Hi, Myron,
On Fri, 2010-10-22 at 04:24 +0800, Myron Stowe wrote:
> This patch optimizes ACPI MMIO remappings by keeping track of the
> remappings on a PAGE_SIZE granularity.
>
> When an ioremap() occurs, the underlying infrastructure works on a 'page'
> based granularity. As such, an ioremap() request for 1 byte for example,
> will end up mapping in an entire (PAGE_SIZE) page. Huang Ying took
> advantage of this in commit 15651291a2f8c11e7e6a42d8bfde7a213ff13262 by
> checking if subsequent ioremap() requests reside within any of the list's
> existing remappings still in place, and if so, incrementing a reference
> count on the existing mapping as opposed to performing another ioremap().
>
>
> Signed-off-by: Myron Stowe <myron.stowe@xxxxxx>
> ---
>
> drivers/acpi/osl.c | 62 +++++++++++++++++++++++++++++++++++++++++++---------
> 1 files changed, 51 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
> index 3282689..885e222 100644
> --- a/drivers/acpi/osl.c
> +++ b/drivers/acpi/osl.c
> @@ -104,6 +104,7 @@ struct acpi_ioremap {
> void __iomem *virt;
> acpi_physical_address phys;
> acpi_size size;
> + struct kref ref;
> };
>
> static LIST_HEAD(acpi_ioremaps);
> @@ -245,15 +246,28 @@ acpi_physical_address __init acpi_os_get_root_pointer(void)
> }
>
> /* Must be called with 'acpi_ioremap_lock' or RCU read lock held. */
> -static void __iomem *
> -acpi_map_vaddr_lookup(acpi_physical_address phys, acpi_size size)
> +static struct acpi_ioremap *
> +acpi_map_lookup(acpi_physical_address phys, acpi_size size)
> {
> struct acpi_ioremap *map;
>
> list_for_each_entry_rcu(map, &acpi_ioremaps, list)
> if (map->phys <= phys &&
> phys + size <= map->phys + map->size)
> - return map->virt + (phys - map->phys);
> + return map;
> +
> + return NULL;
> +}
> +
> +/* Must be called with 'acpi_ioremap_lock' or RCU read lock held. */
> +static void __iomem *
> +acpi_map_vaddr_lookup(acpi_physical_address phys, unsigned int size)
> +{
> + struct acpi_ioremap *map;
> +
> + map = acpi_map_lookup(phys, size);
> + if (map)
> + return map->virt + (phys - map->phys);
>
> return NULL;
> }
> @@ -265,7 +279,8 @@ acpi_map_lookup_virt(void __iomem *virt, acpi_size size)
> struct acpi_ioremap *map;
>
> list_for_each_entry_rcu(map, &acpi_ioremaps, list)
> - if (map->virt == virt && map->size == size)
> + if (map->virt <= virt &&
> + virt + size <= map->virt + map->size)
> return map;
>
> return NULL;
> @@ -274,9 +289,10 @@ acpi_map_lookup_virt(void __iomem *virt, acpi_size size)
> void __iomem *__init_refok
> acpi_os_map_memory(acpi_physical_address phys, acpi_size size)
> {
> - struct acpi_ioremap *map;
> - unsigned long flags;
> + struct acpi_ioremap *map, *tmp_map;
> + unsigned long flags, pg_sz;
> void __iomem *virt;
> + phys_addr_t pg_off;
>
> if (phys > ULONG_MAX) {
> printk(KERN_ERR PREFIX "Cannot map memory that high\n");
> @@ -290,7 +306,9 @@ acpi_os_map_memory(acpi_physical_address phys, acpi_size size)
> if (!map)
> return NULL;
>
> - virt = ioremap(phys, size);
> + pg_off = round_down(phys, PAGE_SIZE);
> + pg_sz = round_up(phys + size, PAGE_SIZE) - pg_off;
> + virt = ioremap(pg_off, pg_sz);
> if (!virt) {
> kfree(map);
> return NULL;
Why not check the existing map (that is, acpi_map_lookup()) before the
ioremap()? In APEI tables, several GAS may be in same page, so we need
ioremap() for the first page only.
Best Regards,
Huang Ying
> @@ -298,21 +316,40 @@ acpi_os_map_memory(acpi_physical_address phys, acpi_size size)
>
> INIT_LIST_HEAD(&map->list);
> map->virt = virt;
> - map->phys = phys;
> - map->size = size;
> + map->phys = pg_off;
> + map->size = pg_sz;
> + kref_init(&map->ref);
>
> spin_lock_irqsave(&acpi_ioremap_lock, flags);
> + /* Check if page has already been mapped. */
> + tmp_map = acpi_map_lookup(phys, size);
> + if (tmp_map) {
> + kref_get(&tmp_map->ref);
> + spin_unlock_irqrestore(&acpi_ioremap_lock, flags);
> + iounmap(map->virt);
> + kfree(map);
> + return tmp_map->virt + (phys - tmp_map->phys);
> + }
> list_add_tail_rcu(&map->list, &acpi_ioremaps);
> spin_unlock_irqrestore(&acpi_ioremap_lock, flags);
>
> - return virt;
> + return map->virt + (phys - map->phys);
> }
> EXPORT_SYMBOL_GPL(acpi_os_map_memory);
>
> +static void acpi_kref_del_iomap(struct kref *ref)
> +{
> + struct acpi_ioremap *map;
> +
> + map = container_of(ref, struct acpi_ioremap, ref);
> + list_del_rcu(&map->list);
> +}
> +
> void __ref acpi_os_unmap_memory(void __iomem *virt, acpi_size size)
> {
> struct acpi_ioremap *map;
> unsigned long flags;
> + int del;
>
> if (!acpi_gbl_permanent_mmap) {
> __acpi_unmap_table(virt, size);
> @@ -328,9 +365,12 @@ void __ref acpi_os_unmap_memory(void __iomem *virt, acpi_size size)
> return;
> }
>
> - list_del_rcu(&map->list);
> + del = kref_put(&map->ref, acpi_kref_del_iomap);
> spin_unlock_irqrestore(&acpi_ioremap_lock, flags);
>
> + if (!del)
> + return;
> +
> synchronize_rcu();
> iounmap(map->virt);
> kfree(map);
>
--
To unsubscribe from this list: send the line "unsubscribe linux-acpi" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
