It is wrong to relate on __FreeBSD_version, either from
include/param.h, kernel, or libc, to check for rtld features.
Rtld might be from newer world than the running userspace.
Add special private symbols exported by rtld itself, to indicate the
changes in runtime behavior, and features that cannot be otherwise
detected or deduced at runtime.
Note that the symbols are not exported from libc, so they intentionally
cannot be linked against, and exported from the private namespace from rtld.
Consumers are required to use dlsym(3). For instance, for
_rtld_version_laddr_offset, user should do
ptr = dlsym(RTLD_DEFAULT, "_rtld_version_laddr_offset")
or even
ptr = dlvsym(RTLD_DEFAULT, "_rtld_version_laddr_offset",
"FBSDprivate_1.0");
Non-null ptr means that the change is present.
Also add _rtld_version__FreeBSD_version indicator to report the
headers version used at time of the rtld build.
Reviewed by: jhb
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D24982
Keep link_map l_addr binary layout compatible, rename l_addr to l_base
where rtld returns map base. Provide relocbase in newly added l_addr.
This effectively reverts the patch to the initial version of D24918.
Reported by: antoine (portmgr)
Reviewed by: jhb, markj
Tested by: markj
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D24946
It previously returned the object map base address, while all other
ELF operating systems return load offset, i.e. the difference between
map base and the link base.
Explain the meaning of the field in the man page.
Stop filling the mips-only l_offs member, which is apparently unused.
PR: 246561
Requested by: Damjan Jovanovic <damjan.jov@gmail.com>
Reviewed by: emaste, jhb, cem (previous version)
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D24918
Assume gcc is at least 6.4, the oldest xtoolchain in the ports tree.
Assume clang is at least 6, which was in 11.2-RELEASE. Drop conditions
for older compilers.
Reviewed by: imp (earlier version), emaste, jhb
MFC after: 2 weeks
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D24802
Clang10 may use FPU instructions for optimizing operations with
memory blocks. But we don't want to do lengthy save/restore of all
FPU registers across each rtld_start() call.
MFC after: 3 week
For PIE binaries, ldd(1) performs dlopen(RTLD_TRACE) on the binary.
It is legal for binary to use initial exec TLS mode, but when such
binary (actually dso) is dlopened, we might not have enough free space
in the finalized static TLS segment. Make ldd operational by skipping
TLS space allocation, we are not going to execute any code from the
dso anyway.
Reported by: tobik
PR: 245677
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
This is continuation of D21163/r359634, which handled the alignment
for global mode.
Non-x86 arches are not handled, maintainers are welcomed.
Tested by: emaste
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
Differential revision: https://reviews.freebsd.org/D24366
See https://sourceware.org/bugzilla/show_bug.cgi?id=24606 for the test case.
See https://reviews.llvm.org/D64930 for the background and more discussion.
Also this fixes another bug in malloc_aligned() where total size of
the allocated memory might be not enough to fit the aligned requested
block after the initial pointer is incremented by the pointer size.
Reviewed by: bdragon
Tested by: antoine (exp-run PR 244866), bdragon, emaste
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
Differential revision: https://reviews.freebsd.org/D21163
realpath(3) is used a lot e.g., by clang and is a major source of getcwd
and fstatat calls. This can be done more efficiently in the kernel.
This works by performing a regular lookup while saving the name and found
parent directory. If the terminal vnode is a directory we can resolve it using
usual means. Otherwise we can use the name saved by lookup and resolve the
parent.
See the review for sample syscall counts.
Reviewed by: kib
Differential Revision: https://reviews.freebsd.org/D23574
lld 10.0 seems to generate this relocation for rdtsc_mb() ifunc in our libc.
Reported, reviewed, and tested by: dim (amd64, previous version)
Discussed with: emaste
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D23652
This allows for rtld to not issue two sigprocmask(2) syscalls for each
symbol binding operation in single-threaded processes. Rtld needs to
block signals as part of locking to ensure signal safety of the bind
process, because signal handlers might need to lazily resolve symbol
references.
As result, number of syscalls issued on startup by simple programs not
using libthr, is typically reduced 2x. For instance, for hello world,
I see:
non-sigfastblock
# (truss ./hello > /dev/null) |& wc -l
63
sigfastblock
# (truss ./hello > /dev/null) |& wc -l
37
Tested by: pho
Disscussed with: cem, emaste, jilles
Sponsored by: The FreeBSD Foundation
Differential revision: https://reviews.freebsd.org/D12773
They were introduced to take care of ifunc, but right now no architecture
provides ifunc'ed variants. Since rtld uses memset extensively this results in
a pessmization. Should someone want to use ifunc here they should provide a
mandatory symbol (e.g., rtld_memset).
See the review for profiling data.
Reviewed by: kib
Differential Revision: https://reviews.freebsd.org/D23176
Move all MD statements into $MACHINE_ARCH/Makefile.inc.
