Unable to compile Xen-2.0

Unable to compile Xen-2.0

[Jerome Brown]

I have the latest Xen-2.0 tarball (downloaded today 27 Oct 04) and get 
the following error while compiling the 2.6.9-xenU kernel:

make -C linux-2.6.9-xenU ARCH=xen INSTALL_PATH=/usr/src/xen-2.0/install 
install
make[2]: Entering directory `/usr/src/xen-2.0/linux-2.6.9-xenU'
   CHK     include/linux/version.h
make[3]: `arch/i386/kernel/asm-offsets.s' is up to date.
   CHK     include/linux/compile.h
   CC      drivers/xen/blkfront/blkfront.o
drivers/xen/blkfront/blkfront.c: In function `blkif_queue_request':
drivers/xen/blkfront/blkfront.c:109: sorry, unimplemented: inlining 
failed in call to 'translate_req_to_pfn': function body not available
drivers/xen/blkfront/blkfront.c:342: sorry, unimplemented: called from here
make[5]: *** [drivers/xen/blkfront/blkfront.o] Error 1
make[4]: *** [drivers/xen/blkfront] Error 2
make[3]: *** [drivers/xen] Error 2
make[2]: *** [drivers] Error 2
make[2]: Leaving directory `/usr/src/xen-2.0/linux-2.6.9-xenU'
make[1]: *** [linux-xenU] Error 2
make[1]: Leaving directory `/usr/src/xen-2.0'
make: *** [dist] Error 2

I am running Gentoo Linux with GCC 3.4.2 and glibc 2.3.4.20040808 
compiled with NPTL only (no LinuxThreads) and both a 2.6.9 and a 2.6.8.1 
kernel. The GCC has ssp-3.4.1 and pie-8.7.6.5 compiled in, but they are 
disabled for the compilation as Xen will not compile with them enabled 
(Are there plans to allow this?). I have tried disabling 
XEN_WRITABLE_PAGETABLES as suggested for an error with the same file on 
this list 2-3 weeks ago, with no success. The base kernels were compiled 
with this setup.

Any thoughts or suggestions are greatly appreciated. I will try with GCC 
3.3.3 to see if that helps.

Cheers

Jerome


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Re: Unable to compile Xen-2.0

[Ian Pratt]

 
> I am running Gentoo Linux with GCC 3.4.2 and glibc 2.3.4.20040808 
> compiled with NPTL only (no LinuxThreads) and both a 2.6.9 and a 2.6.8.1 
> kernel. 
>
> Any thoughts or suggestions are greatly appreciated. I will try with GCC 
> 3.3.3 to see if that helps.

It's probably a gcc version issue. We try to get stuff working
with most gcc versions, but no-one round here uses 3.4 by default
-- it's way too bleeding edge.

> The GCC has ssp-3.4.1 and pie-8.7.6.5 compiled in, but they are 
> disabled for the compilation as Xen will not compile with them enabled 
> (Are there plans to allow this?). 

What are ssp and pie?

Ian


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Re: Unable to compile Xen-2.0

[Jerome Brown]

>>I am running Gentoo Linux with GCC 3.4.2 and glibc 2.3.4.20040808 
>>compiled with NPTL only (no LinuxThreads) and both a 2.6.9 and a 2.6.8.1 
>>kernel. 
>>
>>Any thoughts or suggestions are greatly appreciated. I will try with GCC 
>>3.3.3 to see if that helps.
> 
> It's probably a gcc version issue. We try to get stuff working
> with most gcc versions, but no-one round here uses 3.4 by default
> -- it's way too bleeding edge.

Compiled the xenU fine with gcc 3.3.3 - must be a gcc issue. I'm testing 
on a box at the moment, so have installed all the new toys to play with 
:) Might try with SSP and PIE again ...

>>The GCC has ssp-3.4.1 and pie-8.7.6.5 compiled in, but they are 
>>disabled for the compilation as Xen will not compile with them enabled 
>>(Are there plans to allow this?). 
> 
> What are ssp and pie?

SSP is Stack Smashing Protection - formerly ProPolice (see 
http://www.trl.ibm.com/projects/security/ssp/ for more info) and PIE is 
Position Independent Executable i.e. PIC for binaries. SSP modifies the 
C compiler to insert initialization code into functions that create a 
buffer in memory. At run time, when a buffer is created, SSP adds a 
secret random value, the canary, to the end of the buffer. When the 
function returns, SSP makes sure that the canary is still intact. If an 
attacker were to perform a buffer overflow, he would overwrite this 
value and trigger that stack smashing handler. Currently this kills the 
target process. (Descriptions borrowed from Gentoo Hardened Project 
http://www.gentoo.org/proj/en/hardened/) They provide an extra layer of 
security from attack on a server open to the world.


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Re: Unable to compile Xen-2.0

[Ian Pratt]

> SSP is Stack Smashing Protection - formerly ProPolice (see 
> http://www.trl.ibm.com/projects/security/ssp/ for more info) and PIE is 
> Position Independent Executable i.e. PIC for binaries. SSP modifies the 
> C compiler to insert initialization code into functions that create a 
> buffer in memory. At run time, when a buffer is created, SSP adds a 
> secret random value, the canary, to the end of the buffer. When the 
> function returns, SSP makes sure that the canary is still intact. If an 
> attacker were to perform a buffer overflow, he would overwrite this 
> value and trigger that stack smashing handler. Currently this kills the 
> target process. (Descriptions borrowed from Gentoo Hardened Project 
> http://www.gentoo.org/proj/en/hardened/) They provide an extra layer of 
> security from attack on a server open to the world.

Does stock Linux work when compiled with SSP enabled? Sounds
pretty scary to me...

Ian


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Re: Unable to compile Xen-2.0

[Jerome Brown]

> Does stock Linux work when compiled with SSP enabled? Sounds
> pretty scary to me...

I haven't specifically tried with the -fstack-protector-all flag enabled 
for the stock kernel, and the flag wasn't active when compiling Xen. 
Most of the userland tools on my box are compiled with SSP enabled. What 
about it sounds scary?


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Re: Unable to compile Xen-2.0

[Ian Pratt]

> > Does stock Linux work when compiled with SSP enabled? Sounds
> > pretty scary to me...
> 
> I haven't specifically tried with the -fstack-protector-all flag enabled 
> for the stock kernel, and the flag wasn't active when compiling Xen. 
> Most of the userland tools on my box are compiled with SSP enabled. What 
> about it sounds scary?

Userland tools are one thing, but kernels tend to be rather more
fragile as regards having compilers monkey with their
stack. Also, when the post-call code detects a stack smash,
what's it going to do? I suppose it can execute an illegal
instruction and thus cause a GPF and thus halt.

Ian


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