// SPDX-License-Identifier: GPL-2.0-or-later /* * PowerPC64 SLB support. * * Copyright (C) 2004 David Gibson , IBM * Based on earlier code written by: * Dave Engebretsen and Mike Corrigan {engebret|mikejc}@us.ibm.com * Copyright (c) 2001 Dave Engebretsen * Copyright (C) 2002 Anton Blanchard , IBM */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "internal.h" enum slb_index { LINEAR_INDEX = 0, /* Kernel linear map (0xc000000000000000) */ KSTACK_INDEX = 1, /* Kernel stack map */ }; static long slb_allocate_user(struct mm_struct *mm, unsigned long ea); #define slb_esid_mask(ssize) \ (((ssize) == MMU_SEGSIZE_256M)? ESID_MASK: ESID_MASK_1T) static inline unsigned long mk_esid_data(unsigned long ea, int ssize, enum slb_index index) { return (ea & slb_esid_mask(ssize)) | SLB_ESID_V | index; } static inline unsigned long __mk_vsid_data(unsigned long vsid, int ssize, unsigned long flags) { return (vsid << slb_vsid_shift(ssize)) | flags | ((unsigned long) ssize << SLB_VSID_SSIZE_SHIFT); } static inline unsigned long mk_vsid_data(unsigned long ea, int ssize, unsigned long flags) { return __mk_vsid_data(get_kernel_vsid(ea, ssize), ssize, flags); } bool stress_slb_enabled __initdata; static int __init parse_stress_slb(char *p) { stress_slb_enabled = true; return 0; } early_param("stress_slb", parse_stress_slb); __ro_after_init DEFINE_STATIC_KEY_FALSE(stress_slb_key); static void assert_slb_presence(bool present, unsigned long ea) { #ifdef CONFIG_DEBUG_VM unsigned long tmp; WARN_ON_ONCE(mfmsr() & MSR_EE); if (!cpu_has_feature(CPU_FTR_ARCH_206)) return; /* * slbfee. requires bit 24 (PPC bit 39) be clear in RB. Hardware * ignores all other bits from 0-27, so just clear them all. */ ea &= ~((1UL << SID_SHIFT) - 1); asm volatile(__PPC_SLBFEE_DOT(%0, %1) : "=r"(tmp) : "r"(ea) : "cr0"); WARN_ON(present == (tmp == 0)); #endif } static inline void slb_shadow_update(unsigned long ea, int ssize, unsigned long flags, enum slb_index index) { struct slb_shadow *p = get_slb_shadow(); /* * Clear the ESID first so the entry is not valid while we are * updating it. No write barriers are needed here, provided * we only update the current CPU's SLB shadow buffer. */ WRITE_ONCE(p->save_area[index].esid, 0); WRITE_ONCE(p->save_area[index].vsid, cpu_to_be64(mk_vsid_data(ea, ssize, flags))); WRITE_ONCE(p->save_area[index].esid, cpu_to_be64(mk_esid_data(ea, ssize, index))); } static inline void slb_shadow_clear(enum slb_index index) { WRITE_ONCE(get_slb_shadow()->save_area[index].esid, cpu_to_be64(index)); } static inline void create_shadowed_slbe(unsigned long ea, int ssize, unsigned long flags, enum slb_index index) { /* * Updating the shadow buffer before writing the SLB ensures * we don't get a stale entry here if we get preempted by PHYP * between these two statements. */ slb_shadow_update(ea, ssize, flags, index); assert_slb_presence(false, ea); asm volatile("slbmte %0,%1" : : "r" (mk_vsid_data(ea, ssize, flags)), "r" (mk_esid_data(ea, ssize, index)) : "memory" ); } /* * Insert bolted entries into SLB (which may not be empty, so don't clear * slb_cache_ptr). */ void __slb_restore_bolted_realmode(void) { struct slb_shadow *p = get_slb_shadow(); enum slb_index index; /* No isync needed because realmode. */ for (index = 0; index < SLB_NUM_BOLTED; index++) { asm volatile("slbmte %0,%1" : : "r" (be64_to_cpu(p->save_area[index].vsid)), "r" (be64_to_cpu(p->save_area[index].esid))); } assert_slb_presence(true, local_paca->kstack); } /* * Insert the bolted entries into an empty SLB. */ void slb_restore_bolted_realmode(void) { __slb_restore_bolted_realmode(); get_paca()->slb_cache_ptr = 0; get_paca()->slb_kern_bitmap = (1U << SLB_NUM_BOLTED) - 1; get_paca()->slb_used_bitmap = get_paca()->slb_kern_bitmap; } /* * This flushes all SLB entries including 0, so it must be realmode. */ void slb_flush_all_realmode(void) { asm volatile("slbmte %0,%0; slbia" : : "r" (0)); } static __always_inline void __slb_flush_and_restore_bolted(bool preserve_kernel_lookaside) { struct slb_shadow *p = get_slb_shadow(); unsigned long ksp_esid_data, ksp_vsid_data; u32 ih; /* * SLBIA IH=1 on ISA v2.05 and newer processors may preserve lookaside * information created with Class=0 entries, which we use for kernel * SLB entries (the SLB entries themselves are still invalidated). * * Older processors will ignore this optimisation. Over-invalidation * is fine because we never rely on lookaside information existing. */ if (preserve_kernel_lookaside) ih = 1; else ih = 0; ksp_esid_data = be64_to_cpu(p->save_area[KSTACK_INDEX].esid); ksp_vsid_data = be64_to_cpu(p->save_area[KSTACK_INDEX].vsid); asm volatile(PPC_SLBIA(%0)" \n" "slbmte %1, %2 \n" :: "i" (ih), "r" (ksp_vsid_data), "r" (ksp_esid_data) : "memory"); } /* * This flushes non-bolted entries, it can be run in virtual mode. Must * be called with interrupts disabled. */ void slb_flush_and_restore_bolted(void) { BUILD_BUG_ON(SLB_NUM_BOLTED != 2); WARN_ON(!irqs_disabled()); /* * We can't take a PMU exception in the following code, so hard * disable interrupts. */ hard_irq_disable(); isync(); __slb_flush_and_restore_bolted(false); isync(); assert_slb_presence(true, get_paca()->kstack); get_paca()->slb_cache_ptr = 0; get_paca()->slb_kern_bitmap = (1U << SLB_NUM_BOLTED) - 1; get_paca()->slb_used_bitmap = get_paca()->slb_kern_bitmap; } void slb_save_contents(struct slb_entry *slb_ptr) { int i; unsigned long e, v; /* Save slb_cache_ptr value. */ get_paca()->slb_save_cache_ptr = get_paca()->slb_cache_ptr; if (!slb_ptr) return; for (i = 0; i < mmu_slb_size; i++) { asm volatile("slbmfee %0,%1" : "=r" (e) : "r" (i)); asm volatile("slbmfev %0,%1" : "=r" (v) : "r" (i)); slb_ptr->esid = e; slb_ptr->vsid = v; slb_ptr++; } } void slb_dump_contents(struct slb_entry *slb_ptr) { int i, n; unsigned long e, v; unsigned long llp; if (!slb_ptr) return; pr_err("SLB contents of cpu 0x%x\n", smp_processor_id()); pr_err("Last SLB entry inserted at slot %d\n", get_paca()->stab_rr); for (i = 0; i < mmu_slb_size; i++) { e = slb_ptr->esid; v = slb_ptr->vsid; slb_ptr++; if (!e && !v) continue; pr_err("%02d %016lx %016lx\n", i, e, v); if (!