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The size of a built-in initramfs is calculated in init/initramfs.c by
"__initramfs_end - __initramfs_start". Those symbols are defined in the
linker script include/asm-generic/vmlinux.lds.h:
#define INIT_RAM_FS \
. = ALIGN(PAGE_SIZE); \
VMLINUX_SYMBOL(__initramfs_start) = .; \
*(.init.ramfs) \
VMLINUX_SYMBOL(__initramfs_end) = .;
If the initramfs file has an odd number of bytes, the "__initramfs_end"
symbol points to an odd address, for example, the symbols in the
System.map might look like:
0000000000572000 T __initramfs_start
00000000005bcd05 T __initramfs_end <-- odd address
At least on s390 this causes a problem:
Certain s390 instructions, especially instructions for loading addresses
(larl) or branch addresses must be on even addresses. The compiler loads
the symbol addresses with the "larl" instruction. This instruction sets
the last bit to 0 and, therefore, for odd size files, the calculated size
is one byte less than it should be:
0000000000540a9c <populate_rootfs>:
540a9c: eb cf f0 78 00 24 stmg %r12,%r15,120(%r15),
540aa2: c0 10 00 01 8a af larl %r1,572000 <__initramfs_start>
540aa8: c0 c0 00 03 e1 2e larl %r12,5bcd04 <initramfs_end>
(Instead of 5bcd05)
...
540abe: 1b c1 sr %r12,%r1
To fix the problem, this patch introduces the global variable
__initramfs_size, which is calculated in the "usr/initramfs_data.S" file.
The populate_rootfs() function can then use the start marker of the
.init.ramfs section and the value of __initramfs_size for loading the
initramfs. Because the start marker and size is sufficient, the
__initramfs_end symbol is no longer needed and is removed.
Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Reviewed-by: WANG Cong <xiyou.wangcong@gmail.com>
Acked-by: Michal Marek <mmarek@suse.cz>
Acked-by: "H. Peter Anvin" <hpa@zytor.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Michal Marek <mmarek@suse.cz>
38 lines
1.2 KiB
ArmAsm
38 lines
1.2 KiB
ArmAsm
/*
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initramfs_data includes the compressed binary that is the
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filesystem used for early user space.
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Note: Older versions of "as" (prior to binutils 2.11.90.0.23
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released on 2001-07-14) dit not support .incbin.
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If you are forced to use older binutils than that then the
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following trick can be applied to create the resulting binary:
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ld -m elf_i386 --format binary --oformat elf32-i386 -r \
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-T initramfs_data.scr initramfs_data.cpio.gz -o initramfs_data.o
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ld -m elf_i386 -r -o built-in.o initramfs_data.o
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For including the .init.ramfs sections, see include/asm-generic/vmlinux.lds.
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The above example is for i386 - the parameters vary from architectures.
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Eventually look up LDFLAGS_BLOB in an older version of the
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arch/$(ARCH)/Makefile to see the flags used before .incbin was introduced.
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Using .incbin has the advantage over ld that the correct flags are set
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in the ELF header, as required by certain architectures.
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*/
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#include <linux/stringify.h>
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.section .init.ramfs,"a"
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__irf_start:
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.incbin __stringify(INITRAMFS_IMAGE)
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__irf_end:
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.section .init.ramfs.info,"a"
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.globl __initramfs_size
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__initramfs_size:
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#ifdef CONFIG_32BIT
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.long __irf_end - __irf_start
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#else
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.quad __irf_end - __irf_start
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#endif
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