| // SPDX-License-Identifier: GPL-2.0-or-later |
| /* |
| * MMU context allocation for 64-bit kernels. |
| * |
| * Copyright (C) 2004 Anton Blanchard, IBM Corp. <anton@samba.org> |
| */ |
| |
| #include <linux/sched.h> |
| #include <linux/kernel.h> |
| #include <linux/errno.h> |
| #include <linux/string.h> |
| #include <linux/types.h> |
| #include <linux/mm.h> |
| #include <linux/pkeys.h> |
| #include <linux/spinlock.h> |
| #include <linux/idr.h> |
| #include <linux/export.h> |
| #include <linux/gfp.h> |
| #include <linux/slab.h> |
| #include <linux/cpu.h> |
| |
| #include <asm/mmu_context.h> |
| #include <asm/pgalloc.h> |
| |
| #include "internal.h" |
| |
| static DEFINE_IDA(mmu_context_ida); |
| |
| static int alloc_context_id(int min_id, int max_id) |
| { |
| return ida_alloc_range(&mmu_context_ida, min_id, max_id, GFP_KERNEL); |
| } |
| |
| void hash__reserve_context_id(int id) |
| { |
| int result = ida_alloc_range(&mmu_context_ida, id, id, GFP_KERNEL); |
| |
| WARN(result != id, "mmu: Failed to reserve context id %d (rc %d)\n", id, result); |
| } |
| |
| int hash__alloc_context_id(void) |
| { |
| unsigned long max; |
| |
| if (mmu_has_feature(MMU_FTR_68_BIT_VA)) |
| max = MAX_USER_CONTEXT; |
| else |
| max = MAX_USER_CONTEXT_65BIT_VA; |
| |
| return alloc_context_id(MIN_USER_CONTEXT, max); |
| } |
| EXPORT_SYMBOL_GPL(hash__alloc_context_id); |
| |
| static int realloc_context_ids(mm_context_t *ctx) |
| { |
| int i, id; |
| |
| /* |
| * id 0 (aka. ctx->id) is special, we always allocate a new one, even if |
| * there wasn't one allocated previously (which happens in the exec |
| * case where ctx is newly allocated). |
| * |
| * We have to be a bit careful here. We must keep the existing ids in |
| * the array, so that we can test if they're non-zero to decide if we |
| * need to allocate a new one. However in case of error we must free the |
| * ids we've allocated but *not* any of the existing ones (or risk a |
| * UAF). That's why we decrement i at the start of the error handling |
| * loop, to skip the id that we just tested but couldn't reallocate. |
| */ |
| for (i = 0; i < ARRAY_SIZE(ctx->extended_id); i++) { |
| if (i == 0 || ctx->extended_id[i]) { |
| id = hash__alloc_context_id(); |
| if (id < 0) |
| goto error; |
| |
| ctx->extended_id[i] = id; |
| } |
| } |
| |
| /* The caller expects us to return id */ |
| return ctx->id; |
| |
| error: |
| for (i--; i >= 0; i--) { |
| if (ctx->extended_id[i]) |
| ida_free(&mmu_context_ida, ctx->extended_id[i]); |
| } |
| |
| return id; |
| } |
| |
| static int hash__init_new_context(struct mm_struct *mm) |
| { |
| int index; |
| |
| mm->context.hash_context = kmalloc(sizeof(struct hash_mm_context), |
| GFP_KERNEL); |
| if (!mm->context.hash_context) |
| return -ENOMEM; |
| |
| /* |
| * The old code would re-promote on fork, we don't do that when using |
| * slices as it could cause problem promoting slices that have been |
| * forced down to 4K. |
| * |
| * For book3s we have MMU_NO_CONTEXT set to be ~0. Hence check |
| * explicitly against context.id == 0. This ensures that we properly |
| * initialize context slice details for newly allocated mm's (which will |
| * have id == 0) and don't alter context slice inherited via fork (which |
| * will have id != 0). |
| * |
| * We should not be calling init_new_context() on init_mm. Hence a |
| * check against 0 is OK. |
| */ |
| if (mm->context.id == 0) { |
| memset(mm->context.hash_context, 0, sizeof(struct hash_mm_context)); |
| slice_init_new_context_exec(mm); |
| } else { |
| /* This is fork. Copy hash_context details from current->mm */ |
| memcpy(mm->context.hash_context, current->mm->context.hash_context, sizeof(struct hash_mm_context)); |
| #ifdef CONFIG_PPC_SUBPAGE_PROT |
| /* inherit subpage prot detalis if we have one. */ |
| if (current->mm->context.hash_context->spt) { |
| mm->context.hash_context->spt = kmalloc(sizeof(struct subpage_prot_table), |
| GFP_KERNEL); |
| if (!mm->context.hash_context->spt) { |
| kfree(mm->context.hash_context); |
| return -ENOMEM; |
| } |
| } |
| #endif |
| } |
| |
| index = realloc_context_ids(&mm->context); |
| if (index < 0) { |
| #ifdef CONFIG_PPC_SUBPAGE_PROT |
| kfree(mm->context.hash_context->spt); |
| #endif |
| kfree(mm->context.hash_context); |
| return index; |
| } |
| |
| pkey_mm_init(mm); |
| return index; |
| } |
| |
| void hash__setup_new_exec(void) |
| { |
| slice_setup_new_exec(); |
| |
| slb_setup_new_exec(); |
| } |
| |
| static int radix__init_new_context(struct mm_struct *mm) |
| { |
| unsigned long rts_field; |
| int index, max_id; |
| |
| max_id = (1 << mmu_pid_bits) - 1; |
| index = alloc_context_id(mmu_base_pid, max_id); |
| if (index < 0) |
| return index; |
| |
| /* |
| * set the process table entry, |
