[PATCH v7 0/9] ARM: VDSO

On 06/27/2014 03:51 AM, Jan Glauber wrote:

On Sun, Jun 22, 2014 at 10:11:49PM -0500, Nathan Lynch wrote:

quoted

Provide fast userspace implementations of gettimeofday and
clock_gettime on systems that implement the generic timers extension
defined in ARMv7.  This follows the example of arm64 in conception but
significantly differs in some aspects of the implementation (C vs
assembly, mainly).

Hi Nathan,

applying your patches I get the following compile error under Ubuntu 12.04:

  CC      arch/arm/kernel/vdso.o
  LDS     arch/arm/kernel/vdso/vdso.lds
  CC      arch/arm/kernel/vdso/vgettimeofday.o
  AS      arch/arm/kernel/vdso/datapage.o
  VDSOL   arch/arm/kernel/vdso/vdso.so.raw
  HOSTCC  arch/arm/kernel/vdso/vdsomunge
arch/arm/kernel/vdso/vdsomunge.c: In function ?main?:
arch/arm/kernel/vdso/vdsomunge.c:152:16: error: ?EF_ARM_ABI_FLOAT_HARD? undeclared (first use in this function)
arch/arm/kernel/vdso/vdsomunge.c:152:16: note: each undeclared identifier is reported only once for each function it appears in
arch/arm/kernel/vdso/vdsomunge.c:156:34: error: ?EF_ARM_ABI_FLOAT_SOFT? undeclared (first use in this function)
make[2]: *** [arch/arm/kernel/vdso/vdsomunge] Error 1
make[1]: *** [arch/arm/kernel/vdso] Error 2
make: *** [arch/arm/kernel] Error 2

Looks like the libc dev is too old (EF_ARM_ABI_FLOAT_* not in /usr/include/elf.h).
On a more recent Ubuntu it compiles fine. Not sure how to solve this, maybe disable
vdso if the libc is too old?

We should just define some of the needed ELF constants in the tool if
the host <elf.h> lacks them.  EF_ARM_ABI_FLOAT_HARD/SOFT were added in
2012, EF_ARM_EABI_VER5 in 2009... everything else the tool uses has been
there for twelve years or more.

Thanks for the report -- please try the below?

diff --git a/arch/arm/kernel/vdso/vdsomunge.c

b/arch/arm/kernel/vdso/vdsomunge.c
index 823b84d142bc..b586ef699fb8 100644

--- a/arch/arm/kernel/vdso/vdsomunge.c
+++ b/arch/arm/kernel/vdso/vdsomunge.c

@@ -67,6 +67,21 @@
 #define HOST_ORDER ELFDATA2MSB
 #endif

+/* Some of the ELF constants we'd like to use were added to <elf.h>
+ * relatively recently.
+ */
+#ifndef EF_ARM_EABI_VER5
+#define EF_ARM_EABI_VER5 0x05000000
+#endif
+
+#ifndef EF_ARM_ABI_FLOAT_SOFT
+#define EF_ARM_ABI_FLOAT_SOFT 0x200
+#endif
+
+#ifndef EF_ARM_ABI_FLOAT_HARD
+#define EF_ARM_ABI_FLOAT_HARD 0x400
+#endif
+
 static const char *outfile;

 static void cleanup(void)