• Chris Zankel's avatar
    xtensa: Fix linker script to include .literal sections · 78f3cdfa
    Chris Zankel authored
    
    
    Fix resembles implementation from Marc Gauthier and Piet Denaly:
    
    In the Xtensa architecture, assembly generates literals which must always
    precede the code (the L32R instruction that loads them only uses negative
    PC-relative offsets).  For any *.text section, literals are placed in a
    corresponding *.literal section.  The linker script (vmlinux.lds) must
    place these in the correct order.  It must also combine them, when the
    *.text section can be larger than L32R's 256 kB range.
    
    For example, this doesn't work:  *(.literal) *(.text) because L32R
    instructions at the end of .text can't reach the literals.
    
    The linker can solve this if they are combined in parentheses, like this:
           *(.literal .text)
    because it is now allowed mix literals in .text to bring them in range.
    
    None of this is done by standard vmlinux.lds.h macros such as TEXT_TEXT
    and INIT_TEXT.  To avoid replicating the logic of that header file, we
    instead post-process the generated linker script to convert *(xxx.text)
    to *(xxx.literal xxx.text) for the following text sections:
           .text .ref.text .*init.text .*exit.text .text.*
    using a sed script.  To do this we must override the default rule for
    vmlinux.lds (see scripts/Makefile.build and the top-level Makefile)
    to insert this extra step.
    Signed-off-by: default avatarMarc Gauthier <marc@tensilica.com>
    Signed-off-by: default avatarPete Delaney <piet@tensilica.com>
    Signed-off-by: default avatarChris Zankel <chris@zankel.net>
    78f3cdfa
vmlinux.lds.S 7.67 KB