/*
* 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
*
* NOTE: mmap_sem is already held on entry to this function. This
* guarantees existence of the page tables.
*/
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;
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);
if (unlikely(!pte_present(pte) ||
(write && (!pte_write(pte) || !pte_dirty(pte)))))
return 1;
*paddr = pte_pfn(pte) << PAGE_SHIFT;
#ifdef CONFIG_HUGETLB_PAGE
*pageshift = is_vm_hugetlb_page(vma) ? HPAGE_SHIFT : PAGE_SHIFT;
#else
*pageshift = PAGE_SHIFT;
#endif
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.
*/
rmb(); /* Must/check ms_range_active before loading PTEs */
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);
prefetchw(cbe); /* Harmless on hardware, required for emulator */
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;
}
