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gcc and clang each have their own compiler bugs with respect to asm
goto. Implement a work-around for compiler versions known to have those
bugs.
gcc prior to 4.8.2 miscompiles asm goto.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670
gcc prior to 8.1.0 miscompiles asm goto at O1.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103908
clang prior to version 13.0.1 miscompiles asm goto at O2.
https://github.com/llvm/llvm-project/issues/52735
Work around these issues by adding a volatile inline asm with
memory clobber in the fallthrough after the asm goto and at each
label target. Emit this for all compilers in case other similar
issues are found in the future.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20220124171253.22072-14-mathieu.desnoyers@efficios.com
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The semantic of off_t is for file offsets. We mean to use it as an
offset from a pointer. We really expect it to fit in a single register,
and not use a 64-bit type on 32-bit architectures.
Fix runtime issues on ppc32 where the offset is always 0 due to
inconsistency between the argument type (off_t -> 64-bit) and type
expected by the inline assembler (32-bit).
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20220124171253.22072-11-mathieu.desnoyers@efficios.com
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ppc32 incorrectly uses padding as rseq_cs pointer field. Fix this by
using the rseq_cs.arch.ptr field.
Use this field across all architectures.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20220124171253.22072-9-mathieu.desnoyers@efficios.com
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This is done in preparation for the selftest uplift to become compatible
with glibc-2.35.
glibc-2.35 exposes the rseq per-thread data in the TCB, accessible
at an offset from the thread pointer, rather than through an actual
Thread-Local Storage (TLS) variable, as the kernel selftests initially
expected.
Introduce a rseq_get_abi() helper, initially using the __rseq_abi
TLS variable, in preparation for changing this userspace ABI for one
which is compatible with glibc-2.35.
Note that the __rseq_abi TLS and glibc-2.35's ABI for per-thread data
cannot actively coexist in a process, because the kernel supports only
a single rseq registration per thread.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20220124171253.22072-6-mathieu.desnoyers@efficios.com
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git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest
Pull more kselftest updates from Shuah Khan:
- kselftest framework bpf build/test workflow regression fix
- Fix to kselftest install to use default install path
- Fix to kselftest KBUILD_OUTPUT builds to not clutter main
KBUILD_OUTPUT directory with selftest objects
- .gitignore fixes (Kelsey Skunberg)
- rseq selftests updates (Mathieu Desnoyers and Martin Schwidefsky)
They change the per-architecture pre-abort signatures to ensure those
are valid trap instructions.
The way exit points are presented to debuggers is enhanced, ensuring
all exit points are present, so debuggers don't have to disassemble
rseq critical section to properly skip over them.
Discussions with the glibc community is reaching a consensus of
exposing a __rseq_handled symbol from glibc to coexist with rseq
early adopters. Update the rseq selftest code to expose and use this
symbol.
Support for compiling asm goto with clang is added with the
"-no-integrated-as" compiler switch, similarly to the top level
kernel Makefile.
- kselftest Makefile test run output refactoring and making test output
TAP13 compliant from Kees Cook:
This re-factors the selftest Makefiles to extract the test running
logic to be reused between "run_tests" and "emit_tests", while also
fixing up the test output to be TAP version 13 compliant:
- added "plan" line
- fixed result line syntax
- moved all test output to be "# "-prefixed as TAP "diagnostic"
lines
The prefixing code includes a fallback mode for limited execution
environments.
Additionally, the plan lines are fixed for all callers of
kselftest.h.
* tag 'linux-kselftest-5.2-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest: (25 commits)
selftests: avoid KBUILD_OUTPUT dir cluttering with selftest objects
selftests: drivers: Create .gitignore to include /dma-buf/udmabuf
selftests: pidfd: Create .gitignore to include pidfd_test
selftests: fix bpf build/test workflow regression when KBUILD_OUTPUT is set
selftests: fix install target to use default install path
rseq/selftests: add -no-integrated-as for clang
rseq/selftests: mips: use break instruction for RSEQ_SIG
rseq/selftests: powerpc code signature: generate valid instructions
rseq/selftests: aarch64 code signature: handle big-endian environment
rseq/selftests: arm: use udf instruction for RSEQ_SIG
rseq/selftests: s390: use trap4 for RSEQ_SIG
rseq/selftests: x86: use ud1 instruction as RSEQ_SIG opcode
rseq/selftests: s390: use jg instruction for jumps outside of the asm
rseq/selftests: Use __rseq_handled symbol to coexist with glibc
rseq/selftests: Introduce __rseq_cs_ptr_array, rename __rseq_table to __rseq_cs
rseq/selftests: Add __rseq_exit_point_array section for debuggers
rseq/selftests: x86: Work-around bogus gcc-8 optimisation
selftests: Add test plan API to kselftest.h and adjust callers
selftests: Remove KSFT_TAP_LEVEL
selftests: Move test output to diagnostic lines
...
