![Thadeu Lima de Souza Cascardo](/assets/img/avatar_default.png)
Some devices have a dma-window that starts at the address 0. This allows DMA addresses to be mapped to this address and returned to drivers as a valid DMA address. Some drivers may not behave well in this case, since the address 0 is considered an error or not allocated. The solution to avoid this kind of error from happening is reserve the page addressed as 0 so it cannot be allocated for a DMA mapping. Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@linux.vnet.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
680 lines
18 KiB
C
680 lines
18 KiB
C
/*
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* Copyright (C) 2001 Mike Corrigan & Dave Engebretsen, IBM Corporation
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*
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* Rewrite, cleanup, new allocation schemes, virtual merging:
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* Copyright (C) 2004 Olof Johansson, IBM Corporation
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* and Ben. Herrenschmidt, IBM Corporation
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*
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* Dynamic DMA mapping support, bus-independent parts.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include <linux/init.h>
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#include <linux/types.h>
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#include <linux/slab.h>
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#include <linux/mm.h>
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#include <linux/spinlock.h>
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#include <linux/string.h>
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#include <linux/dma-mapping.h>
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#include <linux/bitmap.h>
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#include <linux/iommu-helper.h>
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#include <linux/crash_dump.h>
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#include <asm/io.h>
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#include <asm/prom.h>
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#include <asm/iommu.h>
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#include <asm/pci-bridge.h>
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#include <asm/machdep.h>
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#include <asm/kdump.h>
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#define DBG(...)
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static int novmerge;
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static void __iommu_free(struct iommu_table *, dma_addr_t, unsigned int);
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static int __init setup_iommu(char *str)
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{
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if (!strcmp(str, "novmerge"))
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novmerge = 1;
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else if (!strcmp(str, "vmerge"))
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novmerge = 0;
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return 1;
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}
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__setup("iommu=", setup_iommu);
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static unsigned long iommu_range_alloc(struct device *dev,
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struct iommu_table *tbl,
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unsigned long npages,
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unsigned long *handle,
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unsigned long mask,
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unsigned int align_order)
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{
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unsigned long n, end, start;
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unsigned long limit;
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int largealloc = npages > 15;
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int pass = 0;
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unsigned long align_mask;
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unsigned long boundary_size;
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align_mask = 0xffffffffffffffffl >> (64 - align_order);
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/* This allocator was derived from x86_64's bit string search */
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/* Sanity check */
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if (unlikely(npages == 0)) {
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if (printk_ratelimit())
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WARN_ON(1);
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return DMA_ERROR_CODE;
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}
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if (handle && *handle)
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start = *handle;
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else
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start = largealloc ? tbl->it_largehint : tbl->it_hint;
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/* Use only half of the table for small allocs (15 pages or less) */
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limit = largealloc ? tbl->it_size : tbl->it_halfpoint;
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if (largealloc && start < tbl->it_halfpoint)
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start = tbl->it_halfpoint;
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/* The case below can happen if we have a small segment appended
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* to a large, or when the previous alloc was at the very end of
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* the available space. If so, go back to the initial start.
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*/
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if (start >= limit)
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start = largealloc ? tbl->it_largehint : tbl->it_hint;
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again:
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if (limit + tbl->it_offset > mask) {
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limit = mask - tbl->it_offset + 1;
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/* If we're constrained on address range, first try
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* at the masked hint to avoid O(n) search complexity,
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* but on second pass, start at 0.
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*/
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if ((start & mask) >= limit || pass > 0)
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start = 0;
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else
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start &= mask;
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}
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if (dev)
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boundary_size = ALIGN(dma_get_seg_boundary(dev) + 1,
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1 << IOMMU_PAGE_SHIFT);
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else
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boundary_size = ALIGN(1UL << 32, 1 << IOMMU_PAGE_SHIFT);
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/* 4GB boundary for iseries_hv_alloc and iseries_hv_map */
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n = iommu_area_alloc(tbl->it_map, limit, start, npages,
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tbl->it_offset, boundary_size >> IOMMU_PAGE_SHIFT,
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align_mask);
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if (n == -1) {
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if (likely(pass < 2)) {
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/* First failure, just rescan the half of the table.
