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SubjectRe: [PATCH 2 of 4] [x86-64] Calgary: only verify the allocation bitmap if CONFIG_IOMMU_DEBUG is on
On Thu, Aug 03, 2006 at 01:59:09AM +0300, Muli Ben-Yehuda wrote:
> 1 files changed, 36 insertions(+), 10 deletions(-)
> arch/x86_64/kernel/pci-calgary.c | 46 +++++++++++++++++++++++++++++---------
>
>
> # HG changeset patch
> # User Muli Ben-Yehuda <muli@il.ibm.com>
> # Date 1154558421 -10800
> # Node ID 515131a26b151f1e459642268184d98099e72a6c
> # Parent 9cd758467ce15605504369cf56f790aea8c74748
> [x86-64] Calgary: only verify the allocation bitmap if CONFIG_IOMMU_DEBUG is on
>
> Introduce new function verify_bit_range(). Define two versions, one
> for CONFIG_IOMMU_DEBUG enabled and one for disabled. Previously we
> were checking that the bitmap was consistent every time we allocated
> or freed an entry in the TCE table, which is good for debugging but
> incurs an unnecessary penalty on non debug builds.
>
> Signed-off-by: Muli Ben-Yehuda <muli@il.ibm.com>
> Signed-off-by: Jon Mason <jdmason@us.ibm.com>
>
> diff -r 9cd758467ce1 -r 515131a26b15 arch/x86_64/kernel/pci-calgary.c
> --- a/arch/x86_64/kernel/pci-calgary.c Thu Aug 03 01:37:12 2006 +0300
> +++ b/arch/x86_64/kernel/pci-calgary.c Thu Aug 03 01:40:21 2006 +0300
> @@ -133,12 +133,35 @@ static inline void tce_cache_blast_stres
> {
> tce_cache_blast(tbl);
> }
> +
> +static inline unsigned long verify_bit_range(unsigned long* bitmap,
> + int expected, unsigned long start, unsigned long end)
> +{
> + unsigned long idx = start;
> +
> + BUG_ON(start > end);

This should be ">=".

Thanks,
Jon

> +
> + while (idx < end) {
> + if (!!test_bit(idx, bitmap) != expected)
> + return idx;
> + ++idx;
> + }
> +
> + /* all bits have the expected value */
> + return ~0UL;
> +}
> #else /* debugging is disabled */
> int debugging __read_mostly = 0;
>
> static inline void tce_cache_blast_stress(struct iommu_table *tbl)
> {
> }
> +
> +static inline unsigned long verify_bit_range(unsigned long* bitmap,
> + int expected, unsigned long start, unsigned long end)
> +{
> + return ~0UL;
> +}
> #endif /* CONFIG_IOMMU_DEBUG */
>
> static inline unsigned int num_dma_pages(unsigned long dma, unsigned int dmalen)
> @@ -162,6 +185,7 @@ static void iommu_range_reserve(struct i
> {
> unsigned long index;
> unsigned long end;
> + unsigned long badbit;
>
> index = start_addr >> PAGE_SHIFT;
>
> @@ -173,14 +197,15 @@ static void iommu_range_reserve(struct i
> if (end > tbl->it_size) /* don't go off the table */
> end = tbl->it_size;
>
> - while (index < end) {
> - if (test_bit(index, tbl->it_map))
> + badbit = verify_bit_range(tbl->it_map, 0, index, end);
> + if (badbit != ~0UL) {
> + if (printk_ratelimit())
> printk(KERN_ERR "Calgary: entry already allocated at "
> "0x%lx tbl %p dma 0x%lx npages %u\n",
> - index, tbl, start_addr, npages);
> - ++index;
> - }
> - set_bit_string(tbl->it_map, start_addr >> PAGE_SHIFT, npages);
> + badbit, tbl, start_addr, npages);
> + }
> +
> + set_bit_string(tbl->it_map, index, npages);
> }
>
> static unsigned long iommu_range_alloc(struct iommu_table *tbl,
> @@ -247,7 +272,7 @@ static void __iommu_free(struct iommu_ta
> unsigned int npages)
> {
> unsigned long entry;
> - unsigned long i;
> + unsigned long badbit;
>
> entry = dma_addr >> PAGE_SHIFT;
>
> @@ -255,11 +280,12 @@ static void __iommu_free(struct iommu_ta
>
> tce_free(tbl, entry, npages);
>
> - for (i = 0; i < npages; ++i) {
> - if (!test_bit(entry + i, tbl->it_map))
> + badbit = verify_bit_range(tbl->it_map, 1, entry, entry + npages);
> + if (badbit != ~0UL) {
> + if (printk_ratelimit())
> printk(KERN_ERR "Calgary: bit is off at 0x%lx "
> "tbl %p dma 0x%Lx entry 0x%lx npages %u\n",
> - entry + i, tbl, dma_addr, entry, npages);
> + badbit, tbl, dma_addr, entry, npages);
> }
>
> __clear_bit_string(tbl->it_map, entry, npages);
-
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