arch/arm64/include/asm/mmu_context.h - linux - Git at Google

 /* 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, bool cnp)
 {
 	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 (cnp)
 		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();
 }

 static inline void cpu_enable_swapper_cnp(void)
 {
 	__cpu_replace_ttbr1(lm_alias(swapper_pg_dir), idmap_pg_dir, true);
 }

 static inline void cpu_replace_ttbr1(pgd_t *pgdp, pgd_t *idmap)
 {
 	/*
 	 * Only for early TTBR1 replacement before cpucaps are finalized and
 	 * before we've decided whether to use CNP.
 	 */
 	WARN_ON(system_capabilities_finalized());
 	__cpu_replace_ttbr1(pgdp, idmap, false);
 }

 /*
  * 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 */
	/* 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, bool cnp)
	{
	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 (cnp)
	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();
	}

	static inline void cpu_enable_swapper_cnp(void)
	{
	__cpu_replace_ttbr1(lm_alias(swapper_pg_dir), idmap_pg_dir, true);
	}

	static inline void cpu_replace_ttbr1(pgd_t pgdp, pgd_t idmap)
	{
	/*
	* Only for early TTBR1 replacement before cpucaps are finalized and
	* before we've decided whether to use CNP.
	*/
	WARN_ON(system_capabilities_finalized());
	__cpu_replace_ttbr1(pgdp, idmap, false);
	}

	/*
	* 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 */