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debug_core: disable hw_breakpoints on all cores in kgdb_cpu_enter() 

The slave cpus do not have the hw breakpoints disabled upon entry to
the debug_core and as a result could cause unrecoverable recursive
faults on badly placed breakpoints, or get out of sync with the arch
specific hw breakpoint operations.

This patch addresses the problem by invoking kgdb_disable_hw_debug()
earlier in kgdb_enter_cpu for each cpu that enters the debug core.

The hw breakpoint dis/enable flow should be:

master_debug_cpu   slave_debug_cpu
         \              /
          kgdb_cpu_enter
                |
        kgdb_disable_hw_debug --> uninstall pre-enabled hw_breakpoint
                |
 do add/rm dis/enable operates to hw_breakpoints on master_debug_cpu..
                |
        correct_hw_break --> correct/install the enabled hw_breakpoint
                |
           leave_kgdb

Signed-off-by: Dongdong Deng <dongdong.deng@windriver.com>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
This commit is contained in:
Dongdong Deng 2010-09-13 06:58:00 -05:00 committed by Jason Wessel
parent 91b152aa85
commit c1bb9a9c19
1 changed files with 5 additions and 2 deletions
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7
kernel/debug/debug_core.c
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@ -485,6 +485,9 @@ static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs)
int error;
int i, cpu;
int trace_on = 0;
kgdb_disable_hw_debug(ks->linux_regs);
acquirelock:
/*
* Interrupts will be restored by the 'trap return' code, except when
@ -569,8 +572,6 @@ return_normal:
if (dbg_io_ops->pre_exception)
dbg_io_ops->pre_exception();
kgdb_disable_hw_debug(ks->linux_regs);
/*
* Get the passive CPU lock which will hold all the non-primary
* CPU in a spin state while the debugger is active
@ -661,6 +662,8 @@ kgdb_restore:
else
kgdb_sstep_pid = 0;
}
if (arch_kgdb_ops.correct_hw_break)
arch_kgdb_ops.correct_hw_break();
if (trace_on)
tracing_on();
/* Free kgdb_active */