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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-11 08:27:49 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-11 08:27:49 +0000 |
commit | ace9429bb58fd418f0c81d4c2835699bddf6bde6 (patch) | |
tree | b2d64bc10158fdd5497876388cd68142ca374ed3 /arch/arm64/include/asm/mmu_context.h | |
parent | Initial commit. (diff) | |
download | linux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.tar.xz linux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.zip |
Adding upstream version 6.6.15.upstream/6.6.15
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'arch/arm64/include/asm/mmu_context.h')
-rw-r--r-- | arch/arm64/include/asm/mmu_context.h | 305 |
1 files changed, 305 insertions, 0 deletions
diff --git a/arch/arm64/include/asm/mmu_context.h b/arch/arm64/include/asm/mmu_context.h new file mode 100644 index 0000000000..a6fb325424 --- /dev/null +++ b/arch/arm64/include/asm/mmu_context.h @@ -0,0 +1,305 @@ +/* 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/daifflags.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_nosync(void) +{ + unsigned long ttbr = phys_to_ttbr(__pa_symbol(reserved_pg_dir)); + + write_sysreg(ttbr, ttbr0_el1); +} + +static inline void cpu_set_reserved_ttbr0(void) +{ + cpu_set_reserved_ttbr0_nosync(); + 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_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; + unsigned long daif; + + /* 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 system_cpucaps 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); + + /* + * We really don't want to take *any* exceptions while TTBR1 is + * in the process of being replaced so mask everything. + */ + daif = local_daif_save(); + replace_phys(ttbr1); + local_daif_restore(daif); + + 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); + +#define mm_untag_mask mm_untag_mask +static inline unsigned long mm_untag_mask(struct mm_struct *mm) +{ + return -1UL >> 8; +} + +#include <asm-generic/mmu_context.h> + +#endif /* !__ASSEMBLY__ */ + +#endif /* !__ASM_MMU_CONTEXT_H */ |