1 files changed, 367 insertions, 0 deletions
diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h
new file mode 100644
index 000000000..cda3118f3
--- /dev/null
+++ b/arch/x86/include/asm/tlbflush.h
@@ -0,0 +1,367 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_X86_TLBFLUSH_H
+#define _ASM_X86_TLBFLUSH_H
+
+#include <linux/mm.h>
+#include <linux/sched.h>
+
+#include <asm/processor.h>
+#include <asm/cpufeature.h>
+#include <asm/special_insns.h>
+#include <asm/smp.h>
+#include <asm/invpcid.h>
+#include <asm/pti.h>
+#include <asm/processor-flags.h>
+
+void __flush_tlb_all(void);
+
+#define TLB_FLUSH_ALL	-1UL
+#define TLB_GENERATION_INVALID	0
+
+void cr4_update_irqsoff(unsigned long set, unsigned long clear);
+unsigned long cr4_read_shadow(void);
+
+/* Set in this cpu's CR4. */
+static inline void cr4_set_bits_irqsoff(unsigned long mask)
+{
+	cr4_update_irqsoff(mask, 0);
+}
+
+/* Clear in this cpu's CR4. */
+static inline void cr4_clear_bits_irqsoff(unsigned long mask)
+{
+	cr4_update_irqsoff(0, mask);
+}
+
+/* Set in this cpu's CR4. */
+static inline void cr4_set_bits(unsigned long mask)
+{
+	unsigned long flags;
+
+	local_irq_save(flags);
+	cr4_set_bits_irqsoff(mask);
+	local_irq_restore(flags);
+}
+
+/* Clear in this cpu's CR4. */
+static inline void cr4_clear_bits(unsigned long mask)
+{
+	unsigned long flags;
+
+	local_irq_save(flags);
+	cr4_clear_bits_irqsoff(mask);
+	local_irq_restore(flags);
+}
+
+#ifndef MODULE
+/*
+ * 6 because 6 should be plenty and struct tlb_state will fit in two cache
+ * lines.
+ */
+#define TLB_NR_DYN_ASIDS	6
+
+struct tlb_context {
+	u64 ctx_id;
+	u64 tlb_gen;
+};
+
+struct tlb_state {
+	/*
+	 * cpu_tlbstate.loaded_mm should match CR3 whenever interrupts
+	 * are on.  This means that it may not match current->active_mm,
+	 * which will contain the previous user mm when we're in lazy TLB
+	 * mode even if we've already switched back to swapper_pg_dir.
+	 *
+	 * During switch_mm_irqs_off(), loaded_mm will be set to
+	 * LOADED_MM_SWITCHING during the brief interrupts-off window
+	 * when CR3 and loaded_mm would otherwise be inconsistent.  This
+	 * is for nmi_uaccess_okay()'s benefit.
+	 */
+	struct mm_struct *loaded_mm;
+
+#define LOADED_MM_SWITCHING ((struct mm_struct *)1UL)
+
+	/* Last user mm for optimizing IBPB */
+	union {
+		struct mm_struct	*last_user_mm;
+		unsigned long		last_user_mm_spec;
+	};
+
+	u16 loaded_mm_asid;
+	u16 next_asid;
+
+	/*
+	 * If set we changed the page tables in such a way that we
+	 * needed an invalidation of all contexts (aka. PCIDs / ASIDs).
+	 * This tells us to go invalidate all the non-loaded ctxs[]
+	 * on the next context switch.
+	 *
+	 * The current ctx was kept up-to-date as it ran and does not
+	 * need to be invalidated.
+	 */
+	bool invalidate_other;
+
+	/*
+	 * Mask that contains TLB_NR_DYN_ASIDS+1 bits to indicate
+	 * the corresponding user PCID needs a flush next time we
+	 * switch to it; see SWITCH_TO_USER_CR3.
+	 */
+	unsigned short user_pcid_flush_mask;
+
+	/*
+	 * Access to this CR4 shadow and to H/W CR4 is protected by
+	 * disabling interrupts when modifying either one.
+	 */
+	unsigned long cr4;
+
+	/*
+	 * This is a list of all contexts that might exist in the TLB.
+	 * There is one per ASID that we use, and the ASID (what the
+	 * CPU calls PCID) is the index into ctxts.
+	 *
+	 * For each context, ctx_id indicates which mm the TLB's user
+	 * entries came from.  As an invariant, the TLB will never
+	 * contain entries that are out-of-date as when that mm reached
+	 * the tlb_gen in the list.
+	 *
+	 * To be clear, this means that it's legal for the TLB code to
+	 * flush the TLB without updating tlb_gen.  This can happen
+	 * (for now, at least) due to paravirt remote flushes.
+	 *
+	 * NB: context 0 is a bit special, since it's also used by
+	 * various bits of init code.  This is fine -- code that
+	 * isn't aware of PCID will end up harmlessly flushing
+	 * context 0.
