From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from madrid.collaboradmins.com (madrid.collaboradmins.com [46.235.227.194]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A03F217B505 for ; Wed, 29 May 2024 08:06:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=46.235.227.194 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716970005; cv=none; b=NzHRdXgWQCFg0ecUUc/ecsMLQeyhQmjRVk7RfBe9aVsm5sNMlj2KobISRQLhOTOmoAeqNJ+MU8lUzOnsE6iUSeUN/fBd709BKi0Kw6lA+GoE9GcoyWy7/kAyA/M0o4EY02r/10vhT9wpO7zxXis6nJmel+g+GISwh8OiWtxEth4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716970005; c=relaxed/simple; bh=C9NThqdx/W9npFCwEseQgicfZl61EOyPH13LNK3W6HM=; h=Message-ID:Date:MIME-Version:Cc:Subject:To:References:From: In-Reply-To:Content-Type; b=NCWnPe8xAbfLDyrgFj/40G6R39zD9Lpq7YQLuQqYdFaeT0zM2ZoHRUYny/DSpMLfZm8aMt7J+z6O7ahpfaN7pdr3/02GfCdIEVRCBpZ64a0LNAuYHy2SUXfiOcm+k9yyHTTMol1W4ObERaalYXLiiqEP93UPusOFMh7B91ht4sY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=collabora.com; spf=pass smtp.mailfrom=collabora.com; dkim=pass (2048-bit key) header.d=collabora.com header.i=@collabora.com header.b=0TPyU/Bm; arc=none smtp.client-ip=46.235.227.194 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=collabora.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=collabora.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=collabora.com header.i=@collabora.com header.b="0TPyU/Bm" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1716970002; bh=C9NThqdx/W9npFCwEseQgicfZl61EOyPH13LNK3W6HM=; h=Date:Cc:Subject:To:References:From:In-Reply-To:From; b=0TPyU/Bmm41hIGdVrpdVaPzXI963Y+no4v0A8ghyC3bQvE3pjAxBLp11ReGn+iJGj kHkobjweMEugNEjPF3NZ9sxAeJaf+HV/ftMvhjdSt4dSK8vN3fgK4BKF3WkP84nv4Q Uahb+JJ/974RBI0oVHnj1sc0Gnbx4U5nBlVRPmFO1reC/hnSF+ebDirAVVv+V4iZIJ 6TOVPgMZK2NgCJxUzGxnXbSQcCWw6962KX8iQ3WtInBEYIve8tSOGA8wdcXd7zEe/c 3bwjDfVc7MQVEqo/FYZPuUoXJ2f/qc/ilOvZu530ffd2p2iCUIfveKG2Hqb4jwtAhz 1Rmw2FBaZJcGA== Received: from [100.113.15.66] (ec2-34-240-57-77.eu-west-1.compute.amazonaws.com [34.240.57.77]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: usama.anjum) by madrid.collaboradmins.com (Postfix) with ESMTPSA id 0A9D23782162; Wed, 29 May 2024 08:06:34 +0000 (UTC) Message-ID: <0816b38b-41a1-431a-90a4-1ac33401a671@collabora.com> Date: Wed, 29 May 2024 13:05:57 +0500 Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Cc: Muhammad Usama Anjum , Mark Brown , Vincenzo Frascino , Colin Ian King , Valentin Obst , linux-kselftest@vger.kernel.org, LKML , llvm@lists.linux.dev Subject: Re: [PATCH v2] selftests/vDSO: fix clang build errors and warnings To: John Hubbard , Shuah Khan References: <20240527211622.290635-1-jhubbard@nvidia.com> Content-Language: en-US From: Muhammad Usama Anjum In-Reply-To: <20240527211622.290635-1-jhubbard@nvidia.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 5/28/24 2:16 AM, John Hubbard wrote: > When building with clang, via: > > make LLVM=1 -C tools/testing/selftests > > ...there are several warnings, and an error. This fixes all of those and > allows these tests to run and pass. > > 1. Fix linker error (undefined reference to memcpy) by providing a local > version of memcpy. > > 2. clang complains about using this form: > > if (g = h & 0xf0000000) > > ...so factor out the assignment into a separate step. > > 3. The code is