On Tue, 27 Jul 2021 at 12:06, Lorenzo Pieralisi
[off-list ref] wrote:

On Mon, Jul 26, 2021 at 05:55:33PM +0200, Ard Biesheuvel wrote:

quoted

On Mon, 26 Jul 2021 at 12:00, Lorenzo Pieralisi
[off-list ref] wrote:

quoted

The memory attributes attached to memory regions depend on architecture
specific mappings.

For some memory regions, the attributes specified by firmware (eg
uncached) are not sufficient to determine how a memory region should be
mapped by an OS (for instance a region that is define as uncached in
firmware can be mapped as Normal or Device memory on arm64) and
therefore the OS must be given control on how to map the region to match
the expected mapping behaviour (eg if a mapping is requested with memory
semantics, it must allow unaligned accesses).

Rework acpi_os_map_memory() and acpi_os_ioremap() back-end to split
them into two separate code paths:

acpi_os_memmap() -> memory semantics
acpi_os_ioremap() -> MMIO semantics

The split allows the architectural implementation back-ends to detect
the default memory attributes required by the mapping in question
(ie the mapping API defines the semantics memory vs MMIO) and map the
memory accordingly.

Link: https://lore.kernel.org/linux-arm-kernel/31ffe8fc-f5ee-2858-26c5-0fd8bdd68702@arm.com (local)
Signed-off-by: Lorenzo Pieralisi <redacted>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Will Deacon <will@kernel.org>
Cc: Hanjun Guo <guohanjun@huawei.com>
Cc: Sudeep Holla <redacted>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: "Rafael J. Wysocki" <redacted>

For the patch in general

Acked-by: Ard Biesheuvel <ardb@kernel.org>

Thanks !

[...]

quoted

quoted

-void __iomem __ref
-*acpi_os_map_iomem(acpi_physical_address phys, acpi_size size)
+static void __iomem __ref
+*__acpi_os_map_iomem(acpi_physical_address phys, acpi_size size, bool memory)
 {
        struct acpi_ioremap *map;
        void __iomem *virt;

@@ -353,7 +356,7 @@ void __iomem __ref

        pg_off = round_down(phys, PAGE_SIZE);
        pg_sz = round_up(phys + size, PAGE_SIZE) - pg_off;
-       virt = acpi_map(phys, size);
+       virt = acpi_map(phys, size, memory);
        if (!virt) {
                mutex_unlock(&acpi_ioremap_lock);
                kfree(map);

@@ -372,11 +375,17 @@ void __iomem __ref
        mutex_unlock(&acpi_ioremap_lock);
        return map->virt + (phys - map->phys);
 }
+
+void __iomem __ref
+*acpi_os_map_iomem(acpi_physical_address phys, acpi_size size)

I am aware that this just duplicated the prototype above, but I think
this should be

void __iomem *__ref

given that the __ref comes after the * in the prototype below.

Yes I just moved/duplicated the prototype above but I believe this is
consistent with include/acpi/acpi_io.h unless I have not understood
what you meant ?

It is probably worth changing it in both places to

void __iomem *__ref

?

I can do that with an additional patch.

Yes, as long as they are all mutually consistent. The __ref is not
part of the type at all, so it should not be between the void and the
*, even if the compiler appears to allow it.

quoted

quoted

+{
+       return __acpi_os_map_iomem(phys, size, false);
+}
 EXPORT_SYMBOL_GPL(acpi_os_map_iomem);

 void *__ref acpi_os_map_memory(acpi_physical_address phys, acpi_size size)
 {
-       return (void *)acpi_os_map_iomem(phys, size);
+       return (void *)__acpi_os_map_iomem(phys, size, true);

I think this should be (__force void *) to shut up sparse address
space warnings.

Yes I can add that attribute in an additional patch and rebase this one
on top of it.

Thanks,
Lorenzo

quoted

quoted

 }
 EXPORT_SYMBOL_GPL(acpi_os_map_memory);

diff --git a/include/acpi/acpi_io.h b/include/acpi/acpi_io.h
index 027faa8883aa..a0212e67d6f4 100644
--- a/include/acpi/acpi_io.h
+++ b/include/acpi/acpi_io.h

@@ -14,6 +14,14 @@ static inline void __iomem *acpi_os_ioremap(acpi_physical_address phys,
 }
 #endif

+#ifndef acpi_os_memmap
+static inline void __iomem *acpi_os_memmap(acpi_physical_address phys,
+                                           acpi_size size)
+{
+       return ioremap_cache(phys, size);
+}
+#endif
+
 extern bool acpi_permanent_mmap;

 void __iomem __ref
--

2.31.0

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