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Subject[PATCH 07/15] binfmt_flat: use __be32 for the on-disk format
Date
So far binfmt_flat has onl been supported on 32-bit platforms, so the
variable size of the fields didn't matter. But the upcoming RISC-V
nommu port supports 64-bit CPUs, and we now have a conflict between
the elf2flt creation tool that always uses 32-bit fields and the kernel
that uses (unsigned) long field. Switch to the userspace view as the
rest of the binfmt_flat format is completely architecture neutral,
and binfmt_flat isn't the right binary format for huge executables to
start with.

While we're at it also ensure these fields are using __be types as
they big endian and are byteswapped when loaded.

Signed-off-by: Christoph Hellwig <hch@lst.de>

wip
---
include/linux/flat.h | 48 ++++++++++++++++++++++----------------------
1 file changed, 24 insertions(+), 24 deletions(-)

diff --git a/include/linux/flat.h b/include/linux/flat.h
index 21d901ba191b..59e892d5fadb 100644
--- a/include/linux/flat.h
+++ b/include/linux/flat.h
@@ -24,26 +24,26 @@
*/

struct flat_hdr {
- char magic[4];
- unsigned long rev; /* version (as above) */
- unsigned long entry; /* Offset of first executable instruction
- with text segment from beginning of file */
- unsigned long data_start; /* Offset of data segment from beginning of
- file */
- unsigned long data_end; /* Offset of end of data segment
- from beginning of file */
- unsigned long bss_end; /* Offset of end of bss segment from beginning
- of file */
+ char magic[4];
+ __be32 rev; /* version (as above) */
+ __be32 entry; /* Offset of first executable instruction
+ with text segment from beginning of file */
+ __be32 data_start; /* Offset of data segment from beginning of
+ file */
+ __be32 data_end; /* Offset of end of data segment from beginning
+ of file */
+ __be32 bss_end; /* Offset of end of bss segment from beginning
+ of file */

/* (It is assumed that data_end through bss_end forms the bss segment.) */

- unsigned long stack_size; /* Size of stack, in bytes */
- unsigned long reloc_start; /* Offset of relocation records from
- beginning of file */
- unsigned long reloc_count; /* Number of relocation records */
- unsigned long flags;
- unsigned long build_date; /* When the program/library was built */
- unsigned long filler[5]; /* Reservered, set to zero */
+ __be32 stack_size; /* Size of stack, in bytes */
+ __be32 reloc_start; /* Offset of relocation records from beginning of
+ file */
+ __be32 reloc_count; /* Number of relocation records */
+ __be32 flags;
+ __be32 build_date; /* When the program/library was built */
+ __u32 filler[5]; /* Reservered, set to zero */
};

#define FLAT_FLAG_RAM 0x0001 /* load program entirely into RAM */
@@ -67,19 +67,19 @@ struct flat_hdr {
#define OLD_FLAT_RELOC_TYPE_BSS 2

typedef union {
- unsigned long value;
+ u32 value;
struct {
# if defined(mc68000) && !defined(CONFIG_COLDFIRE)
- signed long offset : 30;
- unsigned long type : 2;
+ s32 offset : 30;
+ u32 type : 2;
# define OLD_FLAT_FLAG_RAM 0x1 /* load program entirely into RAM */
# elif defined(__BIG_ENDIAN_BITFIELD)
- unsigned long type : 2;
- signed long offset : 30;
+ u32 type : 2;
+ s32 offset : 30;
# define OLD_FLAT_FLAG_RAM 0x1 /* load program entirely into RAM */
# elif defined(__LITTLE_ENDIAN_BITFIELD)
- signed long offset : 30;
- unsigned long type : 2;
+ s32 offset : 30;
+ u32 type : 2;
# define OLD_FLAT_FLAG_RAM 0x1 /* load program entirely into RAM */
# else
# error "Unknown bitfield order for flat files."
--
2.20.1
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