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Use trap4 as the guard instruction for the restartable sequence abort
handler.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
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The branch target range of the "j" instruction is 64K, which is not
enough for the general case.
Suggested-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: Joel Fernandes <joelaf@google.com>
CC: Peter Zijlstra <peterz@infradead.org>
CC: Catalin Marinas <catalin.marinas@arm.com>
CC: Dave Watson <davejwatson@fb.com>
CC: Will Deacon <will.deacon@arm.com>
CC: Shuah Khan <shuah@kernel.org>
CC: Andi Kleen <andi@firstfloor.org>
CC: linux-kselftest@vger.kernel.org
CC: "H . Peter Anvin" <hpa@zytor.com>
CC: Chris Lameter <cl@linux.com>
CC: Russell King <linux@arm.linux.org.uk>
CC: Michael Kerrisk <mtk.manpages@gmail.com>
CC: "Paul E . McKenney" <paulmck@linux.vnet.ibm.com>
CC: Paul Turner <pjt@google.com>
CC: Boqun Feng <boqun.feng@gmail.com>
CC: Josh Triplett <josh@joshtriplett.org>
CC: Steven Rostedt <rostedt@goodmis.org>
CC: Ben Maurer <bmaurer@fb.com>
CC: linux-api@vger.kernel.org
CC: Andy Lutomirski <luto@amacapital.net>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
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The entries within __rseq_table are aligned on 32 bytes due to
linux/rseq.h struct rseq_cs uapi requirements, but the start of the
__rseq_table section is not guaranteed to be 32-byte aligned. It can
cause padding to be added at the start of the section, which makes it
hard to use as an array of items by debuggers.
Considering that __rseq_table does not really consist of a table due to
the presence of padding, rename this section to __rseq_cs.
Create a new __rseq_cs_ptr_array section which contains 64-bit packed
pointers to entries within the __rseq_cs section.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: Joel Fernandes <joelaf@google.com>
CC: Peter Zijlstra <peterz@infradead.org>
CC: Catalin Marinas <catalin.marinas@arm.com>
CC: Dave Watson <davejwatson@fb.com>
CC: Will Deacon <will.deacon@arm.com>
CC: Shuah Khan <shuah@kernel.org>
CC: Andi Kleen <andi@firstfloor.org>
CC: linux-kselftest@vger.kernel.org
CC: "H . Peter Anvin" <hpa@zytor.com>
CC: Chris Lameter <cl@linux.com>
CC: Russell King <linux@arm.linux.org.uk>
CC: Michael Kerrisk <mtk.manpages@gmail.com>
CC: "Paul E . McKenney" <paulmck@linux.vnet.ibm.com>
CC: Paul Turner <pjt@google.com>
CC: Boqun Feng <boqun.feng@gmail.com>
CC: Josh Triplett <josh@joshtriplett.org>
CC: Steven Rostedt <rostedt@goodmis.org>
CC: Ben Maurer <bmaurer@fb.com>
CC: linux-api@vger.kernel.org
CC: Andy Lutomirski <luto@amacapital.net>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
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Knowing all exit points is useful to assist debuggers stepping over the
rseq critical sections without requiring them to disassemble the content
of the critical section to figure out the exit points.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: Joel Fernandes <joelaf@google.com>
CC: Peter Zijlstra <peterz@infradead.org>
CC: Catalin Marinas <catalin.marinas@arm.com>
CC: Dave Watson <davejwatson@fb.com>
CC: Will Deacon <will.deacon@arm.com>
CC: Shuah Khan <shuah@kernel.org>
CC: Andi Kleen <andi@firstfloor.org>
CC: linux-kselftest@vger.kernel.org
CC: "H . Peter Anvin" <hpa@zytor.com>
CC: Chris Lameter <cl@linux.com>
CC: Russell King <linux@arm.linux.org.uk>
CC: Michael Kerrisk <mtk.manpages@gmail.com>
CC: "Paul E . McKenney" <paulmck@linux.vnet.ibm.com>
CC: Paul Turner <pjt@google.com>
CC: Boqun Feng <boqun.feng@gmail.com>
CC: Josh Triplett <josh@joshtriplett.org>
CC: Steven Rostedt <rostedt@goodmis.org>
CC: Ben Maurer <bmaurer@fb.com>
CC: linux-api@vger.kernel.org
CC: Andy Lutomirski <luto@amacapital.net>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
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Use trap4 as the guard instruction for the restartable sequence abort
handler.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Implement support for s390 in the rseq selftests, in order to sanity
check the recently enabled rseq syscall. The Implementation covers both
64-bit and 31-bit mode.
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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