+ /*
+ * init_mm.pgd does not contain any user mappings and it is always
+ * active for kernel addresses in TTBR1. Just set the reserved TTBR0.
+ */
+ if (next == &init_mm) {
+ cpu_set_reserved_ttbr0();
+ return;
+ }
+
+ check_and_switch_context(next);
+}
+
+static inline void
+switch_mm(struct mm_struct *prev, struct mm_struct *next,
+ struct task_struct *tsk)
+{
+ if (prev != next)
+ __switch_mm(next);
+
+ /*
+ * Update the saved TTBR0_EL1 of the scheduled-in task as the previous
+ * value may have not been initialised yet (activate_mm caller) or the
+ * ASID has changed since the last run (following the context switch
+ * of another thread of the same process).
+ */
+ update_saved_ttbr0(tsk, next);
+}
+
+static inline const struct cpumask *
+task_cpu_possible_mask(struct task_struct *p)
+{
+ if (!static_branch_unlikely(&arm64_mismatched_32bit_el0))
+ return cpu_possible_mask;
+
+ if (!is_compat_thread(task_thread_info(p)))
+ return cpu_possible_mask;
+
+ return system_32bit_el0_cpumask();
+}
+#define task_cpu_possible_mask task_cpu_possible_mask
+
+void verify_cpu_asid_bits(void);
+void post_ttbr_update_workaround(void);
+
+unsigned long arm64_mm_context_get(struct mm_struct *mm);
+void arm64_mm_context_put(struct mm_struct *mm);
+
+#include <asm-generic/mmu_context.h>
+
+#endif /* !__ASSEMBLY__ */
+
+#endif /* !__ASM_MMU_CONTEXT_H */