CN114356802A - Method and device, system and storage medium for directly accessing memory physical address - Google Patents

Abstract

The present invention provides a method and device, a system and a storage medium for directly accessing a physical address of a memory. The method for directly accessing the physical address of the memory is applied to an application module outside the kernel of the operating system, and the method includes: acquiring the physical address of the target memory corresponding to the current process in the user space; mapping the physical address of the target memory to the virtual address of the target memory according to the mapping relationship; Directly access the target memory virtual address. The technical solution does not need to copy data into the kernel space, the data transmission and access process is simple, the program development efficiency is higher, and system paralysis can be avoided, so that the security is high.

Description

Method and device, system and storage medium for directly accessing memory physical address

technical field

The present invention relates to the technical field of software development, and more particularly to a method and device, a system and a storage medium for directly accessing a physical address of a memory.

Background technique

The program code can logically directly control the physical address, but on a platform with an operating system, the code needs to be developed in two parts, one in the kernel space and one in the user space. Program code running in user space needs to go through kernel space to access physical addresses. This address access method has at least the following problems:

1. Program development is difficult. This is because: the amount of code and the number of modules in the kernel space program is very large. On the basis of the original hardware knowledge, it is necessary to master the knowledge of the operating system, the principle of the driver, etc. In addition, it is much more difficult to debug the kernel program than the user space program;

2. Poor portability. This is because: if a program developed for bare metal is to be ported to a platform with an operating system, it needs to be redeveloped at both the kernel space and user space levels, so the portability is poor;

3. When reading and writing data to the physical address, the data needs to be copied to the kernel space, so the process is more complicated;

4. The traditional address access method requires program development for the kernel, so when a problem occurs in the development program, the entire system will be paralyzed, so the reliability of the system is relatively poor.

SUMMARY OF THE INVENTION

The present invention has been made in view of the above-mentioned problems. The present invention provides a method and device, a system and a storage medium for directly accessing a physical address of a memory.

According to an aspect of the present invention, a method for directly accessing a physical address of a memory is provided, which is applied to an application module outside the kernel of an operating system, and the method includes:

Get the physical address of the target memory corresponding to the current process in user space;

Map the physical address of the target memory to the virtual address of the target memory according to the mapping relationship;

Directly access the target memory virtual address.

Exemplarily, obtaining the physical address of the target memory corresponding to the current process in the user space includes:

Get the preconfigured memory physical address as the target memory physical address; or,

Get the randomly allocated memory physical address as the target memory physical address.

Exemplarily, mapping the physical address of the target memory to the virtual address of the target memory according to the mapping relationship includes:

Call the memory management unit running in kernel space;

The physical address of the target memory is mapped to the virtual address of the target memory according to the mapping relationship by the memory management unit.

Exemplarily, a mapping relationship is preset in the application module;

Mapping the physical address of the target memory to the virtual address of the target memory according to the mapping relationship includes:

The target memory physical address is directly mapped to the target memory virtual address according to the preset mapping relationship.

Exemplarily, directly accessing the target memory virtual address includes:

read data at the target memory virtual address to obtain the target data, return the target data to the current process; and/or

Write the target data directly to the target memory virtual address.

Exemplarily, after directly accessing the target memory virtual address, the method further includes:

Unmap between the target memory virtual address and the target memory physical address to free the target memory virtual address.

Exemplarily, obtain the physical address of the target memory corresponding to the current process in the user space, including:

Obtain the target memory physical address corresponding to the current process in the user space through a preset hardware driver outside the kernel.

According to another aspect of the present invention, an apparatus for directly accessing a physical address of a memory is provided, comprising:

The acquisition module is used to acquire the physical address of the target memory corresponding to the current process in the user space;

The mapping module is used to map the physical address of the target memory to the virtual address of the target memory according to the mapping relationship;

The access module is used to directly access the target memory virtual address.

According to yet another aspect of the present invention, there is provided a system for directly accessing a physical address of a memory, including a processor and a memory, wherein the memory stores computer program instructions, and the computer program instructions are used by the processor to execute the above-mentioned direct access to the memory when run. physical address method.

