Codegen

Controls a memory area that can switch between writable and executable states, allowing dynamic code generation. More...

Collaboration diagram for Codegen:

Typedefs
typedef enum OSCodegenSecMode	OSCodegenSecMode
	The memory permissions for the codegen area. More...

Enumerations
enum	OSCodegenSecMode {   CODEGEN_RW_ = 0 ,   CODEGEN_R_X = 1 }
	The memory permissions for the codegen area. More...

Functions
void	OSGetCodegenVirtAddrRange (void **outVirtualAddress, uint32_t *outSize)
	Gets the location and size of codegen memory, if available. More...
uint32_t	OSGetCodegenCore ()
	Gets the CPU core that's allowed to use codegen. More...
uint32_t	OSGetCodegenMode ()
BOOL	OSSwitchSecCodeGenMode (OSCodegenSecMode mode)
	Switches the permissions on the codegen memory area. More...
uint32_t	OSGetSecCodeGenMode ()
BOOL	OSCodegenCopy (void *dst, void *src, size_t size)
	Copies data from normal memory into the codegen area, leaving the area in CODEGEN_R_X mode. More...

Detailed Description

Controls a memory area that can switch between writable and executable states, allowing dynamic code generation.

For some applications, a codegen area is avilable for things like JIT or otherwise generating CPU instructions on the fly. Enabled apps can use OSCodegenGetVirtAddrRange to discover this area, then use OSSwitchSecCodeGenMode or OSCodegenCopy to move instructions in and out before executing them. Codegen can only be used from a specific, predetermined CPU core - see OSGetCodegenCore. Codegen can only be used when enabled in an app's cos.xml.

Typedef Documentation

OSCodegenSecMode

typedef enum OSCodegenSecMode OSCodegenSecMode

The memory permissions for the codegen area.

Enumeration Type Documentation

OSCodegenSecMode

enum OSCodegenSecMode

The memory permissions for the codegen area.

Enumerator
CODEGEN_RW_	The area can be read or written to, but not executed.
CODEGEN_R_X	The area can be read or executed, but not written to.

Definition at line 34 of file codegen.h.

Function Documentation

OSGetCodegenVirtAddrRange()

void OSGetCodegenVirtAddrRange	(	void **	outVirtualAddress,
		uint32_t *	outSize
	)

Gets the location and size of codegen memory, if available.

Parameters

outVirtualAddress	Pointer to write the virtual address of the codegen area to. Will write 0 if codegen isn't available.
outSize	Pointer to write the size of the codegen area to. Will write 0 if codegen isn't available.

See also

• OSGetSecCodeGenMode

OSGetCodegenCore()

uint32_t OSGetCodegenCore

(

)

Gets the CPU core that's allowed to use codegen.

Returns

The core id of the core that can use codegen.

See also

• OSGetCoreId

OSGetCodegenMode()

uint32_t OSGetCodegenMode

(

)

OSSwitchSecCodeGenMode()

BOOL OSSwitchSecCodeGenMode

(

OSCodegenSecMode

mode

)

Switches the permissions on the codegen memory area.

Use this function to move between writing code and executing it.

Parameters

mode	The memory permission mode to use - one of OSCodegenSecMode.

Returns

true on success, or false on a failure, such as codegen not being available for this app or CPU core.

OSGetSecCodeGenMode()

uint32_t OSGetSecCodeGenMode

(

)

OSCodegenCopy()

BOOL OSCodegenCopy	(	void *	dst,
		void *	src,
		size_t	size
	)

Copies data from normal memory into the codegen area, leaving the area in CODEGEN_R_X mode.

This function copies into the codegen area regardless of the current permission status by switching modes as required for the copy.

Parameters

dst	The starting virtual address of the area in codegen memory to copy to. Must be a valid pointer
src	The starting virtual address of the source to copy from. Must be a valid pointer.
size	The size of the data to copy. Must not be 0, and must be small enough such that dst + size does not pass the end of the codegen area (see OSCodegenGetVirtAddrRange).

Returns

TRUE on success, indicating the codegen area is now in CODEGEN_R_X, or FALSE on an error, such as invalid pointers or codegen not being available.