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[7.5/10] arch/arm: Build a loadable module and a shared library as FDPIC too. #20360

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Merged
acassis merged 1 commit into from
Sep 25, 2026
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[7.5/10] arch/arm: Build a loadable module and a shared library as FDPIC too. #20360

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21 changes: 20 additions & 1 deletion arch/arm/src/common/Toolchain.defs
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Original file line number Diff line number Diff line change
Expand Up @@ -619,7 +619,10 @@ endif

# Loadable module definitions

# CXXMODULEFLAGS is what apps/Library.mk compiles a C++ shared library with.

CMODULEFLAGS = $(CFLAGS) -fvisibility=hidden -mlong-calls # --target1-abs
CXXMODULEFLAGS = $(CXXFLAGS) -fvisibility=hidden -mlong-calls
LDMODULEFLAGS = -r -T $(call CONVERT_PATH,$(TOPDIR)/libs/libc/elf/gnu-elf.ld)

# ELF module definitions
Expand All @@ -633,9 +636,11 @@ CELFFLAGS = $(filter-out --fixed-r9,$(CFLAGS)) -fvisibility=hidden \
CXXELFFLAGS = $(filter-out --fixed-r9,$(CXXFLAGS)) -fvisibility=hidden \
-mlong-calls

# __dso_handle comes from crtbegin, which a module does not link
# __dso_handle comes from crtbegin, which neither a module nor a shared
# library links

CXXELFFLAGS += -fno-use-cxa-atexit
CXXMODULEFLAGS += -fno-use-cxa-atexit

ifeq ($(CONFIG_PIC),y)
# ARCHCFLAGS, not CFLAGS: board Make.defs reassign CFLAGS with ':='
Expand Down Expand Up @@ -673,6 +678,20 @@ ifeq ($(CONFIG_FDPIC),y)
CXXELFFLAGS += -mfdpic -fPIC -Wa,--noexecstack

LDELFFLAGS += -m armelf_linux_fdpiceabi -shared -z now

# A loadable module and a shared library are the same kind of object here,
# so they are built the same way. The partial link the module path uses
# elsewhere leaves no dynamic section, and the loader has nothing to bind
# an import to.
#
# The entry point is left to the caller: a module is entered at _start,
# a library is only called into.

CMODULEFLAGS += -mfdpic -fPIC -Wa,--noexecstack
CXXMODULEFLAGS += -mfdpic -fPIC -Wa,--noexecstack

LDMODULEFLAGS = -m armelf_linux_fdpiceabi -shared -z now \
-T $(call CONVERT_PATH,$(TOPDIR)/libs/libc/elf/gnu-elf.ld)
else
CELFFLAGS += $(PICFLAGS) -mpic-register=r9
CXXELFFLAGS += $(PICFLAGS) -mpic-register=r9
Expand Down
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