[RFC PATCH, binutils, ARM 10/11, ping] Add support for creating ARM v8-M secure extensions import libraries

[Thomas Preudhomme]

Hi Richard,

Ping? Do you find the current message enough or do you want them improved?

Best regards,

Thomas

On Thursday 14 July 2016 10:23:14 Thomas Preudhomme wrote:
> Hi Richard,
> 
> On Friday 08 July 2016 10:23:11 Thomas Preudhomme wrote:
> > On Thursday 07 July 2016 11:55:28 Richard Earnshaw wrote:
> > > On 29/03/16 15:46, Thomas Preudhomme wrote:
> > > > On Wednesday 23 December 2015 16:01:50 Thomas Preud'homme wrote:
> > > >> Hi,
> > > >> 
> > > >> [Posting patch series as RFC]
> > > >> 
> > > >> This patch is part of a patch series to add support for ARMv8-M
> > > >> security
> > > >> extension[1] to GNU ld. This specific patch adds support for creating
> > > >> *Secure Gateway* import libraries.
> > > >> 
> > > >> ARM v8-M security extensions require [3] a secure gateway import
> > > >> library
> > > >> to
> > > >> be generated for non-secure executable to link against entry points
> > > >> in
> > > >> secure executable. Such an import library must contain all global
> > > >> function
> > > >> symbols from the secure executable that have a corresponding special
> > > >> (ie
> > > >> prefixed by "__acle_se_") symbol and these symbol should be made
> > > >> absolute.
> > > >> 
> > > >> This patch adds support for generating such an import library. It
> > > >> reuses
> > > >> the code to generate an import library by requiring the user to add
> > > >> an
> > > >> extra --cmse-implib option for him/her to state the intent to create
> > > >> a
> > > >> *secure gateway* import library.
> > > >> 
> > > >> 
> > > >> [1] Software requirements for ARMv8-M security extension are
> > > >> described
> > > >> in
> > > >> document ARM-ECM-0359818 [2] [2] Available on
> > > >> http://infocenter.arm.com
> > > >> in
> > > >> Developer guides and articles > Software development > ARM®v8-M
> > > >> Security
> > > >> Extensions: Requirements on Development Tools [3] See requirement 9
> > > >> of
> > > >> ARM-ECM-0359818 [2]
> > > > 
> > > > Please find an updated patch below.
> > > 
> > > One question: What happens if the user tries to use the new option
> > > --cmse-implib on a target that doesn't support v8-M SE?  We should get
> > > some sensible diagnostic in that case.
> > 
> > It depends whether the object file has __acle_se symbols or not. If it
> > doesn't (eg. normal armv7-m object file), the following happens:
> > 
> > ./ld/ld-new: implib.lib: no symbol found for import library
> > ./ld/ld-new: implib.lib: failed to generate import library
> > 
> > Indeed, there is no entry function so the import library would be empty.
> > This is a generic error message, it could be improved indeed with specific
> > logic to detect such a case.
> > 
> > If one of the object file has an __acle_se symbol but is still not v8-m,
> > the following happens:
> > 
> > ./ld/ld-new: cmse-implib.o: Special symbol
> > `__acle_se_exported_entry_veneer2' only allowed for ARMv8-M architecture
> > or
> > later
> > ./ld/ld-new: cannot size stub section: Invalid operation
> > 
> > Are the messages enough in your opinion or should we improve the wordings?
> 
> Ping?
> 
> Best regards,
> 
> Thomas