Link stand/i386 components using a linker script

LLD 10.0.0 changed the behavior of the -Ttext option, so that using
-Ttext=0x0 now causes linking of the loaders to fail with:

ld: error: output file too large: 18446744073707016908 bytes

I reported this in https://bugs.llvm.org/show_bug.cgi?id=44715, and
initially reverted the upstream change in r357259 to work around it.

However, after some discussion with Fangrui Song in the upstream ticket,
I think we can classify this as an unfortunate interaction between using
-Ttext=0 in combination with --no-rosegment.  (We added the latter
in r332090, because btxld does not correctly handle input with more
than 2 PT_LOAD segments.)

Fangrui suggested to use a linker script instead, and Warner was already
attempting this in r305353, but had to revert it due to "crypto-using
boot problems" (not sure what those were :).

This review updates the stand/i386/boot.ldscript to handle more
sections, inserts some symbols like _edata and such that we use in
libsa, and also discards any .interp section.

It uses ORG which is defined on the linker command line using
--defsym ORG=value to set the start of all the sections.

Reviewed by:	imp
MFC after:	2 weeks
Differential Revision: https://reviews.freebsd.org/D23952

1 files changed, 2 insertions, 2 deletions

diff --git a/stand/i386/gptboot/Makefile b/stand/i386/gptboot/Makefile
index 9666c7ab9d99..5ca6ca96535f 100644
--- a/stand/i386/gptboot/Makefile
+++ b/stand/i386/gptboot/Makefile
@@ -51,7 +51,7 @@ gptldr.bin: gptldr.out
 	${OBJCOPY} -S -O binary gptldr.out ${.TARGET}
 
 gptldr.out: gptldr.o
-	${LD} ${LD_FLAGS} -e start -Ttext ${ORG1} -o ${.TARGET} gptldr.o
+	${LD} ${LD_FLAGS} -e start --defsym ORG=${ORG1} -T ${LDSCRIPT} -o ${.TARGET} gptldr.o
 
 CLEANFILES+=	gptboot.bin gptboot.out gptboot.o sio.o drv.o \
 		cons.o ${OPENCRYPTO_XTS}
@@ -60,6 +60,6 @@ gptboot.bin: gptboot.out
 	${OBJCOPY} -S -O binary gptboot.out ${.TARGET}
 
 gptboot.out: ${BTXCRT} gptboot.o sio.o drv.o cons.o ${OPENCRYPTO_XTS}
-	${LD} ${LD_FLAGS} -Ttext ${ORG2} -o ${.TARGET} ${.ALLSRC} ${LIBSA32}
+	${LD} ${LD_FLAGS} --defsym ORG=${ORG2} -T ${LDSCRIPT} -o ${.TARGET} ${.ALLSRC} ${LIBSA32}
 
 .include <bsd.prog.mk>