Messages in this thread |  | | | Date | Tue, 10 Feb 2009 15:19:17 +0100 | | From | Ingo Molnar <> | | Subject | Re: [PATCHSET x86/master] add stack protector support for x86_32 |
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* Tejun Heo <tj@kernel.org> wrote:
> Ingo Molnar wrote: > > * Ingo Molnar <mingo@elte.hu> wrote: > > > >> [...] I might not get around testing it today and pushing it out into tip:master, > >> but i pushed out the core/percpu bits, should you queue up further changes. > > > > ok, activated it for -tip testing, and there's a 64-bit build failure caused by > > it: > > > > arch/x86/kernel/head64.o: In function `x86_64_start_reservations': > > head64.c:(.init.text+0x26): undefined reference to `__stack_chk_guard' > > head64.c:(.init.text+0xc2): undefined reference to `__stack_chk_guard' > > arch/x86/kernel/head64.o: In function `x86_64_start_kernel': > > head64.c:(.init.text+0x104): undefined reference to `__stack_chk_guard' > > head64.c:(.init.text+0x1cd): undefined reference to `__stack_chk_guard' > > arch/x86/kernel/head.o: In function `reserve_ebda_region': > > head.c:(.init.text+0xb): undefined reference to `__stack_chk_guard' > > arch/x86/kernel/head.o:head.c:(.init.text+0x87): more undefined references to > > `__stack_chk_guard' follow > > Call to __stack_chk_guard is probably generated automatically. > Strangely, my gcc only generates calls to __stack_chk_fail. > > > gcc --version > gcc (SUSE Linux) 4.3.2 [gcc-4_3-branch revision 141291] > Copyright (C) 2008 Free Software Foundation, Inc. > This is free software; see the source for copying conditions. There is NO > warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. > > nm build/vmlinux|grep __stack_chk_ > 00000000f0fdf6cb A __crc___stack_chk_fail > ffffffff80d53e50 r __kcrctab___stack_chk_fail > ffffffff80d5ff81 r __kstrtab___stack_chk_fail > ffffffff80d3d140 r __ksymtab___stack_chk_fail > ffffffff80248619 T __stack_chk_fail > > I'll try other compilers but which version are you using? The > difference is that before the patchset, -fno-stack-protector was > always added whether stackprotector was enabled or not so this problem > wasn't visible (at the cost of bogus stackprotector of course). We'll > probably need to add __stack_chk_guard or disable if gcc generates > such symbol. I'll play with different gccs.
that was with a crosscompiler:
aldebaran:~> /opt/crosstool/gcc-4.2.3-glibc-2.3.6/x86_64-unknown-linux-gnu/bin/x86_64-unknown-linux-gnu-gcc -v Using built-in specs. Target: x86_64-unknown-linux-gnu Configured with: /home/mingo/s/crosstool-0.43/build/x86_64-unknown-linux-gnu/gcc-4.2.3-glibc-2.3.6/gcc-4.2.3/configure --target=x86_64-unknown-linux-gnu --host=i686-host_pc-linux-gnu --prefix=/opt/crosstool/gcc-4.2.3-glibc-2.3.6/x86_64-unknown-linux-gnu --disable-multilib --with-sysroot=/opt/crosstool/gcc-4.2.3-glibc-2.3.6/x86_64-unknown-linux-gnu/x86_64-unknown-linux-gnu/sys-root --with-local-prefix=/opt/crosstool/gcc-4.2.3-glibc-2.3.6/x86_64-unknown-linux-gnu/x86_64-unknown-linux-gnu/sys-root --disable-nls --enable-threads=posix --enable-symvers=gnu --enable-__cxa_atexit --enable-languages=c --enable-shared --enable-c99 --enable-long-long Thread model: posix gcc version 4.2.3
The problem is i think GCC's brain-dead stackprotector support - having different models for user-space and kernel-space stackprotector. So this compiler is not _able_ to actually build a stackprotector kernel - but we should auto-discover that.
Ingo
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