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* Second failure, rescan the other half of the table.
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*/
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start = (largealloc ^ pass) ? tbl->it_halfpoint : 0;
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limit = pass ? tbl->it_size : limit;
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pass++;
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goto again;
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} else {
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/* Third failure, give up */
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return DMA_ERROR_CODE;
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}
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}
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end = n + npages;
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/* Bump the hint to a new block for small allocs. */
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if (largealloc) {
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/* Don't bump to new block to avoid fragmentation */
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tbl->it_largehint = end;
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} else {
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/* Overflow will be taken care of at the next allocation */
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tbl->it_hint = (end + tbl->it_blocksize - 1) &
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~(tbl->it_blocksize - 1);
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}
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/* Update handle for SG allocations */
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if (handle)
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*handle = end;
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return n;
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}
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static dma_addr_t iommu_alloc(struct device *dev, struct iommu_table *tbl,
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void *page, unsigned int npages,
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enum dma_data_direction direction,
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unsigned long mask, unsigned int align_order,
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struct dma_attrs *attrs)
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{
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unsigned long entry, flags;
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dma_addr_t ret = DMA_ERROR_CODE;
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int build_fail;
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spin_lock_irqsave(&(tbl->it_lock), flags);
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entry = iommu_range_alloc(dev, tbl, npages, NULL, mask, align_order);
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if (unlikely(entry == DMA_ERROR_CODE)) {
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spin_unlock_irqrestore(&(tbl->it_lock), flags);
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return DMA_ERROR_CODE;
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}
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entry += tbl->it_offset; /* Offset into real TCE table */
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ret = entry << IOMMU_PAGE_SHIFT; /* Set the return dma address */
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/* Put the TCEs in the HW table */
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build_fail = ppc_md.tce_build(tbl, entry, npages,
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(unsigned long)page & IOMMU_PAGE_MASK,
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direction, attrs);
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/* ppc_md.tce_build() only returns non-zero for transient errors.
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* Clean up the table bitmap in this case and return
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* DMA_ERROR_CODE. For all other errors the functionality is
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* not altered.
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*/
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if (unlikely(build_fail)) {
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__iommu_free(tbl, ret, npages);
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spin_unlock_irqrestore(&(tbl->it_lock), flags);
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return DMA_ERROR_CODE;
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}
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/* Flush/invalidate TLB caches if necessary */
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if (ppc_md.tce_flush)
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ppc_md.tce_flush(tbl);
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spin_unlock_irqrestore(&(tbl->it_lock), flags);
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/* Make sure updates are seen by hardware */
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mb();
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return ret;
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}
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static void __iommu_free(struct iommu_table *tbl, dma_addr_t dma_addr,
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unsigned int npages)
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{
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unsigned long entry, free_entry;
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entry = dma_addr >> IOMMU_PAGE_SHIFT;
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free_entry = entry - tbl->it_offset;
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if (((free_entry + npages) > tbl->it_size) ||
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(entry < tbl->it_offset)) {
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if (printk_ratelimit()) {
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printk(KERN_INFO "iommu_free: invalid entry\n");
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printk(KERN_INFO "\tentry = 0x%lx\n", entry);
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printk(KERN_INFO "\tdma_addr = 0x%llx\n", (u64)dma_addr);
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printk(KERN_INFO "\tTable = 0x%llx\n", (u64)tbl);
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printk(KERN_INFO "\tbus# = 0x%llx\n", (u64)tbl->it_busno);
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printk(KERN_INFO "\tsize = 0x%llx\n", (u64)tbl->it_size);
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printk(KERN_INFO "\tstartOff = 0x%llx\n", (u64)tbl->it_offset);
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printk(KERN_INFO "\tindex = 0x%llx\n", (u64)tbl->it_index);
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WARN_ON(1);
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}
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return;
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}
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ppc_md.tce_free(tbl, entry, npages);
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bitmap_clear(tbl->it_map, free_entry, npages);
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}
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static void iommu_free(struct iommu_table *tbl, dma_addr_t dma_addr,
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unsigned int npages)
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{
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unsigned long flags;
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spin_lock_irqsave(&(tbl->it_lock), flags);
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__iommu_free(tbl, dma_addr, npages);
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/* Make sure TLB cache is flushed if the HW needs it. We do
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* not do an mb() here on purpose, it is not needed on any of
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* the current platforms.
