| Age | Commit message (Collapse) | Author | Files | Lines |
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Hook up the generic vDSO implementation to the aarch64 vDSO data page.
The _vdso_rng_data required data is placed within the _vdso_data vvar
page, by using a offset larger than the vdso_data.
The vDSO function requires a ChaCha20 implementation that does not write
to the stack, and that can do an entire ChaCha20 permutation. The one
provided uses NEON on the permute operation, with a fallback to the
syscall for chips that do not support AdvSIMD.
This also passes the vdso_test_chacha test along with
vdso_test_getrandom. The vdso_test_getrandom bench-single result on
Neoverse-N1 shows:
vdso: 25000000 times in 0.783884250 seconds
libc: 25000000 times in 8.780275399 seconds
syscall: 25000000 times in 8.786581518 seconds
A small fixup to arch/arm64/include/asm/mman.h was required to avoid
pulling kernel code into the vDSO, similar to what's already done in
arch/arm64/include/asm/rwonce.h.
Signed-off-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
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glibc added support for .gnu.hash in 2006 and .hash has been obsoleted
for more than one decade in many Linux distributions. Using
--hash-style=sysv might imply unaddressed issues and confuse readers.
Just drop the option and rely on the linker default, which is likely
"both", or "gnu" when the distribution really wants to eliminate sysv
hash overhead.
Similar to commit 6b7e26547fad ("x86/vdso: Emit a GNU hash").
Signed-off-by: Fangrui Song <maskray@google.com>
Link: https://lore.kernel.org/r/20240718173423.1574395-1-maskray@google.com
Signed-off-by: Will Deacon <will@kernel.org>
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Now Kbuild provides reasonable defaults for objtool, sanitizers, and
profilers.
Remove redundant variables.
Note:
This commit changes the coverage for some objects:
- include arch/mips/vdso/vdso-image.o into UBSAN, GCOV, KCOV
- include arch/sparc/vdso/vdso-image-*.o into UBSAN
- include arch/sparc/vdso/vma.o into UBSAN
- include arch/x86/entry/vdso/extable.o into KASAN, KCSAN, UBSAN, GCOV, KCOV
- include arch/x86/entry/vdso/vdso-image-*.o into KASAN, KCSAN, UBSAN, GCOV, KCOV
- include arch/x86/entry/vdso/vdso32-setup.o into KASAN, KCSAN, UBSAN, GCOV, KCOV
- include arch/x86/entry/vdso/vma.o into GCOV, KCOV
- include arch/x86/um/vdso/vma.o into KASAN, GCOV, KCOV
I believe these are positive effects because all of them are kernel
space objects.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Tested-by: Roberto Sassu <roberto.sassu@huawei.com>
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Kbuild conventionally uses $(obj)/ for generated files, and $(src)/ for
checked-in source files. It is merely a convention without any functional
difference. In fact, $(obj) and $(src) are exactly the same, as defined
in scripts/Makefile.build:
src := $(obj)
When the kernel is built in a separate output directory, $(src) does
not accurately reflect the source directory location. While Kbuild
resolves this discrepancy by specifying VPATH=$(srctree) to search for
source files, it does not cover all cases. For example, when adding a
header search path for local headers, -I$(srctree)/$(src) is typically
passed to the compiler.
This introduces inconsistency between upstream and downstream Makefiles
because $(src) is used instead of $(srctree)/$(src) for the latter.
To address this inconsistency, this commit changes the semantics of
$(src) so that it always points to the directory in the source tree.
Going forward, the variables used in Makefiles will have the following
meanings:
$(obj) - directory in the object tree
$(src) - directory in the source tree (changed by this commit)
$(objtree) - the top of the kernel object tree
$(srctree) - the top of the kernel source tree
Consequently, $(srctree)/$(src) in upstream Makefiles need to be replaced
with $(src).
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
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Currently, there is no standard implementation for vdso_install,
leading to various issues:
1. Code duplication
Many architectures duplicate similar code just for copying files
to the install destination.
Some architectures (arm, sparc, x86) create build-id symlinks,
introducing more code duplication.
2. Unintended updates of in-tree build artifacts
The vdso_install rule depends on the vdso files to install.
It may update in-tree build artifacts. This can be problematic,
as explained in commit 19514fc665ff ("arm, kbuild: make
"make install" not depend on vmlinux").
3. Broken code in some architectures
Makefile code is often copied from one architecture to another
without proper adaptation.
'make vdso_install' for parisc does not work.
'make vdso_install' for s390 installs vdso64, but not vdso32.
To address these problems, this commit introduces a generic vdso_install
rule.
Architectures that support vdso_install need to define vdso-install-y
in arch/*/Makefile. vdso-install-y lists the files to install.
For example, arch/x86/Makefile looks like this:
vdso-install-$(CONFIG_X86_64) += arch/x86/entry/vdso/vdso64.so.dbg
vdso-install-$(CONFIG_X86_X32_ABI) += arch/x86/entry/vdso/vdsox32.so.dbg
vdso-install-$(CONFIG_X86_32) += arch/x86/entry/vdso/vdso32.so.dbg
vdso-install-$(CONFIG_IA32_EMULATION) += arch/x86/entry/vdso/vdso32.so.dbg
These files will be installed to $(MODLIB)/vdso/ with the .dbg suffix,
if exists, stripped away.
vdso-install-y can optionally take the second field after the colon
separator. This is needed because some architectures install a vdso
file as a different base name.
The following is a snippet from arch/arm64/Makefile.
vdso-install-$(CONFIG_COMPAT_VDSO) += arch/arm64/kernel/vdso32/vdso.so.dbg:vdso32.so
This will rename vdso.so.dbg to vdso32.so during installation. If such
architectures change their implementation so that the base names match,
this workaround will go away.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Sven Schnelle <svens@linux.ibm.com> # s390
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
Reviewed-by: Guo Ren <guoren@kernel.org>
Acked-by: Helge Deller <deller@gmx.de> # parisc
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
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The two symbols __alt_instructions and __alt_instructions_end are not
used, since the vDSO patching code looks for the '.altinstructions' ELF
section directly.
