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kgdb,x86: fix regression in detach handling 

The fix from ba773f7c51
(x86,kgdb: Fix hw breakpoint regression) was not entirely complete.

The kgdb_remove_all_hw_break() function also needs to call the
hw_break_release_slot() or else a breakpoint can get activated again
after the debugger has detached.

The kgdb test suite exposes the behavior in the form of either a hang
or repetitive failure.  The kernel config that exposes the problem
contains all of the following:

CONFIG_DEBUG_RODATA=y
CONFIG_KGDB_TESTS=y
CONFIG_KGDB_TESTS_ON_BOOT=y
CONFIG_KGDB_TESTS_BOOT_STRING="V1F100"

Reported-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Tested-by: Frederic Weisbecker <fweisbec@gmail.com>
This commit is contained in:
Jason Wessel 2010-11-15 08:07:35 -06:00
parent 5450d90405
commit 10a6e67648
1 changed files with 8 additions and 4 deletions
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12
arch/x86/kernel/kgdb.c
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@ -315,14 +315,18 @@ static void kgdb_remove_all_hw_break(void)
if (!breakinfo[i].enabled) if (!breakinfo[i].enabled)
continue; continue;
bp = *per_cpu_ptr(breakinfo[i].pev, cpu); bp = *per_cpu_ptr(breakinfo[i].pev, cpu);
if (bp->attr.disabled == 1) if (!bp->attr.disabled) {
arch_uninstall_hw_breakpoint(bp);
bp->attr.disabled = 1;
continue; continue;
}
if (dbg_is_early) if (dbg_is_early)
early_dr7 &= ~encode_dr7(i, breakinfo[i].len, early_dr7 &= ~encode_dr7(i, breakinfo[i].len,
breakinfo[i].type); breakinfo[i].type);
else else if (hw_break_release_slot(i))
arch_uninstall_hw_breakpoint(bp); printk(KERN_ERR "KGDB: hw bpt remove failed %lx\n",
bp->attr.disabled = 1; breakinfo[i].addr);
breakinfo[i].enabled = 0;
} }
} }