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*/
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if (ppc_md.tce_flush)
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ppc_md.tce_flush(tbl);
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spin_unlock_irqrestore(&(tbl->it_lock), flags);
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}
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int iommu_map_sg(struct device *dev, struct iommu_table *tbl,
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struct scatterlist *sglist, int nelems,
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unsigned long mask, enum dma_data_direction direction,
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struct dma_attrs *attrs)
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{
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dma_addr_t dma_next = 0, dma_addr;
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unsigned long flags;
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struct scatterlist *s, *outs, *segstart;
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int outcount, incount, i, build_fail = 0;
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unsigned int align;
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unsigned long handle;
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unsigned int max_seg_size;
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BUG_ON(direction == DMA_NONE);
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if ((nelems == 0) || !tbl)
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return 0;
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outs = s = segstart = &sglist[0];
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outcount = 1;
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incount = nelems;
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handle = 0;
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/* Init first segment length for backout at failure */
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outs->dma_length = 0;
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DBG("sg mapping %d elements:\n", nelems);
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spin_lock_irqsave(&(tbl->it_lock), flags);
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max_seg_size = dma_get_max_seg_size(dev);
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for_each_sg(sglist, s, nelems, i) {
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unsigned long vaddr, npages, entry, slen;
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slen = s->length;
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/* Sanity check */
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if (slen == 0) {
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dma_next = 0;
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continue;
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}
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/* Allocate iommu entries for that segment */
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vaddr = (unsigned long) sg_virt(s);
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npages = iommu_num_pages(vaddr, slen, IOMMU_PAGE_SIZE);
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align = 0;
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if (IOMMU_PAGE_SHIFT < PAGE_SHIFT && slen >= PAGE_SIZE &&
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(vaddr & ~PAGE_MASK) == 0)
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align = PAGE_SHIFT - IOMMU_PAGE_SHIFT;
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entry = iommu_range_alloc(dev, tbl, npages, &handle,
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mask >> IOMMU_PAGE_SHIFT, align);
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DBG(" - vaddr: %lx, size: %lx\n", vaddr, slen);
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/* Handle failure */
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if (unlikely(entry == DMA_ERROR_CODE)) {
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if (printk_ratelimit())
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dev_info(dev, "iommu_alloc failed, tbl %p "
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"vaddr %lx npages %lu\n", tbl, vaddr,
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npages);
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goto failure;
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}
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/* Convert entry to a dma_addr_t */
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entry += tbl->it_offset;
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dma_addr = entry << IOMMU_PAGE_SHIFT;
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dma_addr |= (s->offset & ~IOMMU_PAGE_MASK);
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DBG(" - %lu pages, entry: %lx, dma_addr: %lx\n",
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npages, entry, dma_addr);
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/* Insert into HW table */
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build_fail = ppc_md.tce_build(tbl, entry, npages,
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vaddr & IOMMU_PAGE_MASK,
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direction, attrs);
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if(unlikely(build_fail))
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goto failure;
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/* If we are in an open segment, try merging */
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if (segstart != s) {
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DBG(" - trying merge...\n");
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/* We cannot merge if:
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* - allocated dma_addr isn't contiguous to previous allocation
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*/
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if (novmerge || (dma_addr != dma_next) ||
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(outs->dma_length + s->length > max_seg_size)) {
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/* Can't merge: create a new segment */
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segstart = s;
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outcount++;
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outs = sg_next(outs);
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DBG(" can't merge, new segment.\n");
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} else {
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outs->dma_length += s->length;
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DBG(" merged, new len: %ux\n", outs->dma_length);
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}
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}
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if (segstart == s) {
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/* This is a new segment, fill entries */
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DBG(" - filling new segment.\n");
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outs->dma_address = dma_addr;
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outs->dma_length = slen;
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}
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/* Calculate next page pointer for contiguous check */
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dma_next = dma_addr + slen;
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DBG(" - dma next is: %lx\n", dma_next);
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}
