Microcode | Microcode Updates for the USENIX 2017 paper | Reverse Engineering library

Since stdout is line buffered, putchar doesn't write to the terminal directly; it puts the character into a buffer, which is flushed when a newline is encountered. And the buffer for stdout happens to be located on the heap following your heap_book allocation.

So at some point in your copy, you putchar all the characters of your secretinfo method. They are now in the output buffer. A little later, heap_book[i] is within the stdout buffer itself, so you encounter the copy of secretinfo that is there. When you putchar it, you effectively create another copy a little further along in the buffer, and the process repeats.

You can verify this in your debugger. The address of the stdout buffer, on glibc, can be found with p stdout->_IO_buf_base. In my test it's exactly 160 bytes past heap_book.

-march native means -march $MY_HARDWARE. We have no idea what hardware you have. For you, that would be -march=skylake-avx512 (SkyLake SP) The results could be reproduced by specifying your hardware architecture explicitly.

It's quite possible that the errors will decrease with more modern instructions, specifically Fused-Multiply-and-Add (FMA). This is the operation a*b+c, but rounded once instead of twice. That saves one rounding error.

Those compiler options work by generating special asm, whether it's retpolines or lfence or whatever. When you're writing asm by hand, obviously it's still up to you whether to manually include special asm or not.

Changes to OSes are the relevant thing for you. The OS, on a CPU with updated microcode, can defend you from other threads by telling the CPU not to allow branch history from past code to influence future code. (The ability to ask it to do this was added in microcode updates, and usually works by just flushing the branch prediction caches).

Another software thread executing on the other logical core of the same physical core can "attack" your code on most CPUs, because branch predictors are shared. At least in theory; ASLR might make that implausible if both tasks would need to be using the same virtual addresses for their branch targets to prime the predictors.

So in user-space, I think you only need to defend yourself from Spectre if you're worried about code running in the same thread (e.g. a JIT engine running untrusted code inside a browser or JVM has to defend itself) or on the same physical core.

The __common_interrupt: 10.55 No irq handler for vector is a firmware issue. Seems you are using AMD CPU I guess? You will want to checkout whether there is a newer version of bios for your motherboard. And update bios should solve this, if not, just wait for it.

And for the mce: [Hardware Error], probably is caused by the above error, but if your system is working fine. It means it's been corrected. But still you can do:

This issue was resolved. After running the KMD driver for the NVDLA_IP_0 through the instruction mention in the comments and here by Ian Abbott, the node appeared in /pro/iomem.

You can create a relatively simple table with label values like this one:

1. Create a new panel, select source, change format from Time series to Table, select Table visualisation, and enable instant mode:

2. Open Transform tab, add two transforms in this order: 1) Labels to fields, 2) Organize fields. See the picture:

3. Disable unnecessary fields and rename ones you'd like to see.

Using /proc/cpuinfo and free -mh along with awk, search for the strings required, using : as the field delimited, set variables accordingly, splitting the output of free -mh further into an array called arr based on " " as the delimiter. At the end, print the data in the required format using the variables created.

When searching for lines beginning with flag, we search for strings svn or vmx using awk's match function. A match will signified by the RSTART variable not being 0 and so we check this to find the type of virtualisatiion being utilised. As we have set virt to No Virtualisation at the beginning, no matches will print No Virtualisation.

Ok, shortly after posting we figured it out. Seems like a mount point has changed (I expect due to a linux kernel update) and we have not used the nofail option in /etc/fstab as described in the aws knowledge center, this caused the server to hang at boot.

Going forward we will also ensure we use UUID mounting so we are independent on the device naming in /dev/.

your target is a 64bit x86 platform, which is certainly not obscure. the SO question you linked is the best starting point, spin up a VM of the linux distribution you're targeting on your embedded board, compile in that and scp the executable to the board (or just compile on the board itself, your target is not exactly underpowered)