Remove the unused linker symbols.
Fixes: 4e3bca8f7cdd ("arm64: alternative: patch alternatives in the vDSO")
Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Link: https://lore.kernel.org/r/20230726173619.3732-1-jszhang@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
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make C=2 ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- xxx.o
When I use the command above to do a 'make C=2' check on any object file,
the following warnings are always output:
CHECK arch/arm64/kernel/vdso/vgettimeofday.c
arch/arm64/kernel/vdso/vgettimeofday.c:9:5: warning:
symbol '__kernel_clock_gettime' was not declared. Should it be static?
arch/arm64/kernel/vdso/vgettimeofday.c:15:5: warning:
symbol '__kernel_gettimeofday' was not declared. Should it be static?
arch/arm64/kernel/vdso/vgettimeofday.c:21:5: warning:
symbol '__kernel_clock_getres' was not declared. Should it be static?
Therefore, the declaration of the three functions is added to eliminate
these common warnings to provide a clean output.
Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Link: https://lore.kernel.org/r/20230713115831.777-1-thunder.leizhen@huawei.com
Signed-off-by: Will Deacon <will@kernel.org>
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The actual intention is that no dynamic relocation exists in the VDSO. For
this the VDSO build validates that the resulting .so file does not have any
relocations which are specified via $(ARCH_REL_TYPE_ABS) per architecture,
which is fragile as e.g. ARM64 lacks an entry for R_AARCH64_RELATIVE. Aside
of that ARCH_REL_TYPE_ABS is a misnomer as it checks for relative
relocations too.
However, some GNU ld ports produce unneeded R_*_NONE relocation entries. If
a port fails to determine the exact .rel[a].dyn size, the trailing zeros
become R_*_NONE relocations. E.g. ld's powerpc port recently fixed
https://sourceware.org/bugzilla/show_bug.cgi?id=29540). R_*_NONE are
generally a no-op in the dynamic loaders. So just ignore them.
Remove the ARCH_REL_TYPE_ABS defines and just validate that the resulting
.so file does not contain any R_* relocation entries except R_*_NONE.
Signed-off-by: Fangrui Song <maskray@google.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Vincenzo Frascino <vincenzo.frascino@arm.com> # for aarch64
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com> # for vDSO, aarch64
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Link: https://lore.kernel.org/r/20230310190750.3323802-1-maskray@google.com
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Andrew Cooper suggested upgrading the orphan section warning to a hard link
error. However Nathan Chancellor said outright turning the warning into an
error with no escape hatch might be too aggressive, as we have had these
warnings triggered by new compiler generated sections, and suggested turning
orphan sections into an error only if CONFIG_WERROR is set. Kees Cook echoed
and emphasized that the mandate from Linus is that we should avoid breaking
builds. It wrecks bisection, it causes problems across compiler versions, etc.
Thus upgrade the orphan section warning to a hard link error only if
CONFIG_WERROR is set.
Suggested-by: Andrew Cooper <andrew.cooper3@citrix.com>
Suggested-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Xin Li <xin3.li@intel.com>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20221025073023.16137-2-xin3.li@intel.com
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git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux
Pull arm64 updates from Catalin Marinas:
- arm64 perf: DDR PMU driver for Alibaba's T-Head Yitian 710 SoC, SVE
vector granule register added to the user regs together with SVE perf
extensions documentation.
- SVE updates: add HWCAP for SVE EBF16, update the SVE ABI
documentation to match the actual kernel behaviour (zeroing the
registers on syscall rather than "zeroed or preserved" previously).
- More conversions to automatic system registers generation.
- vDSO: use self-synchronising virtual counter access in gettimeofday()
if the architecture supports it.
- arm64 stacktrace cleanups and improvements.
- arm64 atomics improvements: always inline assembly, remove LL/SC
trampolines.
- Improve the reporting of EL1 exceptions: rework BTI and FPAC
exception handling, better EL1 undefs reporting.
- Cortex-A510 erratum 2658417: remove BF16 support due to incorrect
result.
- arm64 defconfig updates: build CoreSight as a module, enable options
necessary for docker, memory hotplug/hotremove, enable all PMUs
provided by Arm.
- arm64 ptrace() support for TPIDR2_EL0 (register provided with the SME
extensions).
- arm64 ftraces updates/fixes: fix module PLTs with mcount, remove
unused function.
- kselftest updates for arm64: simple HWCAP validation, FP stress test
improvements, validation of ZA regs in signal handlers, include
larger SVE and SME vector lengths in signal tests, various cleanups.
- arm64 alternatives (code patching) improvements to robustness and
consistency: replace cpucap static branches with equivalent
alternatives, associate callback alternatives with a cpucap.
- Miscellaneous updates: optimise kprobe performance of patching
single-step slots, simplify uaccess_mask_ptr(), move MTE registers
initialisation to C, support huge vmalloc() mappings, run softirqs on
the per-CPU IRQ stack, compat (arm32) misalignment fixups for
multiword accesses.
* tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (126 commits)
arm64: alternatives: Use vdso/bits.h instead of linux/bits.h
arm64/kprobe: Optimize the performance of patching single-step slot
arm64: defconfig: Add Coresight as module
kselftest/arm64: Handle EINTR while reading data from children
kselftest/arm64: Flag fp-stress as exiting when we begin finishing up
kselftest/arm64: Don't repeat termination handler for fp-stress
ARM64: reloc_test: add __init/__exit annotations to module init/exit funcs
arm64/mm: fold check for KFENCE into can_set_direct_map()
arm64: ftrace: fix module PLTs with mcount
arm64: module: Remove unused plt_entry_is_initialized()
arm64: module: Make plt_equals_entry() static
arm64: fix the build with binutils 2.27
kselftest/arm64: Don't enable v8.5 for MTE selftest builds
arm64: uaccess: simplify uaccess_mask_ptr()
arm64: asm/perf_regs.h: Avoid C++-style comment in UAPI header
kselftest/arm64: Fix typo in hwcap check
arm64: mte: move register initialization to C
arm64: mm: handle ARM64_KERNEL_USES_PMD_MAPS in vmemmap_populate()
arm64: dma: Drop cache invalidation from arch_dma_prep_coherent()
arm64/sve: Add Perf extensions documentation
...
