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>
When the page_size < p_align of the ELF load segment, the loader
will end up creating extra PROT_NONE gap VMA mappings between the
LOAD segments. This problem is exacerbated by Android's zygote
model, where the number of loaded .so's can lead to ~30MB increase
in vm_area_struct unreclaimable slab memory.
Extend the LOAD segment VMA's to cover the range between the
segment's end and the start of the next segment, being careful
to avoid touching regions of the extended mapping where the offset
would overrun the size of the file. This avoids the loader
creating an additional gap VMA for each LOAD segment.
Consider a system with 4KB page size and the ELF files with 64K
alignment. e.g:
$ readelf -Wl /system/lib64/bootstrap/libc.so | grep 'Type\|LOAD'
Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align
LOAD 0x000000 0x0000000000000000 0x0000000000000000 0x0441a8 0x0441a8 R 0x10000
LOAD 0x0441b0 0x00000000000541b0 0x00000000000541b0 0x091860 0x091860 R E 0x10000
LOAD 0x0d5a10 0x00000000000f5a10 0x00000000000f5a10 0x003d40 0x003d40 RW 0x10000
LOAD 0x0d9760 0x0000000000109760 0x0000000000109760 0x0005c0 0x459844 RW 0x10000
Before this patch:
$ cat /proc/1/maps | grep -A1 libc.so
7fa1d4a90000-7fa1d4ad5000 r--p 00000000 fe:09 20635520 /system/lib64/bootstrap/libc.so
7fa1d4ad5000-7fa1d4ae4000 ---p 00000000 00:00 0
7fa1d4ae4000-7fa1d4b76000 r-xp 00044000 fe:09 20635520 /system/lib64/bootstrap/libc.so
7fa1d4b76000-7fa1d4b85000 ---p 00000000 00:00 0
7fa1d4b85000-7fa1d4b8a000 r--p 000d5000 fe:09 20635520 /system/lib64/bootstrap/libc.so
7fa1d4b8a000-7fa1d4b99000 ---p 00000000 00:00 0
7fa1d4b99000-7fa1d4b9a000 rw-p 000d9000 fe:09 20635520 /system/lib64/bootstrap/libc.so
7fa1d4b9a000-7fa1d4feb000 rw-p 00000000 00:00 0 [anon:.bss]
3 additional PROT_NONE (---p) VMAs for gap mappings.
After this patch:
$ cat /proc/1/maps | grep -A1 libc.so
7f468f069000-7f468f0bd000 r--p 00000000 fe:09 20635520 /system/lib64/bootstrap/libc.so
7f468f0bd000-7f468f15e000 r-xp 00044000 fe:09 20635520 /system/lib64/bootstrap/libc.so
7f468f15e000-7f468f163000 r--p 000d5000 fe:09 20635520 /system/lib64/bootstrap/libc.so
7f468f163000-7f468f172000 rw-p 000da000 fe:09 20635520 /system/lib64/bootstrap/libc.so
7f468f172000-7f468f173000 rw-p 000d9000 fe:09 20635520 /system/lib64/bootstrap/libc.so
7f468f173000-7f468f5c4000 rw-p 00000000 00:00 0 [anon:.bss]
No additional gap VMAs. However notice there is an extra RW VMA at
offset 0x000da000. This is caused by the RO protection of the
GNU_RELRO segment, which causes the extended RW VMA to split.
The GNU_RELRO protection extension is handled in the subsequent
patch in this series.
Bug: 316403210
Bug: 300367402
Bug: 307803052
Bug: 312550202
Test: atest -c linker-unit-tests
Test: atest -c bionic-unit-tests
Change-Id: I7150ed22af0723cc0b2d326c046e4e4a8b56ad09
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
This CL is created as a best effort to migrate test targets to the new Android ownership model.
It is based on historical data from repository history and insights from git blame.
Given the nature of this effort, there may be instances of incorrect attribution. If you find incorrect or unnecessary
attribution in this CL, please create a new CL to fix that.
For detailed guidelines and further information on the migration please refer to the link below,
go/new-android-ownership-model
Bug: 304529413
Test: N/A
Change-Id: Ie36b2a3245d9901323affcc5e51dafbb87af9248
The libraries are
- libdl_static
- liblinker_main
- liblinker_malloc
- libsystemproperties
The availability to runtime apex was done implicitly using a baseline map in
build/soong/apex/apex.go. Make this explicit in Android.bp
Bug: 281077552
Test: m nothing
Change-Id: I029ae204f6cfef8c301a20b7c4294636b60b38be
The build breakage is now fixed by the current stable Clang, workaround
is no longer needed.
Test: presubmit
Change-Id: Ice2863844ff886f503d50fa7a006cde78d16492d
This patch adds the necessary bionic code for the linker to protect
global data using MTE.
