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Diffstat (limited to 'arch/arc/mm/tlb.c')
| -rw-r--r-- | arch/arc/mm/tlb.c | 645 |
1 files changed, 645 insertions, 0 deletions
diff --git a/arch/arc/mm/tlb.c b/arch/arc/mm/tlb.c new file mode 100644 index 00000000000..9b9ce23f4ec --- /dev/null +++ b/arch/arc/mm/tlb.c @@ -0,0 +1,645 @@ +/* + * TLB Management (flush/create/diagnostics) for ARC700 + * + * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * vineetg: Aug 2011 + * -Reintroduce duplicate PD fixup - some customer chips still have the issue + * + * vineetg: May 2011 + * -No need to flush_cache_page( ) for each call to update_mmu_cache() + * some of the LMBench tests improved amazingly + * = page-fault thrice as fast (75 usec to 28 usec) + * = mmap twice as fast (9.6 msec to 4.6 msec), + * = fork (5.3 msec to 3.7 msec) + * + * vineetg: April 2011 : + * -MMU v3: PD{0,1} bits layout changed: They don't overlap anymore, + * helps avoid a shift when preparing PD0 from PTE + * + * vineetg: April 2011 : Preparing for MMU V3 + * -MMU v2/v3 BCRs decoded differently + * -Remove TLB_SIZE hardcoding as it's variable now: 256 or 512 + * -tlb_entry_erase( ) can be void + * -local_flush_tlb_range( ): + * = need not "ceil" @end + * = walks MMU only if range spans < 32 entries, as opposed to 256 + * + * Vineetg: Sept 10th 2008 + * -Changes related to MMU v2 (Rel 4.8) + * + * Vineetg: Aug 29th 2008 + * -In TLB Flush operations (Metal Fix MMU) there is a explict command to + * flush Micro-TLBS. If TLB Index Reg is invalid prior to TLBIVUTLB cmd, + * it fails. Thus need to load it with ANY valid value before invoking + * TLBIVUTLB cmd + * + * Vineetg: Aug 21th 2008: + * -Reduced the duration of IRQ lockouts in TLB Flush routines + * -Multiple copies of TLB erase code seperated into a "single" function + * -In TLB Flush routines, interrupt disabling moved UP to retrieve ASID + * in interrupt-safe region. + * + * Vineetg: April 23rd Bug #93131 + * Problem: tlb_flush_kernel_range() doesnt do anything if the range to + * flush is more than the size of TLB itself. + * + * Rahul Trivedi : Codito Technologies 2004 + */ + +#include <linux/module.h> +#include <asm/arcregs.h> +#include <asm/setup.h> +#include <asm/mmu_context.h> +#include <asm/tlb.h> + +/* Need for ARC MMU v2 + * + * ARC700 MMU-v1 had a Joint-TLB for Code and Data and is 2 way set-assoc. + * For a memcpy operation with 3 players (src/dst/code) such that all 3 pages + * map into same set, there would be contention for the 2 ways causing severe + * Thrashing. + * + * Although J-TLB is 2 way set assoc, ARC700 caches J-TLB into uTLBS which has + * much higher associativity. u-D-TLB is 8 ways, u-I-TLB is 4 ways. + * Given this, the thrasing problem should never happen because once the 3 + * J-TLB entries are created (even though 3rd will knock out one of the prev + * two), the u-D-TLB and u-I-TLB will have what is required to accomplish memcpy + * + * Yet we still see the Thrashing because a J-TLB Write cause flush of u-TLBs. + * This is a simple design for keeping them in sync. So what do we do? + * The solution which James came up was pretty neat. It utilised the assoc + * of uTLBs by not invalidating always but only when absolutely necessary. + * + * - Existing TLB commands work as before + * - New command (TLBWriteNI) for TLB write without clearing uTLBs + * - New command (TLBIVUTLB) to invalidate uTLBs. + * + * The