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Make cosmo_dlopen() safer and faster

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If cosmo_dlopen() is linked on AMD64 then the runtime will switch to
using %gs for thread-local storage. This eliminates the need for the
imported symbol trampoline. It's now safer to pass function pointers
back and forth with imported libraries. Your program gets recompiled
at runtime to make it happen and the overhead is a few milliseconds.
This commit is contained in:
Justine Tunney 2024-01-05 20:36:57 -08:00
parent c0eacf2eb1
commit fad1279c61
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GPG key ID: BE714B4575D6E328
8 changed files with 93 additions and 16 deletions
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7
libc/runtime/morph_tls.c
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@ -17,9 +17,9 @@
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "ape/sections.internal.h"
#include "libc/serialize.h"
#include "libc/runtime/internal.h"
#include "libc/runtime/runtime.h"
#include "libc/serialize.h"
#include "libc/thread/tls.h"
typedef char xmm_t __attribute__((__vector_size__(16), __aligned__(1)));
@ -55,11 +55,13 @@ privileged void __morph_tls(void) {
// address 0x30 was promised to us, according to Go team
// https://github.com/golang/go/issues/23617
dis = 0x30;
} else {
} else if (IsWindows()) {
// MSVC __declspec(thread) generates binary code for this
// %gs:0x1480 abi. So long as TlsAlloc() isn't called >64
// times we should be good.
dis = 0x1480 + __tls_index * 8;
} else {
dis = 0;
}
// iterate over modifiable code looking for 9 byte instruction
@ -112,6 +114,7 @@ privileged void __morph_tls(void) {
}
}
__tls_morphed = 1;
__morph_end();
#endif
}