According to another aspect of the present invention, a storage medium is provided, on which program instructions are stored, and the program instructions are used to execute the above-mentioned method for directly accessing a physical address of a memory when running.

According to the above technical solution, the conversion between the physical address and the virtual address of the user space layer is realized by the application module outside the kernel of the operating system, and the direct access to the physical address of the target memory in the user space is further realized. By using the technical solution, the program developed by the bare metal can be directly copied to the platform with the operating system, so that the portability is good. Moreover, compared with the traditional technology, the technical solution does not need to copy data into the kernel space, the data transmission and access process is simple, and the program development efficiency is higher. At the same time, it avoids the risk that the entire system may be paralyzed when the kernel development program encounters a problem, so the security is higher.

Description of drawings

The above and other objects, features and advantages of the present invention will become more apparent from the detailed description of the embodiments of the present invention in conjunction with the accompanying drawings. The accompanying drawings are used to provide a further understanding of the embodiments of the present invention, and constitute a part of the specification, and together with the embodiments of the present invention, they are used to explain the present invention, and do not limit the present invention. In the drawings, the same reference numbers generally refer to the same components or steps.

1 shows a schematic flowchart of a method for directly accessing a physical address of a memory according to an embodiment of the present invention;

FIG. 2 shows a schematic block diagram of an apparatus for directly accessing a physical address of a memory according to an embodiment of the present invention; and

FIG. 3 shows a schematic block diagram of a system for directly accessing a physical address of a memory according to an embodiment of the present invention.

Detailed ways

In order to make the objects, technical solutions and advantages of the present invention more apparent, exemplary embodiments according to the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some of the embodiments of the present invention, not all of the embodiments of the present invention, and it should be understood that the present invention is not limited by the example embodiments described herein. Based on the embodiments of the present invention described in the present invention, all other embodiments obtained by those skilled in the art without creative efforts shall fall within the protection scope of the present invention.

In order to at least partially solve the above problem, an embodiment of the present invention provides a method for directly accessing a physical address of a memory. The method is applied to application modules outside the kernel of the operating system, for example, directly reading and writing the specified memory physical address in the user space of the Linux system. Illustratively, user space is an area of memory accessible to normal applications. In the linux operating system, the lower 3G bytes (from the virtual address 0x00000000 to 0xBFFFFFFF) are used by each process, which is called user space. The kernel space is an area accessed by the operating system kernel, which is independent of ordinary applications and is a protected memory space. In the Linux operating system, the highest 1G byte (from virtual address 0xC0000000 to 0xFFFFFFFF) is used by the kernel, which is called kernel space.

In the prior art, when an application program located in the user space wants to write data to a hardware device, or in other words, when writing to the physical address corresponding to the hardware device, the following steps are usually performed in the kernel space: Step S1 , the kernel space maps the physical address in the access control request sent from the user space to a virtual address; step S2, the kernel space saves the written data in the virtual address; step S3, the kernel space stores the virtual address corresponding to the user space The physical address of the data copied to the hardware device is mapped in the virtual address of the kernel space. Since the hardware device has a mapping relationship between the virtual address in the kernel space and its actual physical address, the data is copied to the physical address of the hardware device in step S3.

As mentioned above, the method of indirectly accessing the physical address through the kernel space to write data to the hardware device is relatively complicated, and there are also problems such as difficulty in development and system paralysis. Different from the prior art, the method for directly accessing the physical address of the memory according to the embodiment of the present invention is implemented by an application module outside the kernel space. For example, an adaptation layer can be set directly in the user space layer, and the direct access to the physical address of the memory can be realized through the adaptation layer, so that the target data can be written into the physical address of the hardware device in the user space or Read data from the physical address of the hardware device.

Referring to FIG. 1 below, FIG. 1 shows a schematic flowchart of a method 1000 for directly accessing a physical address of a memory according to an embodiment of the present invention. As shown in FIG. 1 , the method 1000 for directly accessing a physical address of a memory includes the following steps S1100 , S1200 and S1300 .

It can be understood that the physical address space is an entity that actually exists in the computer, and maintains unique independence in each computer. The virtual address does not really exist in the computer, each process is allocated its own virtual space, and can only access the space allocated and used by itself. There is a mapping relationship between the virtual address corresponding to a certain process data and the physical address.

