The original code did not support dynamically loaded libraries and used
suboptimal access to TLS variables.
New implementation removes lazy resolving of TLS relocation - due to flaw
in TLSDESC design is impossible to switch resolver function at runtime
without expensive locking.
Due to this, 3 specialized resolvers are implemented:
- load time resolver for TLS relocation from libraries loaded with main
executable (thus with known TLS offset).
- resolver for undefined thread weak symbols.
- slower lazy resolver for dynamically loaded libraries with fast path for
already resolved symbols.
PR: 228892, 232149, 233204, 232311
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D18417
The above commit fixed handling overaligned TLS segments in libc's
TLS Variant I implementation, but rtld provides its own implementation
for dynamically-linked executables which lacks these fixes. Thus,
port these changes to rtld.
This was previously commited as r337978 and reverted in r338149 due to
exposing a bug the ARM rtld. This bug was fixed in r338317 by mmel.
Submitted by: James Clarke
Approved by: re (kib)
Reviewed by: kbowling
Testing by: kbowling (powerpc64), br (riscv), kevans (armv7)
Obtained from: CheriBSD
Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D16510
Michal Meloun reports that it breaks ctype (isspace()..) related
functions on armv7 so back out while we diagnose the issue.
Reported by: Michal Meloun <melounmichal@gmail.com>
The above commit fixed handling overaligned TLS segments in libc's
TLS Variant I implementation, but rtld provides its own implementation
for dynamically-linked executables which lacks these fixes. Thus,
port these changes to rtld.
Submitted by: James Clarke
Reviewed by: kbowling
Testing byL kbowling (powerpc64), br (riscv), kevans (armv7)
Obtained from: CheriBSD
Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D16510
objects' init functions instead of doing the setup via a constructor
in libc as the init functions may already depend on these handlers
to be in place. This gets us rid of:
- the undefined order in which libc constructors as __guard_setup()
and jemalloc_constructor() are executed WRT __sparc_utrap_setup(),
- the requirement to link libc last so __sparc_utrap_setup() gets
called prior to constructors in other libraries (see r122883).
For static binaries, crt1.o still sets up the user trap handlers.
o Move misplaced prototypes for MD functions in to the MD prototype
section of rtld.h.
o Sprinkle nitems().
New version is not compatible on supervisor mode with v1.9.1
(previous version).
Highlights:
o BBL (Berkeley Boot Loader) provides no initial page tables
anymore allowing us to choose VM, to build page tables manually
and enable MMU in S-mode.
o SBI interface changed.
o GENERIC kernel.
FDT is now chosen standard for RISC-V hardware description.
DTB is now provided by Spike (golden model simulator). This
allows us to introduce GENERIC kernel. However, description
for console and timer devices is not provided in DTB, so move
these devices temporary to nexus bus.
o Supervisor can't access userspace by default. Solution is to
set SUM (permit Supervisor User Memory access) bit in sstatus
register.
o Compressed extension is now turned on by default.
o External GCC 7.1 compiler used.
o _gp renamed to __global_pointer$
o Compiler -march= string is now in use allowing us to choose
required extensions (compressed, FPU, atomic, etc).
Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D11800
Fix warnings about redundant declarations in rtld
when libthr in increased to WARNS=6.
Reviewed by: kib
MFC after: 3 days
Sponsored by: Dell EMC
Differential Revision: https://reviews.freebsd.org/D10934
From the manpage:
When set to a nonempty string, prevents modifications of the PLT slots
when doing bindings. As result, each call of the PLT-resolved
function is resolved. In combination with debug output, this provides
complete account of all bind actions at runtime.
Same feature exists on Linux and Solaris.
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
rtld-elf has some vestigial support for building as a static executable.
r45501 introduced a partial implementation with a prescient note that it
"might never be enabled." r153515 introduced ELF symbol versioning
support, and removed part of the unused build infrastructure for static
rtld.
GNU ld populates rela relocation addends and GOT entries with the same
values, and rtld's run-time dynamic executable check relied on this.
Alternate toolchains may not populate the GOT entries, which caused
RTLD_IS_DYNAMIC to return false. Simplify rtld by just removing the
unused check.
If we want to restore static rtld support later on we ought to introduce
a build-time #ifdef flag.
PR: 214972
Reviewed by: kan
MFC after: 1 month
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D8687
(hopefully) stock gcc 4.2.1 on i386 and other arches.
In particular:
- Do not use %ebx in the asm constraints on i386, since rtld is
compiled with -fPIC and gcc cannot handle GOT-base register reload
(clang and newer gcc can).
- Avoid direct use of [static N] construct in the function
declaration/definion. In-tree gcc was patched to support this, but
stock 4.2.1 cannot handle the feature.
Requested by: bde
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
CPUID[7].%ebx (cpu_stdext_feature), %ecx (cpu_stdext_feature2) to the
ifunc resolvers on x86.
It is much more clean to use CPUID instruction in usermode to retrieve
this information than to pass AT_HWCAP aux vector from kernel, on
x86. Still, the change does allow for use of AT_HWCAP on arches where it is
needed, by passing aux array to ifunc_init() initializer which should
prepare arguments for ifunc resolvers.
Current signature for resolvers on x86 is
func_t iresolve(uint32_t cpu_feature, uint32_t cpu_feature2,
uint32_t cpu_stdext_feature, uint32_t cpu_stdext_feature2);
where arguments have identical meaning as the kernel variables of the
same name. The ABIs allow to use resolvers with the void or shortened
list of arguments.
Reviewed by: jhb
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D8448
phdr locks locked. This allows to call rtld services from the
callback, which is only reasonable for dlopen(path, RTLD_NOLOAD) to
test existence of the library in the image, and for dlsym(). The
later might still be not quite safe, due to the lazy resolution of
filters.
To allow dropping the locks around iteration in dl_iterate_phdr(3), we
insert markers to track current position between relocks. The global
objects list is converted to tailq and all iterators skip markers,
globallist_next() and globallist_curr() helpers are added.
Reported and tested by: davide
Reviewed by: kan
Sponsored by: The FreeBSD Foundation
MFC after: 3 weeks
