git: 39733922edc4 - main - rtld: actually resolve memcpy plt

The branch main has been updated by rlibby:

URL: https://cgit.FreeBSD.org/src/commit/?id=39733922edc43001e8750307704daa835a14b5ac

commit 39733922edc43001e8750307704daa835a14b5ac
Author:     Ryan Libby <rlibby@FreeBSD.org>
AuthorDate: 2024-07-07 23:46:49 +0000
Commit:     Ryan Libby <rlibby@FreeBSD.org>
CommitDate: 2024-07-07 23:46:49 +0000

    rtld: actually resolve memcpy plt
    
    The call to memcpy() meant to cause plt resolution in _thr_rtld_init()
    was getting optimized by the compiler.  Tell the compiler not to use its
    builtins in thr_rtld.c.  We could avoid just the memcpy builtin but
    disabling all will be more robust against future changes.
    
    Reviewed by:    kib
    Differential Revision:  https://reviews.freebsd.org/D45891
---
 lib/libthr/Makefile | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/lib/libthr/Makefile b/lib/libthr/Makefile
index 85c028f521a1..d3c69a7dc8b7 100644
--- a/lib/libthr/Makefile
+++ b/lib/libthr/Makefile
@@ -32,6 +32,10 @@ CFLAGS+=-I${SRCTOP}/lib/libthread_db
 
 CFLAGS.thr_stack.c+=	-Wno-cast-align
 CFLAGS.rtld_malloc.c+=	-Wno-cast-align
+# Disable compiler builtins so that the compiler does not optimize away rtld's
+# attempts to force early PLT resolution for certain functions that may be
+# replaced by builtins.
+CFLAGS.thr_rtld.c+=	-fno-builtin
 CFLAGS.thr_symbols.c+=	-Wno-missing-variable-declarations
 .if ${MK_ASAN} != "no"
 # False-positive ASAN error claiming the local "struct sigaction act;" is