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In preparation for removing CC_FLAGS_CFI from CC_FLAGS_LTO, explicitly
filter out CC_FLAGS_CFI in all the makefiles where we currently filter
out CC_FLAGS_LTO.
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Tested-by: Kees Cook <keescook@chromium.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20220908215504.3686827-2-samitolvanen@google.com
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Make it possible to use alternatives in the vDSO, so that better
implementations can be used if possible.
Signed-off-by: Joey Gouly <joey.gouly@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20220830104833.34636-3-joey.gouly@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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The vDSO will not contain absolute relocations, so place these
sections in .rodata.
Signed-off-by: Joey Gouly <joey.gouly@arm.com>
Link: https://lore.kernel.org/linux-arm-kernel/00abb0c5-6360-0004-353f-e7a88b3bd22c@arm.com/
Cc: Will Deacon <will@kernel.org>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Link: https://lore.kernel.org/r/20220628151307.35561-3-joey.gouly@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
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Like vmlinux, enable orphan-handling for the VDSO. This can catch
subtle errors that might arise from unexpected sections being included.
Signed-off-by: Joey Gouly <joey.gouly@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Kees Cook <keescook@chromium.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Link: https://lore.kernel.org/r/20220510095834.32394-3-joey.gouly@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
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Use macros from vmlinux.lds.h to explicitly name sections that are included
in the VDSO output.
Signed-off-by: Joey Gouly <joey.gouly@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Kees Cook <keescook@chromium.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Link: https://lore.kernel.org/r/20220510095834.32394-2-joey.gouly@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
Pull kernel hardening updates from Kees Cook:
- usercopy hardening expanded to check other allocation types (Matthew
Wilcox, Yuanzheng Song)
- arm64 stackleak behavioral improvements (Mark Rutland)
- arm64 CFI code gen improvement (Sami Tolvanen)
- LoadPin LSM block dev API adjustment (Christoph Hellwig)
- Clang randstruct support (Bill Wendling, Kees Cook)
* tag 'kernel-hardening-v5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: (34 commits)
loadpin: stop using bdevname
mm: usercopy: move the virt_addr_valid() below the is_vmalloc_addr()
gcc-plugins: randstruct: Remove cast exception handling
af_unix: Silence randstruct GCC plugin warning
niu: Silence randstruct warnings
big_keys: Use struct for internal payload
gcc-plugins: Change all version strings match kernel
randomize_kstack: Improve docs on requirements/rationale
lkdtm/stackleak: fix CONFIG_GCC_PLUGIN_STACKLEAK=n
arm64: entry: use stackleak_erase_on_task_stack()
stackleak: add on/off stack variants
lkdtm/stackleak: check stack boundaries
lkdtm/stackleak: prevent unexpected stack usage
lkdtm/stackleak: rework boundary management
lkdtm/stackleak: avoid spurious failure
stackleak: rework poison scanning
stackleak: rework stack high bound handling
stackleak: clarify variable names
stackleak: rework stack low bound handling
stackleak: remove redundant check
...
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There is currently no dependency for vdso*-wrap.S on vdso*.so, which means that
you can get a build that uses a stale vdso*-wrap.o.
In commit a5b8ca97fbf8, the file that includes the vdso.so was moved and renamed
from arch/arm64/kernel/vdso/vdso.S to arch/arm64/kernel/vdso-wrap.S, when this
happened the Makefile was not updated to force the dependcy on vdso.so.
Fixes: a5b8ca97fbf8 ("arm64: do not descend to vdso directories twice")
Signed-off-by: Joey Gouly <joey.gouly@arm.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20220510102721.50811-1-joey.gouly@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
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To enable the new Clang randstruct implementation[1], move
randstruct into its own Makefile and split the CFLAGS from
GCC_PLUGINS_CFLAGS into RANDSTRUCT_CFLAGS.
[1] https://reviews.llvm.org/D121556
Cc: linux-hardening@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20220503205503.3054173-5-keescook@chromium.org
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If compiling the arm64 kernel with W=1 the following warning is produced:
| arch/arm64/kernel/vdso/vgettimeofday.c:9:5: error: no previous prototype for ‘__kernel_clock_gettime’ [-Werror=missing-prototypes]
| 9 | int __kernel_clock_gettime(clockid_t clock,
| | ^~~~~~~~~~~~~~~~~~~~~~
| arch/arm64/kernel/vdso/vgettimeofday.c:15:5: error: no previous prototype for ‘__kernel_gettimeofday’ [-Werror=missing-prototypes]
| 15 | int __kernel_gettimeofday(struct __kernel_old_timeval *tv,
| | ^~~~~~~~~~~~~~~~~~~~~
| arch/arm64/kernel/vdso/vgettimeofday.c:21:5: error: no previous prototype for ‘__kernel_clock_getres’ [-Werror=missing-prototypes]
| 21 | int __kernel_clock_getres(clockid_t clock_id,
| | ^~~~~~~~~~~~~~~~~~~~~
This patch removes "-Wmissing-prototypes" and "-Wmissing-declarations" compilers
flags from the compilation of vgettimeofday.c to make possible to build the
kernel with CONFIG_WERROR enabled.
Cc: Will Deacon <will@kernel.org>
Reported-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Tested-by: Marc Kleine-Budde <mkl@pengutronix.de>
Link: https://lore.kernel.org/r/20220121121234.47273-1-vincenzo.frascino@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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This patch enables KCSAN for arm64, with updates to build rules
to not use KCSAN for several incompatible compilation units.
Recent GCC version(at least GCC10) made outline-atomics as the
default option(unlike Clang), which will cause linker errors
for kernel/kcsan/core.o. Disables the out-of-line atomics by
no-outline-atomics to fix the linker errors.