Unconditionally apply version script to rtld, the interpreter is not
functional without it for long time.
Reviewed by: brooks, emaste
Sponsored by: The FreeBSD Foundation
Differential revision: https://reviews.freebsd.org/D23083
The path is already absolute.
Noted and reviewed by: rstone
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D23121
instead of killing the process. The same behaviour of terminating
image activation if the $ORIGIN cannot be resolved for the main
object, is kept.
Reported by: Greg V <greg@unrelenting.technology>
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D23053
We know the binary relative name and can reliably calculate cwd path.
Because realpath(3) was already linked into ld-elf.so.1, reuse it
there to resolve dots and dotdots making the path more canonical.
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D23014
binpath local was changed from char array to a char pointer, update
strlcpy/strlcat uses.
Reported by: Coverity through vangyzen
CID: 1412239 and 1412240
Reviewed by: emaste, imp, vangyzen
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D23090
When rtld is directly executed with arguments, it has to move the
program arguments, environment and elf aux data up a few slots to
remove its own arguments before the process being executed sees
them. When copying the environment, rtld was incorrectly testing
whether the location about to be written to currently contained
NULL, when was supposed to check whether it had just copied the
NULL terminator of the environment string. This had the result
that the ELF aux data was mostly treated as environment variables,
and rtld would quickly crash when it tried to access required
ELF aux data that it didn't think was present.
Differential Revision: https://reviews.freebsd.org/D23008
Reviewed by: kib
MFC after: 1 month
When activated in direct exec mode, kernel-provided AT_EXECPATH points
to the interpreter. We need to recalculate auxv to point to the
string with the path to the executable which is actually executed.
The somewhat problematic case is when the executable path is relative
and either $PATH use is not enabled or it contains '/' so $PATH search
is not performed. In this case resulting AT_EXECPATH is relative, I
might fix this later.
Reported and reviewed by: rstone
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D22894
Summary:
As a transition aide, implement an alternative elfN_freebsd_fixup which
is called for old powerpc binaries. Similarly, add a translation to rtld to
convert old values to new ones (as expected by a new rtld).
Translation of old<->new values is incomplete, but sufficient to allow an
installworld of a new userspace from an old one when a new kernel is running.
Test Plan:
Someone needs to see how a new kernel/rtld/libc works with an old
binary. If if works we can probalby ship this. If not we probalby need
some more compat bits.
Submitted by: brooks
Reviewed by: jhibbits
Differential Revision: https://reviews.freebsd.org/D20799
As PowerPC is moving to clang, we can finally start taking advantage of
IFUNC.
Implement the MD parts of IFUNC handling for rtld.
Currently, it is necessary to look for R_PPC_IRELATIVE in the PLT in
addition to RELA. This is an ABI violation, but LLD9 has some .iplt bugs
that require this as a workaround.
Reviewed by: jhibbits
Differential Revision: https://reviews.freebsd.org/D22855
As PowerPC is moving to clang, we can finally start taking advantage of
IFUNC.
Implement the MD parts of IFUNC handling for rtld.
Currently, it is necessary to look for R_PPC_IRELATIVE in the PLT in
addition to RELA. This is an ABI violation, but LLD9 has some .iplt bugs
that require this as a workaround.
Reviewed by: kib
Differential Revision: https://reviews.freebsd.org/D22789
When a PT_LOAD segment has a zero p_filesz, skip the data mmap, as mmapping
zero bytes from a file is an error.
A PT_LOAD with zero p_filesz is legal (but somewhat uncommon due to segment
merging in modern linkers, as it is more efficient to merge .data and .bss
by just extending p_memsz in the previous segment, assuming compatible
page protection.)
This was seen on ports/graphics/glew on a powerpc64 ELFv2 experimental
build.
Submitted by: Alfredo Dal'Ava Junior <alfredo.junior@eldorado.org.br>
Reviewed by: kib
Differential Revision: https://reviews.freebsd.org/D22634
TP points to the start of the TLS block after the tcb, but
Obj_Entry.tlsoffset includes the tcb, so subtract the size of the tcb
to compute the offset relative to TP.
This is identical to the same fixes for powerpc in r339072 and r342671.
Reviewed by: James Clarke
Sponsored by: DARPA
Differential Revision: https://reviews.freebsd.org/D22661
Four bytes of padding are needed in the regular powerpc case to bring the
stack frame size up to a multiple of 16 bytes to meet ABI requirements.
Fixes odd hangs I was encountering during testing.
Summary:
We need to save off the full 64-bit register, not just the low 32 bits,
of all registers getting saved off in _rtld_bind_start. Additionally,
we need to save off the other SPE registers (SPEFSCR and accumulator),
so that their program state is not affected by the PLT resolver.