| */ |
| rts_field = radix__get_tree_size(); |
| process_tb[index].prtb0 = cpu_to_be64(rts_field | __pa(mm->pgd) | RADIX_PGD_INDEX_SIZE); |
| |
| /* |
| * Order the above store with subsequent update of the PID |
| * register (at which point HW can start loading/caching |
| * the entry) and the corresponding load by the MMU from |
| * the L2 cache. |
| */ |
| asm volatile("ptesync;isync" : : : "memory"); |
| |
| mm->context.hash_context = NULL; |
| |
| return index; |
| } |
| |
| int init_new_context(struct task_struct *tsk, struct mm_struct *mm) |
| { |
| int index; |
| |
| if (radix_enabled()) |
| index = radix__init_new_context(mm); |
| else |
| index = hash__init_new_context(mm); |
| |
| if (index < 0) |
| return index; |
| |
| mm->context.id = index; |
| |
| mm->context.pte_frag = NULL; |
| mm->context.pmd_frag = NULL; |
| #ifdef CONFIG_SPAPR_TCE_IOMMU |
| mm_iommu_init(mm); |
| #endif |
| atomic_set(&mm->context.active_cpus, 0); |
| atomic_set(&mm->context.copros, 0); |
| |
| return 0; |
| } |
| |
| void __destroy_context(int context_id) |
| { |
| ida_free(&mmu_context_ida, context_id); |
| } |
| EXPORT_SYMBOL_GPL(__destroy_context); |
| |
| static void destroy_contexts(mm_context_t *ctx) |
| { |
| int index, context_id; |
| |
| for (index = 0; index < ARRAY_SIZE(ctx->extended_id); index++) { |
| context_id = ctx->extended_id[index]; |
| if (context_id) |
| ida_free(&mmu_context_ida, context_id); |
| } |
| kfree(ctx->hash_context); |
| } |
| |
| static void pmd_frag_destroy(void *pmd_frag) |
| { |
| int count; |
| struct page *page; |
| |
| page = virt_to_page(pmd_frag); |
| /* drop all the pending references */ |
| count = ((unsigned long)pmd_frag & ~PAGE_MASK) >> PMD_FRAG_SIZE_SHIFT; |
| /* We allow PTE_FRAG_NR fragments from a PTE page */ |
| if (atomic_sub_and_test(PMD_FRAG_NR - count, &page->pt_frag_refcount)) { |
| pgtable_pmd_page_dtor(page); |
| __free_page(page); |
| } |
| } |
| |
| static void destroy_pagetable_cache(struct mm_struct *mm) |
| { |
| void *frag; |
| |
| frag = mm->context.pte_frag; |
| if (frag) |
| pte_frag_destroy(frag); |
| |
| frag = mm->context.pmd_frag; |
| if (frag) |
| pmd_frag_destroy(frag); |
| return; |
| } |
| |
| void destroy_context(struct mm_struct *mm) |
| { |
| #ifdef CONFIG_SPAPR_TCE_IOMMU |
| WARN_ON_ONCE(!list_empty(&mm->context.iommu_group_mem_list)); |
| #endif |
| /* |
| * For tasks which were successfully initialized we end up calling |
| * arch_exit_mmap() which clears the process table entry. And |
| * arch_exit_mmap() is called before the required fullmm TLB flush |
| * which does a RIC=2 flush. Hence for an initialized task, we do clear |
| * any cached process table entries. |
| * |
| * The condition below handles the error case during task init. We have |
| * set the process table entry early and if we fail a task |
| * initialization, we need to ensure the process table entry is zeroed. |
| * We need not worry about process table entry caches because the task |
| * never ran with the PID value. |
| */ |
| if (radix_enabled()) |
| process_tb[mm->context.id].prtb0 = 0; |
| else |
| subpage_prot_free(mm); |
| destroy_contexts(&mm->context); |
| mm->context.id = MMU_NO_CONTEXT; |
| } |
| |
| void arch_exit_mmap(struct mm_struct *mm) |
| { |
| destroy_pagetable_cache(mm); |
| |
| if (radix_enabled()) { |
| /* |
| * Radix doesn't have a valid bit in the process table |
| * entries. However we know that at least P9 implementation |
| * will avoid caching an entry with an invalid RTS field, |
| * and 0 is invalid. So this will do. |
| * |
| * This runs before the "fullmm" tlb flush in exit_mmap, |
| * which does a RIC=2 tlbie to clear the process table |
| * entry. See the "fullmm" comments in tlb-radix.c. |
| * |
| * No barrier required here after the store because |
| * this process will do the invalidate, which starts with |
| * ptesync. |
| */ |
| process_tb[mm->context.id].prtb0 = 0; |
| } |
| } |
| |
| #ifdef CONFIG_PPC_RADIX_MMU |
| void radix__switch_mmu_context(struct mm_struct *prev, struct mm_struct *next) |
| { |
| mtspr(SPRN_PID, next->context.id); |
| isync(); |
| } |
| #endif |
| |
| /** |
| * cleanup_cpu_mmu_context - Clean up MMU details for this CPU (newly offlined) |
| * |
| * This clears the CPU from mm_cpumask for all processes, and then flushes the |
| * local TLB to ensure TLB coherency in case the CPU is onlined again. |
| * |
| * KVM guest translations are not necessarily flushed here. If KVM started |
| * using mm_cpumask or the Linux APIs which do, this would have to be resolved. |
| */ |
| #ifdef CONFIG_HOTPLUG_CPU |
| void cleanup_cpu_mmu_context(void) |
| { |
| int cpu = smp_processor_id(); |
| |
| clear_tasks_mm_cpumask(cpu); |
| tlbiel_all(); |
| } |
| #endif |