(e & SLB_ESID_V)) { pr_err("\n"); continue; } llp = v & SLB_VSID_LLP; if (v & SLB_VSID_B_1T) { pr_err(" 1T ESID=%9lx VSID=%13lx LLP:%3lx\n", GET_ESID_1T(e), (v & ~SLB_VSID_B) >> SLB_VSID_SHIFT_1T, llp); } else { pr_err(" 256M ESID=%9lx VSID=%13lx LLP:%3lx\n", GET_ESID(e), (v & ~SLB_VSID_B) >> SLB_VSID_SHIFT, llp); } } pr_err("----------------------------------\n"); /* Dump slb cache entires as well. */ pr_err("SLB cache ptr value = %d\n", get_paca()->slb_save_cache_ptr); pr_err("Valid SLB cache entries:\n"); n = min_t(int, get_paca()->slb_save_cache_ptr, SLB_CACHE_ENTRIES); for (i = 0; i < n; i++) pr_err("%02d EA[0-35]=%9x\n", i, get_paca()->slb_cache[i]); pr_err("Rest of SLB cache entries:\n"); for (i = n; i < SLB_CACHE_ENTRIES; i++) pr_err("%02d EA[0-35]=%9x\n", i, get_paca()->slb_cache[i]); } void slb_vmalloc_update(void) { /* * vmalloc is not bolted, so just have to flush non-bolted. */ slb_flush_and_restore_bolted(); } static bool preload_hit(struct thread_info *ti, unsigned long esid) { unsigned char i; for (i = 0; i < ti->slb_preload_nr; i++) { unsigned char idx; idx = (ti->slb_preload_tail + i) % SLB_PRELOAD_NR; if (esid == ti->slb_preload_esid[idx]) return true; } return false; } static bool preload_add(struct thread_info *ti, unsigned long ea) { unsigned char idx; unsigned long esid; if (mmu_has_feature(MMU_FTR_1T_SEGMENT)) { /* EAs are stored >> 28 so 256MB segments don't need clearing */ if (ea & ESID_MASK_1T) ea &= ESID_MASK_1T; } esid = ea >> SID_SHIFT; if (preload_hit(ti, esid)) return false; idx = (ti->slb_preload_tail + ti->slb_preload_nr) % SLB_PRELOAD_NR; ti->slb_preload_esid[idx] = esid; if (ti->slb_preload_nr == SLB_PRELOAD_NR) ti->slb_preload_tail = (ti->slb_preload_tail + 1) % SLB_PRELOAD_NR; else ti->slb_preload_nr++; return true; } static void preload_age(struct thread_info *ti) { if (!ti->slb_preload_nr) return; ti->slb_preload_nr--; ti->slb_preload_tail = (ti->slb_preload_tail + 1) % SLB_PRELOAD_NR; } void slb_setup_new_exec(void) { struct thread_info *ti = current_thread_info(); struct mm_struct *mm = current->mm; unsigned long exec = 0x10000000; WARN_ON(irqs_disabled()); /* * preload cache can only be used to determine whether a SLB * entry exists if it does not start to overflow. */ if (ti->slb_preload_nr + 2 > SLB_PRELOAD_NR) return; hard_irq_disable(); /* * We have no good place to clear the slb preload cache on exec, * flush_thread is about the earliest arch hook but that happens * after we switch to the mm and have aleady preloaded the SLBEs. * * For the most part that's probably okay to use entries from the * previous exec, they will age out if unused. It may turn out to * be an advantage to clear the cache before switching to it, * however. */ /* * preload some userspace segments into the SLB. * Almost all 32 and 64bit PowerPC executables are linked at * 0x10000000 so it makes sense to preload this segment. */ if (!is_kernel_addr(exec)) { if (preload_add(ti, exec)) slb_allocate_user(mm, exec); } /* Libraries and mmaps. */ if (!is_kernel_addr(mm->mmap_base)) { if (preload_add(ti, mm->mmap_base)) slb_allocate_user(mm, mm->mmap_base); } /* see switch_slb */ asm volatile("isync" : : : "memory"); local_irq_enable(); } void preload_new_slb_context(unsigned long start, unsigned long sp) { struct thread_info *ti = current_thread_info(); struct mm_struct *mm = current->mm; unsigned