uTLBs need only be invalidated when pages are being removed from the + * OS page table. If a 'victim' TLB entry is being overwritten in the main TLB + * as a result of a miss, the removed entry is still allowed to exist in the + * uTLBs as it is still valid and present in the OS page table. This allows the + * full associativity of the uTLBs to hide the limited associativity of the main + * TLB. + * + * During a miss handler, the new "TLBWriteNI" command is used to load + * entries without clearing the uTLBs. + * + * When the OS page table is updated, TLB entries that may be associated with a + * removed page are removed (flushed) from the TLB using TLBWrite. In this + * circumstance, the uTLBs must also be cleared. This is done by using the + * existing TLBWrite command. An explicit IVUTLB is also required for those + * corner cases when TLBWrite was not executed at all because the corresp + * J-TLB entry got evicted/replaced. + */ + +/* A copy of the ASID from the PID reg is kept in asid_cache */ +int asid_cache = FIRST_ASID; + +/* ASID to mm struct mapping. We have one extra entry corresponding to + * NO_ASID to save us a compare when clearing the mm entry for old asid + * see get_new_mmu_context (asm-arc/mmu_context.h) + */ +struct mm_struct *asid_mm_map[NUM_ASID + 1]; + +/* + * Utility Routine to erase a J-TLB entry + * The procedure is to look it up in the MMU. If found, ERASE it by + * issuing a TlbWrite CMD with PD0 = PD1 = 0 + */ + +static void __tlb_entry_erase(void) +{ + write_aux_reg(ARC_REG_TLBPD1, 0); + write_aux_reg(ARC_REG_TLBPD0, 0); + write_aux_reg(ARC_REG_TLBCOMMAND, TLBWrite); +} + +static void tlb_entry_erase(unsigned int vaddr_n_asid) +{ + unsigned int idx; + + /* Locate the TLB entry for this vaddr + ASID */ + write_aux_reg(ARC_REG_TLBPD0, vaddr_n_asid); + write_aux_reg(ARC_REG_TLBCOMMAND, TLBProbe); + idx = read_aux_reg(ARC_REG_TLBINDEX); + + /* No error means entry found, zero it out */ + if (likely(!(idx & TLB_LKUP_ERR))) { + __tlb_entry_erase(); + } else { /* Some sort of Error */ + + /* Duplicate entry error */ + if (idx & 0x1) { + /* TODO we need to handle this case too */ + pr_emerg("unhandled Duplicate flush for %x\n", + vaddr_n_asid); + } + /* else entry not found so nothing to do */ + } +} + +/**************************************************************************** + * ARC700 MMU caches recently used J-TLB entries (RAM) as uTLBs (FLOPs) + * + * New IVUTLB cmd in MMU v2 explictly invalidates the uTLB + * + * utlb_invalidate ( ) + * -For v2 MMU calls Flush uTLB Cmd + * -For v1 MMU does nothing (except for Metal Fix v1 MMU) + * This is because in v1 TLBWrite itself invalidate uTLBs + ***************************************************************************/ + +static void utlb_invalidate(void) +{ +#if (CONFIG_ARC_MMU_VER >= 2) + +#if (CONFIG_ARC_MMU_VER < 3) + /* MMU v2 introduced the uTLB Flush command. + * There was however an obscure hardware bug, where uTLB flush would + * fail when a prior probe for J-TLB (both totally unrelated) would + * return lkup err - because the entry didnt exist in MMU. + * The Workround was to set Index reg with some valid value, prior to + * flush. This was fixed in MMU v3 hence not needed any more + */ + unsigned int idx; + + /* make sure INDEX Reg is valid */ + idx = read_aux_reg(ARC_REG_TLBINDEX); + + /* If not write some dummy val */ + if (unlikely(idx & TLB_LKUP_ERR)) + write_aux_reg(ARC_REG_TLBINDEX, 