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ACPI: Clean up acpi_os_map/unmap_memory() to eliminate __iomem.

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ACPICA doesn't include protections around address space checking, Linux
build tests always complain increased sparse warnings around ACPICA
internal acpi_os_map/unmap_memory() invocations.  This patch tries to fix
this issue permanently.

There are 2 choices left for us to solve this issue:
 1. Add __iomem address space awareness into ACPICA.
 2. Remove sparse checker of __iomem from ACPICA source code.

This patch chooses solution 2, because:
 1.  Most of the acpi_os_map/unmap_memory() invocations are used for ACPICA.
     table mappings, which in fact are not IO addresses.
 2.  The only IO addresses usage is for "system memory space" mapping code in:
      drivers/acpi/acpica/exregion.c
      drivers/acpi/acpica/evrgnini.c
      drivers/acpi/acpica/exregion.c
    The mapped address is accessed in the handler of "system memory space"
    - acpi_ex_system_memory_space_handler().  This function in fact can be
    changed to invoke acpi_os_read/write_memory() so that __iomem can
    always be type-casted in the OSL layer.

According to the above investigation, we drew the following conclusion:
It is not a good idea to introduce __iomem address space awareness into
ACPICA mostly in order to protect non-IO addresses.

We can simply remove __iomem for acpi_os_map/unmap_memory() to remove
__iomem checker for ACPICA code. Then we need to enforce external usages
to invoke other APIs that are aware of __iomem address space.
The external usages are:
 drivers/acpi/apei/einj.c
 drivers/acpi/acpi_extlog.c
 drivers/char/tpm/tpm_acpi.c
 drivers/acpi/nvs.c

This patch thus performs cleanups in this way:
 1. Add acpi_os_map/unmap_iomem() to be invoked by non-ACPICA code.
 2. Remove __iomem from acpi_os_map/unmap_memory().

Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Lv Zheng
2014-05-20 15:39:41 +08:00
committed by Rafael J. Wysocki
parent 92985ef1db
commit a238317ce8
8 changed files with 39 additions and 33 deletions
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4
drivers/char/tpm/tpm_acpi.c
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@@ -95,7 +95,7 @@ int read_log(struct tpm_bios_log *log)
log->bios_event_log_end = log->bios_event_log + len;
virt = acpi_os_map_memory(start, len);
virt = acpi_os_map_iomem(start, len);
if (!virt) {
kfree(log->bios_event_log);
printk("%s: ERROR - Unable to map memory\n", __func__);
@@ -104,6 +104,6 @@ int read_log(struct tpm_bios_log *log)
memcpy_fromio(log->bios_event_log, virt, len);
acpi_os_unmap_memory(virt, len);
acpi_os_unmap_iomem(virt, len);
return 0;
}