diff options
| -rw-r--r-- | drivers/misc/sgi-gru/grufault.c | 633 |
1 files changed, 633 insertions, 0 deletions
diff --git a/drivers/misc/sgi-gru/grufault.c b/drivers/misc/sgi-gru/grufault.c new file mode 100644 index 000000000000..3d33015bbf31 --- /dev/null +++ b/drivers/misc/sgi-gru/grufault.c @@ -0,0 +1,633 @@ +/* + * SN Platform GRU Driver + * + * FAULT HANDLER FOR GRU DETECTED TLB MISSES + * + * This file contains code that handles TLB misses within the GRU. + * These misses are reported either via interrupts or user polling of + * the user CB. + * + * Copyright (c) 2008 Silicon Graphics, Inc. All Rights Reserved. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + */ + +#include <linux/kernel.h> +#include <linux/errno.h> +#include <linux/spinlock.h> +#include <linux/mm.h> +#include <linux/hugetlb.h> +#include <linux/device.h> +#include <linux/io.h> +#include <linux/uaccess.h> +#include <asm/pgtable.h> +#include "gru.h" +#include "grutables.h" +#include "grulib.h" +#include "gru_instructions.h" +#include <asm/uv/uv_hub.h> + +/* + * Test if a physical address is a valid GRU GSEG address + */ +static inline int is_gru_paddr(unsigned long paddr) +{ + return paddr >= gru_start_paddr && paddr < gru_end_paddr; +} + +/* + * Find the vma of a GRU segment. Caller must hold mmap_sem. + */ +struct vm_area_struct *gru_find_vma(unsigned long vaddr) +{ + struct vm_area_struct *vma; + + vma = find_vma(current->mm, vaddr); + if (vma && vma->vm_start <= vaddr && vma->vm_ops == &gru_vm_ops) + return vma; + return NULL; +} + +/* + * Find and lock the gts that contains the specified user vaddr. + * + * Returns: + * - *gts with the mmap_sem locked for read and the GTS locked. + * - NULL if vaddr invalid OR is not a valid GSEG vaddr. + */ + +static struct gru_thread_state *gru_find_lock_gts(unsigned long vaddr) +{ + struct mm_struct *mm = current->mm; + struct vm_area_struct *vma; + struct gru_thread_state *gts = NULL; + + down_read(&mm->mmap_sem); + vma = gru_find_vma(vaddr); + if (vma) + gts = gru_find_thread_state(vma, TSID(vaddr, vma)); + if (gts) + mutex_lock(>s->ts_ctxlock); + else + up_read(&mm->mmap_sem); + return gts; +} + +static struct gru_thread_state *gru_alloc_locked_gts(unsigned long vaddr) +{ + struct mm_struct *mm = current->mm; + struct vm_area_struct *vma; + struct gru_thread_state *gts = NULL; + + down_write(&mm->mmap_sem); + vma = gru_find_vma(vaddr); + if (vma) + gts = gru_alloc_thread_state(vma, TSID(vaddr, vma)); + if (gts) { + mutex_lock(>s->ts_ctxlock); + downgrade_write(&mm->mmap_sem); + } else { + up_write(&mm->mmap_sem); + } + + return gts; +} + +/* + * Unlock a GTS that was previously locked with gru_find_lock_gts(). + */ +static void gru_unlock_gts(struct gru_thread_state *gts) +{ + mutex_unlock(>s->ts_ctxlock); + up_read(¤t->mm->mmap_sem); +} + +/* + * Set a CB.istatus to active using a user virtual address. This must be done + * just prior to a TFH RESTART. The new cb.istatus is an in-cache status ONLY. + * If the line is evicted, the status may be lost. The in-cache update + * is necessary to prevent the user from seeing a stale cb.istatus that will + * change as soon as the TFH restart is complete. Races may cause an + * occasional failure to clear the cb.istatus, but that is ok. + * + * If the cb address is not valid (should