Commit 10a6e676 authored Nov 15, 2010 by Jason Wessel

kgdb,x86: fix regression in detach handling



The fix from ba773f7c
(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>

parent 5450d904

arch/x86/kernel/kgdb.c

+8 −4

Original line number	Diff line number	Diff line
		@@ -315,14 +315,18 @@ static void kgdb_remove_all_hw_break(void)
		if (!breakinfo[i].enabled)
		continue;
		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;
		}
		if (dbg_is_early)
		early_dr7 &= ~encode_dr7(i, breakinfo[i].len,
		breakinfo[i].type);
		else
		arch_uninstall_hw_breakpoint(bp);
		bp->attr.disabled = 1;
		else if (hw_break_release_slot(i))
		printk(KERN_ERR "KGDB: hw bpt remove failed %lx\n",
		breakinfo[i].addr);
		breakinfo[i].enabled = 0;
		}
		}