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Donenfeld" Cc: "Christophe Leroy (CS GROUP)" , Nick Desaulniers , Andy Lutomirski , Thomas Gleixner , Theodore Ts'o , Vincenzo Frascino , Bill Wendling , Justin Stitt , Catalin Marinas , Will Deacon , Mark Rutland , Huacai Chen , WANG Xuerui , Madhavan Srinivasan , Michael Ellerman , Nicholas Piggin , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" , x86@kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, loongarch@lists.linux.dev, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, llvm@lists.linux.dev Subject: Re: [PATCH v2] random: vDSO: Avoid call to memset() when zeroing reserved in __cvdso_getrandom_data() Message-ID: <20261002094932.GA3435055@ax162> References: <20260930133813.GA3142230@ax162> <20260930151337.GD3142230@ax162> <20261001102059.GA4176271@ax162> <20261001110310.GA138012@ax162> X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261001110310.GA138012@ax162> On Thu, Oct 01, 2026 at 01:03:10PM +0200, Nathan Chancellor wrote: > On Thu, Oct 01, 2026 at 12:48:10PM +0200, Jason A. Donenfeld wrote: > > Does this commit seem okay with you? I used the diff you sent below and > > adjusted the commit message: https://git.zx2c4.com/linux-rng/commit/?id=56ff95ee85715047eb5b5220243778af657778c8 > > Yeah, that seems fine to me, thanks for taking care of it! Can you adjust the LLVM value by one from 4294967295 to 4294967294? ~0U is actually a special value, so we hit an assertion in the SystemZ backend. https://github.com/llvm/llvm-project/blob/3f48e22a1f321d5d3341bd812803694cea588785/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp#L9547 https://github.com/llvm/llvm-project/blob/3f48e22a1f321d5d3341bd812803694cea588785/llvm/lib/Target/SystemZ/SystemZISelLowering.cpp#L1470-L1471 clang: llvm/lib/Target/SystemZ/SystemZISelLowering.cpp:1471: virtual bool llvm::SystemZTargetLowering::findOptimalMemOpLowering(LLVMContext &, std::vector &, unsigned int, const MemOp &, unsigned int, unsigned int, const AttributeList &, EVT *) const: Assertion `Limit != ~0U && "Expected EmitTargetCodeForMemXXX() to handle AlwaysInline cases."' failed. PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace and dumped files. Stack dump: 0. Program arguments: ... 1. parser at end of file 2. Code generation 3. Running pass 'Function Pass Manager' on module 'arch/s390/kernel/vdso/vgetrandom.c'. 4. Running pass 'SystemZ DAG->DAG Pattern Instruction Selection' on function '@__kernel_getrandom' ... -- Cheers, Nathan