+	 */
+	struct tlb_context ctxs[TLB_NR_DYN_ASIDS];
+};
+DECLARE_PER_CPU_ALIGNED(struct tlb_state, cpu_tlbstate);
+
+struct tlb_state_shared {
+	/*
+	 * We can be in one of several states:
+	 *
+	 *  - Actively using an mm.  Our CPU's bit will be set in
+	 *    mm_cpumask(loaded_mm) and is_lazy == false;
+	 *
+	 *  - Not using a real mm.  loaded_mm == &init_mm.  Our CPU's bit
+	 *    will not be set in mm_cpumask(&init_mm) and is_lazy == false.
+	 *
+	 *  - Lazily using a real mm.  loaded_mm != &init_mm, our bit
+	 *    is set in mm_cpumask(loaded_mm), but is_lazy == true.
+	 *    We're heuristically guessing that the CR3 load we
+	 *    skipped more than makes up for the overhead added by
+	 *    lazy mode.
+	 */
+	bool is_lazy;
+};
+DECLARE_PER_CPU_SHARED_ALIGNED(struct tlb_state_shared, cpu_tlbstate_shared);
+
+bool nmi_uaccess_okay(void);
+#define nmi_uaccess_okay nmi_uaccess_okay
+
+/* Initialize cr4 shadow for this CPU. */
+static inline void cr4_init_shadow(void)
+{
+	this_cpu_write(cpu_tlbstate.cr4, __read_cr4());
+}
+
+extern unsigned long mmu_cr4_features;
+extern u32 *trampoline_cr4_features;
+
+extern void initialize_tlbstate_and_flush(void);
+
+/*
+ * TLB flushing:
+ *
+ *  - flush_tlb_all() flushes all processes TLBs
+ *  - flush_tlb_mm(mm) flushes the specified mm context TLB's
+ *  - flush_tlb_page(vma, vmaddr) flushes one page
+ *  - flush_tlb_range(vma, start, end) flushes a range of pages
+ *  - flush_tlb_kernel_range(start, end) flushes a range of kernel pages
+ *  - flush_tlb_multi(cpumask, info) flushes TLBs on multiple cpus
+ *
+ * ..but the i386 has somewhat limited tlb flushing capabilities,
+ * and page-granular flushes are available only on i486 and up.
+ */
+struct flush_tlb_info {
+	/*
+	 * We support several kinds of flushes.
+	 *
+	 * - Fully flush a single mm.  .mm will be set, .end will be
+	 *   TLB_FLUSH_ALL, and .new_tlb_gen will be the tlb_gen to
+	 *   which the IPI sender is trying to catch us up.
+	 *
+	 * - Partially flush a single mm.  .mm will be set, .start and
+	 *   .end will indicate the range, and .new_tlb_gen will be set
+	 *   such that the changes between generation .new_tlb_gen-1 and
+	 *   .new_tlb_gen are entirely contained in the indicated range.
+	 *
+	 * - Fully flush all mms whose tlb_gens have been updated.  .mm
+	 *   will be NULL, .end will be TLB_FLUSH_ALL, and .new_tlb_gen
+	 *   will be zero.
+	 */
+	struct mm_struct	*mm;
+	unsigned long		start;
+	unsigned long		end;
+	u64			new_tlb_gen;
+	unsigned int		initiating_cpu;
+	u8			stride_shift;
+	u8			freed_tables;
+};
+
+void flush_tlb_local(void);
+void flush_tlb_one_user(unsigned long addr);
+void flush_tlb_one_kernel(unsigned long addr);
+void flush_tlb_multi(const struct cpumask *cpumask,
+		      const struct flush_tlb_info *info);
+
+#ifdef CONFIG_PARAVIRT
+#include <asm/paravirt.h>
+#endif
+
+#define flush_tlb_mm(mm)						\
+		flush_tlb_mm_range(mm, 0UL, TLB_FLUSH_ALL, 0UL, true)
+
+#define flush_tlb_range(vma, start, end)				\
+	flush_tlb_mm_range((vma)->vm_mm, start, end,			\
+			   ((vma)->vm_flags & VM_HUGETLB)		\
+				? huge_page_shift(hstate_vma(vma))	\
+				: PAGE_SHIFT, false)
+
+extern void flush_tlb_all(void);
+extern void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start,
+				unsigned long end, unsigned int stride_shift,
+				bool freed_tables);
+extern void flush_tlb_kernel_range(unsigned long start, unsigned long end);
+
+static inline void flush_tlb_page(struct vm_area_struct *vma, unsigned long a)
+{
+	flush_tlb_mm_range(vma->vm_mm, a, a + PAGE_SIZE, PAGE_SHIFT, false);
+}
+
+static inline u64 inc_mm_tlb_gen(struct mm_struct *mm)
+{
+	/*
+	 * Bump the generation count.  This also serves as a full barrier
+	 * that synchronizes with switch_mm(): callers are required to order
+	 * their read of mm_cpumask after their writes to the paging
+	 * structures.