The implementation is described in the MemtagABI addendum to the
AArch64 ELF ABI:
https://github.com/ARM-software/abi-aa/blob/main/memtagabielf64/memtagabielf64.rst
In summary, this patch includes:
1. When MTE globals is requested, the linker maps writable SHF_ALLOC
sections as anonymous pages with PROT_MTE (copying the file contents
into the anonymous mapping), rather than using a file-backed private
mapping. This is required as file-based mappings are not necessarily
backed by the kernel with tag-capable memory. For sections already
mapped by the kernel when the linker is invoked via. PT_INTERP, we
unmap the contents, remap a PROT_MTE+anonymous mapping in its place,
and re-load the file contents from disk.
2. When MTE globals is requested, the linker tags areas of global memory
(as defined in SHT_AARCH64_MEMTAG_GLOBALS_DYNAMIC) with random tags,
but ensuring that adjacent globals are never tagged using the same
memory tag (to provide detemrinistic overflow detection).
3. Changes to RELATIVE, ABS64, and GLOB_DAT relocations to load and
store tags in the right places. This ensures that the address tags are
materialized into the GOT entries as well. These changes are a
functional no-op to existing binaries and/or non-MTE capable hardware.
Bug: N/A
Test: atest bionic-unit-tests CtsBionicTestCases --test-filter=*Memtag*
Change-Id: Id7b1a925339b14949d5a8f607dd86928624bda0e
This mode instructs the linker to search for libraries in hwasan
subdirectories of all library search paths. This is set up to contain a
hwasan-enabled copy of libc, which is needed for HWASan programs to
operate. There are two ways this mode can be enabled:
* for native binaries, by using the linker_hwasan64 symlink as its
interpreter
* for apps: by setting the LD_HWASAN environment variable in wrap.sh
Bug: 276930343
Change-Id: I0f4117a50091616f26947fbe37a28ee573b97ad0
The only meaningful change from alibaba's version is jr instead of jalr.
Also fix the comment that's in all the begin.S files while we're here.
Signed-off-by: Mao Han <han_mao@linux.alibaba.com>
Signed-off-by: Xia Lifang <lifang_xia@linux.alibaba.com>
Signed-off-by: Chen Guoyin <chenguoyin.cgy@linux.alibaba.com>
Signed-off-by: Wang Chen <wangchen20@iscas.ac.cn>
Signed-off-by: Lu Xufan <luxufan@iscas.ac.cn>
Test: ran mksh
Change-Id: I2645c78bd700b8a55bde363600d7f8b87de641a1
liblog_for_runtime_apex is a static variant of liblog which is
explicitly marked as available to the runtime APEX. Any static
dependency to liblog from inside the runtime APEX is changed from liblog
to liblog_for_runtime_apex.
Previously, to support the need for using liblog inside the runtime
APEX, the entire (i.e. both static and shared variants) liblog module
was marked as available to the runtime APEX, although in reality only
the static variant of the library was needed there. This was not only
looking dirty, but also has caused a problem like b/241259844.
To fix this, liblog is separated into two parts. (1) liblog and (2)
liblog_for_runtime_apex. (1) no longer is available to the runtime APEX
and is intended to be depended on in most cases: either from the
non-updatable platform, or from other APEXes. (2) is a static library
which is explicitly marked as available to the runtime APEX and also
visible to certain modules that are included in the runtime APEX.
Bug: 241259844
Test: m and check that liblog depends on stub library of libc
Change-Id: Ib21f6e64da0c7592341b97b95ca8485d7c29ac4d
As with libc.so, add the debug frame into the linker for arm32
to make any crashes unwindable.
Bug: 242162222
Test: Forced a crash on wembley where an unwind failed before and
Test: verified it unwinds properly with the debug frame.
Change-Id: I2b904af63f670b038d169f5a7d907637b352ab4e
For convenience, builds against musl libc currently use the
linux_glibc properties because they are almost always linux-specific
and not glibc-specific. In preparation for removing this hack,
tweak the linux_glibc properties by either moving them to host_linux,
which will apply to linux_glibc, linux_musl and linux_bionic, or
by setting appropriate musl or linux_musl properties. Properties
that must not be repeated while musl uses linux_musl and also still
uses the linux_glibc properties are moved to glibc properties, which
don't apply to musl. Whether these stay as glibc properties or get
moved back to linux_glibc later once the musl hack is removed is TBD.
Bug: 223257095
Test: m checkbuild
Test: m USE_HOST_MUSL=true host-native
Change-Id: I809bf1ba783dff02f6491d87fbdc9fa7fc0975b0
Clang cannot build ifunc with LTO. This is a KI: https://bugs.llvm.org/show_bug.cgi?id=46488
Move the LTO: never down to libc itself, so that we can have LTO for the
rest of linker.
Test: m GLOBAL_THINLTO=true linker
Change-Id: I483fc3944e340638a664fb390279e211c2ae224b
This also effectively re-enables linker_wrapper, which may have been
independently fixed some time ago.
Test: mixed_droid.sh
Change-Id: I9bc7e099fe3c5da1c4da12c79128baf6f807354a
The only symbol that actually needs a prefix to avoid a collision is
_start, and that can be handled with a copy of begin.S that uses a
"#define" to rename _start to __dlwrap__start. Removing the prefixed
symbols will also allow simplifying the host bionic build process by
letting it directly reference the real _start.
