[PATCH 4.1 46/86] ARM: 8445/1: fix vdsomunge not to depend on glibc specific byteswap.h

Greg Kroah-Hartman
2015-11-06T20:17:48Z

From: "H. Nikolaus Schaller" <hns@goldelico.com>

commit 8a603f91cc4848ab1a0458bc065aa9f64322e123 upstream.

If the host toolchain is not glibc based then the arm kernel build
fails with

HOSTCC arch/arm/vdso/vdsomunge
arch/arm/vdso/vdsomunge.c:48:22: fatal error: byteswap.h: No such file or directory

Observed: with omap2plus_defconfig and compile on Mac OS X with arm ELF
cross-compiler.

Reason: byteswap.h is a glibc only header.

Solution: replace by private byte-swapping macros (taken from
arch/mips/boot/elf2ecoff.c and kindly improved by Russell King)

Tested to compile on Mac OS X 10.9.5 host.

Signed-off-by: H. Nikolaus Schaller <hns@goldelico.com>
Signed-off-by: Nathan Lynch <nathan_lynch@mentor.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/arm/vdso/vdsomunge.c | 17 +++++++++++++----
1 file changed, 13 insertions(+), 4 deletions(-)

--- a/arch/arm/vdso/vdsomunge.c
+++ b/arch/arm/vdso/vdsomunge.c
@@ -45,7 +45,6 @@
* it does.
*/

-#include <byteswap.h>
#include <elf.h>
#include <errno.h>
#include <fcntl.h>
@@ -59,6 +58,16 @@
#include <sys/types.h>
#include <unistd.h>

+#define swab16(x) \
+ ((((x) & 0x00ff) << 8) | \
+ (((x) & 0xff00) >> 8))
+
+#define swab32(x) \
+ ((((x) & 0x000000ff) << 24) | \
+ (((x) & 0x0000ff00) << 8) | \
+ (((x) & 0x00ff0000) >> 8) | \
+ (((x) & 0xff000000) << 24))
+
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
#define HOST_ORDER ELFDATA2LSB
#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
@@ -104,17 +113,17 @@ static void cleanup(void)

static Elf32_Word read_elf_word(Elf32_Word word, bool swap)
{
- return swap ? bswap_32(word) : word;
+ return swap ? swab32(word) : word;
}

static Elf32_Half read_elf_half(Elf32_Half half, bool swap)
{
- return swap ? bswap_16(half) : half;
+ return swap ? swab16(half) : half;
}

static void write_elf_word(Elf32_Word val, Elf32_Word *dst, bool swap)
{
- *dst = swap ? bswap_32(val) : val;
+ *dst = swap ? swab32(val) : val;
}

int main(int argc, char **argv)