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Fri, 17 May 2024 14:27:36 -0700 (PDT) Received: from www.outflux.net ([198.0.35.241]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-1ef0c2567absm160788595ad.297.2024.05.17.14.27.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 17 May 2024 14:27:35 -0700 (PDT) Date: Fri, 17 May 2024 14:27:35 -0700 From: Kees Cook To: Masahiro Yamada Cc: Andy Lutomirski , Will Drewry , linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, Alexandre Belloni , Benjamin Tissoires , Christian Borntraeger , Claudio Imbrenda , David Hildenbrand , Janosch Frank , Jiri Kosina , Shuah Khan , bpf@vger.kernel.org, kvm@vger.kernel.org, linux-input@vger.kernel.org, linux-rtc@vger.kernel.org Subject: Re: [PATCH 0/2] selftests: harness: refactor __constructor_order Message-ID: <202405171426.B1ED9AD@keescook> References: <20240517114506.1259203-1-masahiroy@kernel.org> Precedence: bulk X-Mailing-List: linux-rtc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240517114506.1259203-1-masahiroy@kernel.org> On Fri, May 17, 2024 at 08:45:04PM +0900, Masahiro Yamada wrote: > > This series refactors __constructor_order because > __constructor_order_last() is unneeded. > > BTW, the comments in kselftest_harness.h was confusing to me. > > As far as I tested, all arches executed constructors in the forward > order. > > [test code] > > #include > > static int x; > > static void __attribute__((constructor)) increment(void) > { > x += 1; > } > > static void __attribute__((constructor)) multiply(void) > { > x *= 2; > } > > int main(void) > { > printf("foo = %d\n", x); > return 0; > } > > It should print 2 for forward order systems, 1 for reverse order systems. > > I executed it on some archtes by using QEMU. I always got 2. IIRC, and it was a long time ago now, it was actually a difference between libc implementations where I encountered the problem. Maybe glibc vs Bionic? -Kees -- Kees Cook