Test: build and run host bionic binary
Change-Id: I50be786c16fe04b7f05c14ebfb74f710c7446ed9
To take advantage of file-backed huge pages for the text segments of key
shared libraries (go/android-hugepages), the dynamic linker must load
candidate ELF files at an appropriately aligned address and mark
executable segments with MADV_HUGEPAGE.
This patches uses segments' p_align values to determine when a file is
PMD aligned (2MB alignment), and performs load operations accordingly.
Bug: 158135888
Test: Verified PMD aligned libraries are backed with huge pages on
supporting kernel versions.
Change-Id: Ia2367fd5652f663d50103e18f7695c59dc31c7b9
Introduces a cc_defaults category hugepage_aligned that passes the
requisite linker flags to produce shared object files with 2MB-aligned
sections. This enables supporting platforms to back the text segments of
these libraries with hugepages.
Bug: 158135888
Test: Built and confirmed ELF layout
Change-Id: I5c8ce35d8f8bf6647ec19d58398740bd494cc89c
These lines shouldn't actually matter, because the DSOs are using
version scripts to allow-list exported symbols.
Bug: none
Test: bionic unit tests
Change-Id: I39d3df8c4f8053624f862b3c6994e30c693e928c
For libc.so, use a special build of libunwind.a whose symbols aren't
hidden ("libunwind-exported"), because libc.so exports the _Unwind_*
APIs.
Bug: http://b/153025717
Test: bionic unit tests
Change-Id: I7435e076ec8cc4410e3e6086d3cf5d2c6011c80c
There are multiple build breakages with bionic when we enable ThinLTO
globally. Opt bionic out of ThinLTO for now.
#global-thinlto-opt-out
Test: TreeHugger
Bug: 169004486
Change-Id: I546a8074f9c3e0ddbd01d3b7cd730e215e3c0c49
This patch adds support to load BTI-enabled objects.
According to the ABI, BTI is recorded in the .note.gnu.property section.
The new parser evaluates the property section, if exists.
It searches for .note section with NT_GNU_PROPERTY_TYPE_0.
Once found it tries to find GNU_PROPERTY_AARCH64_FEATURE_1_AND.
The results are cached.
The main change in linker is when protection of loaded ranges gets
applied. When BTI is requested and the platform also supports it
the prot flags have to be amended with PROT_BTI for executable ranges.
Failing to add PROT_BTI flag would disable BTI protection.
Moreover, adding the new PROT flag for shared objects without BTI
compatibility would break applications.
Kernel does not add PROT_BTI to a loaded ELF which has interpreter.
Linker handles this case too.
Test: 1. Flame boots
2. Tested on FVP with BTI enabled
Change-Id: Iafdf223b74c6e75d9f17ca90500e6fe42c4c1218
As we enable arm64-based Bionic host target (linux_bionic_arm64),
linker_wrapper is added with the corresponding source.
Bug: 159685774
Test: HOST_CROSS_OS=linux_bionic HOST_CROSS_ARCH=arm64 m
Test: copy out/soong/host/linux_bionic_arm64/ to an ARM64 emulator
running Linux and execute the binaries
Change-Id: I4f367a349f7e0015318352cb7f2870fc856eab05
Before this Soong added hardcoded system include paths to
bionic/libc/{include,kernel}, which won't work when Bionic libs are
packaged up as prebuilts in an SDK module snapshot.
Test: Build and boot
Test: Check in out/verbose.log.gz that a C file doesn't get any bionic
include path for linux_glibc.
Bug: 153590472
Change-Id: I13c8eb3dd7150d6e0fee001b290b53fcebebcfea
This reverts commit 8dba7fefb0.
Reason for revert: This workaround is not necessary with ag/10700799
Merged-In: I2bf469bfe00f3a70e67085abfb3822db6908d522
Change-Id: If351aedfce23d60582f0c5ff965f94356d1900d9
Bug: 150860940
When libbase is built for an APEX, it uses dlsym to reflectively access
liblog symbols that are added in R. This is because the APEX where
libbasse is packaged into might be running in pre-R devices where the
symbols don't exist in liblog.so.
This however causes a problem for a static executable in an APEX. Since
it is in an APEX, the dlsym is used. But libdl.so which provides dlsym
is not available to static executable. Currently, the dynamic linker is
the only executable in an APEX that all of its dependencies are
statically linked. Fixing the issue by providing fake dlsym by
statically linking to libdl.a.
Exempt-From-Owner-Approval: cherry-pick rvc-dev
Bug: 149569129
Test: m
Merged-In: I2e9e45d9876c2d6c878e541715389e6d1ef56996
(cherry picked from commit ec829ed4ea)
Change-Id: I2e9e45d9876c2d6c878e541715389e6d1ef56996
XOM is no longer supported by the build system, so remove these
properties.
Bug: 123034666
Bug: 147300048
Test: Build succeeds.
Change-Id: I77efc98241f45b1a78b1cca5560f64eef5ef22f4
