[Xen-devel] Need help with xen-detect patch

Benjamin Schweikert
Wed, 15 Jun 2011 11:10:07 -0000

Hi,

me and a friend of mine working on a patch with which xen-tools build with
the CFLAGS pie/pic and stack-protection. We saw, that everything builds
expect of xen-detect. We developed a patch with which xen-detect builds and
we can execute the binary after that, but we dont get the right information,
that for example we are running a PV fedora domain. Maybe someone, who is
better in assembly than we are can give us some hints.

thanx and bye

Ben

xen-detect: Change assembly cpuinfo code that allows this to be built with
-fPIC.

diff -r 4b0692880dfa tools/misc/xen-detect.c
--- a/tools/misc/xen-detect.c Thu May 05 17:40:34 2011 +0100
+++ b/tools/misc/xen-detect.c Fri May 06 17:14:46 2011 +0200
@@ -41,8 +41,20 @@
int pv_context)
{
asm volatile (
- "test %1,%1 ; jz 1f ; ud2a ; .ascii \"xen\" ; 1: cpuid"
- : "=a" (*eax), "=b" (*ebx), "=c" (*ecx),
"=d" (*edx)
+ "test %1,%1 ; jz 1f ; ud2a ; .ascii \"xen\" ;"
+#if defined(__PIC__)&& defined(__i386__)
+ "1: pushl %%ebx;"
+ "cpuid;"
+ "movl %%ebx,%%esi;"
+ "popl %%ebx"
+ : "=S" (*ebx),
+#else
+ "1: cpuid"
+ : "=b" (*ebx),
+#endif
+ "=a" (*eax),
+ "=c" (*ecx),
+ "=d" (*edx)
: "0" (idx), "1" (pv_context) );
}