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Support Linux binfmt_misc and APE loading on Apple

Browse source 
The "no modify self" variant of Actually Portable Executable is now
supported on all platforms. If you use `$(APE_NO_MODIFY_SELF)` then
ld.bfd will embed a 4096 byte ELF binary and a 4096 byte Macho file
which are installed on the fly to ${TMPDIR:-/tmp}, which enables us
launch the executable, without needing to copy the whole executable

To prevent it from copying a tiny executable to your temp directory
you need to install the `ape` command (renamed from ape-loader), to
a system path. For example:

    # FreeBSD / NetBSD / OpenBSD
    make -j8 o//ape/ape
    cp o//ape/ape /usr/bin/ape

    # Mac OS
    # make -j8 o//ape/ape.macho
    curl https://justine.lol/ape.macho >/usr/bin/ape
    chmod +x /usr/bin/ape

On Linux you can get even more performance with the new binfmt_misc
support which makes launching non-modifying APE binaries as fast as
launching ELF executables. Running the following command:

    # Linux
    ape/apeinstall.sh

Will copy APE loader to /usr/bin/ape and register with binfmt_misc
Lastly, this change also fixes a really interesting race condition
with OpenBSD thread joining.
This commit is contained in:
Justine Tunney 2022-05-21 07:52:58 -07:00
parent 7838edae88
commit db0d8dd806
31 changed files with 1089 additions and 305 deletions
Download patch file Download diff file Expand all files Collapse all files

18
libc/runtime/clone.c
View file

@ -58,7 +58,10 @@ struct CloneArgs {
uint32_t utid;
int64_t tid64;
};
int lock;
union {
int lock;
void *pstack;
};
int *ctid;
int *ztid;
char *tls;
@ -287,12 +290,18 @@ __attribute__((__used__, __no_reorder__))
static privileged wontreturn void
OpenbsdThreadMain(struct CloneArgs *wt) {
wt->func(wt->arg);
// we no longer use the stack after this point
// we no longer use the stack after this point. however openbsd
// validates the rsp register too so a race condition can still
// happen if the parent tries to free the stack. we'll solve it
// by simply changing rsp back to the old value before exiting!
// although ideally there should be a better solution.
//
// void __threxit(%rdi = int32_t *notdead);
asm volatile("movl\t$0,%0\n\t" // *wt->ztid = 0
asm volatile("mov\t%3,%%rsp\n\t"
"movl\t$0,%0\n\t" // *wt->ztid = 0
"syscall" // _Exit1()
: "=m"(*wt->ztid)
: "a"(302), "D"(0)
: "a"(302), "D"(0), "r"(wt->pstack)
: "rcx", "r11", "memory");
unreachable;
}
@ -307,6 +316,7 @@ static int CloneOpenbsd(int (*func)(void *), char *stk, size_t stksz, int flags,
-alignof(struct CloneArgs));
wt->ctid = flags & CLONE_CHILD_SETTID ? ctid : &wt->tid;
wt->ztid = flags & CLONE_CHILD_CLEARTID ? ctid : &wt->tid;
wt->pstack = __builtin_frame_address(0);
wt->func = func;
wt->arg = arg;
params.tf_stack = wt;