0xa); +#endif + + write_aux_reg(ARC_REG_TLBCOMMAND, TLBIVUTLB); +#endif + +} + +/* + * Un-conditionally (without lookup) erase the entire MMU contents + */ + +noinline void local_flush_tlb_all(void) +{ + unsigned long flags; + unsigned int entry; + struct cpuinfo_arc_mmu *mmu = &cpuinfo_arc700[smp_processor_id()].mmu; + + local_irq_save(flags); + + /* Load PD0 and PD1 with template for a Blank Entry */ + write_aux_reg(ARC_REG_TLBPD1, 0); + write_aux_reg(ARC_REG_TLBPD0, 0); + + for (entry = 0; entry < mmu->num_tlb; entry++) { + /* write this entry to the TLB */ + write_aux_reg(ARC_REG_TLBINDEX, entry); + write_aux_reg(ARC_REG_TLBCOMMAND, TLBWrite); + } + + utlb_invalidate(); + + local_irq_restore(flags); +} + +/* + * Flush the entrie MM for userland. The fastest way is to move to Next ASID + */ +noinline void local_flush_tlb_mm(struct mm_struct *mm) +{ + /* + * Small optimisation courtesy IA64 + * flush_mm called during fork,exit,munmap etc, multiple times as well. + * Only for fork( ) do we need to move parent to a new MMU ctxt, + * all other cases are NOPs, hence this check. + */ + if (atomic_read(&mm->mm_users) == 0) + return; + + /* + * Workaround for Android weirdism: + * A binder VMA could end up in a task such that vma->mm != tsk->mm + * old code would cause h/w - s/w ASID to get out of sync + */ + if (current->mm != mm) + destroy_context(mm); + else + get_new_mmu_context(mm); +} + +/* + * Flush a Range of TLB entries for userland. + * @start is inclusive, while @end is exclusive + * Difference between this and Kernel Range Flush is + * -Here the fastest way (if range is too large) is to move to next ASID + * without doing any explicit Shootdown + * -In case of kernel Flush, entry has to be shot down explictly + */ +void local_flush_tlb_range(struct vm_area_struct *vma, unsigned long start, + unsigned long end) +{ + unsigned long flags; + unsigned int asid; + + /* If range @start to @end is more than 32 TLB entries deep, + * its better to move to a new ASID rather than searching for + * individual entries and then shooting them down + * + * The calc above is rough, doesn't account for unaligned parts, + * since this is heuristics based anyways + */ + if (unlikely((end - start) >= PAGE_SIZE * 32)) { + local_flush_tlb_mm(vma->vm_mm); + return; + } + + /* + * @start moved to page start: this alone suffices for checking + * loop end condition below, w/o need for aligning @end to end + * e.g. 2000 to 4001 will anyhow loop twice + */ + start &= PAGE_MASK; + + local_irq_save(flags); + asid = vma->vm_mm->context.asid; + + if (asid != NO_ASID) { + while (start < end) { + tlb_entry_erase(start | (asid & 0xff)); + start += PAGE_SIZE; + } + } + + utlb_invalidate(); + + local_irq_restore(flags); +} + +/* Flush the kernel TLB entries - vmalloc/modules (Global from MMU perspective) + * @start, @end interpreted as kvaddr + * Interestingly, shared TLB entries can also be flushed using just + * @start,@end alone (interpreted as user vaddr), although technically SASID + * is also needed. However our smart TLbProbe lookup takes care of that. + */ +void local_flush_tlb_kernel_range(unsigned long start, unsigned long end) +{ + unsigned long flags; + + /* exactly same as above, except for TLB entry not taking ASID */ + + if (unlikely((end - start) >= PAGE_SIZE * 32)) { + local_flush_tlb_all(); + return; + } + + start &= PAGE_MASK; + + local_irq_save(flags); + while (start < end) { + tlb_entry_erase(start); + start += PAGE_SIZE; + } + + utlb_invalidate(); + + local_irq_restore(flags); +} + +/* + * Delete TLB entry in MMU for a given page (??? address) + * NOTE One TLB entry contains translation for single PAGE + */ + +void local_flush_tlb_page(struct vm_area_struct *vma, unsigned long page) +{ + unsigned long flags; + + /* Note that it is critical that interrupts are DISABLED between + * checking the ASID and using it flush the TLB entry + */ + local_irq_save(flags); + + if (vma->vm_mm->context.asid != NO_ASID) { + tlb_entry_erase((page & PAGE_MASK) | + (vma->vm_mm->context.asid & 0xff)); + utlb_invalidate(); + } + + local_irq_restore(flags); +} + +/* + * Routine to create a TLB entry + */ +void create_tlb(struct vm_area_struct *vma, unsigned long address, pte_t *ptep) +{ + unsigned long flags; + unsigned int idx, asid_or_sasid; + unsigned long pd0_flags; + + /* + * create_tlb() assumes that current->mm == vma->mm, since + * -it ASID for TLB entry is fetched from MMU ASID reg (valid for curr) + * -completes the lazy write to SASID reg (again valid for curr tsk) + * + * Removing the assumption involves + * -Using vma->mm->context{ASID,SASID}, as opposed to MMU reg. + * -Fix the TLB paranoid debug code to not trigger false negatives. + * -More importantly it makes this handler inconsistent with fast-path + * TLB Refill handler which always deals with "current" + * + * Lets see the use cases when current->mm != vma->mm and we land here + * 1. execve->copy_strings()->__get_user_pages->handle_mm_fault + * Here VM wants to pre-install a TLB entry for user stack while + * current->mm still points to pre-execve mm (hence the condition). + * However the stack vaddr is soon relocated (randomization) and + * move_page_tables() tries to undo that TLB entry. + * Thus not creating TLB entry is not any worse. + * + * 2. ptrace(POKETEXT) causes a CoW - debugger(current) inserting a + * breakpoint in debugged task. Not creating a TLB now is not + * performance critical. + * + * Both the cases above are not good enough for code churn. + */ + if (current->active_mm != vma->vm_mm) + return; + + local_irq_save(flags); + + tlb_paranoid_check(vma->vm_mm->context.asid, address); + + address &= PAGE_MASK; + + /* update this PTE credentials */ + pte_val(*ptep) |= (_PAGE_PRESENT | _PAGE_ACCESSED); + + /* Create HW TLB entry Flags (in PD0) from PTE Flags */ +#if (CONFIG_ARC_MMU_VER <= 2) + pd0_flags = ((pte_val(*ptep) & PTE_BITS_IN_PD0) >> 1); +#else + pd0_flags = ((pte_val(*ptep) & PTE_BITS_IN_PD0)); +#endif + + /* ASID for this task */ + asid_or_sasid = read_aux_reg(ARC_REG_PID) & 0xff; + + write_aux_reg(ARC_REG_TLBPD0, address | pd0_flags | asid_or_sasid); + + /* Load remaining info in PD1 (Page Frame Addr and Kx/Kw/Kr Flags) */ + write_aux_reg(ARC_REG_TLBPD1, (pte_val(*ptep) & PTE_BITS_IN_PD1)); + + /* First verify if entry for this vaddr+ASID already exists */ + write_aux_reg(ARC_REG_TLBCOMMAND, TLBProbe); + idx = read_aux_reg(ARC_REG_TLBINDEX); + + /* + * If Not already present get a free slot from MMU. + * Otherwise, Probe would have located the entry and set INDEX Reg + * with existing location. This will cause Write CMD to over-write + * existing entry with new PD0 and PD1 + */ + if (likely(idx & TLB_LKUP_ERR)) + write_aux_reg(ARC_REG_TLBCOMMAND, TLBGetIndex); + + /* + * Commit the Entry to MMU + * It doesnt sound safe to use the TLBWriteNI cmd here + * which