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37afff0d87
Introduce a new "protect-exec" reserved sram area type which is makes use of the the existing functionality provided for the "pool" sram region type for use with the genalloc framework and with the added requirement that it be maintained as read-only and executable while allowing for an arbitrary number of drivers to share the space. This introduces a common way to maintain a region of sram as read-only and executable and also introduces a helper function, sram_exec_copy, which allows for copying data to this protected region while maintaining locking to avoid conflicts between multiple users of the same space. A region of memory that is marked with the "protect-exec" flag in the device tree also has the requirement of providing a page aligned block of memory so that the page attribute manipulation does not affect surrounding regions. Also, selectively enable this only for builds that support set_memory_* calls, for now just ARM, through the use of Kconfig. Signed-off-by: Dave Gerlach <d-gerlach@ti.com> Acked-by: Tony Lindgren <tony@atomide.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
79 lines
2.3 KiB
Plaintext
79 lines
2.3 KiB
Plaintext
Generic on-chip SRAM
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Simple IO memory regions to be managed by the genalloc API.
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Required properties:
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- compatible : mmio-sram or atmel,sama5d2-securam
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- reg : SRAM iomem address range
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Reserving sram areas:
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---------------------
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Each child of the sram node specifies a region of reserved memory. Each
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child node should use a 'reg' property to specify a specific range of
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reserved memory.
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Following the generic-names recommended practice, node names should
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reflect the purpose of the node. Unit address (@<address>) should be
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appended to the name.
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Required properties in the sram node:
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- #address-cells, #size-cells : should use the same values as the root node
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- ranges : standard definition, should translate from local addresses
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within the sram to bus addresses
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Optional properties in the sram node:
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- no-memory-wc : the flag indicating, that SRAM memory region has not to
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be remapped as write combining. WC is used by default.
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Required properties in the area nodes:
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- reg : iomem address range, relative to the SRAM range
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Optional properties in the area nodes:
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- compatible : standard definition, should contain a vendor specific string
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in the form <vendor>,[<device>-]<usage>
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- pool : indicates that the particular reserved SRAM area is addressable
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and in use by another device or devices
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- export : indicates that the reserved SRAM area may be accessed outside
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of the kernel, e.g. by bootloader or userspace
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- protect-exec : Same as 'pool' above but with the additional
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constraint that code wil be run from the region and
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that the memory is maintained as read-only, executable
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during code execution. NOTE: This region must be page
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aligned on start and end in order to properly allow
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manipulation of the page attributes.
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- label : the name for the reserved partition, if omitted, the label
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is taken from the node name excluding the unit address.
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Example:
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sram: sram@5c000000 {
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compatible = "mmio-sram";
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reg = <0x5c000000 0x40000>; /* 256 KiB SRAM at address 0x5c000000 */
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#address-cells = <1>;
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#size-cells = <1>;
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ranges = <0 0x5c000000 0x40000>;
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smp-sram@100 {
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compatible = "socvendor,smp-sram";
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reg = <0x100 0x50>;
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};
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device-sram@1000 {
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reg = <0x1000 0x1000>;
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pool;
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};
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exported@20000 {
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reg = <0x20000 0x20000>;
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export;
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};
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};
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