With the new SysV style process init args, it's a bit easier to finally
parse out argc, argv, and envp from the stack and pass them on to main
functions.
With the move to dynamic executables, crt0's _start was only ever
calling libc's __init_libc, which only ran libc's init_array list. Now
make crt0 itself (which is statically linked into every executable) call
it's own init_array list and have ld.so call every other image's ctor
lists.
Now the init args are a linked list - this also means ld.so can use its
own plus those of the program (eg, SLP and VFS handles). __init_libj6
now adds the head of the list to its global init_args structure, and the
j6_find_init_handle function can be used to find a handle in those args
for a given proto.
This fixes situations like the logger using the wrong mailbox for the
service locator and never finding the uart driver.
In the CRT startup code, when linked in a PIC executable, jumps to
`__init_libj6`, `__init_libc`, `main`, and `exit` were not linked
correctly. They needed a bit more support for looking up the GOT, and
getting the symbol address out of it.
Now libutil has a `got.inc` file for inclusion in asm code that needs to
reference symbols from the GOT.
Added an `API` macro in `j6/api.h` that expands to mark the given
declaration as a default-visible symbol. Also change `format` and
`vformat` to non-template functions, and make calls to `main`, `exit`,
and the library init functions in `_start` GOT-relative.
The libc CRT _start function had a stray pop left in it, which was
causing the stack to never be 16-byte aligned and thus causing crashes
when SSE instructions were called.
Clang will complain if main() is not declared with 0, 2, or 3 arguments.
In order to allow an extra 4th parameter, a new weak main() symbol which
just jumps to driver_main is defined, and _start passes the extra init
pointer to main.
Additionally, libc's crt0.s _start is made weak, and a matching
_libc_crt0_start symbol is defined for implementations that wish to
override _start but still call libc's _start. (Will be used by init.)
For the coming switch to cap/handle ref-counting being the main lifetime
determiner of objects, get rid of self handles for threads and processes
to avoid circular references. Instead, passing 0 to syscalls expecting a
thread or process handle signifies "this process/thread".
The __init_libc function was already running the .init_array functions,
but was never running the .preinit_array functions. Now it runs them
both, in the correct order.
This new libc is mostly from scratch, with *printf() functions provided
by Marco Paland and Eyal Rozenberg's tiny printf library, and malloc and
friends provided by dlmalloc.