Meanwhile, as Mark said[1], some latent issues are needed to be
fixed which isn't just a KCSAN problem, we make the KCSAN depends
on EXPERT for now.
Tested selftest and kcsan_test(built with GCC11 and Clang 13),
and all passed.
[1] https://lkml.kernel.org/r/YadiUPpJ0gADbiHQ@FVFF77S0Q05N
Acked-by: Marco Elver <elver@google.com> # kernel/kcsan
Tested-by: Joey Gouly <joey.gouly@arm.com>
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Link: https://lore.kernel.org/r/20211211131734.126874-1-wangkefeng.wang@huawei.com
[catalin.marinas@arm.com: added comment to justify EXPERT]
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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The -nostdlib option requests the compiler to not use the standard
system startup files or libraries when linking. It is effective only
when $(CC) is used as a linker driver.
Since commit 691efbedc60d ("arm64: vdso: use $(LD) instead of $(CC)
to link VDSO"), $(LD) is directly used, hence -nostdlib is unneeded.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Link: https://lore.kernel.org/r/20211107161802.323125-1-masahiroy@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
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The arm64 assembler in binutils 2.32 and above generates a program
property note in a note section, .note.gnu.property, to encode used x86
ISAs and features. But the kernel linker script only contains a single
NOTE segment:
PHDRS
{
text PT_LOAD FLAGS(5) FILEHDR PHDRS; /* PF_R|PF_X */
dynamic PT_DYNAMIC FLAGS(4); /* PF_R */
note PT_NOTE FLAGS(4); /* PF_R */
}
The NOTE segment generated by the vDSO linker script is aligned to 4 bytes.
But the .note.gnu.property section must be aligned to 8 bytes on arm64.
$ readelf -n vdso64.so
Displaying notes found in: .note
Owner Data size Description
Linux 0x00000004 Unknown note type: (0x00000000)
description data: 06 00 00 00
readelf: Warning: note with invalid namesz and/or descsz found at offset 0x20
readelf: Warning: type: 0x78, namesize: 0x00000100, descsize: 0x756e694c, alignment: 8
Since the note.gnu.property section in the vDSO is not checked by the
dynamic linker, discard the .note.gnu.property sections in the vDSO.
Similar to commit 4caffe6a28d31 ("x86/vdso: Discard .note.gnu.property
sections in vDSO"), but for arm64.
Signed-off-by: Bill Wendling <morbo@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20210423205159.830854-1-morbo@google.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
Pull clang LTO updates from Kees Cook:
"Clang Link Time Optimization.
This is built on the work done preparing for LTO by arm64 folks,
tracing folks, etc. This includes the core changes as well as the
remaining pieces for arm64 (LTO has been the default build method on
Android for about 3 years now, as it is the prerequisite for the
Control Flow Integrity protections).
While x86 LTO enablement is done, it depends on some pending objtool
clean-ups. It's possible that I'll send a "part 2" pull request for
LTO that includes x86 support.
For merge log posterity, and as detailed in commit dc5723b02e52
("kbuild: add support for Clang LTO"), here is the lt;dr to do an LTO
build:
make LLVM=1 LLVM_IAS=1 defconfig
scripts/config -e LTO_CLANG_THIN
make LLVM=1 LLVM_IAS=1
(To do a cross-compile of arm64, add "CROSS_COMPILE=aarch64-linux-gnu-"
and "ARCH=arm64" to the "make" command lines.)
Summary:
- Clang LTO build infrastructure and arm64-specific enablement (Sami
Tolvanen)
- Recursive build CC_FLAGS_LTO fix (Alexander Lobakin)"
* tag 'clang-lto-v5.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
kbuild: prevent CC_FLAGS_LTO self-bloating on recursive rebuilds
arm64: allow LTO to be selected
arm64: disable recordmcount with DYNAMIC_FTRACE_WITH_REGS
arm64: vdso: disable LTO
drivers/misc/lkdtm: disable LTO for rodata.o
efi/libstub: disable LTO
scripts/mod: disable LTO for empty.c
modpost: lto: strip .lto from module names
PCI: Fix PREL32 relocations for LTO
init: lto: fix PREL32 relocations
init: lto: ensure initcall ordering
kbuild: lto: add a default list of used symbols
kbuild: lto: merge module sections
kbuild: lto: limit inlining
kbuild: lto: fix module versioning
kbuild: add support for Clang LTO
tracing: move function tracer options to Kconfig
|
|
BSD sed ignores whitespace character escape sequences such as '\t' in
the replacement string, causing this script to produce the following
incorrect output:
#define vdso_offset_sigtrampt0x089c
Changing the hard tab to ' ' causes both BSD and GNU dialects of sed
to produce equivalent output.
Signed-off-by: John Millikin <john@john-millikin.com>
Link: https://lore.kernel.org/r/15147ffb-7e67-b607-266d-f56599ecafd1@john-millikin.com
Signed-off-by: Will Deacon <will@kernel.org>
|
|
arm64 descends into each vdso directory twice; first in vdso_prepare,
second during the ordinary build process.
PPC mimicked it and uncovered a problem [1]. In the first descend,
Kbuild directly visits the vdso directories, therefore it does not
inherit subdir-ccflags-y from upper directories.
This means the command line parameters may differ between the two.
If it happens, the offset values in the generated headers might be
different from real offsets of vdso.so in the kernel.
This potential danger should be avoided. The vdso directories are
built in the vdso_prepare stage, so the second descend is unneeded.
[1]: https://lore.kernel.org/linux-kbuild/CAK7LNARAkJ3_-4gX0VA2UkapbOftuzfSTVMBbgbw=HD8n7N+7w@mail.gmail.com/T/#ma10dcb961fda13f36d42d58fa6cb2da988b7e73a
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Link: https://lore.kernel.org/r/20201218024540.1102650-1-masahiroy@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
|
|
Disable LTO for the vDSO by filtering out CC_FLAGS_LTO, as there's no
point in using link-time optimization for the small amount of C code.
