Looks like I'd been bad here, and added new stuff to this file rather
than <elf.h> directly. I've also done nothing to upstream any of this.
This patch at least addresses the former problem, moving our stuff out
into <elf.h>.
Rather than *delete* anything that conflicts with Linux in elf_common.h,
I've disable it with // or #if, and marked those as Android changes to
make it less likely that the next update accidentally drops them (which
isn't super likely, since most of them should actually cause build
failures when they conflict with uapi).
Test: treehugger
Change-Id: Id0deccc7305c60b0f708b55e2eed0dedc0bca41d
arm32/arm64: Previously, the loader miscalculated a negative value for
offset_bionic_tcb_ when the executable's alignment was greater than
(8 * sizeof(void*)). The process then tended to crash.
riscv: Previously, the loader didn't propagate the p_align field of the
PT_TLS segment into StaticTlsLayout::alignment_, so high alignment
values were ignored.
__bionic_check_tls_alignment: Stop capping alignment at page_size().
There is no need to cap it, and the uncapped value is necessary for
correctly positioning the TLS segment relative to the thread pointer
(TP) for ARM and x86. The uncapped value is now used for computing
static TLS layout, but only a page of alignment is actually provided:
* static TLS: __allocate_thread_mapping uses mmap, which provides only
a page's worth of alignment
* dynamic TLS: BionicAllocator::memalign caps align to page_size()
* There were no callers to StaticTlsLayout::alignment(), so remove it.
Allow PT_TLS.p_align to be 0: quietly convert it to 1.
For static TLS, ensure that the address of a TLS block is congruent to
p_vaddr, modulo p_align. That is, ensure this formula holds:
(&tls_block % p_align) == (p_vaddr % p_align)
For dynamic TLS, a TLS block is still allocated congruent to 0 modulo
p_align. Fixing dynamic TLS congruence is mostly a separate problem
from fixing static TLS congruence, and requires changing the dynamic
TLS allocator and/or DTV structure, so it should be fixed in a
later follow-up commit.
Typically (p_vaddr % p_align) is zero, but it's currently possible to
get a non-zero value with LLD: when .tbss has greater than page
alignment, but .tdata does not, LLD can produce a TLS segment where
(p_vaddr % p_align) is non-zero. LLD calculates TP offsets assuming
the loader will align the segment using (p_vaddr % p_align).
Previously, Bionic and LLD disagreed on the offsets from the TP to
the executable's TLS variables.
Add unit tests for StaticTlsLayout in bionic-unit-tests-static.
See also:
* https://github.com/llvm/llvm-project/issues/40872
* https://sourceware.org/bugzilla/show_bug.cgi?id=24606
* https://reviews.llvm.org/D61824
* https://reviews.freebsd.org/D31538
Bug: http://b/133354825
Bug: http://b/328844725
Bug: http://b/328844839
Test: bionic-unit-tests bionic-unit-tests-static
Change-Id: I8850c32ff742a45d3450d8fc39075c10a1e11000
We're starting to see projects _only_ use the SPDX identifiers (and
they're more readable "at a glance" anyway), so it's probably time to
include these...
Test: N/A
Change-Id: I5c76d77dcd392a8db1166108e410389d349a42c3
We're still copy & pasting this workaround about, but the bug was supposedly fixed years ago!
Bug: http://b/34945607
Bug: http://b/33942619
Bug: http://b/34195559
Change-Id: Icf3d184d2ddb447dff7dacccea1dc903da816505
It's usually more helpful to see all the output so far.
If we're worried about fflush() failing because of the state we're in, we shouldn't be using stdio at all!
If this _does_ become a problem, we should probably switch to using the internal functions: `__assert2` for bionic, `__assert_fail` for musl/glibc, and `__assert_rtn` for macOS.
Unfortunately although `__assert2` and `__assert_fail` take the same arguments, they're in a different order, so we can't simply add a symbol alias to make that difference go away, and it's not clear that there's enough value to adding an otherwise unused symbol.
Change-Id: I653183737ab6368890bbd9d0e2f37fc5cb2e1dec
This avoids a diagnostic on arm32/arm64 when running ldd on a shared
library with a PT_TLS segment:
executable's TLS segment is underaligned: alignment is 8, needs to be at least 64 for ARM64 Bionic
Bug: http://b/328822319
Test: ldd /system/lib64/libc.so
Change-Id: Idb061b980333ba3b5b3f44b52becf041d76ea0b7
The loader doesn't currently support using TLS within itself.
Previously, if a TLS segment was accidentally linked into the loader,
then the loader's `soinfo_tls* tls_` field would be initialized with a
valid TlsSegment, but the loader soinfo wouldn't be registered with
linker_tls.cpp, so the module ID would be 0. (The first valid module ID
is 1.)
The result was architecture-dependent. On x86, everything worked until
the first TLS access, which segfaulted. On arm64, relocating TLSDESC
hit a CHECK() failure on the invalid module ID.
Make the loader more robust:
* Abort in the loader if it detects that it has a TLS segment.
* For R_GENERIC_TLS_DTPMOD, verify that a module ID is valid before
writing it.
Bug: none
Test: manually add a thread_local variable to the loader
Test: bionic-unit-tests
Change-Id: I93c17ca65df4af2d46288957a0e483b0e2b13862
Change the AT_All_XXX to AT_ALL_XXX.
Change the name of the from_prot and to_prot parameters to be more
descriptive.
Add a few extra large page sizes. Without this, it jumps from a
relatively small size to an extreme large size and nothing in
between.
Clang-format modified the args_shorthand initialization.
Test: Ran benchmarks on device.
Change-Id: I5105788cbf05793fcb4d86c26037ec435635631e
Only zero the partial page at the end of the segment. There may be
entire pages beyond first page boundary after the segment -- due to
segment padding (VMA extension); but these are not expected to be
touched (faulted).
Do not attempt to zero the extended region past the first partial page,
since doing so may:
1) Result in a SIGBUS, as the region is not backed by the underlying
file.
2) Break the COW backing, faulting in new anon pages for a region
that will not be used.
Bug: 327600007
Bug: 328797737
Test: Dexcom G7 app
Test: atest -c linker-unit-tests
Test: bootup/idle/system-processes-memory-direct
Change-Id: Ib76b022f94bfc4a4b7eaca2c155af81478741b91
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
