Re: [PATCH] BaseTools/tools_def AARCH64: move GCC49/GGC5 to 4 KB section alignment

[Laszlo Ersek <lersek@redhat.com>]

On 12/10/18 15:13, Ard Biesheuvel wrote:
> Since 4 KB section alignment is required when mapping PE/COFF images
> with strict permissions, update the default section alignment when
> using GCC49 and GCC5 in RELEASE mode. Note that XIP modules such as
> SEC, PEIMs or PEI core are not affected by this change, since the
> override to 32 byte aligment remains in effect.
> 
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> ---
>  BaseTools/Conf/tools_def.template | 24 +++++++++++---------
>  1 file changed, 13 insertions(+), 11 deletions(-)
> 
> diff --git a/BaseTools/Conf/tools_def.template b/BaseTools/Conf/tools_def.template
> index e0e68fd7fb49..5d34333dc54f 100755
> --- a/BaseTools/Conf/tools_def.template
> +++ b/BaseTools/Conf/tools_def.template
> @@ -4263,11 +4263,11 @@ DEFINE GCC49_ARM_ASM_FLAGS           = DEF(GCC48_ARM_ASM_FLAGS)
>  DEFINE GCC49_AARCH64_ASM_FLAGS       = DEF(GCC48_AARCH64_ASM_FLAGS)
>  DEFINE GCC49_ARM_CC_FLAGS            = DEF(GCC48_ARM_CC_FLAGS)
>  DEFINE GCC49_ARM_CC_XIPFLAGS         = DEF(GCC48_ARM_CC_XIPFLAGS)
> -DEFINE GCC49_AARCH64_CC_FLAGS        = $(ARCHCC_FLAGS) $(PLATFORM_FLAGS) DEF(GCC44_ALL_CC_FLAGS) DEF(GCC_AARCH64_CC_FLAGS)
> +DEFINE GCC49_AARCH64_CC_FLAGS        = $(ARCHCC_FLAGS) $(PLATFORM_FLAGS) DEF(GCC44_ALL_CC_FLAGS) DEF(GCC_AARCH64_CC_FLAGS) -mcmodel=small
>  DEFINE GCC49_AARCH64_CC_XIPFLAGS     = DEF(GCC48_AARCH64_CC_XIPFLAGS)
>  DEFINE GCC49_ARM_DLINK_FLAGS         = DEF(GCC48_ARM_DLINK_FLAGS)
>  DEFINE GCC49_ARM_DLINK2_FLAGS        = DEF(GCC48_ARM_DLINK2_FLAGS)
> -DEFINE GCC49_AARCH64_DLINK_FLAGS     = DEF(GCC48_AARCH64_DLINK_FLAGS)
> +DEFINE GCC49_AARCH64_DLINK_FLAGS     = DEF(GCC48_AARCH64_DLINK_FLAGS) -z common-page-size=0x1000
>  DEFINE GCC49_AARCH64_DLINK2_FLAGS    = DEF(GCC48_AARCH64_DLINK2_FLAGS)
>  DEFINE GCC49_ARM_ASLDLINK_FLAGS      = DEF(GCC48_ARM_ASLDLINK_FLAGS)
>  DEFINE GCC49_AARCH64_ASLDLINK_FLAGS  = DEF(GCC48_AARCH64_ASLDLINK_FLAGS)
> @@ -5034,15 +5034,16 @@ RELEASE_GCC49_ARM_CC_FLAGS       = DEF(GCC49_ARM_CC_FLAGS) -Wno-unused-but-set-v
>  *_GCC49_AARCH64_VFRPP_FLAGS      = $(ARCHCC_FLAGS) $(PLATFORM_FLAGS) DEF(GCC_VFRPP_FLAGS)
>  *_GCC49_AARCH64_CC_XIPFLAGS      = DEF(GCC49_AARCH64_CC_XIPFLAGS)
>  
> -  DEBUG_GCC49_AARCH64_CC_FLAGS     = DEF(GCC49_AARCH64_CC_FLAGS) -O0 -mcmodel=small
> -  DEBUG_GCC49_AARCH64_DLINK_FLAGS  = DEF(GCC49_AARCH64_DLINK_FLAGS) -z common-page-size=0x1000
> +  DEBUG_GCC49_AARCH64_CC_FLAGS     = DEF(GCC49_AARCH64_CC_FLAGS) -O0
> +  DEBUG_GCC49_AARCH64_DLINK_FLAGS  = DEF(GCC49_AARCH64_DLINK_FLAGS)
>    DEBUG_GCC49_AARCH64_DLINK_XIPFLAGS = -z common-page-size=0x20
>  
> -RELEASE_GCC49_AARCH64_CC_FLAGS     = DEF(GCC49_AARCH64_CC_FLAGS) -Wno-unused-but-set-variable -Wno-unused-const-variable -mcmodel=tiny
> +RELEASE_GCC49_AARCH64_CC_FLAGS     = DEF(GCC49_AARCH64_CC_FLAGS) -Wno-unused-but-set-variable -Wno-unused-const-variable
>  RELEASE_GCC49_AARCH64_DLINK_FLAGS  = DEF(GCC49_AARCH64_DLINK_FLAGS)
> +RELEASE_GCC49_AARCH64_DLINK_XIPFLAGS = -z common-page-size=0x20
>  
> -  NOOPT_GCC49_AARCH64_CC_FLAGS     = DEF(GCC49_AARCH64_CC_FLAGS) -O0 -mcmodel=small
> -  NOOPT_GCC49_AARCH64_DLINK_FLAGS  = DEF(GCC49_AARCH64_DLINK_FLAGS) -z common-page-size=0x1000 -O0
> +  NOOPT_GCC49_AARCH64_CC_FLAGS     = DEF(GCC49_AARCH64_CC_FLAGS) -O0
> +  NOOPT_GCC49_AARCH64_DLINK_FLAGS  = DEF(GCC49_AARCH64_DLINK_FLAGS) -O0
>    NOOPT_GCC49_AARCH64_DLINK_XIPFLAGS = -z common-page-size=0x20 -O0
>  
>  ####################################################################################
> @@ -5189,14 +5190,15 @@ RELEASE_GCC5_ARM_DLINK_FLAGS     = DEF(GCC5_ARM_DLINK_FLAGS) -flto -Os -L$(WORKS
>  *_GCC5_AARCH64_VFRPP_FLAGS       = $(ARCHCC_FLAGS) $(PLATFORM_FLAGS) DEF(GCC_VFRPP_FLAGS)
>  *_GCC5_AARCH64_CC_XIPFLAGS       = DEF(GCC5_AARCH64_CC_XIPFLAGS)
>  
> -  DEBUG_GCC5_AARCH64_CC_FLAGS    = DEF(GCC5_AARCH64_CC_FLAGS) -flto -Wno-unused-but-set-variable -Wno-unused-const-variable -mcmodel=small
> -  DEBUG_GCC5_AARCH64_DLINK_FLAGS = DEF(GCC5_AARCH64_DLINK_FLAGS) -z common-page-size=0x1000 -flto -Os -L$(WORKSPACE)/ArmPkg/Library/GccLto -llto-aarch64 -Wl,-plugin-opt=-pass-through=-llto-aarch64 -Wno-lto-type-mismatch -mcmodel=small
> +  DEBUG_GCC5_AARCH64_CC_FLAGS    = DEF(GCC5_AARCH64_CC_FLAGS) -flto -Wno-unused-but-set-variable -Wno-unused-const-variable
> +  DEBUG_GCC5_AARCH64_DLINK_FLAGS = DEF(GCC5_AARCH64_DLINK_FLAGS) -flto -Os -L$(WORKSPACE)/ArmPkg/Library/GccLto -llto-aarch64 -Wl,-plugin-opt=-pass-through=-llto-aarch64 -Wno-lto-type-mismatch
>    DEBUG_GCC5_AARCH64_DLINK_XIPFLAGS = -z common-page-size=0x20
>  
> -RELEASE_GCC5_AARCH64_CC_FLAGS    = DEF(GCC5_AARCH64_CC_FLAGS) -flto -Wno-unused-but-set-variable -Wno-unused-const-variable -mcmodel=tiny
> +RELEASE_GCC5_AARCH64_CC_FLAGS    = DEF(GCC5_AARCH64_CC_FLAGS) -flto -Wno-unused-but-set-variable -Wno-unused-const-variable
>  RELEASE_GCC5_AARCH64_DLINK_FLAGS = DEF(GCC5_AARCH64_DLINK_FLAGS) -flto -Os -L$(WORKSPACE)/ArmPkg/Library/GccLto -llto-aarch64 -Wl,-plugin-opt=-pass-through=-llto-aarch64 -Wno-lto-type-mismatch
> +RELEASE_GCC5_AARCH64_DLINK_XIPFLAGS = -z common-page-size=0x20
>  
> -  NOOPT_GCC5_AARCH64_CC_FLAGS    = DEF(GCC5_AARCH64_CC_FLAGS) -O0 -mcmodel=small
> +  NOOPT_GCC5_AARCH64_CC_FLAGS    = DEF(GCC5_AARCH64_CC_FLAGS) -O0
>    NOOPT_GCC5_AARCH64_DLINK_FLAGS = DEF(GCC5_AARCH64_DLINK_FLAGS) -z common-page-size=0x1000 -O0
>    NOOPT_GCC5_AARCH64_DLINK_XIPFLAGS = -z common-page-size=0x20 -O0
>  
> 