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/* Flush/invalidate TLB caches if necessary */
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if (ppc_md.tce_flush)
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ppc_md.tce_flush(tbl);
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spin_unlock_irqrestore(&(tbl->it_lock), flags);
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DBG("mapped %d elements:\n", outcount);
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/* For the sake of iommu_unmap_sg, we clear out the length in the
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* next entry of the sglist if we didn't fill the list completely
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*/
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if (outcount < incount) {
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outs = sg_next(outs);
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outs->dma_address = DMA_ERROR_CODE;
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outs->dma_length = 0;
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}
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/* Make sure updates are seen by hardware */
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mb();
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return outcount;
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failure:
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for_each_sg(sglist, s, nelems, i) {
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if (s->dma_length != 0) {
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unsigned long vaddr, npages;
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vaddr = s->dma_address & IOMMU_PAGE_MASK;
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npages = iommu_num_pages(s->dma_address, s->dma_length,
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IOMMU_PAGE_SIZE);
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__iommu_free(tbl, vaddr, npages);
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s->dma_address = DMA_ERROR_CODE;
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s->dma_length = 0;
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}
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if (s == outs)
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break;
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}
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spin_unlock_irqrestore(&(tbl->it_lock), flags);
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return 0;
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}
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void iommu_unmap_sg(struct iommu_table *tbl, struct scatterlist *sglist,
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int nelems, enum dma_data_direction direction,
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struct dma_attrs *attrs)
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{
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struct scatterlist *sg;
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unsigned long flags;
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BUG_ON(direction == DMA_NONE);
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if (!tbl)
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return;
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spin_lock_irqsave(&(tbl->it_lock), flags);
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sg = sglist;
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while (nelems--) {
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unsigned int npages;
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dma_addr_t dma_handle = sg->dma_address;
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if (sg->dma_length == 0)
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break;
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npages = iommu_num_pages(dma_handle, sg->dma_length,
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IOMMU_PAGE_SIZE);
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__iommu_free(tbl, dma_handle, npages);
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sg = sg_next(sg);
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}
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/* Flush/invalidate TLBs if necessary. As for iommu_free(), we
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* do not do an mb() here, the affected platforms do not need it
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* when freeing.
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*/
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if (ppc_md.tce_flush)
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ppc_md.tce_flush(tbl);
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spin_unlock_irqrestore(&(tbl->it_lock), flags);
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}
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static void iommu_table_clear(struct iommu_table *tbl)
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{
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if (!is_kdump_kernel()) {
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/* Clear the table in case firmware left allocations in it */
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ppc_md.tce_free(tbl, tbl->it_offset, tbl->it_size);
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return;
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}
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#ifdef CONFIG_CRASH_DUMP
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if (ppc_md.tce_get) {
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unsigned long index, tceval, tcecount = 0;
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/* Reserve the existing mappings left by the first kernel. */
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for (index = 0; index < tbl->it_size; index++) {
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tceval = ppc_md.tce_get(tbl, index + tbl->it_offset);
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/*
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* Freed TCE entry contains 0x7fffffffffffffff on JS20
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*/
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if (tceval && (tceval != 0x7fffffffffffffffUL)) {
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__set_bit(index, tbl->it_map);
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tcecount++;
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}
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}
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if ((tbl->it_size - tcecount) < KDUMP_MIN_TCE_ENTRIES) {
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printk(KERN_WARNING "TCE table is full; freeing ");
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printk(KERN_WARNING "%d entries for the kdump boot\n",
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KDUMP_MIN_TCE_ENTRIES);
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for (index = tbl->it_size - KDUMP_MIN_TCE_ENTRIES;
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index < tbl->it_size; index++)
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__clear_bit(index, tbl->it_map);
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}
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}
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#endif
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}
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/*
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* Build a iommu_table structure. This contains a bit map which
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* is used to manage allocation of the tce space.
