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-rw-r--r--arch/powerpc/mm/book3s64/slb.c905
1 files changed, 905 insertions, 0 deletions
diff --git a/arch/powerpc/mm/book3s64/slb.c b/arch/powerpc/mm/book3s64/slb.c
new file mode 100644
index 000000000..ccf0a876a
--- /dev/null
+++ b/arch/powerpc/mm/book3s64/slb.c
@@ -0,0 +1,905 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * PowerPC64 SLB support.
+ *
+ * Copyright (C) 2004 David Gibson <dwg@au.ibm.com>, 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 <anton@au.ibm.com>, IBM
+ */
+
+#include <asm/asm-prototypes.h>
+#include <asm/mmu.h>
+#include <asm/mmu_context.h>
+#include <asm/paca.h>
+#include <asm/lppaca.h>
+#include <asm/ppc-opcode.h>
+#include <asm/cputable.h>
+#include <asm/cacheflush.h>
+#include <asm/smp.h>
+#include <linux/compiler.h>
+#include <linux/context_tracking.h>
+#include <linux/mm_types.h>
+#include <linux/pgtable.h>
+
+#include <asm/udbg.h>
+#include <asm/code-patching.h>
+
+#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();
+ }
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-09 20:13:07 +0000