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[Bug breakpoints/15761] New: tracepoint with Linux kernel stub auto be set to disable


http://sourceware.org/bugzilla/show_bug.cgi?id=15761

            Bug ID: 15761
           Summary: tracepoint with Linux kernel stub auto be set to
                    disable
           Product: gdb
           Version: HEAD
            Status: NEW
          Severity: normal
          Priority: P2
         Component: breakpoints
          Assignee: unassigned at sourceware dot org
          Reporter: teawater at gmail dot com

Following is the step to reproduce this issue:
uname -r
3.2.0-49-generic
sudo gdb /usr/lib/debug/boot/vmlinux-$(uname -r)

#Conect to KGTP or another gdb stub (for example: gdb stub of qemu)
(gdb) target remote /sys/kernel/debug/gtp

(gdb) trace arch_local_irq_disable
Tracepoint 1 at 0xffffffff810041e3: arch_local_irq_disable. (289 locations)
(gdb) info tracepoints 
Num     Type           Disp Enb Address            What
1       tracepoint     keep n   <MULTIPLE>         
1.1                         y     0xffffffff810041e3 in xen_load_sp0 
                                                   at
/build/buildd/linux-3.2.0/arch/x86/include/asm/paravirt.h:881
You can see that the tracepoint 1 was auto set to disable.  If you want use it,
you need "enable" to open it.
Please note that this issue cannot be reproduced after GDB connect this stub
some times.



But I cannot reproduce this issue with new Linux kernel.  I think the reason is
the code around arch_local_irq_disable was changed:
uname -r
3.9.6-301.fc19.x86_64
(gdb) target remote /sys/kernel/debug/gtp
Remote debugging using /sys/kernel/debug/gtp
0x0000000000000000 in irq_stack_union ()
(gdb) trace arch_local_irq_disable
Tracepoint 1 at 0xffffffff8137e8d4: arch_local_irq_disable. (3 locations)
(gdb) info tracepoints 
Num     Type           Disp Enb Address            What
1       tracepoint     keep y   <MULTIPLE>         
1.1                         y     0xffffffff8137e8d4 in arch_local_irq_disable 
                                                   at
/usr/src/debug/kernel-3.9.fc19/linux-3.9.6-301.fc19.x86_64/arch/x86/include/asm/paravirt.h:838
    not installed on target
1.2                         y     0xffffffff81d04b2f in start_kernel 
                                                   at
/usr/src/debug/kernel-3.9.fc19/linux-3.9.6-301.fc19.x86_64/arch/x86/include/asm/paravirt.h:838
    not installed on target
1.3                         y     0xffffffff81d04ce3 in start_kernel 
                                                   at
/usr/src/debug/kernel-3.9.fc19/linux-3.9.6-301.fc19.x86_64/arch/x86/include/asm/paravirt.h:838
    not installed on target

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