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    SubjectRe: sparc/ppc/arm compat siginfo ABI regressions: sending SIGFPE via kill() returns wrong values in si_pid and si_uid
    Hi,

    On Mon, Apr 09, 2018 at 06:22:53PM +0300, Dmitry V. Levin wrote:
    > There seems to be a regression in v4.16 on ppc compat very similar
    > to sparc compat regression reported earlier at
    > https://marc.info/?l=linux-sparc&m=151501500704383 .
    >
    > The symptoms are exactly the same: the same signal_receive test from
    > the strace test suite fails with the same diagnostics:
    > https://build.opensuse.org/public/build/home:ldv_alt/openSUSE_Factory_PowerPC/ppc/strace/_log

    The log is big, just look for "KERNEL BUG".

    > Unfortunately, I do not have any means to investigate further,
    > so just passing this information on to those who care.

    OK, the faulty commit is v4.16-rc1~159^2~39
    ("signal/powerpc: Document conflicts with SI_USER and SIGFPE and SIGTRAP").

    One might think that a commit called "Document conflicts" shouldn't
    introduce an ABI regression, but this one definitely does by defining
    FPE_FIXME and TRAP_FIXME in arch/powerpc/include/uapi/asm/siginfo.h
    that affect siginfo_layout().

    A similar commit v4.16-rc1~159^2~37
    ("signal/arm: Document conflicts with SI_USER and SIGFPE") must have
    introduced a similar ABI regression to compat arm.

    An earlier commit v4.14-rc1~60^2^2~5
    ("signal/sparc: Document a conflict with SI_USER with SIGFPE") introduced
    a similar ABI regression to compat sparc.

    There is a clear pattern of sneaking in ABI changes using innocently
    looking commit messages.


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