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20201211184633.3213045-15-samitolvanen@google.com
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Currently with ld.lld we emit an empty .eh_frame_hdr section (and a
corresponding program header) into the vDSO. With ld.bfd the section
is not emitted but the program header is, with p_vaddr set to 0. This
can lead to unwinders attempting to interpret the data at whichever
location the program header happens to point to as an unwind info
header. This happens to be mostly harmless as long as the byte at
that location (interpreted as a version number) has a value other
than 1, causing both libgcc and LLVM libunwind to ignore the section
(in libunwind's case, after printing an error message to stderr),
but it could lead to worse problems if the byte happened to be 1 or
the program header points to non-readable memory (e.g. if the empty
section was placed at a page boundary).
Instead of disabling .eh_frame_hdr via --no-eh-frame-hdr (which
also has the downside of being unsupported by older versions of GNU
binutils), disable it by discarding the section, and stop emitting
the program header that points to it.
I understand that we intend to emit valid unwind info for the vDSO
at some point. Once that happens this patch can be reverted.
Signed-off-by: Peter Collingbourne <pcc@google.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Link: https://linux-review.googlesource.com/id/If745fd9cadcb31b4010acbf5693727fe111b0863
Link: https://lore.kernel.org/r/20201230221954.2007257-1-pcc@google.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
|
|
When building with LTO, there is an increased risk of the compiler
converting an address dependency headed by a READ_ONCE() invocation
into a control dependency and consequently allowing for harmful
reordering by the CPU.
Ensure that such transformations are harmless by overriding the generic
READ_ONCE() definition with one that provides acquire semantics when
building with LTO.
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux
Pull more arm64 updates from Will Deacon:
"A small selection of further arm64 fixes and updates. Most of these
are fixes that came in during the merge window, with the exception of
the HAVE_MOVE_PMD mremap() speed-up which we discussed back in 2018
and somehow forgot to enable upstream.
- Improve performance of Spectre-v2 mitigation on Falkor CPUs (if
you're lucky enough to have one)
- Select HAVE_MOVE_PMD. This has been shown to improve mremap()
performance, which is used heavily by the Android runtime GC, and
it seems we forgot to enable this upstream back in 2018.
- Ensure linker flags are consistent between LLVM and BFD
- Fix stale comment in Spectre mitigation rework
- Fix broken copyright header
- Fix KASLR randomisation of the linear map
- Prevent arm64-specific prctl()s from compat tasks (return -EINVAL)"
Link: https://lore.kernel.org/kvmarm/20181108181201.88826-3-joelaf@google.com/
* tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
arm64: proton-pack: Update comment to reflect new function name
arm64: spectre-v2: Favour CPU-specific mitigation at EL2
arm64: link with -z norelro regardless of CONFIG_RELOCATABLE
arm64: Fix a broken copyright header in gen_vdso_offsets.sh
arm64: mremap speedup - Enable HAVE_MOVE_PMD
arm64: mm: use single quantity to represent the PA to VA translation
arm64: reject prctl(PR_PAC_RESET_KEYS) on compat tasks
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git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild
Pull Kbuild updates from Masahiro Yamada:
- Support 'make compile_commands.json' to generate the compilation
database more easily, avoiding stale entries
- Support 'make clang-analyzer' and 'make clang-tidy' for static checks
using clang-tidy
- Preprocess scripts/modules.lds.S to allow CONFIG options in the
module linker script
- Drop cc-option tests from compiler flags supported by our minimal
GCC/Clang versions
- Use always 12-digits commit hash for CONFIG_LOCALVERSION_AUTO=y
- Use sha1 build id for both BFD linker and LLD
- Improve deb-pkg for reproducible builds and rootless builds
- Remove stale, useless scripts/namespace.pl
- Turn -Wreturn-type warning into error
- Fix build error of deb-pkg when CONFIG_MODULES=n
- Replace 'hostname' command with more portable 'uname -n'
- Various Makefile cleanups
* tag 'kbuild-v5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (34 commits)
kbuild: Use uname for LINUX_COMPILE_HOST detection
kbuild: Only add -fno-var-tracking-assignments for old GCC versions
kbuild: remove leftover comment for filechk utility
treewide: remove DISABLE_LTO
kbuild: deb-pkg: clean up package name variables
kbuild: deb-pkg: do not build linux-headers package if CONFIG_MODULES=n
kbuild: enforce -Werror=return-type
scripts: remove namespace.pl
builddeb: Add support for all required debian/rules targets
builddeb: Enable rootless builds
builddeb: Pass -n to gzip for reproducible packages
kbuild: split the build log of kallsyms
kbuild: explicitly specify the build id style
scripts/setlocalversion: make git describe output more reliable
kbuild: remove cc-option test of -Werror=date-time
kbuild: remove cc-option test of -fno-stack-check
kbuild: remove cc-option test of -fno-strict-overflow
kbuild: move CFLAGS_{KASAN,UBSAN,KCSAN} exports to relevant Makefiles
kbuild: remove redundant CONFIG_KASAN check from scripts/Makefile.kasan
kbuild: do not create built-in objects for external module builds
...
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This change removes all instances of DISABLE_LTO from
Makefiles, as they are currently unused, and the preferred
method of disabling LTO is to filter out the flags instead.
Note added by Masahiro Yamada:
DISABLE_LTO was added as preparation for GCC LTO, but GCC LTO was
not pulled into the mainline. (https://lkml.org/lkml/2014/4/8/272)
Suggested-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
|
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I was going to copy this but I didn't want to chase around the build
system stuff so I did it a different way.
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
Link: https://lore.kernel.org/r/20201017002637.503579-1-palmer@dabbelt.com
Signed-off-by: Will Deacon <will@kernel.org>
|
|
This reverts commit 3acf4be235280f14d838581a750532219d67facc.
The minimum supported version of clang is clang 10.0.1.
Suggested-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Fangrui Song <maskray@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Cc: Sedat Dilek <sedat.dilek@gmail.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lkml.kernel.org/r/20200902225911.209899-5-ndesaulniers@google.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
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ld's --build-id defaults to "sha1" style, while lld defaults to "fast".