+	 */
+	return atomic64_inc_return(&mm->context.tlb_gen);
+}
+
+static inline void arch_tlbbatch_add_mm(struct arch_tlbflush_unmap_batch *batch,
+					struct mm_struct *mm)
+{
+	inc_mm_tlb_gen(mm);
+	cpumask_or(&batch->cpumask, &batch->cpumask, mm_cpumask(mm));
+}
+
+extern void arch_tlbbatch_flush(struct arch_tlbflush_unmap_batch *batch);
+
+static inline bool pte_flags_need_flush(unsigned long oldflags,
+					unsigned long newflags,
+					bool ignore_access)
+{
+	/*
+	 * Flags that require a flush when cleared but not when they are set.
+	 * Only include flags that would not trigger spurious page-faults.
+	 * Non-present entries are not cached. Hardware would set the
+	 * dirty/access bit if needed without a fault.
+	 */
+	const pteval_t flush_on_clear = _PAGE_DIRTY | _PAGE_PRESENT |
+					_PAGE_ACCESSED;
+	const pteval_t software_flags = _PAGE_SOFTW1 | _PAGE_SOFTW2 |
+					_PAGE_SOFTW3 | _PAGE_SOFTW4;
+	const pteval_t flush_on_change = _PAGE_RW | _PAGE_USER | _PAGE_PWT |
+			  _PAGE_PCD | _PAGE_PSE | _PAGE_GLOBAL | _PAGE_PAT |
+			  _PAGE_PAT_LARGE | _PAGE_PKEY_BIT0 | _PAGE_PKEY_BIT1 |
+			  _PAGE_PKEY_BIT2 | _PAGE_PKEY_BIT3 | _PAGE_NX;
+	unsigned long diff = oldflags ^ newflags;
+
+	BUILD_BUG_ON(flush_on_clear & software_flags);
+	BUILD_BUG_ON(flush_on_clear & flush_on_change);
+	BUILD_BUG_ON(flush_on_change & software_flags);
+
+	/* Ignore software flags */
+	diff &= ~software_flags;
+
+	if (ignore_access)
+		diff &= ~_PAGE_ACCESSED;
+
+	/*
+	 * Did any of the 'flush_on_clear' flags was clleared set from between
+	 * 'oldflags' and 'newflags'?
+	 */
+	if (diff & oldflags & flush_on_clear)
+		return true;
+
+	/* Flush on modified flags. */
+	if (diff & flush_on_change)
+		return true;
+
+	/* Ensure there are no flags that were left behind */
+	if (IS_ENABLED(CONFIG_DEBUG_VM) &&
+	    (diff & ~(flush_on_clear | software_flags | flush_on_change))) {
+		VM_WARN_ON_ONCE(1);
+		return true;
+	}
+
+	return false;
+}
+
+/*
+ * pte_needs_flush() checks whether permissions were demoted and require a
+ * flush. It should only be used for userspace PTEs.
+ */
+static inline bool pte_needs_flush(pte_t oldpte, pte_t newpte)
+{
+	/* !PRESENT -> * ; no need for flush */
+	if (!(pte_flags(oldpte) & _PAGE_PRESENT))
+		return false;
+
+	/* PFN changed ; needs flush */
+	if (pte_pfn(oldpte) != pte_pfn(newpte))
+		return true;
+
+	/*
+	 * check PTE flags; ignore access-bit; see comment in
+	 * ptep_clear_flush_young().
+	 */
+	return pte_flags_need_flush(pte_flags(oldpte), pte_flags(newpte),
+				    true);
+}
+#define pte_needs_flush pte_needs_flush
+
+/*
+ * huge_pmd_needs_flush() checks whether permissions were demoted and require a
+ * flush. It should only be used for userspace huge PMDs.
+ */
+static inline bool huge_pmd_needs_flush(pmd_t oldpmd, pmd_t newpmd)
+{
+	/* !PRESENT -> * ; no need for flush */
+	if (!(pmd_flags(oldpmd) & _PAGE_PRESENT))
+		return false;
+
+	/* PFN changed ; needs flush */
+	if (pmd_pfn(oldpmd) != pmd_pfn(newpmd))
+		return true;
+
+	/*
+	 * check PMD flags; do not ignore access-bit; see
+	 * pmdp_clear_flush_young().
+	 */
+	return pte_flags_need_flush(pmd_flags(oldpmd), pmd_flags(newpmd),
+				    false);
+}
+#define huge_pmd_needs_flush huge_pmd_needs_flush
+
+#endif /* !MODULE */
+
+static inline void __native_tlb_flush_global(unsigned long cr4)
+{
+	native_write_cr4(cr4 ^ X86_CR4_PGE);
+	native_write_cr4(cr4);
+}
+#endif /* _ASM_X86_TLBFLUSH_H */