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* selftests/rseq: Change type of rseq_offset to ptrdiff_tMathieu Desnoyers2022-02-111-2/+3
| | | | | | | | | | | Just before the 2.35 release of glibc, the __rseq_offset userspace ABI was changed from int to ptrdiff_t. Adapt to this change in the kernel selftests. Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://sourceware.org/pipermail/libc-alpha/2022-February/136024.html
* selftests/rseq: Uplift rseq selftests for compatibility with glibc-2.35Mathieu Desnoyers2022-02-021-84/+77
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | glibc-2.35 (upcoming release date 2022-02-01) 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 Linux kernel selftests initially expected. 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. Here is the scheme introduced to ensure selftests can work both with an older glibc and with glibc-2.35+: - librseq exposes its own "rseq_offset, rseq_size, rseq_flags" ABI. - librseq queries for glibc rseq ABI (__rseq_offset, __rseq_size, __rseq_flags) using dlsym() in a librseq library constructor. If those are found, copy their values into rseq_offset, rseq_size, and rseq_flags. - Else, if those glibc symbols are not found, handle rseq registration from librseq and use its own IE-model TLS to implement the rseq ABI per-thread storage. Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20220124171253.22072-8-mathieu.desnoyers@efficios.com
* selftests/rseq: Remove volatile from __rseq_abiMathieu Desnoyers2022-02-021-2/+2
| | | | | | | | | | | | | This is done in preparation for the selftest uplift to become compatible with glibc-2.35. All accesses to the __rseq_abi fields are volatile, but remove the volatile from the TLS variable declaration, otherwise we are stuck with volatile for the upcoming rseq_get_abi() helper. Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20220124171253.22072-5-mathieu.desnoyers@efficios.com
* selftests/rseq: introduce own copy of rseq uapi headerMathieu Desnoyers2022-02-021-7/+7
| | | | | | | | | | | | | | | | | | The Linux kernel rseq uapi header has a broken layout for the rseq_cs.ptr field on 32-bit little endian architectures. The entire rseq_cs.ptr field is planned for removal, leaving only the 64-bit rseq_cs.ptr64 field available. Both glibc and librseq use their own copy of the Linux kernel uapi header, where they introduce proper union fields to access to the 32-bit low order bits of the rseq_cs pointer on 32-bit architectures. Introduce a copy of the Linux kernel uapi headers in the Linux kernel selftests. Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20220124171253.22072-2-mathieu.desnoyers@efficios.com
* selftests/rseq: remove ARRAY_SIZE define from individual testsShuah Khan2021-12-101-2/+1
| | | | | | | | | | | | ARRAY_SIZE is defined in several selftests. Remove definitions from individual test files and include header file for the define instead. ARRAY_SIZE define is added in a separate patch to prepare for this change. Remove ARRAY_SIZE from rseq tests and pickup the one defined in kselftest.h. Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
* rseq/selftests: Use __rseq_handled symbol to coexist with glibcMathieu Desnoyers2019-05-071-8/+47
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | In order to integrate rseq into user-space applications, expose a __rseq_handled symbol so many rseq users can be linked into the same application (e.g. librseq and glibc). The __rseq_refcount TLS variable is static to the librseq library. It ensures that rseq syscall registration/unregistration happens only for the most early/late caller to rseq_{,un}register_current_thread for each thread, thus ensuring that rseq is registered across the lifetime of all rseq users for a given thread. Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> CC: Shuah Khan <shuah@kernel.org> CC: Carlos O'Donell <carlos@redhat.com> CC: Florian Weimer <fweimer@redhat.com> CC: Joseph Myers <joseph@codesourcery.com> CC: Szabolcs Nagy <szabolcs.nagy@arm.com> CC: Thomas Gleixner <tglx@linutronix.de> CC: Ben Maurer <bmaurer@fb.com> CC: Peter Zijlstra <peterz@infradead.org> CC: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> CC: Boqun Feng <boqun.feng@gmail.com> CC: Will Deacon <will.deacon@arm.com> CC: Dave Watson <davejwatson@fb.com> CC: Paul Turner <pjt@google.com> CC: linux-api@vger.kernel.org Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
* rseq/selftests: Provide rseq libraryMathieu Desnoyers2018-06-061-0/+117
This rseq helper library provides a user-space API to the rseq() system call. The rseq fast-path exposes the instruction pointer addresses where the rseq assembly blocks begin and end, as well as the associated abort instruction pointer, in the __rseq_table section. This section allows debuggers may know where to place breakpoints when single-stepping through assembly blocks which may be aborted at any point by the kernel. Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: 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 <shuahkh@osg.samsung.com> 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: Andrew Hunter <ahh@google.com> 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> Link: https://lkml.kernel.org/r/20180602124408.8430-13-mathieu.desnoyers@efficios.com