long heap = mm->start_brk; WARN_ON(irqs_disabled()); /* see above */ if (ti->slb_preload_nr + 3 > SLB_PRELOAD_NR) return; hard_irq_disable(); /* Userspace entry address. */ if (!is_kernel_addr(start)) { if (preload_add(ti, start)) slb_allocate_user(mm, start); } /* Top of stack, grows down. */ if (!is_kernel_addr(sp)) { if (preload_add(ti, sp)) slb_allocate_user(mm, sp); } /* Bottom of heap, grows up. */ if (heap && !is_kernel_addr(heap)) { if (preload_add(ti, heap)) slb_allocate_user(mm, heap); } /* see switch_slb */ asm volatile("isync" : : : "memory"); local_irq_enable(); } static void slb_cache_slbie_kernel(unsigned int index) { unsigned long slbie_data = get_paca()->slb_cache[index]; unsigned long ksp = get_paca()->kstack; slbie_data <<= SID_SHIFT; slbie_data |= 0xc000000000000000ULL; if ((ksp & slb_esid_mask(mmu_kernel_ssize)) == slbie_data) return; slbie_data |= mmu_kernel_ssize << SLBIE_SSIZE_SHIFT; asm volatile("slbie %0" : : "r" (slbie_data)); } static void slb_cache_slbie_user(unsigned int index) { unsigned long slbie_data = get_paca()->slb_cache[index]; slbie_data <<= SID_SHIFT; slbie_data |= user_segment_size(slbie_data) << SLBIE_SSIZE_SHIFT; slbie_data |= SLBIE_C; /* user slbs have C=1 */ asm volatile("slbie %0" : : "r" (slbie_data)); } /* Flush all user entries from the segment table of the current processor. */ void switch_slb(struct task_struct *tsk, struct mm_struct *mm) { struct thread_info *ti = task_thread_info(tsk); unsigned char i; /* * We need interrupts hard-disabled here, not just soft-disabled, * so that a PMU interrupt can't occur, which might try to access * user memory (to get a stack trace) and possible cause an SLB miss * which would update the slb_cache/slb_cache_ptr fields in the PACA. */ hard_irq_disable(); isync(); if (stress_slb()) { __slb_flush_and_restore_bolted(false); isync(); get_paca()->slb_cache_ptr = 0; get_paca()->slb_kern_bitmap = (1U << SLB_NUM_BOLTED) - 1; } else if (cpu_has_feature(CPU_FTR_ARCH_300)) { /* * SLBIA IH=3 invalidates all Class=1 SLBEs and their * associated lookaside structures, which matches what * switch_slb wants. So ARCH_300 does not use the slb * cache. */ asm volatile(PPC_SLBIA(3)); } else { unsigned long offset = get_paca()->slb_cache_ptr; if (!mmu_has_feature(MMU_FTR_NO_SLBIE_B) && offset <= SLB_CACHE_ENTRIES) { /* * Could assert_slb_presence(true) here, but * hypervisor or machine check could have come * in and removed the entry at this point. */ for (i = 0; i < offset; i++) slb_cache_slbie_user(i); /* Workaround POWER5 < DD2.1 issue */ if (!cpu_has_feature(CPU_FTR_ARCH_207S) && offset == 1) slb_cache_slbie_user(0); } else { /* Flush but retain kernel lookaside information */ __slb_flush_and_restore_bolted(true); isync(); get_paca()->slb_kern_bitmap = (1U << SLB_NUM_BOLTED) - 1; } get_paca()->slb_cache_ptr = 0; } get_paca()->slb_used_bitmap = get_paca()->slb_kern_bitmap; copy_mm_to_paca(mm); /* * We gradually age out SLBs after a number of context switches to * reduce reload overhead of unused entries (like we do with FP/VEC * reload). Each time we wrap 256 switches, take an entry out of the * SLB preload cache. */ tsk->thread.load_slb++; if (!tsk->thread.load_slb) { unsigned long pc = KSTK_EIP(tsk); preload_age(ti); preload_add(ti, pc); } for (i = 0; i < ti->slb_preload_nr; i++) { unsigned char idx; unsigned long ea; idx = (ti->slb_preload_tail + i) % SLB_PRELOAD_NR; ea = (unsigned long)ti->slb_preload_esid[idx] << SID_SHIFT; slb_allocate_user(mm, ea); } /* * Synchronize slbmte preloads with possible subsequent user memory * address accesses by the kernel (user mode won't happen until * rfid, which is safe). */ isync(); } void slb_set_size(u16 size) { mmu_slb_size = size; } void slb_initialize(void) { unsigned long linear_llp, vmalloc_llp, io_llp; unsigned long lflags; static int slb_encoding_inited; #ifdef CONFIG_SPARSEMEM_VMEMMAP unsigned long vmemmap_llp; #endif /* Prepare our SLB miss handler based on our page size */ linear_llp = mmu_psize_defs[mmu_linear_psize].sllp; io_llp = mmu_psize_defs[mmu_io_psize].sllp; vmalloc_llp = mmu_psize_defs[mmu_vmalloc_psize].sllp; get_paca()->vmalloc_sllp = SLB_VSID_KERNEL | vmalloc_llp; #ifdef CONFIG_SPARSEMEM_VMEMMAP vmemmap_llp = mmu_psize_defs[mmu_vmemmap_psize].sllp; #endif if (!slb_encoding_inited) { slb_encoding_inited = 1; pr_devel("SLB: linear LLP = %04lx\n", linear_llp); pr_devel("SLB: io LLP = %04lx\n", io_llp); #ifdef CONFIG_SPARSEMEM_VMEMMAP pr_devel("SLB: vmemmap LLP = %04lx\n", vmemmap_llp); #endif } get_paca()->stab_rr = SLB_NUM_BOLTED - 1; get_paca()->slb_kern_bitmap = (1U << SLB_NUM_BOLTED) - 1; get_paca()->slb_used_bitmap = get_paca()->slb_kern_bitmap; lflags = SLB_VSID_KERNEL | linear_llp; /* Invalidate the entire SLB (even entry 0) & all the ERATS */ asm volatile("isync":::"memory"); asm volatile("slbmte %0,%0"::"r" (0) : "memory"); asm volatile("isync; slbia; isync":::"memory"); create_shadowed_slbe(PAGE_OFFSET, mmu_kernel_ssize, lflags, LINEAR_INDEX); /* * For the boot cpu, we're running on the stack in init_thread_union, * which is in the first segment of the linear mapping, and also * get_paca()->kstack hasn't been initialized yet. * For secondary cpus, we need to bolt the kernel stack entry now. */ slb_shadow_clear(KSTACK_INDEX); if (raw_smp_processor_id() != boot_cpuid && (get_paca()->kstack & slb_esid_mask(mmu_kernel_ssize)) > PAGE_OFFSET) create_shadowed_slbe(get_paca()->kstack, mmu_kernel_ssize, lflags, KSTACK_INDEX); asm volatile("isync":::"memory"); } static void slb_cache_update(unsigned long esid_data) { int slb_cache_index; if (cpu_has_feature(CPU_FTR_ARCH_300)) return; /* ISAv3.0B and later does not use slb_cache */ if (stress_slb()) return; /* * Now update slb cache entries */ slb_cache_index = local_paca->slb_cache_ptr; if (slb_cache_index < SLB_CACHE_ENTRIES) { /* * We have space in slb cache for optimized switch_slb(). * Top 36 bits from esid_data as per ISA */ local_paca->slb_cache[slb_cache_index++] = esid_data >> SID_SHIFT; local_paca->slb_cache_ptr++; } else { /* * Our cache is full and the current cache content strictly * doesn't indicate the active SLB conents. Bump the ptr * so that switch_slb() will ignore the cache. */ local_paca->slb_cache_ptr = SLB_CACHE_ENTRIES + 1; } } static enum slb_index alloc_slb_index(bool kernel) { enum