Problem:
- C functions with no arguments require a single `void` in the argument list.
Solution:
- Put the `void` in the argument list of functions in C header files.
We were using ring 0 selectors everywhere (the bottom 3 bits of a
selector determines the ring.) This doesn't really make any practical
difference since UE doesn't run code in other rings anyway, but let's
have correct-looking segment selectors. :^)
Make it possible to bail out of ELF::Image::for_each_program_header()
and then do exactly that if something goes wrong during executable
loading in the kernel.
Also make the errors we return slightly more nuanced than just ENOEXEC.
This commit gets rid of ELF::Loader entirely since its very ambiguous
purpose was actually to load executables for the kernel, and that is
now handled by the kernel itself.
This patch includes some drive-by cleanup in LibDebug and CrashDaemon
enabled by the fact that we no longer need to keep the ref-counted
ELF::Loader around.
Problem:
- `(void)` simply casts the expression to void. This is understood to
indicate that it is ignored, but this is really a compiler trick to
get the compiler to not generate a warning.
Solution:
- Use the `[[maybe_unused]]` attribute to indicate the value is unused.
Note:
- Functions taking a `(void)` argument list have also been changed to
`()` because this is not needed and shows up in the same grep
command.
Keep the debug symbols for shared libraries in memory after we opened
them the first time. This dramatically speeds up symbolication of
backtraces when running dynamically linked programs in UE.
When loading dynamic objects, the emulator loads the interpreter,
generates an auxiliary vector and starts executing the loader.
Additionally, this commits also makes the MallocTracer and backtrace
symbolication work for dynamically loaded programs.
We don't want the next_address pointer losing its alignment somehow.
This whole thing should be replaced at some point, since UE hosted
programs won't be able to run forever with this allocation strategy.
* AK: Add formatter for JsonValue.
* Inspector: Use new format functions.
* Profiler: Use new format functions.
* UserspaceEmulator: Use new format functions.
In the future all (normal) output should be written by any of the
following functions:
out (currently called new_out)
outln
dbg (currently called new_dbg)
dbgln
warn (currently called new_warn)
warnln
However, there are still a ton of uses of the old out/warn/dbg in the
code base so the new functions are called new_out/new_warn/new_dbg. I am
going to rename them as soon as all the other usages are gone (this
might take a while.)
I also added raw_out/raw_dbg/raw_warn which don't do any escaping,
this should be useful if no formatting is required and if the input
contains tons of curly braces. (I am not entirely sure if this function
will stay, but I am adding it for now.)
The kernel doesn't support msg_iovlens != 1 yet and nothing passes
an amount != 1, but if anyone ever adds support for this they won't
have to worry about ue at least.
When SO_TIMESTAMP is set as an option on a SOCK_DGRAM socket, then
recvmsg() will return a SCM_TIMESTAMP control message that
contains a struct timeval with the system time that was current
when the socket was received.
The implementation only supports a single iovec for now.
Some might say having more than one iovec is the main point of
recvmsg() and sendmsg(), but I'm interested in the control message
bits.
* Pass the correct source address for copying tine addr_length.
Previously, this was broken when addr_length was non-nullptr.
* Copy min(sizeof(address), address_length) bytes into address,
instead of sizeof(address), which might be larger than the
user buffer.
* Use sockaddr_storage instead of sockaddr_un. In practice they're
both the same size, but this is what sockaddr_storage is for.
With this (in particular, the first fix), `ue /bin/ntpquery`
actually gets past the recvfrom() call :^)
With this, `ue /bin/ntpquery` can be used to test sendto() and
recvfrom() in ue. (It eventually hits an unimplemented FILD_RM64,
but not before doing emulated network i/o and printing response
details.)
Since the CPU already does almost all necessary validation steps
for us, we don't really need to attempt to do this. Doing it
ourselves doesn't really work very reliably, because we'd have to
account for other processors modifying virtual memory, and we'd
have to account for e.g. pages not being able to be allocated
due to insufficient resources.
So change the copy_to/from_user (and associated helper functions)
to use the new safe_memcpy, which will return whether it succeeded
or not. The only manual validation step needed (which the CPU
can't perform for us) is making sure the pointers provided by user
mode aren't pointing to kernel mappings.
To make it easier to read/write from/to either kernel or user mode
data add the UserOrKernelBuffer helper class, which will internally
either use copy_from/to_user or directly memcpy, or pass the data
through directly using a temporary buffer on the stack.
Last but not least we need to keep syscall params trivial as we
need to copy them from/to user mode using copy_from/to_user.
