From 78f3cdfa2ac0aa2b72b3ee7e4b3c3e550230179f Mon Sep 17 00:00:00 2001 From: Chris Zankel Date: Tue, 21 Apr 2009 00:34:15 -0700 Subject: xtensa: Fix linker script to include .literal sections 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: Marc Gauthier Signed-off-by: Pete Delaney Signed-off-by: Chris Zankel --- arch/xtensa/kernel/Makefile | 21 ++++++++++++++++++--- 1 file changed, 18 insertions(+), 3 deletions(-) (limited to 'arch/xtensa/kernel/Makefile') diff --git a/arch/xtensa/kernel/Makefile b/arch/xtensa/kernel/Makefile index 7419dbccf027..fe3186de6a33 100644 --- a/arch/xtensa/kernel/Makefile +++ b/arch/xtensa/kernel/Makefile @@ -4,15 +4,30 @@ extra-y := head.o vmlinux.lds - obj-y := align.o entry.o irq.o coprocessor.o process.o ptrace.o \ setup.o signal.o syscall.o time.o traps.o vectors.o platform.o \ pci-dma.o init_task.o io.o -## windowspill.o - obj-$(CONFIG_KGDB) += xtensa-stub.o obj-$(CONFIG_PCI) += pci.o obj-$(CONFIG_MODULES) += xtensa_ksyms.o module.o +# In the Xtensa architecture, assembly generates literals which must always +# precede the L32R instruction with a relative offset less than 256 kB. +# Therefore, the .text and .literal section must be combined in parenthesis +# in the linker script, such as: *(.literal .text). +# +# We need to post-process the generated vmlinux.lds scripts to convert +# *(xxx.text) to *(xxx.literal xxx.text) for the following text sections: +# .text .ref.text .*init.text .*exit.text .text.* +# +# Replicate rules in scripts/Makefile.build + +sed-y = -e 's/(\(\.[a-z]*it\|\.ref\|\)\.text)/(\1.literal \1.text)/g' \ + -e 's/(\(\.text\.[a-z]*\))/(\1.literal \1)/g' + +quiet_cmd__cpp_lds_S = LDS $@ + cmd__cpp_lds_S = $(CPP) $(cpp_flags) -D__ASSEMBLY__ $< | sed $(sed-y) >$@ +$(obj)/vmlinux.lds: $(src)/vmlinux.lds.S FORCE + $(call if_changed_dep,_cpp_lds_S) -- cgit v1.2.3