kgdb,x86: fix regression in detach handling
The fix from ba773f7c510c0b252145933926c636c439889207
(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>
diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c
index ec592ca..cd21b65 100644
--- a/arch/x86/kernel/kgdb.c
+++ b/arch/x86/kernel/kgdb.c
@@ -315,14 +315,18 @@
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;
}
}