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
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
Although these are slightly obsolete in favor of R_AARCH64_TLSDESC,
gcc -mtls-dialect=trad still use them.
Please note that definition of TLS_DTPMOD64 and TLS_DTPREL64 are incorrectly
exchanged in GNU binutils. TLS_DTPREL64 should be encoded to 1028 (as is
defined in ARM ELF ABI) but binutils encode it to 1029. And vice versa,
TLS_DTPMOD64 should be encoded to 1029 but binutils encode it to 1028.
While I'm in, add also R_AARCH64_NONE. It can be produced as result of linker
relaxation.
MFC after: 1 week
- don't relocate jump slots multiple times (if LD_BIND_NOW is defined).
- process only R_AARCH64_JUMP_SLOT here, other relocation types are handled
by reloc_plt().
MFC after: 1 week
This is based on the amd64 implementation. Support for both PLT and
non-PLT (e.g. a global variable initilised with a pointer to an ifunc)
cases are supported.
We don't pass anything to the resolver as it is expected they will read
the ID registers directly, with the number of registers with CPU info
likely to increase in the future.
Reviewed by: kib
Approved by: re (gjb)
Differential Revision: https://reviews.freebsd.org/D17341
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().
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
both the plt and non-plt case.
This fixes an issue where libraries built with LLD can fail with
"Unhandled relocation 1031"
PR: 214971
Obtained from: 1 week
Sponsored by: DARPA, AFRL
(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
on the Variant II code, however arm64 uses Variant I. The former placed the
thread pointer after the data, pointing at the thread control block, while
the latter places these before said data.
Because of this we need to use the size of the previous entry to calculate
where to place the current entry. We also need to reserve 16 bytes at the
start for the thread control block.
This also fixes the value of TLS_TCB_SIZE to be correct. This is the size
of two unsigned longs, i.e. 2 * 8 bytes.
While here remove the bogus adjustment of the pointer in the
R_AARCH64_TLS_TPREL64 case. It should be the offset of the data relative
to the thread pointer, including the thread control block.
Sponsored by: ABT Systems Ltd
ABI specifies that, for R_AARCH64_TLSDESC relocations, we use the symbol
value, addend, and object tls offset to calculate the offset from the tls
base. We then cache this value for future reference.
Differential Revision: https://reviews.freebsd.org/D2183
Reviewed by: kib
Sponsored by: The FreeBSD Foundation
still need libc_pic for a few things, but this is expected to be ready
soon.
Differential Revision: https://reviews.freebsd.org/D2136
Reviewed by: kib
Sponsored by: The FreeBSD Foundation