Reviewed by: bdragon
Differential Revision: https://reviews.freebsd.org/D22520
Alter bsd.compat.mk to set MACHINE and MACHINE_ARCH when included
directly so MD paths in Makefiles work. In the process centralize
setting them in LIBCOMPATWMAKEENV.
Alter .PATH and CFLAGS settings in work when the Makefile is included.
While here only support LIB32 on supported platforms rather than always
enabling it and requiring users of MK_LIB32 to filter based
TARGET/MACHINE_ARCH.
The net effect of this change is to make Makefile.libcompat only build
compatability libraries.
Changes relative to r354449:
Correct detection of the compiler type when bsd.compat.mk is used
outside Makefile.libcompat. Previously it always matched the clang
case.
Set LDFLAGS including the linker emulation for mips where -m32 seems to
be insufficent.
Reviewed by: imp, kib (origional version in r354449)
Obtained from: CheriBSD (conceptually)
Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D22251
Alter bsd.compat.mk to set MACHINE and MACHINE_ARCH when included
directly so MD paths in Makefiles work. In the process centralize
setting them in LIBCOMPATWMAKEENV.
Alter .PATH and CFLAGS settings in work when the Makefile is included.
While here only support LIB32 on supported platforms rather than always
enabling it and requiring users of MK_LIB32 to filter based
TARGET/MACHINE_ARCH.
The net effect of this change is to make Makefile.libcompat only build
compatability libraries.
Reviewed by: imp, kib
Obtained from: CheriBSD (conceptually)
Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D22251
After the aux vector is moved, it is necessary to re-digest aux_info so the
pointers are updated to the new locations.
This was causing thread creation to fail on powerpc64 when using direct
execution due to a nonsense value being read for aux_info[AT_STACKPROT].
Approved by: jhibbits (mentor)
Differential Revision: https://reviews.freebsd.org/D21656
In the past, this allocator seems to have allocated things larger than
a page seperately. Much of this code was removed at some point (perhaps
along with sbrk() used) so remove the rest. Instead, keep allocating in
power-of-two bins up to FIRST_BUCKET_SIZE << (NBUCKETS - 1). If we want
something more efficent, we should use a fancier allocator.
While here, remove some vestages of sbrk() use. Most importantly, don't
try to page align the pagepool since it's always page aligned by mmap().
Reviewed by: kib
Obtained from: CheriBSD
Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D21453
In Seventh Edition UNIX, the last pointer passed to free() was
guaranteed to not actually have been freed allowing memory to be
"compacted" via the following pattern:
free(foo);
foo = realloc(foo, newsize);
Further, Andrew Koenig reports in "C Traps and Pitfalls" that the
original realloc() implementation required this pattern.
The C standard is clear that this is Undefined Behavior. Modern
allocators don't support it and no portable code could rely on it so
remove this support.
Note: the removed implementation contains an off-by-one error and if
an item isn't found on the freelist, then twice as much memory as the
largest possible allocation will be copied.
Reviewed by: kib, imp
Obtained from: CheriBSD
Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D21296
Instead of restoring the saved values of argc, argv and envp,
these must be loaded from the stack that _rtld() modifies.
This fixes rtld direct exec mode.
E.g.: /libexec/ld-elf.so.1 /bin/ls
Reviewed by: jhibbits
Differential Revision: https://reviews.freebsd.org/D21131
First, amd64 version of the script cannot work at least due to the
wrong architecture specification. Second, kernel can activate shared
objects for long time, due to PIE support.
It seems the intent was to allow ld-elf.so.1 to be build and used as
an executable. Since we have direct exec mode implemented for dso
ld-elf.so.1, the non-functional and commented out scripts can be
finally removed.
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
I found this on one of the CheriBSD Jenkins builders. Using
beforelinking instead of ${PROG} should fix the dependency for the
DEBUG_FILES case.
Reviewed by: brooks
Currently RTLD is linked against libc_nossp_pic which means that any libc
symbol used in rtld can pull in a lot of depedencies. This was causing
symbol such as __libc_interposing and all the pthread stubs to be included
in RTLD even though they are not required. It turns out most of these
dependencies can easily be avoided by providing overrides inside of rtld.
This change is motivated by CHERI, where we have an experimental ABI that
requires additional relocation processing to allow the use of function
pointers inside of rtld. Instead of adding this self-relocation code to
RTLD I attempted to remove most function pointers from RTLD and discovered
that most of them came from the libc dependencies instead of being actually
used inside rtld.
A nice side-effect of this change is that rtld is now 22% smaller on amd64.
text data bss dec hex filename
0x21eb6 0xce0 0xe60 145910 239f6 /home/alr48/ld-elf-x86.before.so.1
0x1a6ed 0x728 0xdd8 113645 1bbed /home/alr48/ld-elf-x86.after.so.1
The number of R_X86_64_RELATIVE relocations that need to be processed on
startup has also gone down from 368 to 187 (almost 50% less).
Reviewed By: kib
Differential Revision: https://reviews.freebsd.org/D20663
