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Link stand/i386 components using a linker script

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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
This commit is contained in:
Dimitry Andric 2020-03-04 21:01:22 +00:00
parent 89839cad79
commit a2037dba7e
8 changed files with 28 additions and 21 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
stand/i386/Makefile.inc
View File

@ -22,9 +22,8 @@ CFLAGS+= -I${BTXLIB}
# compact binary with no padding between text, data, bss
LDSCRIPT= ${BOOTSRC}/i386/boot.ldscript
# LDFLAGS_BIN=-e start -Ttext ${ORG} -Wl,-T,${LDSCRIPT},-S,--oformat,binary
# LD_FLAGS_BIN=-static -T ${LDSCRIPT} --gc-sections
LDFLAGS_BIN=-e start -Ttext ${ORG} -Wl,-N,-S,--oformat,binary
LDFLAGS_ORG= -Wl,--defsym,ORG=${ORG},-T,${LDSCRIPT}
LDFLAGS_BIN= -e start ${LDFLAGS_ORG} -Wl,-N,-S,--oformat,binary
.if ${LINKER_FEATURES:Mbuild-id} != ""
LDFLAGS_BIN+= -Wl,--build-id=none
.endif

16
stand/i386/boot.ldscript
View File

@ -1,11 +1,17 @@
/* $FreeBSD$ */
/* Merge text, data and bss together almost no padding */
/* Simplified linker script for the boot loaders. */
OUTPUT_FORMAT("elf32-i386-freebsd")
OUTPUT_ARCH(i386)
ENTRY(_start)
SECTIONS {
. = 0x08048000 + SIZEOF_HEADERS;
.text : { *(.text) } =0x90909090 /* Pad with nops, if needed */
.data : { *(.data) } _edata = .;
.bss : { *(.bss) } _end = .;
. = ORG;
.text : { *(.text .text.*) } =0xcccccccc /* Pad with int3, if needed */
.rodata : { *(.rodata .rodata.*) }
.got : { *(.got) *(.igot) }
.got.plt : { *(.got.plt) *(.igot.plt) }
.data : { *(.data .data.*) }
_edata = .; PROVIDE (edata = .);
.bss : { *(.bss .bss.*) }
_end = .; PROVIDE (end = .);
/DISCARD/ : { *(.interp) }
}

4
stand/i386/boot2/Makefile
View File

@ -56,7 +56,7 @@ boot1: boot1.out
${OBJCOPY} -S -O binary boot1.out ${.TARGET}
boot1.out: boot1.o
${LD} ${LD_FLAGS} -e start -Ttext ${ORG1} -o ${.TARGET} boot1.o
${LD} ${LD_FLAGS} -e start --defsym ORG=${ORG1} -T ${LDSCRIPT} -o ${.TARGET} boot1.o
CLEANFILES+= boot2 boot2.ld boot2.ldr boot2.bin boot2.out boot2.o \
boot2.h sio.o
@ -84,7 +84,7 @@ CFLAGS.ashldi3.c= -Wno-missing-prototypes -Wno-missing-declarations
CLEANFILES+= ashldi3.o
boot2.out: ${BTXCRT} boot2.o sio.o ashldi3.o
${LD} ${LD_FLAGS} -Ttext ${ORG2} -o ${.TARGET} ${.ALLSRC}
${LD} ${LD_FLAGS} --defsym ORG=${ORG2} -T ${LDSCRIPT} -o ${.TARGET} ${.ALLSRC}
SRCS= boot2.c boot2.h

4
stand/i386/gptboot/Makefile
View File

@ -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>

4
stand/i386/gptzfsboot/Makefile
View File

@ -57,7 +57,7 @@ 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+= gptzfsboot.bin gptzfsboot.out zfsboot.o sio.o cons.o \
drv.o gpt.o ${OPENCRYPTO_XTS}
@ -67,7 +67,7 @@ gptzfsboot.bin: gptzfsboot.out
gptzfsboot.out: ${BTXCRT} zfsboot.o sio.o gpt.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}
zfsboot.o: ${ZFSSRC}/zfsimpl.c

4
stand/i386/isoboot/Makefile
View File

@ -53,7 +53,7 @@ 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+= isoboot.bin isoboot.out isoboot.o sio.o drv.o \
cons.o ${OPENCRYPTO_XTS}
@ -62,6 +62,6 @@ isoboot.bin: isoboot.out
${OBJCOPY} -S -O binary isoboot.out ${.TARGET}
isoboot.out: ${BTXCRT} isoboot.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>

4
stand/i386/loader/Makefile
View File

@ -46,8 +46,10 @@ HELP_FILES= ${.CURDIR}/help.i386
CLEANFILES+= ${LOADER} ${LOADER}.bin
ORG= 0x0
CFLAGS+= -Wall
LDFLAGS+= -static -Ttext 0x0 -Wl,--gc-sections
LDFLAGS+= -static ${LDFLAGS_ORG} -Wl,--gc-sections
# i386 standalone support library
LIBI386= ${BOOTOBJ}/i386/libi386/libi386.a

4
stand/i386/zfsboot/Makefile
View File

@ -49,7 +49,7 @@ zfsboot1: zfsldr.out
${OBJCOPY} -S -O binary zfsldr.out ${.TARGET}
zfsldr.out: zfsldr.o
${LD} ${LD_FLAGS} -e start -Ttext ${ORG1} -o ${.TARGET} zfsldr.o
${LD} ${LD_FLAGS} -e start --defsym ORG=${ORG1} -T ${LDSCRIPT} -o ${.TARGET} zfsldr.o
CLEANFILES+= zfsboot2 zfsboot.ld zfsboot.ldr zfsboot.bin zfsboot.out \
zfsboot.o zfsboot.s zfsboot.s.tmp sio.o cons.o drv.o
@ -75,7 +75,7 @@ zfsboot.bin: zfsboot.out
${OBJCOPY} -S -O binary zfsboot.out ${.TARGET}
zfsboot.out: ${BTXCRT} zfsboot.o sio.o drv.o cons.o
${LD} ${LD_FLAGS} -Ttext ${ORG2} -o ${.TARGET} ${.ALLSRC} ${LIBSA32}
${LD} ${LD_FLAGS} --defsym ORG=${ORG2} -T ${LDSCRIPT} -o ${.TARGET} ${.ALLSRC} ${LIBSA32}
SRCS= zfsboot.c