kernel/tools/testing/selftests/rseq/rseq.h, branch linux-6.2.y

Merge tag 'riscv-for-linus-5.18-mw0' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux

2022-03-25T17:11:38Z

Pull RISC-V updates from Palmer Dabbelt: - Support for Sv57-based virtual memory. - Various improvements for the MicroChip PolarFire SOC and the associated Icicle dev board, which should allow upstream kernels to boot without any additional modifications. - An improved memmove() implementation. - Support for the new Ssconfpmf and SBI PMU extensions, which allows for a much more useful perf implementation on RISC-V systems. - Support for restartable sequences. * tag 'riscv-for-linus-5.18-mw0' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux: (36 commits) rseq/selftests: Add support for RISC-V RISC-V: Add support for restartable sequence MAINTAINERS: Add entry for RISC-V PMU drivers Documentation: riscv: Remove the old documentation RISC-V: Add sscofpmf extension support RISC-V: Add perf platform driver based on SBI PMU extension RISC-V: Add RISC-V SBI PMU extension definitions RISC-V: Add a simple platform driver for RISC-V legacy perf RISC-V: Add a perf core library for pmu drivers RISC-V: Add CSR encodings for all HPMCOUNTERS RISC-V: Remove the current perf implementation RISC-V: Improve /proc/cpuinfo output for ISA extensions RISC-V: Do no continue isa string parsing without correct XLEN RISC-V: Implement multi-letter ISA extension probing framework RISC-V: Extract multi-letter extension names from "riscv, isa" RISC-V: Minimal parser for "riscv, isa" strings RISC-V: Correctly print supported extensions riscv: Fixed misaligned memory access. Fixed pointer comparison. MAINTAINERS: update riscv/microchip entry riscv: dts: microchip: add new peripherals to icicle kit device tree ...

rseq/selftests: Add support for RISC-V

2022-03-22T21:45:19Z

Add support for RISC-V in the rseq selftests, which covers both 64-bit and 32-bit ISA with little endian mode. Signed-off-by: Vincent Chen Tested-by: Eric Lin Reviewed-by: Mathieu Desnoyers Signed-off-by: Palmer Dabbelt

selftests/rseq: Change type of rseq_offset to ptrdiff_t

2022-02-11T22:30:08Z

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 Signed-off-by: Peter Zijlstra (Intel) Link: https://sourceware.org/pipermail/libc-alpha/2022-February/136024.html

selftests/rseq: Fix: work-around asm goto compiler bugs

2022-02-02T12:11:37Z

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 Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20220124171253.22072-14-mathieu.desnoyers@efficios.com

selftests/rseq: Uplift rseq selftests for compatibility with glibc-2.35

2022-02-02T12:11:35Z

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 Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20220124171253.22072-8-mathieu.desnoyers@efficios.com

selftests/rseq: Introduce rseq_get_abi() helper

2022-02-02T12:11:35Z

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 Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20220124171253.22072-6-mathieu.desnoyers@efficios.com

selftests/rseq: Remove volatile from __rseq_abi

2022-02-02T12:11:34Z

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 Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20220124171253.22072-5-mathieu.desnoyers@efficios.com

selftests/rseq: introduce own copy of rseq uapi header

2022-02-02T12:11:33Z

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 Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20220124171253.22072-2-mathieu.desnoyers@efficios.com

rseq/selftests: Clarify rseq_prepare_unload() helper requirements

2019-12-23T17:52:41Z

The rseq.h UAPI now documents that the rseq_cs field must be cleared before reclaiming memory that contains the targeted struct rseq_cs, but also that the rseq_cs field must be cleared before reclaiming memory of the code pointed to by the rseq_cs start_ip and post_commit_offset fields. While we can expect that use of dlclose(3) will typically unmap both struct rseq_cs and its associated code at once, nothing would theoretically prevent a JIT from reclaiming the code without reclaiming the struct rseq_cs, which would erroneously allow the kernel to consider new code which is not a rseq critical section as a rseq critical section following a code reclaim. Suggested-by: Florian Weimer Signed-off-by: Mathieu Desnoyers Cc: Shuah Khan Cc: Florian Weimer Cc: Thomas Gleixner Cc: Peter Zijlstra (Intel) Cc: "Paul E. McKenney" Cc: Boqun Feng Cc: "H . Peter Anvin" Cc: Paul Turner Cc: Dmitry Vyukov Signed-off-by: Shuah Khan

rseq/selftests: Use __rseq_handled symbol to coexist with glibc

2019-05-07T21:31:46Z

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 CC: Shuah Khan CC: Carlos O'Donell CC: Florian Weimer CC: Joseph Myers CC: Szabolcs Nagy CC: Thomas Gleixner CC: Ben Maurer CC: Peter Zijlstra CC: "Paul E. McKenney" CC: Boqun Feng CC: Will Deacon CC: Dave Watson CC: Paul Turner CC: linux-api@vger.kernel.org Signed-off-by: Shuah Khan