Link to the citations in Scopus. Fingerprint Dive into the research topics of 'A dynamic control mechanism of interrupt stack overflow on real-time embedded monitor REMON '.
Together they form a unique fingerprint. View full fingerprint. Electronics and Communications in Japan , 98 3 , In: Electronics and Communications in Japan , Vol. It took a complete re-write of the code but it made lots of stuff easier in the end.
You can do a search here on that subject of "cooperative multitasking" and find a lot of stuff. Kartman took me on as a padawan on this subject. He can tell you a lot as well. As I work in isolation I've never had the benefit of some one elses experience.
My logic was to get the main program loop to do as little as possible so that I always had plenty of time to waste in ISR's. I see now that I must get the ISR's to do the bare minimum and so that I have more of a luxury with time in the main body of my program. I'll do the old switch-eroo and re-build then let you know how I go. Thanks again. Ultimately you will be happy you made the switcheroo. It is painful and somewhat non-intuitive at first but eventually you will reap benefits.
If the main loop is pretty simple, then it is no big deal to move the code currently in the interrupt to the main loop. Later, as you get more loops in your main program, as stated above, you will have to be careful to check the important interrupt flags so that they get processed in a timely manner. When the program gets more complicated and there are a bunch of things you would like to do "simultaneously", then you need to institute cooperative multitasking.
It sounds almost as if there are 2 or 3 different approaches here, but in reality they are all the same but some with more complexity and some with more control in addition to the complexity. When you see it as a spectrum, then you will be able to seamlessly incorporate greater degrees of control without really having to change much of the individual code components e.
Spamiam wrote: camerongarner wrote: thanks for all the help guys. It's not all that counter-intuitive if one thinks about what happens with an interrupt: Everything else stops. The main routine doesn't get to make any more decisions until the ISR returns.
The ISR will deal only with its own event. During a long ISR, other interrupt-causing events can occur, but they won't cause interrupts until the current ISR returns. The times at which the events occurred will be lost. With short ISRs the main routine can make decisions in a timely manner. Moderation in all things. Tony spamiam - I had to look up the term 'padawan' as I had not come across it before.
Google set me straight quickly - seems my knowlege of Star Wars stopped after the first movie. May the force be with you! Kartman wrote: Tony spamiam - I had to look up the term 'padawan' as I had not come across it before. I had to google it to find out how to spell Padawan! But I thought it was an appropriate term for someone who is learning the mystical arts of proper programming from a master.
Just a guess since I am not familiar with your compiler but if your isr is indeed in a separate. Otherwise I can't see how the compiler could generate the correct code for the isr i. One popular scheme is for an ISR to set a state machine's next-state variable then exit. The state machine is implemented in the non-ISR code. A method I don't like is state machine in the form of a giant switch statement. Skip to main content. Interrupt causes stack overflow. Log in or register to post comments.
Go To Last Post. Level: Rookie. Posts: 35 View posts. Posted by camerongarner : Mon. Nov 3, - AM. Fivestar widget 1 2 3 4 5. He is the author of three books on the subject, all published by Butterworth-Heinemann. E-mail him at. Massey, Russel. Ganssle, Jack. Return to June Table of Contents. You must Sign in or Register to post a comment. This site uses Akismet to reduce spam. Learn how your comment data is processed. You must verify your email address before signing in.
Check your email for your verification email, or enter your email address in the form below to resend the email. Please confirm the information below before signing in.
Already have an account? Sign In. Please check your email and click on the link to verify your email address. We've sent an email with instructions to create a new password. Your existing password has not been changed. Sorry, we could not verify that email address.
Enter your email below, and we'll send you another email. Thank you for verifiying your email address. We didn't recognize that password reset code. We've sent you an email with instructions to create a new password. Skip to content Search for:. Home Blog Introduction to Interrupt Debugging. Race conditions A race condition is probably the most common interrupt-related problem. Take a look at Figure 1 along with the two pseudo-code fragments below: Figure 1: A race condition Mainline code: 1.
Store result back at variable X Let's say that the shared variable X is tracking the number of bytes in a buffer. Restore prior interrupt state By far, the best solution is to avoid sharing variables and hardware registers between ISR and mainline code. Hardware complications Some peripherals have more internal registers than externally addressable locations. Stack overflow Another potential problem with interrupts is stack overflow.
Back 2. Tags: EDA , Industry. For more information or to change your cookie settings, click here. If you continue to browse this site without changing your cookie settings, you agree to this use. View Cookie Policy for full details. Stack-based buffer overflow exploits are likely the shiniest and most common form of exploit for remotely taking over the code execution of a process. These exploits were extremely common 20 years ago, but since then, a huge amount of effort has gone into mitigating stack-based overflow attacks by operating system developers, application developers, and hardware manufacturers, with changes even being made to the standard libraries developers use.
Below, we will explore how stack-based overflows work and detail the mitigation strategies that are put in place to try to prevent them. Understanding stack-based overflow attacks involves at least a basic understanding of computer memory. Memory in a computer is simply a storage place for data and instructions—data for storing numbers, letters, images, and anything else, and instructions that tell the computer what to do with the data.
Both are stored in the same memory because memory was prohibitively expensive in the early days of computing, and reserving it for one type of storage or another was wasteful.
Such an approach where data and instructions are stored together is known as a Von Neumann architecture. The interesting thing about this program is that it creates two buffers in memory called realPassword and givenPassword as local variables. Each buffer has space for 20 characters. When we run the program, space for these local variables is created in-memory and specifically stored on the stack with all other local variables and some other stuff. The stack is a very structured, sequential memory space, so the relative distance between any two local variables in-memory is guaranteed to be relatively small.
After this program creates the variables, it populates the realPassword value with a string, then prompts the user for a password and copies the provided password into the givenPassword value.
Once it has both passwords, it compares them. The password we entered does not match the expected password. There is a catch here: The programmer me made several really bad mistakes, which we will talk about later. Debuggers let us see what the program is doing and what the memory looks like on a running basis.
As mentioned, the stack is sequentially stored data. You can see above that they are right next to each other in memory. The realPassword buffer is right after the givenPassword buffer. First, developers should never, ever, ever use the gets function because it does not check to make sure that the size of the data it reads in matches the size of the memory location it uses to save the data.
It just blindly reads the text and dumps it into memory. There are many functions that do the exact same thing—these are known as unbounded functions because developers cannot predict when they will stop reading from or writing to memory. Every developer should know these functions and avoid them, and every project should automatically audit source code for them. These functions all date from a period where security was not as imperative as it is today.
0コメント