Step S1100: Obtain the target memory physical address corresponding to the current process in the user space.

Exemplarily, acquiring the physical address of the target memory corresponding to the current process in the user space (step S1100 ) may include: acquiring the physical address of the target memory corresponding to the current process in the user space through a preset hardware driver outside the kernel. For example, in the user space, a preset hardware driver may be included, and the target memory physical address corresponding to the current process in the user space may be obtained through the hardware driver. Optionally, the hardware driver may be executed in response to the user's click operation on the "query physical address" control on the operation interface.

The connection between the user space and the external hardware device can be established through the hardware driver outside the kernel, so that the user space can obtain the target memory physical address of the hardware device without calling the kernel program.

Step S1200: Map the physical address of the target memory to the virtual address of the target memory according to the mapping relationship.

Because the physical address is directly used, it is not convenient to isolate the process address space; and the physical memory space is limited, converting the physical address into a virtual address can realize time-sharing multiplexing and sharing of multiple processes. In this embodiment of the present invention, an application module outside the kernel of the operating system includes: an address translation submodule, which can map a physical address of the target memory to a virtual address of the target memory through a preset mapping relationship in the address translation submodule.

The mapping relationship can be set according to the size of the physical memory and address space in the user space. It can be a one-to-one mapping from physical addresses to virtual addresses, that is, linear mapping, or a combination of linear mapping and nonlinear mapping. For example, the user space can be divided into a linear mapping area and a non-linear mapping area. According to different application goals, the nonlinear mapping area can be divided into three parts: dynamic memory mapping (vmalloc) area, persistent mapping area and temporary mapping area. Different nonlinear mapping partitions can adopt different mapping relationships. Map the physical address of the target memory of the current process to the virtual address of the target memory according to the corresponding mapping relationship.

Step S1300, directly accessing the target memory virtual address.

Exemplarily, directly accessing the virtual address of the target memory includes: reading data at the virtual address of the target memory to obtain the target data, returning the target data to the current process; and/or directly writing the target data to the virtual address of the target memory.

When only data needs to be read, the step S1300 may only include reading data at the target memory virtual address to obtain the target data, and returning the target data to the current process. Since the target memory virtual address is mapped to the target memory physical address, reading target data from the target memory virtual address is equivalent to reading target data from the target memory physical address.

When only data needs to be written, this step S1300 only includes writing the target data directly into the target memory virtual address. Since the target memory virtual address is mapped to the target memory physical address, writing target data to the target memory virtual address is equivalent to writing target data to the target memory physical address.

When the process includes reading and writing data, step S1300 includes reading data at the target memory virtual address to obtain the target data, returning the target data to the current process, and writing the target data into the target memory virtual address.

According to the above technical solution, the conversion between the physical address and the virtual address of the user space layer is realized by the application module outside the kernel of the operating system, and the direct access to the physical address of the target memory in the user space is further realized. By using the technical solution, the program developed by the bare metal can be directly copied to the platform with the operating system, so that the portability is good. Moreover, compared with the traditional technology, the technical solution does not need to copy data into the kernel space, the data transmission and access process is simple, and the program development efficiency is higher. At the same time, it avoids the risk that the entire system may be paralyzed when the kernel development program encounters a problem, so the security is higher.

Exemplarily, acquiring the target memory physical address corresponding to the current process in the user space (step S1100) may include: acquiring a preconfigured memory physical address as the target memory physical address; or acquiring a randomly allocated memory physical address as the target memory physical address .

Pre-configured memory physical addresses, for example, set them in different memory physical address subspaces according to different types of processes. Exemplarily, assuming that according to the preset configuration rules, the type of the current process should be configured in the memory physical address subspace A, then the memory physical address of the current process can be set in the target memory corresponding to the last configured process in A. after the physical address. Optionally, a random allocation method may also be adopted, and the randomly allocated memory physical address may be used as the target memory physical address of the current process.

Through the above technical solution, the physical address of the target memory corresponding to the current process in the user space can be obtained by pre-configuration or random allocation. Different ways of configuring the physical address of the memory can be adopted according to the size of the user space, the attributes of the process or the usage requirements of the user, so as to facilitate the efficient loading and running of the process.

