• Chris Metcalf's avatar
    nmi_backtrace: add more trigger_*_cpu_backtrace() methods · 9a01c3ed
    Chris Metcalf authored
    Patch series "improvements to the nmi_backtrace code" v9.
    
    This patch series modifies the trigger_xxx_backtrace() NMI-based remote
    backtracing code to make it more flexible, and makes a few small
    improvements along the way.
    
    The motivation comes from the task isolation code, where there are
    scenarios where we want to be able to diagnose a case where some cpu is
    about to interrupt a task-isolated cpu.  It can be helpful to see both
    where the interrupting cpu is, and also an approximation of where the
    cpu that is being interrupted is.  The nmi_backtrace framework allows us
    to discover the stack of the interrupted cpu.
    
    I've tested that the change works as desired on tile, and build-tested
    x86, arm, mips, and sparc64.  For x86 I confirmed that the generic
    cpuidle stuff as well as the architecture-specific routines are in the
    new cpuidle section.  For arm, mips, and sparc I just build-tested it
    and made sure the generic cpuidle routines were in the new cpuidle
    section, but I didn't attempt to figure out which the platform-specific
    idle routines might be.  That might be more usefully done by someone
    with platform experience in follow-up patches.
    
    This patch (of 4):
    
    Currently you can only request a backtrace of either all cpus, or all
    cpus but yourself.  It can also be helpful to request a remote backtrace
    of a single cpu, and since we want that, the logical extension is to
    support a cpumask as the underlying primitive.
    
    This change modifies the existing lib/nmi_backtrace.c code to take a
    cpumask as its basic primitive, and modifies the linux/nmi.h code to use
    the new "cpumask" method instead.
    
    The existing clients of nmi_backtrace (arm and x86) are converted to
    using the new cpumask approach in this change.
    
    The other users of the backtracing API (sparc64 and mips) are converted
    to use the cpumask approach rather than the all/allbutself approach.
    The mips code ignored the "include_self" boolean but with this change it
    will now also dump a local backtrace if requested.
    
    Link: http://lkml.kernel.org/r/1472487169-14923-2-git-send-email-cmetcalf@mellanox.comSigned-off-by: default avatarChris Metcalf <cmetcalf@mellanox.com>
    Tested-by: Daniel Thompson <daniel.thompson@linaro.org> [arm]
    Reviewed-by: default avatarAaron Tomlin <atomlin@redhat.com>
    Reviewed-by: default avatarPetr Mladek <pmladek@suse.com>
    Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
    Cc: Russell King <linux@arm.linux.org.uk>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Ingo Molnar <mingo@elte.hu>
    Cc: Ralf Baechle <ralf@linux-mips.org>
    Cc: David Miller <davem@davemloft.net>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    9a01c3ed
process_64.c 18.9 KB