doesn't flush uTLBs. I'd rather be safe than sorry. + */ + write_aux_reg(ARC_REG_TLBCOMMAND, TLBWrite); + + local_irq_restore(flags); +} + +/* arch hook called by core VM at the end of handle_mm_fault( ), + * when a new PTE is entered in Page Tables or an existing one + * is modified. We aggresively pre-install a TLB entry + */ + +void update_mmu_cache(struct vm_area_struct *vma, unsigned long vaddress, + pte_t *ptep) +{ + + create_tlb(vma, vaddress, ptep); +} + +/* Read the Cache Build Confuration Registers, Decode them and save into + * the cpuinfo structure for later use. + * No Validation is done here, simply read/convert the BCRs + */ +void __init read_decode_mmu_bcr(void) +{ + unsigned int tmp; + struct bcr_mmu_1_2 *mmu2; /* encoded MMU2 attr */ + struct bcr_mmu_3 *mmu3; /* encoded MMU3 attr */ + struct cpuinfo_arc_mmu *mmu = &cpuinfo_arc700[smp_processor_id()].mmu; + + tmp = read_aux_reg(ARC_REG_MMU_BCR); + mmu->ver = (tmp >> 24); + + if (mmu->ver <= 2) { + mmu2 = (struct bcr_mmu_1_2 *)&tmp; + mmu->pg_sz = PAGE_SIZE; + mmu->sets = 1 << mmu2->sets; + mmu->ways = 1 << mmu2->ways; + mmu->u_dtlb = mmu2->u_dtlb; + mmu->u_itlb = mmu2->u_itlb; + } else { + mmu3 = (struct bcr_mmu_3 *)&tmp; + mmu->pg_sz = 512 << mmu3->pg_sz; + mmu->sets = 1 << mmu3->sets; + mmu->ways = 1 << mmu3->ways; + mmu->u_dtlb = mmu3->u_dtlb; + mmu->u_itlb = mmu3->u_itlb; + } + + mmu->num_tlb = mmu->sets * mmu->ways; +} + +char *arc_mmu_mumbojumbo(int cpu_id, char *buf, int len) +{ + int n = 0; + struct cpuinfo_arc_mmu *p_mmu = &cpuinfo_arc700[smp_processor_id()].mmu; + + n += scnprintf(buf + n, len - n, "ARC700 MMU [v%x]\t: %dk PAGE, ", + p_mmu->ver, TO_KB(p_mmu->pg_sz)); + + n += scnprintf(buf + n, len - n, + "J-TLB %d (%dx%d), uDTLB %d, uITLB %d, %s\n", + p_mmu->num_tlb, p_mmu->sets, p_mmu->ways, + p_mmu->u_dtlb, p_mmu->u_itlb, + __CONFIG_ARC_MMU_SASID_VAL ? "SASID" : ""); + + return buf; +} + +void __init arc_mmu_init(void) +{ + char str[256]; + struct cpuinfo_arc_mmu *mmu = &cpuinfo_arc700[smp_processor_id()].mmu; + + printk(arc_mmu_mumbojumbo(0, str, sizeof(str))); + + /* For efficiency sake, kernel is compile time built for a MMU ver + * This must match the hardware it is running on. + * Linux built for MMU V2, if run on MMU V1 will break down because V1 + * hardware doesn't understand cmds such as WriteNI, or IVUTLB + * On the other hand, Linux built for V1 if run on MMU V2 will do + * un-needed workarounds to prevent memcpy thrashing. + * Similarly MMU V3 has new features which won't work on older MMU + */ + if (mmu->ver != CONFIG_ARC_MMU_VER) { + panic("MMU ver %d doesn't match kernel built for %d...\n", + mmu->ver, CONFIG_ARC_MMU_VER); + } + + if (mmu->pg_sz != PAGE_SIZE) + panic("MMU pg size != PAGE_SIZE (%luk)\n", TO_KB(PAGE_SIZE)); + + /* + * ASID mgmt data structures are compile time init + * asid_cache = FIRST_ASID and asid_mm_map[] all zeroes + */ + + local_flush_tlb_all(); + + /* Enable the MMU */ + write_aux_reg(ARC_REG_PID, MMU_ENABLE); + + /* In smp we use this reg for interrupt 1 scratch */ +#ifndef CONFIG_SMP + /* swapper_pg_dir is the pgd for the kernel, used by vmalloc */ + write_aux_reg(ARC_REG_SCRATCH_DATA0, swapper_pg_dir); +#endif +} + +/* + * TLB Programmer's Model uses Linear Indexes: 0 to {255, 511} for 128 x {2,4} + * The mapping is Column-first. + * --------------------- ----------- + * |way0|way1|way2|way3| |way0|way1| + * --------------------- ----------- + * [set0] | 