The build IDs are very different between the two, which may confuse
programs that reference them.
Signed-off-by: Bill Wendling <morbo@google.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
|
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The vdso linker script is preprocessed on demand.
Adding it to 'targets' is enough to include the .cmd file.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Greentime Hu <green.hu@gmail.com>
|
|
Allocate the time namespace page among VVAR pages. Provide
__arch_get_timens_vdso_data() helper for VDSO code to get the
code-relative position of VVARs on that special page.
If a task belongs to a time namespace then the VVAR page which contains
the system wide VDSO data is replaced with a namespace specific page
which has the same layout as the VVAR page. That page has vdso_data->seq
set to 1 to enforce the slow path and vdso_data->clock_mode set to
VCLOCK_TIMENS to enforce the time namespace handling path.
The extra check in the case that vdso_data->seq is odd, e.g. a concurrent
update of the VDSO data is in progress, is not really affecting regular
tasks which are not part of a time namespace as the task is spin waiting
for the update to finish and vdso_data->seq to become even again.
If a time namespace task hits that code path, it invokes the corresponding
time getter function which retrieves the real VVAR page, reads host time
and then adds the offset for the requested clock which is stored in the
special VVAR page.
The time-namespace page isn't allocated on !CONFIG_TIME_NAMESPACE, but
vma is the same size, which simplifies criu/vdso migration between
different kernel configs.
Signed-off-by: Andrei Vagin <avagin@gmail.com>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: Dmitry Safonov <dima@arista.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20200624083321.144975-4-avagin@gmail.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
|
|
Don't use gcc plugins for building arch/arm64/kernel/vdso/vgettimeofday.c
to avoid unneeded instrumentation.
Signed-off-by: Alexander Popov <alex.popov@linux.com>
Link: https://lore.kernel.org/r/20200624123330.83226-4-alex.popov@linux.com
Signed-off-by: Will Deacon <will@kernel.org>
|
|
Commit 87676cfca141 ("arm64: vdso: Disable dwarf unwinding through the
sigreturn trampoline") unconditionally passes the '--no-eh-frame-hdr'
option to the linker when building the native vDSO in an attempt to
prevent generation of the .eh_frame_hdr section, the presence of which
has been implicated in segfaults originating from the libgcc unwinder.
Unfortunately, not all versions of binutils support this option, which
has been shown to cause build failures in linux-next:
| CALL scripts/atomic/check-atomics.sh
| CALL scripts/checksyscalls.sh
| LD arch/arm64/kernel/vdso/vdso.so.dbg
| ld: unrecognized option '--no-eh-frame-hdr'
| ld: use the --help option for usage information
| arch/arm64/kernel/vdso/Makefile:64: recipe for target
| 'arch/arm64/kernel/vdso/vdso.so.dbg' failed
| make[1]: *** [arch/arm64/kernel/vdso/vdso.so.dbg] Error 1
| arch/arm64/Makefile:175: recipe for target 'vdso_prepare' failed
| make: *** [vdso_prepare] Error 2
Only link the vDSO with '--no-eh-frame-hdr' when the linker supports it.
If we end up with the section due to linker defaults, the absence of CFI
information in the sigreturn trampoline will prevent the unwinder from
breaking.
Link: https://lore.kernel.org/r/7a7e31a8-9a7b-2428-ad83-2264f20bdc2d@hisilicon.com
Fixes: 87676cfca141 ("arm64: vdso: Disable dwarf unwinding through the sigreturn trampoline")
Reported-by: Shaokun Zhang <zhangshaokun@hisilicon.com>
Tested-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Will Deacon <will@kernel.org>
|
|
Commit 7e9f5e6629f6 ("arm64: vdso: Add --eh-frame-hdr to ldflags") results
in a .eh_frame_hdr section for the vDSO, which in turn causes the libgcc
unwinder to unwind out of signal handlers using the .eh_frame information
populated by our .cfi directives. In conjunction with a4eb355a3fda
("arm64: vdso: Fix CFI directives in sigreturn trampoline"), this has
been shown to cause segmentation faults originating from within the
unwinder during thread cancellation:
| Thread 14 "virtio-net-rx" received signal SIGSEGV, Segmentation fault.
| 0x0000000000435e24 in uw_frame_state_for ()
| (gdb) bt
| #0 0x0000000000435e24 in uw_frame_state_for ()
| #1 0x0000000000436e88 in _Unwind_ForcedUnwind_Phase2 ()
| #2 0x00000000004374d8 in _Unwind_ForcedUnwind ()
| #3 0x0000000000428400 in __pthread_unwind (buf=<optimized out>) at unwind.c:121
| #4 0x0000000000429808 in __do_cancel () at ./pthreadP.h:304
| #5 sigcancel_handler (sig=32, si=0xffff33c743f0, ctx=<optimized out>) at nptl-init.c:200
| #6 sigcancel_handler (sig=<optimized out>, si=0xffff33c743f0, ctx=<optimized out>) at nptl-init.c:165
| #7 <signal handler called>
| #8 futex_wait_cancelable (private=0, expected=0, futex_word=0x3890b708) at ../sysdeps/unix/sysv/linux/futex-internal.h:88
After considerable bashing of heads, it appears that our CFI directives
for unwinding out of the sigreturn trampoline are only processed by libgcc
when both a .eh_frame_hdr section is present *and* the mysterious NOP is
covered by an entry in .eh_frame. With both of these now in place, it has
highlighted that our CFI directives are not comprehensive enough to
restore the stack pointer of the interrupted context. This results in libgcc
falling back to an arm64-specific unwinder after computing a bogus PC value
from the unwind tables. The unwinder promptly dereferences this bogus address
in an attempt to see if the pointed-to instruction sequence looks like
the sigreturn trampoline.
Restore the old unwind behaviour, which relied solely on heuristics in
the unwinder, by removing the .eh_frame_hdr section from the vDSO and
commenting out the insufficient CFI directives for now. Add comments to
explain the current, miserable state of affairs.