passing a signed const char* to elf_hash(), which expects > a const unsigned char *. There are several callers, so fix this at > the source by allowing the function to accept a signed argument, and > then converting to unsigned operations, once inside the function. > > 4. clang doesn't have __attribute__((externally_visible)) and generates > a warning to that effect. Fortunately, gcc 12 and gcc 13 do not seem > to require that attribute in order to build, run and pass tests here, > so remove it. Just checked with GCC 5.1, it builds fine without any errors. > > [1] https://lore.kernel.org/all/20240329-selftests-libmk-llvm-rfc-v1-1-2f9ed7d1c49f@valentinobst.de/ > > Signed-off-by: John Hubbard LGTM Reviewed-by: Muhammad Usama Anjum Tested-by: Muhammad Usama Anjum > --- > > Changes since the first version: > > 1) Rebased onto Linux 6.10-rc1 > > thanks, > John Hubbard > > tools/testing/selftests/vDSO/parse_vdso.c | 16 +++++++++++----- > .../selftests/vDSO/vdso_standalone_test_x86.c | 18 ++++++++++++++++-- > 2 files changed, 27 insertions(+), 7 deletions(-) > > diff --git a/tools/testing/selftests/vDSO/parse_vdso.c b/tools/testing/selftests/vDSO/parse_vdso.c > index 413f75620a35..4ae417372e9e 100644 > --- a/tools/testing/selftests/vDSO/parse_vdso.c > +++ b/tools/testing/selftests/vDSO/parse_vdso.c > @@ -55,14 +55,20 @@ static struct vdso_info > ELF(Verdef) *verdef; > } vdso_info; > > -/* Straight from the ELF specification. */ > -static unsigned long elf_hash(const unsigned char *name) > +/* > + * Straight from the ELF specification...and then tweaked slightly, in order to > + * avoid a few clang warnings. > + */ > +static unsigned long elf_hash(const char *name) > { > unsigned long h = 0, g; > - while (*name) > + const unsigned char *uch_name = (const unsigned char *)name; > + > + while (*uch_name) > { > - h = (h << 4) + *name++; > - if (g = h & 0xf0000000) > + h = (h << 4) + *uch_name++; > + g = h & 0xf0000000; > + if (g) > h ^= g >> 24; > h &= ~g; > } > diff --git a/tools/testing/selftests/vDSO/vdso_standalone_test_x86.c b/tools/testing/selftests/vDSO/vdso_standalone_test_x86.c > index 8a44ff973ee1..27f6fdf11969 100644 > --- a/tools/testing/selftests/vDSO/vdso_standalone_test_x86.c > +++ b/tools/testing/selftests/vDSO/vdso_standalone_test_x86.c > @@ -18,7 +18,7 @@ > > #include "parse_vdso.h" > > -/* We need a libc functions... */ > +/* We need some libc functions... */ > int strcmp(const char *a, const char *b) > { > /* This implementation is buggy: it never returns -1. */ > @@ -34,6 +34,20 @@ int strcmp(const char *a, const char *b) > return 0; > } > > +/* > + * The clang build needs this, although gcc does not. > + * Stolen from lib/string.c. > + */ > +void *memcpy(void *dest, const void *src, size_t count) > +{ > + char *tmp = dest; > + const char *s = src; > + > + while (count--) > + *tmp++ = *s++; > + return dest; > +} > + > /* ...and two syscalls. This is x86-specific. */ > static inline long x86_syscall3(long nr, long a0, long a1, long a2) > { > @@ -70,7 +84,7 @@ void to_base10(char *lastdig, time_t n) > } > } > > -__attribute__((externally_visible)) void c_main(void **stack) > +void c_main(void **stack) > { > /* Parse the stack */ > long argc = (long)*stack; > > base-commit: 2bfcfd584ff5ccc8bb7acde19b42570414bf880b -- BR, Muhammad Usama Anjum