Differential D20663 Diff 58907 libexec/rtld-elf/rtld-libc/Makefile.inc

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libexec/rtld-elf/rtld-libc/Makefile.inc

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				# $FreeBSD$

				# Add the necessary libc dependencies for RTLD without pulling in all of the
				# complex libc bits such as locales, etc.
				# TODO: avoid linking libc_pic
				LIBADD= c_nossp_pic
				CFLAGS+= -I${SRCTOP}/libexec/rtld-elf/rtld-libc

				# Build all the files that use __libc_interposing here with -DIN_RTLD. With that
				# define they avoid the use of __libc_interposing and call the syscall directly.
				.PATH: ${SRCTOP}/lib/libc/gen
				SRCS+= opendir.c closedir.c readdir.c telldir.c

				# Avoid further dependencies by providing simple implementations of libc
				# functions such as __error(), etc.
				.PATH: ${SRCTOP}/libexec/rtld-elf/rtld-libc
				kibUnsubmitted Done Inline Actions Is this needed ? kib: Is this needed ?
				arichardsonAuthorUnsubmitted Done Inline Actions This is needed for CHERI where we convert the variadic system call to always pass the optional argument (since the variadic calling convention is different and passes all arguments on the stack. I forgot to remove that part of the diff and will only add it to CheriBSD. arichardson: This is needed for CHERI where we convert the variadic system call to always pass the optional…
				SRCS+= rtld_libc.c
				kibUnsubmitted Done Inline Actions Is that happens due to -DIN_RTLD or because of rtld-hacked namespace.h ? kib: Is that happens due to -DIN_RTLD or because of rtld-hacked namespace.h ?
				arichardsonAuthorUnsubmitted Done Inline Actions I'm afraid I don't understand the question. Are you asking why we need those files for CHERI? For all non-CHERI architectures it is fine to call the system call with a variadic calling convention, but for CHERI we need the wrapper that fetches the optional argument from the stack and places it in the register that is expected by the syscall. arichardson: I'm afraid I don't understand the question. Are you asking why we need those files for CHERI?
				kibUnsubmitted Done Inline Actions No, I am asking, what magic gets rid of the interposing calls. Your comment claims that this is because of -DIN_RTLD defined while dir.c files are compiled, but IMO it happens because you provide different namespace.h which directs interposed calls to non-interposed functions. kib:* No, I am asking, what magic gets rid of the interposing calls. Your comment claims that this…
				arichardsonAuthorUnsubmitted Done Inline Actions Yes, it is a combination of the two. For opendir.o it's both the ifdefs and the macros that redirect to __sys_foo arichardson: Yes, it is a combination of the two. For opendir.o it's both the ifdefs and the macros that…
				kibUnsubmitted Not Done Inline Actions Which specific #ifdef do you mean there ? kib: Which specific #ifdef do you mean there ?
				arichardsonAuthorUnsubmitted Done Inline Actions -DIN_RTLD arichardson: -DIN_RTLD
				kibUnsubmitted Not Done Inline Actions I should be extremely explicit. Please give me the line number in opendir.c which contains that #ifdef. kib: I should be extremely explicit. Please give me the line number in opendir.c which contains…
				arichardsonAuthorUnsubmitted Done Inline Actions Sorry I got confused here. -DIN_RTLD only affects the CheriBSD-specific compiles of fctnl.c and open.c. In this patch it doesn't actually change anything in opendir. The changes in opendir are due to the defines at the start of rtld_libc.h to avoid calling pthreads functions. arichardson: Sorry I got confused here. -DIN_RTLD only affects the CheriBSD-specific compiles of fctnl.c and…
				kibUnsubmitted Not Done Inline Actions So the comment is misleading, which is why I am so attached to this point. It is not -DIN_RTLD which avoids interposing for FreeBSD. kib: So the comment is misleading, which is why I am so attached to this point. It is not -DIN_RTLD…

				# The following logic was used to avoid dependencies. If you would like to
				# verify that we haven't started including more files from libc due to more
				# recent changes, you can compile with -DRTLD_VERIFY_LIBC_DEPENDENCIES and
				# check that rtld still compiles.
				.ifdef RTLD_VERIFY_LIBC_DEPENDENCIES
				# __libc_interposing adds lots of unncessary dependencies
				kibUnsubmitted Not Done Inline Actions Is this a stray comment ? kib: Is this a stray comment ?
				arichardsonAuthorUnsubmitted Done Inline Actions I could keep this in under `.ifdef DEBUG_RTLD_LIBC_DEPENDENCIES` so that we can check that other architectures don't accidentally pull in more files (I only tested MIPS and x86). arichardson: I could keep this in under `.ifdef DEBUG_RTLD_LIBC_DEPENDENCIES` so that we can check that…
				_blacklisted_symbols=__libc_interposing
				# So does _elf_aux_info (it pulls in pthreads)
				_blacklisted_symbols+= _elf_aux_info
				# Avoid pthreads depedency
				_blacklisted_symbols+=_pthread_mutex_lock pthread_mutex_lock
				# And fprintf (pulls in all the locale code)
				_blacklisted_symbols+=fprintf
				# Now list all symbols inside the __libc_interposing table:
				_blacklisted_symbols+=accept accept4 aio_suspend close connect fcntl fsync \
				fork msync nanosleep openat poll pselect recvfrom recvmsg select sendmsg \
				sendto setcontext sigaction sigsuspend sigwait sigtimedwait sigwaitinfo \
				swapcontext system tcdrain read readv wait4 write writev \
				_pthread_mutex_init_calloc_cb spinlock spinunlock kevent wait6 ppoll \
				map_stacks_exec fdatasync clock_nanosleep distribute_static_tls
				# Some more symbols that were previously defined in rtld (but are not needed)
				_blacklisted_symbols+=__pthread_cxa_finalize
				_blacklisted_symbols+=exit

				# Note: this library is a hack to verify that we didn't link those symbols. It
				# would be nice if LD supported a flag that caused an error when linking against
				# a given symbol.
				LDADD+=${.OBJDIR}/rtld_verify_linked_symbols.a
				${sym}.c: ensure_not_linked.h
				_blacklisted_objs=
				LDFLAGS+= -Wl,--trace
				.for sym in ${_blacklisted_symbols}
				${sym}.c: ensure_not_linked.h
				printf "#include \"ensure_not_linked.h\"\nLINK_ERROR_ON_REFERENCE(${sym})\n" > ${sym}.c
				${sym}.o: ${sym}.c
				${CC} ${CFLAGS} ${sym}.c -c -o ${sym}.o
				_blacklisted_objs+= ${sym}.o
				CLEANFILES+=${sym}.o
				LDFLAGS+= -Wl,--trace-symbol=${sym}
				.endfor

				rtld_verify_linked_symbols.a: ensure_not_linked.h ${_blacklisted_objs}
				${AR} cr ${.OBJDIR}/${.TARGET} ${_blacklisted_objs}
				CLEANFILES+=rtld_verify_linked_symbols.a
				${PROG}: rtld_verify_linked_symbols.a
				.endif RTLD_VERIFY_LIBC_DEPENDENCIES
				kibUnsubmitted Done Inline Actions FIXME ? kib: FIXME ?