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*/
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struct iommu_table *iommu_init_table(struct iommu_table *tbl, int nid)
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{
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unsigned long sz;
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static int welcomed = 0;
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struct page *page;
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/* Set aside 1/4 of the table for large allocations. */
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tbl->it_halfpoint = tbl->it_size * 3 / 4;
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/* number of bytes needed for the bitmap */
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sz = (tbl->it_size + 7) >> 3;
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page = alloc_pages_node(nid, GFP_ATOMIC, get_order(sz));
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if (!page)
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panic("iommu_init_table: Can't allocate %ld bytes\n", sz);
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tbl->it_map = page_address(page);
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memset(tbl->it_map, 0, sz);
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|
|
/*
|
|
* Reserve page 0 so it will not be used for any mappings.
|
|
* This avoids buggy drivers that consider page 0 to be invalid
|
|
* to crash the machine or even lose data.
|
|
*/
|
|
if (tbl->it_offset == 0)
|
|
set_bit(0, tbl->it_map);
|
|
|
|
tbl->it_hint = 0;
|
|
tbl->it_largehint = tbl->it_halfpoint;
|
|
spin_lock_init(&tbl->it_lock);
|
|
|
|
iommu_table_clear(tbl);
|
|
|
|
if (!welcomed) {
|
|
printk(KERN_INFO "IOMMU table initialized, virtual merging %s\n",
|
|
novmerge ? "disabled" : "enabled");
|
|
welcomed = 1;
|
|
}
|
|
|
|
return tbl;
|
|
}
|
|
|
|
void iommu_free_table(struct iommu_table *tbl, const char *node_name)
|
|
{
|
|
unsigned long bitmap_sz, i;
|
|
unsigned int order;
|
|
|
|
if (!tbl || !tbl->it_map) {
|
|
printk(KERN_ERR "%s: expected TCE map for %s\n", __func__,
|
|
node_name);
|
|
return;
|
|
}
|
|
|
|
/* verify that table contains no entries */
|
|
/* it_size is in entries, and we're examining 64 at a time */
|
|
for (i = 0; i < (tbl->it_size/64); i++) {
|
|
if (tbl->it_map[i] != 0) {
|
|
printk(KERN_WARNING "%s: Unexpected TCEs for %s\n",
|
|
__func__, node_name);
|
|
break;
|
|
}
|
|
}
|
|
|
|
/* calculate bitmap size in bytes */
|
|
bitmap_sz = (tbl->it_size + 7) / 8;
|
|
|
|
/* free bitmap */
|
|
order = get_order(bitmap_sz);
|
|
free_pages((unsigned long) tbl->it_map, order);
|
|
|
|
/* free table */
|
|
kfree(tbl);
|
|
}
|
|
|
|
/* Creates TCEs for a user provided buffer. The user buffer must be
|
|
* contiguous real kernel storage (not vmalloc). The address passed here
|
|
* comprises a page address and offset into that page. The dma_addr_t
|
|
* returned will point to the same byte within the page as was passed in.