Looking at this patch with "--word-diff" helps a little (it's too bad we
can't break these mile long option sequences to multiple lines). So:

* For GCC49:

- The compiler option "-mcmodel=small" is upstreamed from both
NOOPT_GCC49_AARCH64_CC_FLAGS and DEBUG_GCC49_AARCH64_CC_FLAGS to
GCC49_AARCH64_CC_FLAGS. This is a no-op for DEBUG and NOOPT, however the
option will now also apply to RELEASE.

- As a consequence, "-mcmodel=tiny" is not usable for RELEASE, and it is
removed.

- The same upstreaming occurs for "-z common-page-size=0x1000", in
GCC49_AARCH64_DLINK_FLAGS. RELEASE needs no fixup, it simply benefits
from the change. However, RELEASE_GCC49_AARCH64_DLINK_XIPFLAGS needs an
override, to stick with the original 0x20 alignment.

* For GCC5:

- GCC5_AARCH64_CC_FLAGS is defined as GCC49_AARCH64_CC_FLAGS, therefore
the "-mcmodel=small" inheritance from the above is automatic. Only the
DEBUG/NOOPT removals, and the RELEASE fixup are needed.

- GCC5_AARCH64_DLINK_FLAGS is defined as GCC49_AARCH64_DLINK_FLAGS,
therefore the same inheritance pattern applies to "-z
common-page-size=0x1000". I'm noticing an omission here however: "-z
common-page-size=0x1000" should have been removed from
NOOPT_GCC5_AARCH64_DLINK_FLAGS as well.

- The RELEASE_GCC5_AARCH64_DLINK_XIPFLAGS override is spelled out the same.


So... do you agree that NOOPT_GCC5_AARCH64_DLINK_FLAGS should have been
trimmed as well?

Furthermore, I suggest squeezing the word RELEASE into the subject,
given that the change is only observable in RELEASE builds.

Thanks!
Laszlo