From: Anton Vorontsov <anton.vorontsov@linaro.org>
To: Andrew Morton <akpm@linux-foundation.org>,
Russell King <linux@arm.linux.org.uk>,
Jason Wessel <jason.wessel@windriver.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Alan Cox <alan@linux.intel.com>
Cc: "Arve Hjønnevåg" <arve@android.com>,
"Colin Cross" <ccross@android.com>,
"Brian Swetland" <swetland@google.com>,
"John Stultz" <john.stultz@linaro.org>,
"Thomas Gleixner" <tglx@linutronix.de>,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linaro-kernel@lists.linaro.org, patches@linaro.org,
kernel-team@android.com, kgdb-bugreport@lists.sourceforge.net,
linux-serial@vger.kernel.org
Subject: [PATCH 01/11] kernel/debug: Mask KGDB NMI upon entry
Date: Thu, 13 Sep 2012 08:03:25 -0700 [thread overview]
Message-ID: <1347548615-18227-1-git-send-email-anton.vorontsov@linaro.org> (raw)
In-Reply-To: <20120913150133.GA16238@lizard>
The new arch callback should manage NMIs that usually cause KGDB to
enter. That is, not all NMIs should be enabled/disabled, but only
those that issue kgdb_handle_exception().
We must mask it as serial-line interrupt can be used as an NMI, so
if the original KGDB-entry cause was say a breakpoint, then every
input to KDB console will cause KGDB to reenter, which we don't want.
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
---
include/linux/kgdb.h | 23 +++++++++++++++++++++++
kernel/debug/debug_core.c | 36 +++++++++++++++++++++++++++++++++---
2 files changed, 56 insertions(+), 3 deletions(-)
diff --git a/include/linux/kgdb.h b/include/linux/kgdb.h
index c4d2fc1..3b111a6 100644
--- a/include/linux/kgdb.h
+++ b/include/linux/kgdb.h
@@ -221,6 +221,29 @@ extern int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt);
*/
extern void kgdb_arch_late(void);
+/**
+ * kgdb_arch_enable_nmi - Enable or disable KGDB-entry NMI
+ * @on: Flag to either enable or disable an NMI
+ *
+ * This is an architecture-specific "back-end" for kgdb_enable_nmi(). The
+ * call does not count disable/enable requests, do not use it directly.
+ */
+extern void kgdb_arch_enable_nmi(bool on);
+
+/**
+ * kgdb_enable_nmi - Enable or disable KGDB-entry NMI
+ * @on: Flag to either enable or disable an NMI
+ *
+ * This function manages NMIs that usually cause KGDB to enter. That is,
+ * not all NMIs should be enabled or disabled, but only those that issue
+ * kgdb_handle_exception().
+ *
+ * The call counts disable requests, and thus allows to nest disables.
+ * But trying to enable already enabled NMI is an error. The call returns
+ * 1 if NMI has been actually enabled after the call, and a value <= 0 if
+ * it is still disabled.
+ */
+extern int kgdb_enable_nmi(bool on);
/**
* struct kgdb_arch - Describe architecture specific values.
diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c
index 0557f24..b621d1e 100644
--- a/kernel/debug/debug_core.c
+++ b/kernel/debug/debug_core.c
@@ -214,6 +214,30 @@ int __weak kgdb_skipexception(int exception, struct pt_regs *regs)
return 0;
}
+void __weak kgdb_arch_enable_nmi(bool on)
+{
+}
+
+int kgdb_enable_nmi(bool on)
+{
+ static atomic_t cnt;
+ int ret;
+
+ ret = atomic_add_return(on ? 1 : -1, &cnt);
+ if (ret > 1 && on) {
+ /*
+ * There should be only one instance that calls this function
+ * in "enable, disable" order. All other users must call
+ * disable first, then enable. If not, something is wrong.
