Commit 37afff0d authored by Dave Gerlach's avatar Dave Gerlach Committed by Greg Kroah-Hartman
Browse files

misc: sram: Integrate protect-exec reserved sram area type 



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: default avatarDave Gerlach <d-gerlach@ti.com>
Acked-by: default avatarTony Lindgren <tony@atomide.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 728bbe75

Documentation/devicetree/bindings/sram/sram.txt

+6 −0
Original line number Diff line number Diff line
@@ -42,6 +42,12 @@ Optional properties in the area nodes: 
         and in use by another device or devices

- export : indicates that the reserved SRAM area may be accessed outside

           of the kernel, e.g. by bootloader or userspace

- protect-exec : Same as 'pool' above but with the additional

		 constraint that code wil be run from the region and

		 that the memory is maintained as read-only, executable

		 during code execution. NOTE: This region must be page

		 aligned on start and end in order to properly allow

		 manipulation of the page attributes.

- label : the name for the reserved partition, if omitted, the label

          is taken from the node name excluding the unit address.

drivers/misc/Kconfig

+4 −0
Original line number Diff line number Diff line
@@ -474,11 +474,15 @@ config SRAM 
	bool "Generic on-chip SRAM driver"

	depends on HAS_IOMEM

	select GENERIC_ALLOCATOR

	select SRAM_EXEC if ARM

	help

	  This driver allows you to declare a memory region to be managed by

	  the genalloc API. It is supposed to be used for small on-chip SRAM

	  areas found on many SoCs.



config SRAM_EXEC

	bool



config VEXPRESS_SYSCFG

	bool "Versatile Express System Configuration driver"

	depends on VEXPRESS_CONFIG

drivers/misc/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -47,6 +47,7 @@ obj-$(CONFIG_INTEL_MEI) += mei/ 
obj-$(CONFIG_VMWARE_VMCI)	+= vmw_vmci/

obj-$(CONFIG_LATTICE_ECP3_CONFIG)	+= lattice-ecp3-config.o

obj-$(CONFIG_SRAM)		+= sram.o

obj-$(CONFIG_SRAM_EXEC)		+= sram-exec.o

obj-y				+= mic/

obj-$(CONFIG_GENWQE)		+= genwqe/

obj-$(CONFIG_ECHO)		+= echo/

drivers/misc/sram.c

+19 −2
Original line number Diff line number Diff line
@@ -122,6 +122,18 @@ static int sram_add_partition(struct sram_dev *sram, struct sram_reserve *block, 
		if (ret)

			return ret;

	}

	if (block->protect_exec) {

		ret = sram_check_protect_exec(sram, block, part);

		if (ret)

			return ret;



		ret = sram_add_pool(sram, block, start, part);

		if (ret)

			return ret;



		sram_add_protect_exec(part);

	}



	sram->partitions++;



	return 0;
@@ -207,7 +219,11 @@ static int sram_reserve_regions(struct sram_dev *sram, struct resource *res) 
		if (of_find_property(child, "pool", NULL))

			block->pool = true;



		if ((block->export || block->pool) && block->size) {

		if (of_find_property(child, "protect-exec", NULL))

			block->protect_exec = true;



		if ((block->export || block->pool || block->protect_exec) &&

		    block->size) {

			exports++;



			label = NULL;
@@ -269,7 +285,8 @@ static int sram_reserve_regions(struct sram_dev *sram, struct resource *res) 
			goto err_chunks;

		}



		if ((block->export || block->pool) && block->size) {

		if ((block->export || block->pool || block->protect_exec) &&

		    block->size) {

			ret = sram_add_partition(sram, block,

						 res->start + block->start);

			if (ret) {

drivers/misc/sram.h

+1 −0
Original line number Diff line number Diff line
@@ -34,6 +34,7 @@ struct sram_reserve { 
	u32 size;

	bool export;

	bool pool;

	bool protect_exec;

	const char *label;

};

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