Cc: Tamas Zsoldos <tamas.zsoldos@arm.com>
Cc: Szabolcs Nagy <szabolcs.nagy@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Daniel Kiss <daniel.kiss@arm.com>
Acked-by: Dave Martin <Dave.Martin@arm.com>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Reported-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>
|
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git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux
Pull arm64 updates from Will Deacon:
"A sizeable pile of arm64 updates for 5.8.
Summary below, but the big two features are support for Branch Target
Identification and Clang's Shadow Call stack. The latter is currently
arm64-only, but the high-level parts are all in core code so it could
easily be adopted by other architectures pending toolchain support
Branch Target Identification (BTI):
- Support for ARMv8.5-BTI in both user- and kernel-space. This allows
branch targets to limit the types of branch from which they can be
called and additionally prevents branching to arbitrary code,
although kernel support requires a very recent toolchain.
- Function annotation via SYM_FUNC_START() so that assembly functions
are wrapped with the relevant "landing pad" instructions.
- BPF and vDSO updates to use the new instructions.
- Addition of a new HWCAP and exposure of BTI capability to userspace
via ID register emulation, along with ELF loader support for the
BTI feature in .note.gnu.property.
- Non-critical fixes to CFI unwind annotations in the sigreturn
trampoline.
Shadow Call Stack (SCS):
- Support for Clang's Shadow Call Stack feature, which reserves
platform register x18 to point at a separate stack for each task
that holds only return addresses. This protects function return
control flow from buffer overruns on the main stack.
- Save/restore of x18 across problematic boundaries (user-mode,
hypervisor, EFI, suspend, etc).
- Core support for SCS, should other architectures want to use it
too.
- SCS overflow checking on context-switch as part of the existing
stack limit check if CONFIG_SCHED_STACK_END_CHECK=y.
CPU feature detection:
- Removed numerous "SANITY CHECK" errors when running on a system
with mismatched AArch32 support at EL1. This is primarily a concern
for KVM, which disabled support for 32-bit guests on such a system.
- Addition of new ID registers and fields as the architecture has
been extended.
Perf and PMU drivers:
- Minor fixes and cleanups to system PMU drivers.
Hardware errata:
- Unify KVM workarounds for VHE and nVHE configurations.
- Sort vendor errata entries in Kconfig.
Secure Monitor Call Calling Convention (SMCCC):
- Update to the latest specification from Arm (v1.2).
- Allow PSCI code to query the SMCCC version.
Software Delegated Exception Interface (SDEI):
- Unexport a bunch of unused symbols.
- Minor fixes to handling of firmware data.
Pointer authentication:
- Add support for dumping the kernel PAC mask in vmcoreinfo so that
the stack can be unwound by tools such as kdump.
- Simplification of key initialisation during CPU bringup.
BPF backend:
- Improve immediate generation for logical and add/sub instructions.
vDSO:
- Minor fixes to the linker flags for consistency with other
architectures and support for LLVM's unwinder.
- Clean up logic to initialise and map the vDSO into userspace.
ACPI:
- Work around for an ambiguity in the IORT specification relating to
the "num_ids" field.
- Support _DMA method for all named components rather than only PCIe
root complexes.
- Minor other IORT-related fixes.
Miscellaneous:
- Initialise debug traps early for KGDB and fix KDB cacheflushing
deadlock.
- Minor tweaks to early boot state (documentation update, set
TEXT_OFFSET to 0x0, increase alignment of PE/COFF sections).
- Refactoring and cleanup"
* tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (148 commits)
KVM: arm64: Move __load_guest_stage2 to kvm_mmu.h
KVM: arm64: Check advertised Stage-2 page size capability
arm64/cpufeature: Add get_arm64_ftr_reg_nowarn()
ACPI/IORT: Remove the unused __get_pci_rid()
arm64/cpuinfo: Add ID_MMFR4_EL1 into the cpuinfo_arm64 context
arm64/cpufeature: Add remaining feature bits in ID_AA64PFR1 register
arm64/cpufeature: Add remaining feature bits in ID_AA64PFR0 register
arm64/cpufeature: Add remaining feature bits in ID_AA64ISAR0 register
arm64/cpufeature: Add remaining feature bits in ID_MMFR4 register
arm64/cpufeature: Add remaining feature bits in ID_PFR0 register
arm64/cpufeature: Introduce ID_MMFR5 CPU register
arm64/cpufeature: Introduce ID_DFR1 CPU register
arm64/cpufeature: Introduce ID_PFR2 CPU register
arm64/cpufeature: Make doublelock a signed feature in ID_AA64DFR0
arm64/cpufeature: Drop TraceFilt feature exposure from ID_DFR0 register
arm64/cpufeature: Add explicit ftr_id_isar0[] for ID_ISAR0 register
arm64: mm: Add asid_gen_match() helper
firmware: smccc: Fix missing prototype warning for arm_smccc_version_init
arm64: vdso: Fix CFI directives in sigreturn trampoline
arm64: vdso: Don't prefix sigreturn trampoline with a BTI C instruction
...
