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    SubjectRe: [PATCHSET x86/master] add stack protector support for x86_32

    * Tejun Heo <tj@kernel.org> wrote:

    > Ingo Molnar wrote:
    > >>> 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.
    > >> Can't reproduce with gcc-4.1 or 4.2. Any chance you're using distcc
    > >> w/ a build machine w/ glibc < 2.4? __stack_chk_guard is the symbol
    > >> gcc fetches stack canary from if TLS is not supported, so somehow gcc
    > >> thought that TLS wasn't available while building head64.
    > >
    > > yeah - i also used distcc. Maybe the nostackp makefile magic gets confused
    > > about that?
    >
    > It seems that even with the same gcc versions, gcc built against libc
    > w/o TLS support generates __stack_chk_guard, so if you mix the two
    > flavors, the has-stack-protector check can be compiled on machines w/
    > TLS while some other files end up being built on machines w/o TLS
    > support thus circumventing the support check. Can you please see
    > whether non-distcc build fails too?

    That build succeeds:

    rhea:~/tip> make -j30 bzImage ARCH=x86_64 CROSS_COMPILE='/opt/crosstool/gcc-4.2.3-glibc-2.3.6/x86_64-unknown-linux-gnu/bin/x86_64-unknown-linux-gnu-'
    /home/mingo/tip/arch/x86/Makefile:82: stack protector enabled but no compiler support
    CHK include/linux/version.h
    [...]
    BFD: arch/x86/boot/compressed/vmlinux.bin: warning: allocated section `.bss' not in segment
    [...]
    Root device is (8, 3)
    Setup is 11996 bytes (padded to 12288 bytes).
    System is 5690 kB
    CRC be1b2e21
    Kernel: arch/x86/boot/bzImage is ready (#3)

    Some shell variable expansion bug? If CROSS_COMPILE is not a single word
    we fail to detect the compiler borkage at arch/x86/Makefile line 82?

    Ingo


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