[Bug backtrace/11705] New: RFE: x86* last-branch support

["jan dot kratochvil at redhat dot com" <sourceware-bugzilla at sourceware dot org>]

x86* processors have MSR Branch Trace Store (BTS) - Last Branch Record (LBR).

It can catch callers using tail-call optimization (call+ret -> jump) so that one
cannot find out which function called abort().  Tail-call optimization is also
used for noreturn functions such as abort()

http://developer.intel.com/products/processor/manuals/
Volume 3A: System Programming Guide
http://developer.intel.com/Assets/PDF/manual/253668.pdf
16.4.5 Branch Trace Store (BTS) 16-17

Intel Nehalem CPUs remember 16 last branch events.

There is some very negligible cost which may be possibly even acceptable for
processes not under the debug to include the last branch record stack into core.

Googled off-trunk Linux kernel ptrace interface patches:
http://lwn.net/Articles/259339/
http://lwn.net/Articles/280420/

-- 
           Summary: RFE: x86* last-branch support
           Product: gdb
           Version: unknown
            Status: UNCONFIRMED
          Severity: enhancement
          Priority: P2
         Component: backtrace
        AssignedTo: unassigned at sourceware dot org
        ReportedBy: jan dot kratochvil at redhat dot com
                CC: gdb-prs at sourceware dot org
GCC target triplet: x86_64-unknown-linux-gnu


http://sourceware.org/bugzilla/show_bug.cgi?id=11705

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