We are required in our syscall emulation to handle cases where pointers
are invalid. This means we need to pessimistically assume a memcpy will
fault when reading application memory.
This implements a signal handler based approach to catching the SIGSEGV
on memcpy and returning an EFAULT if it faults.
The ARM64EC SRA layout will use x0-3 for x86_64 registers, as such any
arguments passed to C ABI functions need to proxy their arguments
through the temporaries and move as appropriate.
The -deps target is the wrong target to add this to, since its compile flags
are propagated to both Guest.cpp and Host.cpp. Instead, define the flag only
when processing files within a guest context.
I added the `pkg-config` that is missing in the Dockerfile, and make the git clone the repository direct from the image, so the user don't need to clone it manually and after that pulls inside the Dockerfile!
We had a chance of doing an additional bogus wfe if the expected value
was hit in one iteration of a loop. Not the biggest problem on current
hardware where WFE only ever sleeps for 1-4 system cycles, but on future
hardware where WFE might actually sleep for longer then this could have
been an issue.
This can be used to allow automatically handling structures that require
special behavior for one member but are automatically repackable otherwise.
The feature is enabled using the new custom_repack annotation and requires
additional repacking functions to be defined in the host file for each
customized member.
Noticed this while writing #3342.
Fixes#3343
The syscall instruction is defined in the documentation that it will set
RCX to the next instruction's RIP and R11 to be RFLAGS. We entirely
skipped this which I noticed while writing unit tests.
Adds unittests to test both 32-bit and 64-bit behaviour because our
helper shares code with both.
I don't know if anything actually relied on this behaviour but we should
definitely support it.
This behaves exactly like pidof but only searches for FEX applications.
This fixes a long standing annoyance of mine that pidof doesn't work for
FEX. This behaves exactly like pidof but knows how to decode the command
line options to pull out the program data.
If the Linux kernel ever accepts the patches for binfmt_misc to change
how the interpreter is handled then this will become redundant, but
until that happens here is a utility that I want.
cmpxchg handles rax specially, so cmpxchg with dest=rax is a special case. test
also the general case.
Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
To avoid performance traps, several conditions must hold for exit repacking
to apply:
* Argument must be a pointer
* The pointee type must have differing data layout between guest and host
* The pointee type must be non-const
Arguments that don't meet the first two conditions are safe *not* to repack
on exit, since they're either passed by copy or have consistent data layout.
The third condition is a heuristic: In principle, an API function could modify
data through nested pointers even if the argument pointer is const. However,
automatic repacking is not supported for such types anyway, so this is a safe
heuristic to use.