slb_index index; /* * The allocation bitmaps can become out of synch with the SLB * when the _switch code does slbie when bolting a new stack * segment and it must not be anywhere else in the SLB. This leaves * a kernel allocated entry that is unused in the SLB. With very * large systems or small segment sizes, the bitmaps could slowly * fill with these entries. They will eventually be cleared out * by the round robin allocator in that case, so it's probably not * worth accounting for. */ /* * SLBs beyond 32 entries are allocated with stab_rr only * POWER7/8/9 have 32 SLB entries, this could be expanded if a * future CPU has more. */ if (local_paca->slb_used_bitmap != U32_MAX) { index = ffz(local_paca->slb_used_bitmap); local_paca->slb_used_bitmap |= 1U << index; if (kernel) local_paca->slb_kern_bitmap |= 1U << index; } else { /* round-robin replacement of slb starting at SLB_NUM_BOLTED. */ index = local_paca->stab_rr; if (index < (mmu_slb_size - 1)) index++; else index = SLB_NUM_BOLTED; local_paca->stab_rr = index; if (index < 32) { if (kernel) local_paca->slb_kern_bitmap |= 1U << index; else local_paca->slb_kern_bitmap &= ~(1U << index); } } BUG_ON(index < SLB_NUM_BOLTED); return index; } static long slb_insert_entry(unsigned long ea, unsigned long context, unsigned long flags, int ssize, bool kernel) { unsigned long vsid; unsigned long vsid_data, esid_data; enum slb_index index; vsid = get_vsid(context, ea, ssize); if (!vsid) return -EFAULT; /* * There must not be a kernel SLB fault in alloc_slb_index or before * slbmte here or the allocation bitmaps could get out of whack with * the SLB. * * User SLB faults or preloads take this path which might get inlined * into the caller, so add compiler barriers here to ensure unsafe * memory accesses do not come between. */ barrier(); index = alloc_slb_index(kernel); vsid_data = __mk_vsid_data(vsid, ssize, flags); esid_data = mk_esid_data(ea, ssize, index); /* * No need for an isync before or after this slbmte. The exception * we enter with and the rfid we exit with are context synchronizing. * User preloads should add isync afterwards in case the kernel * accesses user memory before it returns to userspace with rfid. */ assert_slb_presence(false, ea); if (stress_slb()) { int slb_cache_index = local_paca->slb_cache_ptr; /* * stress_slb() does not use slb cache, repurpose as a * cache of inserted (non-bolted) kernel SLB entries. All * non-bolted kernel entries are flushed on any user fault, * or if there are already 3 non-boled kernel entries. */ BUILD_BUG_ON(SLB_CACHE_ENTRIES < 3); if (!kernel || slb_cache_index == 3) { int i; for (i = 0; i < slb_cache_index; i++) slb_cache_slbie_kernel(i); slb_cache_index = 0; } if (kernel) local_paca->slb_cache[slb_cache_index++] = esid_data >> SID_SHIFT; local_paca->slb_cache_ptr = slb_cache_index; } asm volatile("slbmte %0, %1" : : "r" (vsid_data), "r" (esid_data)); barrier(); if (!kernel) slb_cache_update(esid_data); return 0; } static long slb_allocate_kernel(unsigned long ea, unsigned long id) { unsigned long context; unsigned long flags; int ssize; if (id == LINEAR_MAP_REGION_ID) { /* We only support upto