+ */
+ WARN_ON(1);
+ return 1;
+ }
+
+ kgdb_arch_enable_nmi(ret > 0);
+ return ret;
+}
+
/*
* Some architectures need cache flushes when we set/clear a
* breakpoint:
@@ -672,6 +696,9 @@ kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs)
{
struct kgdb_state kgdb_var;
struct kgdb_state *ks = &kgdb_var;
+ int ret = 0;
+
+ kgdb_enable_nmi(0);
ks->cpu = raw_smp_processor_id();
ks->ex_vector = evector;
@@ -681,11 +708,14 @@ kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs)
ks->linux_regs = regs;
if (kgdb_reenter_check(ks))
- return 0; /* Ouch, double exception ! */
+ goto out; /* Ouch, double exception ! */
if (kgdb_info[ks->cpu].enter_kgdb != 0)
- return 0;
+ goto out;
- return kgdb_cpu_enter(ks, regs, DCPU_WANT_MASTER);
+ ret = kgdb_cpu_enter(ks, regs, DCPU_WANT_MASTER);
+out:
+ kgdb_enable_nmi(1);
+ return ret;
}
int kgdb_nmicallback(int cpu, void *regs)
--
1.7.11.5
next prev parent reply other threads:[~2012-09-13 15:06 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-13 15:01 [PATCH v7 0/11] KGDB/KDB FIQ (NMI) debugger Anton Vorontsov
2012-09-13 15:03 ` Anton Vorontsov [this message]
2012-09-19 11:52 ` [PATCH 01/11] kernel/debug: Mask KGDB NMI upon entry Jason Wessel
2012-09-13 15:03 ` [PATCH 02/11] kdb: Implement disable_nmi command Anton Vorontsov
2012-09-19 11:52 ` Jason Wessel
2012-09-13 15:03 ` [PATCH 03/11] kdb: Turn KGDB_KDB=n stubs into static inlines Anton Vorontsov
2012-09-13 15:03 ` [PATCH 04/11] tty/serial/core: Introduce poll_init callback Anton Vorontsov
2012-09-13 15:03 ` [PATCH 05/11] tty/serial/amba-pl011: Implement " Anton Vorontsov
2012-09-13 15:03 ` [PATCH 06/11] tty/serial/amba-pl011: Quiesce interrupts in poll_get_char Anton Vorontsov
2012-09-13 15:03 ` [PATCH 07/11] tty/serial: Add kgdb_nmi driver Anton Vorontsov
2012-09-15 15:52 ` Francesco Lavra
2012-09-17 1:07 ` [PATCH updated " Anton Vorontsov
2012-09-19 11:52 ` [PATCH " Jason Wessel
2012-09-19 16:54 ` Anton Vorontsov
2012-09-13 15:03 ` [PATCH 08/11] ARM: Move some macros from entry-armv to entry-header Anton Vorontsov
2012-09-13 15:03 ` [PATCH 09/11] ARM: Add KGDB/KDB FIQ debugger generic code Anton Vorontsov
2012-09-13 15:03 ` [PATCH 10/11] ARM: VIC: Add a couple of low-level FIQ management helpers Anton Vorontsov
2012-09-13 15:03 ` [PATCH 11/11] ARM: versatile: Make able to use UART ports for KGDB FIQ debugger Anton Vorontsov
2012-09-13 17:04 ` [PATCH v7 0/11] KGDB/KDB FIQ (NMI) debugger Alan Cox
2012-09-13 16:55 ` Anton Vorontsov
2012-09-17 11:37 ` Greg Kroah-Hartman
2012-09-17 12:43 ` Jason Wessel
2012-09-17 12:54 ` Greg Kroah-Hartman
2012-09-17 15:39 ` Anton Vorontsov
2012-09-17 15:54 ` Greg Kroah-Hartman
2012-09-19 11:57 ` Jason Wessel
2012-09-19 16:57 ` Anton Vorontsov
2012-09-19 23:40 [PATCH v8 " Anton Vorontsov
2012-09-19 23:41 ` [PATCH 01/11] kernel/debug: Mask KGDB NMI upon entry Anton Vorontsov
2012-09-24 21:26 [PATCH v9 0/11] KGDB/KDB FIQ (NMI) debugger Anton Vorontsov
2012-09-24 21:27 ` [PATCH 01/11] kernel/debug: Mask KGDB NMI upon entry Anton Vorontsov
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