Exemplarily, mapping the physical address of the target memory to the virtual address of the target memory according to the mapping relationship (step S1200) may include: step S1210, calling the memory management unit MMU running in the kernel space; step S1220, using the memory management unit MMU according to the mapping Relationships map target memory physical addresses to target memory virtual addresses. The kernel space includes a memory management unit (MMU), which is used to implement the mapping of physical addresses and virtual addresses, and can convert physical addresses into virtual addresses and virtual addresses into physical addresses.

Exemplarily, a mapping relationship is preset in an application module outside the kernel of the operating system; mapping the physical address of the target memory to a virtual address of the target memory according to the mapping relationship (step S1200) may include: directly mapping the target memory according to the preset mapping relationship. Physical addresses are mapped to target memory virtual addresses.

According to the above technical solution, the mapping relationship between the physical memory address and the virtual memory address is directly set in the user space, and the physical address of the target memory can be mapped to the virtual address of the target memory directly according to the mapping relationship. Compared with the technical solution of setting the mapping relationship in the kernel space, this embodiment can shorten the path for finding the virtual address of the target memory.

Exemplarily, after directly accessing the target memory virtual address, the method 1000 for directly accessing the memory physical address may further include: unmapping between the target memory virtual address and the target memory physical address to release the target memory virtual address.

Optionally, virtual memory to physical memory can be unmapped using the munmap() function. When the process ends or uses exec-related functions to execute other programs, the mapped memory will be automatically released. As a result, the freed target memory virtual address can be used by other processes, so the use efficiency of the virtual memory can be improved.

According to another aspect of the present invention, an apparatus 200 for directly accessing a physical address of a memory is provided. FIG. 2 shows a schematic block diagram of an apparatus 200 for directly accessing a physical address of a memory according to an embodiment of the present invention. As shown in FIG. 2 , the apparatus 200 includes an acquisition module 210 , a mapping module 220 and an access module 230 . Each of the modules can respectively execute various steps/functions of the method for directly accessing a physical address of a memory described above in conjunction with FIG. 1 . Only the main functions of the components of the apparatus 200 for directly accessing the physical address of the memory will be described below, and the details that have been described above will be omitted.

The obtaining module 210 is configured to obtain the target memory physical address corresponding to the current process in the user space.

The mapping module 220 is configured to map the physical address of the target memory into a virtual address of the target memory according to the mapping relationship.

The access module 230 is used to directly access the target memory virtual address.

Exemplarily, the obtaining module 210 may include: a first obtaining submodule, configured to obtain a preconfigured memory physical address as the target memory physical address; or obtain a randomly allocated memory physical address as the target memory physical address.

Exemplarily, the mapping module 220 may include a calling sub-module for calling a preset process running in the kernel space; the mapping module 220 may also include a first mapping sub-module for calling the target memory according to the mapping relationship through the preset process. Physical addresses are mapped to target memory virtual addresses.

Exemplarily, a mapping relationship is preset in the application module; the mapping module 220 may include: a second mapping sub-module for directly mapping the physical address of the target memory to the virtual address of the target memory according to the preset mapping relationship.

For example, the access module 230 may include a first access sub-module and/or a second access sub-module. Wherein, the first access sub-module is used for reading data at the virtual address of the target memory to obtain the target data, and returning the target data to the current process. The second access submodule is used for directly writing target data into the target memory virtual address.

Exemplarily, the apparatus 200 further includes a release module configured to release the mapping between the virtual address of the target memory and the physical address of the target memory, so as to release the virtual address of the target memory.

Exemplarily, the obtaining module 210 may include: a second obtaining sub-module, configured to obtain the target memory physical address corresponding to the current process in the user space through a preset hardware driver outside the kernel.

According to yet another aspect of the present invention, a system 300 for directly accessing a physical address of a memory is provided. FIG. 3 shows a schematic block diagram of a system 300 for directly accessing memory physical addresses according to an embodiment of the present invention. As shown in FIG. 3 , the system 300 includes a processor 310 and a memory 320, wherein the memory 320 stores computer program instructions, and the computer program instructions are used to execute the above-mentioned method 100 for directly accessing a physical address of a memory when the computer program instructions are run by the processor 310. .