0 | 1 | 2 | 3 | | 0 | 1 | + * [set1] | 4 | 5 | 6 | 7 | | 2 | 3 | + * ~ ~ ~ ~ + * [set127] | 508| 509| 510| 511| | 254| 255| + * --------------------- ----------- + * For normal operations we don't(must not) care how above works since + * MMU cmd getIndex(vaddr) abstracts that out. + * However for walking WAYS of a SET, we need to know this + */ +#define SET_WAY_TO_IDX(mmu, set, way) ((set) * mmu->ways + (way)) + +/* Handling of Duplicate PD (TLB entry) in MMU. + * -Could be due to buggy customer tapeouts or obscure kernel bugs + * -MMU complaints not at the time of duplicate PD installation, but at the + * time of lookup matching multiple ways. + * -Ideally these should never happen - but if they do - workaround by deleting + * the duplicate one. + * -Knob to be verbose abt it.(TODO: hook them up to debugfs) + */ +volatile int dup_pd_verbose = 1;/* Be slient abt it or complain (default) */ + +void do_tlb_overlap_fault(unsigned long cause, unsigned long address, + struct pt_regs *regs) +{ + int set, way, n; + unsigned int pd0[4], pd1[4]; /* assume max 4 ways */ + unsigned long flags, is_valid; + struct cpuinfo_arc_mmu *mmu = &cpuinfo_arc700[smp_processor_id()].mmu; + + local_irq_save(flags); + + /* re-enable the MMU */ + write_aux_reg(ARC_REG_PID, MMU_ENABLE | read_aux_reg(ARC_REG_PID)); + + /* loop thru all sets of TLB */ + for (set = 0; set < mmu->sets; set++) { + + /* read out all the ways of current set */ + for (way = 0, is_valid = 0; way < mmu->ways; way++) { + write_aux_reg(ARC_REG_TLBINDEX, + SET_WAY_TO_IDX(mmu, set, way)); + write_aux_reg(ARC_REG_TLBCOMMAND, TLBRead); + pd0[way] = read_aux_reg(ARC_REG_TLBPD0); + pd1[way] = read_aux_reg(ARC_REG_TLBPD1); + is_valid |= pd0[way] & _PAGE_PRESENT; + } + + /* If all the WAYS in SET are empty, skip to next SET */ + if (!is_valid) + continue; + + /* Scan the set for duplicate ways: needs a nested loop */ + for (way = 0; way < mmu->ways; way++) { + if (!pd0[way]) + continue; + + for (n = way + 1; n < mmu->ways; n++) { + if ((pd0[way] & PAGE_MASK) == + (pd0[n] & PAGE_MASK)) { + + if (dup_pd_verbose) { + pr_info("Duplicate PD's @" + "[%d:%d]/[%d:%d]\n", + set, way, set, n); + pr_info("TLBPD0[%u]: %08x\n", + way, pd0[way]); + } + + /* + * clear entry @way and not @n. This is + * critical to our optimised loop + */ + pd0[way] = pd1[way] = 0; + write_aux_reg(ARC_REG_TLBINDEX, + SET_WAY_TO_IDX(mmu, set, way)); + __tlb_entry_erase(); + } + } + } + } + + local_irq_restore(flags); +} + +/*********************************************************************** + * Diagnostic Routines + * -Called from Low Level TLB Hanlders if things don;t look good + **********************************************************************/ + +#ifdef CONFIG_ARC_DBG_TLB_PARANOIA + +/* + * Low Level ASM TLB handler calls this if it finds that HW and SW ASIDS + * don't match + */ +void print_asid_mismatch(int is_fast_path) +{ + int pid_sw, pid_hw; + pid_sw = current->active_mm->context.asid; + pid_hw = read_aux_reg(ARC_REG_PID) & 0xff; + + pr_emerg("ASID Mismatch in %s Path Handler: sw-pid=0x%x hw-pid=0x%x\n", + is_fast_path ? "Fast" : "Slow", pid_sw, pid_hw); + + __asm__ __volatile__("flag 1"); +} + +void tlb_paranoid_check(unsigned int pid_sw, unsigned long addr) +{ + unsigned int pid_hw; + + pid_hw = read_aux_reg(ARC_REG_PID) & 0xff; + + if (addr < 0x70000000 && ((pid_hw != pid_sw) || (pid_sw == NO_ASID))) + print_asid_mismatch(0); +} +#endif |