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Donenfeld" , Nathan Chancellor Cc: Christophe Leroy , Vincenzo Frascino , Nick Desaulniers , 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() Date: Fri, 2 Oct 2026 12:57:06 +0200 Message-ID: <179093852073.149722.832232613857480812.b4-ty@kernel.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260925-vdso-getrandom-avoid-memset-llvm-24-v2-1-ce640f872393@kernel.org> References: <20260925-vdso-getrandom-avoid-memset-llvm-24-v2-1-ce640f872393@kernel.org> 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="utf-8" X-Developer-Signature: v=1; a=openpgp-sha256; l=948; i=chleroy@kernel.org; h=from:subject:message-id; bh=cZWyz0y5XGYe9zKs9PNHSxiUlxW65egvfT4xEgdntpI=; b=owGbwMvMwCV2d0KB2p7V54MZT6slMWTt7+OJ/rvq89WD/OHOTgfiuFYb3eV9siQjX6ZB4uV8W fGZTfsNOkpZGMS4GGTFFFmO/+feNaPrS2r+1F36MHNYmUCGMHBxCsBElsQyMkw/0pmesd3U1s2/ +cCt35+i1GxcP3PlXZzn80qx+rxOmQLD/5gj9bZ29RUatWfD9vbt1+NKmTHbS7kya1+avMNCTlt NfgA= X-Developer-Key: i=chleroy@kernel.org; a=openpgp; fpr=10FFE6F8B390DE17ACC2632368A92FEB01B8DD78 Content-Transfer-Encoding: 8bit On Fri, 25 Sep 2026 22:46:32 +0100, Nathan Chancellor wrote: > After a recent change in LLVM [1], builds with the random vDSO > implementation, such as PowerPC and RISC-V, fail when checking the vDSO: > > arch/powerpc/kernel/vdso/vdso32.so.dbg: dynamic relocations are not supported > arch/riscv/kernel/vdso/vdso.so.dbg: dynamic relocations are not supported > > memset() is now generated when zeroing params->reserved for some builds > because LLVM has an optimization (now run in more instances) that can > recognize at compile time when it is assigning a static value to a > contiguous area of memory and turn that into a call to memset(). Both > clang and GCC assume memset() is always available [2]. > > [...] Applied, thanks! [1/1] random: vDSO: Avoid call to memset() when zeroing reserved in __cvdso_getrandom_data() (no commit info) Best regards, -- Christophe Leroy (CS GROUP)