|
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Support for Clang's Shadow Call Stack in the kernel
(Sami Tolvanen and Will Deacon)
* for-next/scs:
arm64: entry-ftrace.S: Update comment to indicate that x18 is live
scs: Move DEFINE_SCS macro into core code
scs: Remove references to asm/scs.h from core code
scs: Move scs_overflow_check() out of architecture code
arm64: scs: Use 'scs_sp' register alias for x18
scs: Move accounting into alloc/free functions
arm64: scs: Store absolute SCS stack pointer value in thread_info
efi/libstub: Disable Shadow Call Stack
arm64: scs: Add shadow stacks for SDEI
arm64: Implement Shadow Call Stack
arm64: Disable SCS for hypervisor code
arm64: vdso: Disable Shadow Call Stack
arm64: efi: Restore register x18 if it was corrupted
arm64: Preserve register x18 when CPU is suspended
arm64: Reserve register x18 from general allocation with SCS
scs: Disable when function graph tracing is enabled
scs: Add support for stack usage debugging
scs: Add page accounting for shadow call stack allocations
scs: Add support for Clang's Shadow Call Stack (SCS)
|
|
Support for Branch Target Identification (BTI) in user and kernel
(Mark Brown and others)
* for-next/bti: (39 commits)
arm64: vdso: Fix CFI directives in sigreturn trampoline
arm64: vdso: Don't prefix sigreturn trampoline with a BTI C instruction
arm64: bti: Fix support for userspace only BTI
arm64: kconfig: Update and comment GCC version check for kernel BTI
arm64: vdso: Map the vDSO text with guarded pages when built for BTI
arm64: vdso: Force the vDSO to be linked as BTI when built for BTI
arm64: vdso: Annotate for BTI
arm64: asm: Provide a mechanism for generating ELF note for BTI
arm64: bti: Provide Kconfig for kernel mode BTI
arm64: mm: Mark executable text as guarded pages
arm64: bpf: Annotate JITed code for BTI
arm64: Set GP bit in kernel page tables to enable BTI for the kernel
arm64: asm: Override SYM_FUNC_START when building the kernel with BTI
arm64: bti: Support building kernel C code using BTI
arm64: Document why we enable PAC support for leaf functions
arm64: insn: Report PAC and BTI instructions as skippable
arm64: insn: Don't assume unrecognized HINTs are skippable
arm64: insn: Provide a better name for aarch64_insn_is_nop()
arm64: insn: Add constants for new HINT instruction decode
arm64: Disable old style assembly annotations
...
|
|
Daniel reports that the .cfi_startproc is misplaced for the sigreturn
trampoline, which causes LLVM's unwinder to misbehave:
| I run into this with LLVM’s unwinder.
| This combination was always broken.
This prompted Dave to question our use of CFI directives more generally,
and I ended up going down a rabbit hole trying to figure out how this
very poorly documented stuff gets used.
Move the CFI directives so that the "mysterious NOP" is included in
the .cfi_{start,end}proc block and add a bunch of comments so that I
can save myself another headache in future.
Cc: Tamas Zsoldos <tamas.zsoldos@arm.com>
Reported-by: Dave Martin <dave.martin@arm.com>
Reported-by: Daniel Kiss <daniel.kiss@arm.com>
Tested-by: Daniel Kiss <daniel.kiss@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
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For better or worse, GDB relies on the exact instruction sequence in the
VDSO sigreturn trampoline in order to unwind from signals correctly.
Commit c91db232da48 ("arm64: vdso: Convert to modern assembler annotations")
unfortunately added a BTI C instruction to the start of __kernel_rt_sigreturn,
which breaks this check. Thankfully, it's also not required, since the
trampoline is called from a RET instruction when returning from the signal
handler
Remove the unnecessary BTI C instruction from __kernel_rt_sigreturn,
and do the same for the 32-bit VDSO as well for good measure.
Cc: Daniel Kiss <daniel.kiss@arm.com>
Cc: Tamas Zsoldos <tamas.zsoldos@arm.com>
Reviewed-by: Dave Martin <dave.martin@arm.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Fixes: c91db232da48 ("arm64: vdso: Convert to modern assembler annotations")
Signed-off-by: Will Deacon <will@kernel.org>
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Shadow stacks are only available in the kernel, so disable SCS
instrumentation for the vDSO.
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>
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When the kernel and hence vDSO are built with BTI enabled force the linker
to link the vDSO as BTI. This will cause the linker to warn if any of the
input files do not have the BTI annotation, ensuring that we don't silently
fail to provide a vDSO that is built and annotated for BTI when the
kernel is being built with BTI.
Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20200506195138.22086-11-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
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Generate BTI annotations for all assembly files included in the 64 bit
vDSO.
Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20200506195138.22086-10-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
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LLVM's unwinder depends on the .eh_frame_hdr being present for
unwinding. However, when compiling Linux with GCC, the section
is not present in the vdso library object and when compiling
with Clang, it is present, but it has zero length.
With GCC the problem was not spotted because libgcc unwinder does
not require the .eh_frame_hdr section to be present.
Add --eh-frame-hdr to ldflags to correctly generate and populate
the section for both GCC and LLVM.
Fixes: 28b1a824a4f44 ("arm64: vdso: Substitute gettimeofday() with C implementation")
Reported-by: Tamas Zsoldos <tamas.zsoldos@arm.com>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Tested-by: Tamas Zsoldos <tamas.zsoldos@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20200507104049.47834-1-vincenzo.frascino@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
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On arm64 linux gcc uses -fasynchronous-unwind-tables -funwind-tables
by default since gcc-8, so now the de facto platform ABI is to allow
unwinding from async signal handlers.
However on bare metal targets (aarch64-none-elf), and on old gcc,
async and sync unwind tables are not enabled by default to avoid
runtime memory costs.
This means if linux is built with a baremetal toolchain the vdso.so
may not have unwind tables which breaks the gcc platform ABI guarantee
in userspace.
Add -fasynchronous-unwind-tables explicitly to the vgettimeofday.o
cflags to address the ABI change.
Fixes: 28b1a824a4f4 ("arm64: vdso: Substitute gettimeofday() with C implementation")
Cc: Will Deacon <will@kernel.org>
Reported-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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Commit 28b1a824a4f44 ("arm64: vdso: Substitute gettimeofday() with C
implementation") introduced an unused 'VDSO_LDFLAGS' variable to the
vdso Makefile, suggesting that we should be passing '-Bsymbolic' to the
linker, as we do when linking the compat vDSO.
Although it's not strictly necessary to pass this flag, it would be
required if we were to add any internal references to the exported
symbols. It's also consistent with how we link the compat vdso so, since
there's no real downside from passing it, add '-Bsymbolic' to the ldflags
for the native vDSO.
Fixes: 28b1a824a4f44 ("arm64: vdso: Substitute gettimeofday() with C implementation")
Reported-by: Geoff Levand <geoff@infradead.org>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20200428150854.33130-1-vincenzo.frascino@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
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