According to another aspect of the present invention, a storage medium is provided, and program instructions are stored on the storage medium, and the program instructions are used to execute the above-mentioned method 100 for directly accessing a physical address of a memory when running. The storage medium may include, for example, a memory card of a smartphone, a storage component of a tablet computer, a hard disk of a personal computer, read only memory (ROM), erasable programmable read only memory (EPROM), portable compact disk read only memory (CD-ROM), USB memory, or any combination of the above storage media.

Although example embodiments have been described herein with reference to the accompanying drawings, it should be understood that the above-described example embodiments are exemplary only, and are not intended to limit the scope of the invention thereto. Various changes and modifications can be made therein by those of ordinary skill in the art without departing from the scope and spirit of the invention. All such changes and modifications are intended to be included within the scope of the invention as claimed in the appended claims.

Those of ordinary skill in the art can realize that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Skilled artisans may implement the described functionality using different methods for each particular application, but such implementations should not be considered beyond the scope of the present invention.

It should be noted that the above-described embodiments illustrate rather than limit the invention, and that alternative embodiments may be devised by those skilled in the art without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps not listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention can be implemented by means of hardware comprising several different elements and by means of a suitably programmed computer. In a unit claim enumerating several means, several of these means may be embodied by one and the same item of hardware. The use of the words first, second, and third, etc. do not denote any order. These words can be interpreted as names.

The above is only the specific embodiment of the present invention or the description of the specific embodiment, and the protection scope of the present invention is not limited thereto. Any changes or substitutions should be included within the protection scope of the present invention. The protection scope of the present invention shall be subject to the protection scope of the claims.

Claims (10)

1. a method for directly accessing memory physical address, is characterized in that, is applied to the application module outside the kernel of operating system, comprises: Get the physical address of the target memory corresponding to the current process in user space; mapping the physical address of the target memory to a virtual address of the target memory according to the mapping relationship; Directly access the target memory virtual address. 2. The method according to claim 1, wherein the obtaining the target memory physical address corresponding to the current process in the user space comprises: Obtain a preconfigured memory physical address as the target memory physical address; or, A randomly allocated memory physical address is obtained as the target memory physical address. 3. The method of claim 1, wherein the mapping the target memory physical address to the target memory virtual address according to the mapping relationship comprises: Call the memory management unit running in kernel space; The target memory physical address is mapped to the target memory virtual address by the memory management unit according to the mapping relationship. 4. The method of claim 1, wherein the mapping relationship is preset in the application module; The mapping of the target memory physical address to the target memory virtual address according to the mapping relationship includes: The target memory physical address is directly mapped to the target memory virtual address according to the preset mapping relationship. 5. The method of claim 1, wherein the directly accessing the target memory virtual address comprises: reading data at the target memory virtual address to obtain target data, returning the target data to the current process; and/or Write target data directly into the target memory virtual address. 6. The method of claim 1, after the direct access to the target memory virtual address, the method further comprises: Unmapping between the target memory virtual address and the target memory physical address to release the target memory virtual address. 7. The method of claim 1, wherein the acquisition of the target memory physical address corresponding to the current process in the user space comprises: The target memory physical address corresponding to the current process in the user space is acquired through a preset hardware driver outside the kernel. 8. A device for directly accessing a physical address of memory, comprising: The acquisition module is used to acquire the physical address of the target memory corresponding to the current process in the user space; a mapping module for mapping the physical address of the target memory to a virtual address of the target memory according to the mapping relationship; The access module is used to directly access the virtual address of the target memory. 9. A system for directly accessing a physical address of a memory, comprising a processor and a memory, wherein the memory stores computer program instructions, the computer program instructions being used by the processor to execute the steps of claims 1 to 10 when executed by the processor. 7. The method for directly accessing the physical address of the memory according to any one of the items. 10 . A storage medium on which program instructions are stored, the program instructions are used to execute the method for directly accessing a physical address of a memory according to any one of claims 1 to 7 when running. 11 .

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