|
|
*/
|
|
dma_addr_t iommu_map_page(struct device *dev, struct iommu_table *tbl,
|
|
struct page *page, unsigned long offset, size_t size,
|
|
unsigned long mask, enum dma_data_direction direction,
|
|
struct dma_attrs *attrs)
|
|
{
|
|
dma_addr_t dma_handle = DMA_ERROR_CODE;
|
|
void *vaddr;
|
|
unsigned long uaddr;
|
|
unsigned int npages, align;
|
|
|
|
BUG_ON(direction == DMA_NONE);
|
|
|
|
vaddr = page_address(page) + offset;
|
|
uaddr = (unsigned long)vaddr;
|
|
npages = iommu_num_pages(uaddr, size, IOMMU_PAGE_SIZE);
|
|
|
|
if (tbl) {
|
|
align = 0;
|
|
if (IOMMU_PAGE_SHIFT < PAGE_SHIFT && size >= PAGE_SIZE &&
|
|
((unsigned long)vaddr & ~PAGE_MASK) == 0)
|
|
align = PAGE_SHIFT - IOMMU_PAGE_SHIFT;
|
|
|
|
dma_handle = iommu_alloc(dev, tbl, vaddr, npages, direction,
|
|
mask >> IOMMU_PAGE_SHIFT, align,
|
|
attrs);
|
|
if (dma_handle == DMA_ERROR_CODE) {
|
|
if (printk_ratelimit()) {
|
|
dev_info(dev, "iommu_alloc failed, tbl %p "
|
|
"vaddr %p npages %d\n", tbl, vaddr,
|
|
npages);
|
|
}
|
|
} else
|
|
dma_handle |= (uaddr & ~IOMMU_PAGE_MASK);
|
|
}
|
|
|
|
return dma_handle;
|
|
}
|
|
|
|
void iommu_unmap_page(struct iommu_table *tbl, dma_addr_t dma_handle,
|
|
size_t size, enum dma_data_direction direction,
|
|
struct dma_attrs *attrs)
|
|
{
|
|
unsigned int npages;
|
|
|
|
BUG_ON(direction == DMA_NONE);
|
|
|
|
if (tbl) {
|
|
npages = iommu_num_pages(dma_handle, size, IOMMU_PAGE_SIZE);
|
|
iommu_free(tbl, dma_handle, npages);
|
|
}
|
|
}
|
|
|
|
/* Allocates a contiguous real buffer and creates mappings over it.
|
|
* Returns the virtual address of the buffer and sets dma_handle
|
|
* to the dma address (mapping) of the first page.
|
|
*/
|
|
void *iommu_alloc_coherent(struct device *dev, struct iommu_table *tbl,
|
|
size_t size, dma_addr_t *dma_handle,
|
|
unsigned long mask, gfp_t flag, int node)
|
|
{
|
|
void *ret = NULL;
|
|
dma_addr_t mapping;
|
|
unsigned int order;
|
|
unsigned int nio_pages, io_order;
|
|
struct page *page;
|
|
|
|
size = PAGE_ALIGN(size);
|
|
order = get_order(size);
|
|
|
|
/*
|
|
* Client asked for way too much space. This is checked later
|
|
* anyway. It is easier to debug here for the drivers than in
|
|
* the tce tables.
|
|
*/
|
|
if (order >= IOMAP_MAX_ORDER) {
|
|
dev_info(dev, "iommu_alloc_consistent size too large: 0x%lx\n",
|
|
size);
|
|
return NULL;
|
|
}
|
|
|
|
if (!tbl)
|
|
return NULL;
|
|
|
|
/* Alloc enough pages (and possibly more) */
|
|
page = alloc_pages_node(node, flag, order);
|
|
if (!page)
|
|
return NULL;
|
|
ret = page_address(page);
|
|
memset(ret, 0, size);
|
|
|
|
/* Set up tces to cover the allocated range */
|
|
nio_pages = size >> IOMMU_PAGE_SHIFT;
|
|
io_order = get_iommu_order(size);
|
|
mapping = iommu_alloc(dev, tbl, ret, nio_pages, DMA_BIDIRECTIONAL,
|
|
mask >> IOMMU_PAGE_SHIFT, io_order, NULL);
|
|
if (mapping == DMA_ERROR_CODE) {
|
|
free_pages((unsigned long)ret, order);
|
|
return NULL;
|
|
}
|
|
*dma_handle = mapping;
|
|
return ret;
|
|
}
|
|
|
|
void iommu_free_coherent(struct iommu_table *tbl, size_t size,
|
|
void *vaddr, dma_addr_t dma_handle)
|
|
{
|
|
if (tbl) {
|
|
unsigned int nio_pages;
|
|
|
|
size = PAGE_ALIGN(size);
|
|
nio_pages = size >> IOMMU_PAGE_SHIFT;
|
|
iommu_free(tbl, dma_handle, nio_pages);
|
|
size = PAGE_ALIGN(size);
|
|
free_pages((unsigned long)vaddr, get_order(size));
|
|
}
|
|
}
|