not happen, but...), nothing + * bad will happen.. The get_user()/put_user() will fail but there + * are no bad side-effects. + */ +static void gru_cb_set_istatus_active(unsigned long __user *cb) +{ + union { + struct gru_instruction_bits bits; + unsigned long dw; + } u; + + if (cb) { + get_user(u.dw, cb); + u.bits.istatus = CBS_ACTIVE; + put_user(u.dw, cb); + } +} + +/* + * Convert a interrupt IRQ to a pointer to the GRU GTS that caused the + * interrupt. Interrupts are always sent to a cpu on the blade that contains the + * GRU (except for headless blades which are not currently supported). A blade + * has N grus; a block of N consecutive IRQs is assigned to the GRUs. The IRQ + * number uniquely identifies the GRU chiplet on the local blade that caused the + * interrupt. Always called in interrupt context. + */ +static inline struct gru_state *irq_to_gru(int irq) +{ + return &gru_base[uv_numa_blade_id()]->bs_grus[irq - IRQ_GRU]; +} + +/* + * Read & clear a TFM + * + * The GRU has an array of fault maps. A map is private to a cpu + * Only one cpu will be accessing a cpu's fault map. + * + * This function scans the cpu-private fault map & clears all bits that + * are set. The function returns a bitmap that indicates the bits that + * were cleared. Note that sense the maps may be updated asynchronously by + * the GRU, atomic operations must be used to clear bits. + */ +static void get_clear_fault_map(struct gru_state *gru, + struct gru_tlb_fault_map *map) +{ + unsigned long i, k; + struct gru_tlb_fault_map *tfm; + + tfm = get_tfm_for_cpu(gru, gru_cpu_fault_map_id()); + prefetchw(tfm); /* Helps on hardware, required for emulator */ + for (i = 0; i < BITS_TO_LONGS(GRU_NUM_CBE); i++) { + k = tfm->fault_bits[i]; + if (k) + k = xchg(&tfm->fault_bits[i], 0UL); + map->fault_bits[i] = k; + } + + /* + * Not functionally required but helps performance. (Required + * on emulator) + */ + gru_flush_cache(tfm); +} + +/* + * Atomic (interrupt context) & non-atomic (user context) functions to + * convert a vaddr into a physical address. The size of the page + * is returned in pageshift. + * returns: + * 0 - successful + * < 0 - error code + * 1 - (atomic only) try again in non-atomic context + */ +static int non_atomic_pte_lookup(struct vm_area_struct *vma, + unsigned long vaddr, int write, + unsigned long *paddr, int *pageshift) +{ + struct page *page; + + /* ZZZ Need to handle HUGE pages */ + if (is_vm_hugetlb_page(vma)) + return -EFAULT; + *pageshift = PAGE_SHIFT; + if (get_user_pages + (current, current->mm, vaddr, 1, write, 0, &page, NULL) <= 0) + return -EFAULT; + *paddr = page_to_phys(page); + put_page(page); + return 0; +} + +/* + * + * atomic_pte_lookup + * + * Convert a user virtual address to a physical address + * Only supports Intel large pages (2MB only) on x86_64. + * ZZZ - hugepage support is incomplete + */ +static int atomic_pte_lookup(struct vm_area_struct *vma, unsigned long vaddr, + int write, unsigned long *paddr, int *pageshift) +{ + pgd_t *pgdp; + pmd_t *pmdp; + pud_t *pudp; + pte_t pte; + + WARN_ON(irqs_disabled()); /* ZZZ debug */ + + local_irq_disable(); + pgdp = pgd_offset(vma->vm_mm, vaddr); + if (unlikely(pgd_none(*pgdp))) + goto err; + + pudp = pud_offset(pgdp, vaddr); + if (unlikely(pud_none(*pudp))) + goto err; + + pmdp = pmd_offset(pudp, vaddr); + if (unlikely(pmd_none(*pmdp))) + goto err; +#ifdef CONFIG_X86_64 + if (unlikely(pmd_large(*pmdp))) + pte = *(pte_t *) pmdp; + else +#endif + pte = *pte_offset_kernel(pmdp, vaddr); + + local_irq_enable(); + + if (unlikely(!pte_present(pte) || + (write && (!pte_write(pte) || !pte_dirty(pte))))) + return 1; + + *paddr = pte_pfn(pte) << PAGE_SHIFT; + *pageshift = is_vm_hugetlb_page(vma) ? HPAGE_SHIFT : PAGE_SHIFT; + return 0; + +err: + local_irq_enable(); + return 1; +} + +/* + * Drop a TLB entry into the GRU. The fault is described by info in an TFH. + * Input: + * cb Address of user CBR. Null if not running in user context + * Return: + * 0 = dropin, exception, or switch to UPM successful + * 1 = range invalidate active + * < 0 = error code + * + */ +static int gru_try_dropin(struct gru_thread_state *gts, + struct gru_tlb_fault_handle *tfh, + unsigned long __user *cb) +{ + struct mm_struct *mm = gts->ts_mm; + struct vm_area_struct *vma; + int pageshift, asid, write, ret; + unsigned long paddr, gpa, vaddr; + + /* + * NOTE: The GRU contains magic hardware that eliminates races between + * TLB invalidates and TLB dropins. If an invalidate occurs + * in the window between reading the TFH and the subsequent TLB dropin, + * the dropin is ignored. This eliminates the need for additional locks. + */ + + /* + * Error if TFH state is IDLE or FMM mode & the user issuing a UPM call. + * Might be a hardware race OR a stupid user. Ignore FMM because FMM + * is a transient state. + */ + if (tfh->state == TFHSTATE_IDLE) + goto failidle; + if (tfh->state == TFHSTATE_MISS_FMM && cb) + goto failfmm; + + write = (tfh->cause & TFHCAUSE_TLB_MOD) != 0; + vaddr = tfh->missvaddr; + asid = tfh->missasid; + if (asid == 0) + goto failnoasid; + + rmb(); /* TFH must be cache resident before reading ms_range_active */ + + /* + * TFH is cache resident - at least briefly. Fail the dropin + * if a range invalidate is active. + */ + if (atomic_read(>s->ts_gms->ms_range_active)) + goto failactive; + + vma = find_vma(mm, vaddr); + if (!vma) + goto failinval; + + /* + * Atomic lookup is faster & usually works even if called in non-atomic + * context. + */ + ret = atomic_pte_lookup(vma, vaddr, write, &paddr, &pageshift); + if (ret) { + if (!cb) + goto failupm; + if (non_atomic_pte_lookup(vma, vaddr, write, &paddr, + &pageshift)) + goto failinval; + } + if (is_gru_paddr(paddr)) + goto failinval; + + paddr = paddr & ~((1UL << pageshift) - 1); + gpa = uv_soc_phys_ram_to_gpa(paddr); + gru_cb_set_istatus_active(cb); + tfh_write_restart(tfh, gpa, GAA_RAM, vaddr, asid, write, + GRU_PAGESIZE(pageshift)); + STAT(tlb_dropin); + gru_dbg(grudev, + "%s: tfh 0x%p, vaddr 0x%lx, asid 0x%x, ps %d, gpa 0x%lx\n", + ret ? "non-atomic" : "atomic", tfh, vaddr, asid, + pageshift, gpa); + return 0; + +failnoasid: + /* No asid (delayed unload). */ + STAT(tlb_dropin_fail_no_asid); + gru_dbg(grudev, "FAILED no_asid tfh: 0x%p, vaddr 0x%lx\n", tfh, vaddr); + if (!cb) + tfh_user_polling_mode(tfh); + else + gru_flush_cache(tfh); + return -EAGAIN; + +failupm: + /* Atomic failure switch CBR to UPM */ + tfh_user_polling_mode(tfh); + STAT(tlb_dropin_fail_upm); + gru_dbg(grudev, "FAILED upm tfh: 0x%p, vaddr 0x%lx\n", tfh, vaddr); + return 1; + +failfmm: + /* FMM state on UPM call */ + STAT(tlb_dropin_fail_fmm); + gru_dbg(grudev, "FAILED fmm tfh: 0x%p, state %d\n", tfh, tfh->state); + return 0; + +failidle: + /* TFH was idle - no miss pending */ + gru_flush_cache(tfh); + if (cb) + gru_flush_cache(cb); + STAT(tlb_dropin_fail_idle); + gru_dbg(grudev, "FAILED idle tfh: 0x%p, state %d\n", tfh, tfh->state); + return 0; + +failinval: + /* All errors (atomic & non-atomic) switch CBR to EXCEPTION state */ + tfh_exception(tfh); + STAT(tlb_dropin_fail_invalid); + gru_dbg(grudev, "FAILED inval tfh: 0x%p, vaddr 0x%lx\n", tfh, vaddr); + return -EFAULT; + +failactive: + /* Range invalidate active. Switch to UPM iff atomic */ + if (!cb) + tfh_user_polling_mode(tfh); + else + gru_flush_cache(tfh); + STAT(tlb_dropin_fail_range_active); + gru_dbg(grudev, "FAILED range active: tfh 0x%p, vaddr 0x%lx\n", + tfh, vaddr); + return 1; +} + +/* + * Process an external interrupt from the GRU. This interrupt is + * caused by a TLB miss. + * Note that this is the interrupt handler that is registered with linux + * interrupt handlers. + */ +irqreturn_t gru_intr(int irq, void *dev_id) +{ + struct gru_state *gru; + struct gru_tlb_fault_map map; + struct gru_thread_state *gts; + struct gru_tlb_fault_handle *tfh = NULL; + int cbrnum, ctxnum; + + STAT(intr); + + gru = irq_to_gru(irq); + if (!gru) { + dev_err(grudev, "GRU: invalid interrupt: cpu %d, irq %d\n", + raw_smp_processor_id(), irq); + return IRQ_NONE; + } + get_clear_fault_map(gru, &map); + gru_dbg(grudev, "irq %d, gru %x, map 0x%lx\n", irq, gru->gs_gid, + map.fault_bits[0]); + + for_each_cbr_in_tfm(cbrnum, map.fault_bits) { + tfh = get_tfh_by_index(gru, cbrnum); + prefetchw(tfh); /* Helps on hdw, required for emulator */ + + /* + * When hardware sets a bit in the faultmap, it implicitly + * locks the GRU context so that it cannot be unloaded. + * The gts cannot change until a TFH start/writestart command + * is issued. + */ + ctxnum = tfh->ctxnum; + gts = gru->gs_gts[ctxnum]; + + /* + * This is running in interrupt context. Trylock the mmap_sem. + * If it fails, retry the fault in user context. + */ + if (down_read_trylock(>s->ts_mm->mmap_sem)) { + gru_try_dropin(gts, tfh, NULL); + up_read(>s->ts_mm->mmap_sem); + } else { + tfh_user_polling_mode(tfh); + } + } + return IRQ_HANDLED; +} + + +static int gru_user_dropin(struct gru_thread_state *gts, + struct gru_tlb_fault_handle *tfh, + unsigned long __user *cb) +{ + struct gru_mm_struct *gms = gts->ts_gms; + int ret; + + while (1) { + wait_event(gms->ms_wait_queue, + atomic_read(&gms->ms_range_active) == 0); + prefetchw(tfh); /* Helps on hdw, required for emulator */ + ret = gru_try_dropin(gts, tfh, cb); + if (ret <= 0) + return ret; + STAT(call_os_wait_queue); + } +} + +/* + * This interface is called as a result of a user detecting a "call OS" bit + * in a user CB. Normally means that a TLB fault has occurred. + * cb - user virtual address of the CB + */ +int gru_handle_user_call_os(unsigned long cb) +{ + struct gru_tlb_fault_handle *tfh; + struct gru_thread_state *gts; + unsigned long __user *cbp; + int ucbnum, cbrnum, ret = -EINVAL; + + STAT(call_os); + gru_dbg(grudev, "address 0x%lx\n", cb); + + /* sanity check the cb pointer */ + ucbnum = get_cb_number((void *)cb); + if ((cb & (GRU_HANDLE_STRIDE - 1)) || ucbnum >= GRU_NUM_CB) + return -EINVAL; + cbp = (unsigned long *)cb; + + gts = gru_find_lock_gts(cb); + if (!gts) + return -EINVAL; + + if (ucbnum >= gts->ts_cbr_au_count * GRU_CBR_AU_SIZE) { + ret = -EINVAL; + goto exit; + } + + /* + * If force_unload is set, the UPM TLB fault is phony. The task + * has migrated to another node and the GSEG must be moved. Just + * unload the context. The task will page fault and assign a new + * context. + */ + ret = -EAGAIN; + cbrnum = thread_cbr_number(gts, ucbnum); + if (gts->ts_force_unload) { + gru_unload_context(gts, 1); + } else if (gts->ts_gru) { + tfh = get_tfh_by_index(gts->ts_gru, cbrnum); + ret = gru_user_dropin(gts, tfh, cbp); + } +exit: + gru_unlock_gts(gts); + return ret; +} + +/* + * Fetch the exception detail information for a CB that terminated with + * an exception. + */ +int gru_get_exception_detail(unsigned long arg) +{ + struct control_block_extended_exc_detail excdet; + struct gru_control_block_extended *cbe; + struct gru_thread_state *gts; + int ucbnum, cbrnum, ret; + + STAT(user_exception); + if (copy_from_user(&excdet, (void __user *)arg, sizeof(excdet))) + return -EFAULT; + + gru_dbg(grudev, "address 0x%lx\n", excdet.cb); + gts = gru_find_lock_gts(excdet.cb); + if (!gts) + return -EINVAL; + + if (gts->ts_gru) { + ucbnum = get_cb_number((void *)excdet.cb); + cbrnum = thread_cbr_number(gts, ucbnum); + cbe = get_cbe_by_index(gts->ts_gru, cbrnum); + excdet.opc = cbe->opccpy; + excdet.exopc = cbe->exopccpy; + excdet.ecause = cbe->ecause; + excdet.exceptdet0 = cbe->idef1upd; + excdet.exceptdet1 = cbe->idef3upd; + ret = 0; + } else { + ret = -EAGAIN; + } + gru_unlock_gts(gts); + + gru_dbg(grudev, "address 0x%lx, ecause 0x%x\n", excdet.cb, + excdet.ecause); + if (!ret && copy_to_user((void __user *)arg, &excdet, sizeof(excdet))) + ret = -EFAULT; + return ret; +} + +/* + * User request to unload a context. Content is saved for possible reload. + */ +int gru_user_unload_context(unsigned long arg) +{ + struct gru_thread_state *gts; + struct gru_unload_context_req req; + + STAT(user_unload_context); + if (copy_from_user(&req, (void __user *)arg, sizeof(req))) + return -EFAULT; + + gru_dbg(grudev, "gseg 0x%lx\n", req.gseg); + + gts = gru_find_lock_gts(req.gseg); + if (!gts) + return -EINVAL; + + if (gts->ts_gru) + gru_unload_context(gts, 1); + gru_unlock_gts(gts); + + return 0; +} + +/* + * User request to flush a range of virtual addresses from the GRU TLB + * (Mainly for testing). + */ +int gru_user_flush_tlb(unsigned long arg) +{ + struct gru_thread_state *gts; + struct gru_flush_tlb_req req; + + STAT(user_flush_tlb); + if (copy_from_user(&req, (void __user *)arg, sizeof(req))) + return -EFAULT; + + gru_dbg(grudev, "gseg 0x%lx, vaddr 0x%lx, len 0x%lx\n", req.gseg, + req.vaddr, req.len); + + gts = gru_find_lock_gts(req.gseg); + if (!gts) + return -EINVAL; + + gru_flush_tlb_range(gts->ts_gms, req.vaddr, req.vaddr + req.len); + gru_unlock_gts(gts); + + return 0; +} + +/* + * Register the current task as the user of the GSEG slice. + * Needed for TLB fault interrupt targeting. + */ +int gru_set_task_slice(long address) +{ + struct gru_thread_state *gts; + + STAT(set_task_slice); + gru_dbg(grudev, "address 0x%lx\n", address); + gts = gru_alloc_locked_gts(address); + if (!gts) + return -EINVAL; + + gts->ts_tgid_owner = current->tgid; + gru_unlock_gts(gts); + + return 0; +} |