H_MAX_PHYSMEM_BITS */ if ((ea & EA_MASK) > (1UL << H_MAX_PHYSMEM_BITS)) return -EFAULT; flags = SLB_VSID_KERNEL | mmu_psize_defs[mmu_linear_psize].sllp; #ifdef CONFIG_SPARSEMEM_VMEMMAP } else if (id == VMEMMAP_REGION_ID) { if (ea >= H_VMEMMAP_END) return -EFAULT; flags = SLB_VSID_KERNEL | mmu_psize_defs[mmu_vmemmap_psize].sllp; #endif } else if (id == VMALLOC_REGION_ID) { if (ea >= H_VMALLOC_END) return -EFAULT; flags = local_paca->vmalloc_sllp; } else if (id == IO_REGION_ID) { if (ea >= H_KERN_IO_END) return -EFAULT; flags = SLB_VSID_KERNEL | mmu_psize_defs[mmu_io_psize].sllp; } else { return -EFAULT; } ssize = MMU_SEGSIZE_1T; if (!mmu_has_feature(MMU_FTR_1T_SEGMENT)) ssize = MMU_SEGSIZE_256M; context = get_kernel_context(ea); return slb_insert_entry(ea, context, flags, ssize, true); } static long slb_allocate_user(struct mm_struct *mm, unsigned long ea) { unsigned long context; unsigned long flags; int bpsize; int ssize; /* * consider this as bad access if we take a SLB miss * on an address above addr limit. */ if (ea >= mm_ctx_slb_addr_limit(&mm->context)) return -EFAULT; context = get_user_context(&mm->context, ea); if (!context) return -EFAULT; if (unlikely(ea >= H_PGTABLE_RANGE)) { WARN_ON(1); return -EFAULT; } ssize = user_segment_size(ea); bpsize = get_slice_psize(mm, ea); flags = SLB_VSID_USER | mmu_psize_defs[bpsize].sllp; return slb_insert_entry(ea, context, flags, ssize, false); } long do_slb_fault(struct pt_regs *regs, unsigned long ea) { unsigned long id = get_region_id(ea); /* IRQs are not reconciled here, so can't check irqs_disabled */ VM_WARN_ON(mfmsr() & MSR_EE); if (unlikely(!(regs->msr & MSR_RI))) return -EINVAL; /* * SLB kernel faults must be very careful not to touch anything * that is not bolted. E.g., PACA and global variables are okay, * mm->context stuff is not. * * SLB user faults can access all of kernel memory, but must be * careful not to touch things like IRQ state because it is not * "reconciled" here. The difficulty is that we must use * fast_exception_return to return from kernel SLB faults without * looking at possible non-bolted memory. We could test user vs * kernel faults in the interrupt handler asm and do a full fault, * reconcile, ret_from_except for user faults which would make them * first class kernel code. But for performance it's probably nicer * if they go via fast_exception_return too. */ if (id >= LINEAR_MAP_REGION_ID) { long err; #ifdef CONFIG_DEBUG_VM /* Catch recursive kernel SLB faults. */ BUG_ON(local_paca->in_kernel_slb_handler); local_paca->in_kernel_slb_handler = 1; #endif err = slb_allocate_kernel(ea, id); #ifdef CONFIG_DEBUG_VM local_paca->in_kernel_slb_handler = 0; #endif return err; } else { struct mm_struct *mm = current->mm; long err; if (unlikely(!mm)) return -EFAULT; err = slb_allocate_user(mm, ea); if (!err) preload_add(current_thread_info(), ea); return err; } } void do_bad_slb_fault(struct pt_regs *regs, unsigned long ea, long err) { if (err == -EFAULT) { if (user_mode(regs)) _exception(SIGSEGV, regs, SEGV_BNDERR, ea); else bad_page_fault(regs, ea, SIGSEGV); } else if (err == -EINVAL) { unrecoverable_exception(regs); } else { BUG(); } }