Re: [PATCH] CryptoPkg/OpensslLib AARCH64: clear XIP CC flags

[Leif Lindholm <leif.lindholm@linaro.org>]

On Fri, Jul 14, 2017 at 06:19:13PM +0100, Ard Biesheuvel wrote:
> Commit 0df6c8c157af ("BaseTools/tools_def AARCH64: avoid SIMD registers
> in XIP code") updated the compiler flags used by AARCH64 when building
> modules (including BASE libraries) that may execute before the MMU is
> enabled.
> 
> This broke the build for OpensslLib/OpensslLibCrypto because the SIMD
> register file is shared with the FPU, and since OpenSSL contains some
> references to float/double types (which are mostly unused for UEFI btw),
> disabling floating point prevents the compiler from building OpenSSL
> at all.
> 
> When introducing the support for XIP CC flags, we were aware that this
> would affect BASE libraries as well, but were not expecting this to
> have any performance impact. However, in the case of software crypto,
> it makes sense not to needlessly inhibit the compiler's ability to
> generate fast code, and even if OpenssLib is a BASE library, it is
> guaranteed not to run with the MMU off, so we can create a local
> exception, and clear its XIP CC flags for AARCH64.
> 
> Contributed-under: TianoCore Contribution Agreement 1.0
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>

> ---
> Note that this un-breaks the currently broken AARCH64 build for
> platforms that have secure boot enabled
> 
>  CryptoPkg/Library/OpensslLib/OpensslLib.inf       | 11 +++++++++++
>  CryptoPkg/Library/OpensslLib/OpensslLibCrypto.inf | 11 +++++++++++
>  2 files changed, 22 insertions(+)
> 
> diff --git a/CryptoPkg/Library/OpensslLib/OpensslLib.inf b/CryptoPkg/Library/OpensslLib/OpensslLib.inf
> index cbabb34bdd7c..1d15da6660b2 100644
> --- a/CryptoPkg/Library/OpensslLib/OpensslLib.inf
> +++ b/CryptoPkg/Library/OpensslLib/OpensslLib.inf
> @@ -580,3 +580,14 @@ [BuildOptions]
>    RVCT:*_*_ARM_CC_FLAGS     = $(OPENSSL_FLAGS) --library_interface=aeabi_clib99 --diag_suppress=1296,1295,550,1293,111,68,177,223,144,513,188,128,546,1,3017 -JCryptoPkg/Include
>    XCODE:*_*_IA32_CC_FLAGS   = -mmmx -msse -U_WIN32 -U_WIN64 $(OPENSSL_FLAGS) -w
>    XCODE:*_*_X64_CC_FLAGS    = -mmmx -msse -U_WIN32 -U_WIN64 $(OPENSSL_FLAGS) -w
> +
> +  #
> +  # AARCH64 uses strict alignment and avoids SIMD registers for code that may execute
> +  # with the MMU off. This involves SEC, PEI_CORE and PEIM modules as well as BASE
> +  # libraries, given that they may be included into such modules.
> +  # This library, even though of the BASE type, is never used in such cases, and
> +  # avoiding the SIMD register file (which is shared with the FPU) prevents the
> +  # compiler from successfully building some of the OpenSSL source files that
> +  # use floating point types, so clear the flags here.
> +  #
> +  GCC:*_*_AARCH64_CC_XIPFLAGS ==
> diff --git a/CryptoPkg/Library/OpensslLib/OpensslLibCrypto.inf b/CryptoPkg/Library/OpensslLib/OpensslLibCrypto.inf
> index 026b551bcafa..6fc8884da492 100644
> --- a/CryptoPkg/Library/OpensslLib/OpensslLibCrypto.inf
> +++ b/CryptoPkg/Library/OpensslLib/OpensslLibCrypto.inf
> @@ -541,3 +541,14 @@ [BuildOptions]
>    RVCT:*_*_ARM_CC_FLAGS     = $(OPENSSL_FLAGS) --library_interface=aeabi_clib99 --diag_suppress=1296,1295,550,1293,111,68,177,223,144,513,188,128,546,1,3017 -JCryptoPkg/Include
>    XCODE:*_*_IA32_CC_FLAGS   = -mmmx -msse -U_WIN32 -U_WIN64 $(OPENSSL_FLAGS) -w
>    XCODE:*_*_X64_CC_FLAGS    = -mmmx -msse -U_WIN32 -U_WIN64 $(OPENSSL_FLAGS) -w
> +
> +  #
> +  # AARCH64 uses strict alignment and avoids SIMD registers for code that may execute
> +  # with the MMU off. This involves SEC, PEI_CORE and PEIM modules as well as BASE
> +  # libraries, given that they may be included into such modules.
> +  # This library, even though of the BASE type, is never used in such cases, and
> +  # avoiding the SIMD register file (which is shared with the FPU) prevents the
> +  # compiler from successfully building some of the OpenSSL source files that
> +  # use floating point types, so clear the flags here.
> +  #
> +  GCC:*_*_AARCH64_CC_XIPFLAGS ==
> -- 
> 2.9.3
>