* Re: [PATCH v7 0/11] KGDB/KDB FIQ (NMI) debugger
From: Anton Vorontsov @ 2012-09-13 16:55 UTC (permalink / raw)
To: Alan Cox
Cc: Andrew Morton, Russell King, Jason Wessel, Greg Kroah-Hartman,
Arve Hjønnevåg, Colin Cross, Brian Swetland,
John Stultz, Thomas Gleixner, linux-kernel, linux-arm-kernel,
linaro-kernel, patches, kernel-team, kgdb-bugreport, linux-serial
In-Reply-To: <20120913180457.1396637b@bob.linux.org.uk>
On Thu, Sep 13, 2012 at 06:04:57PM +0100, Alan Cox wrote:
> On Thu, 13 Sep 2012 08:01:33 -0700
> Anton Vorontsov <anton.vorontsov@linaro.org> wrote:
>
> > Hi all,
> >
> > Here comes the lucky v7:
> >
> > - Per Alan Cox's suggestion added hangup method and removed a small
> > leftover;
> > - Per Colin Cross' suggestion moved IRQ quiescing logic into
> > poll_get_char routine. IIUC, Alan is less unhappy about it. As a
> > result, clear_irq() callback dropped.
>
> Ok that has my ack. Some of it is not pretty but debugger hooks that
> have to run behind the OS while debugging it never are.
>
> Acked-by: Alan Cox <alan@linux.intel.com>
Great! Much thanks for reviews, Alan.
^ permalink raw reply
* Re: [PATCH v7 0/11] KGDB/KDB FIQ (NMI) debugger
From: Alan Cox @ 2012-09-13 17:04 UTC (permalink / raw)
To: Anton Vorontsov
Cc: Andrew Morton, Russell King, Jason Wessel, Greg Kroah-Hartman,
Arve Hjønnevåg, Colin Cross, Brian Swetland,
John Stultz, Thomas Gleixner, linux-kernel, linux-arm-kernel,
linaro-kernel, patches, kernel-team, kgdb-bugreport, linux-serial
In-Reply-To: <20120913150133.GA16238@lizard>
On Thu, 13 Sep 2012 08:01:33 -0700
Anton Vorontsov <anton.vorontsov@linaro.org> wrote:
> Hi all,
>
> Here comes the lucky v7:
>
> - Per Alan Cox's suggestion added hangup method and removed a small
> leftover;
> - Per Colin Cross' suggestion moved IRQ quiescing logic into
> poll_get_char routine. IIUC, Alan is less unhappy about it. As a
> result, clear_irq() callback dropped.
Ok that has my ack. Some of it is not pretty but debugger hooks that
have to run behind the OS while debugging it never are.
Acked-by: Alan Cox <alan@linux.intel.com>
^ permalink raw reply
* [PATCH 07/11] tty/serial: Add kgdb_nmi driver
From: Anton Vorontsov @ 2012-09-13 15:03 UTC (permalink / raw)
To: Andrew Morton, Russell King, Jason Wessel, Greg Kroah-Hartman,
Alan Cox
Cc: Arve Hjønnevåg, Colin Cross, Brian Swetland,
John Stultz, Thomas Gleixner, linux-kernel, linux-arm-kernel,
linaro-kernel, patches, kernel-team, kgdb-bugreport, linux-serial
In-Reply-To: <20120913150133.GA16238@lizard>
This special driver makes it possible to temporary use NMI debugger port
as a normal console by issuing 'nmi_console' command (assuming that the
port is attached to KGDB).
Unlike KDB's disable_nmi command, with this driver you are always able
to go back to the debugger using KGDB escape sequence ($3#33). This is
because this console driver processes the input in NMI context, and thus
is able to intercept the magic sequence.
Note that since the console interprets input and uses polling
communication methods, for things like PPP it is still better to fully
detach debugger port from the KGDB NMI (i.e. disable_nmi), and use raw
console.
Usually, to enter the debugger one have to type the magic sequence, so
initially the kernel will print the following prompt on the NMI debugger
console:
Type $3#33 to enter the debugger>
For convenience, there is a kgdb_fiq.knock kernel command line option,
when set to 0, this turns the special command to just a return key
press, so the kernel will be printing this:
Hit <return> to enter the debugger>
This is more convenient for long debugging sessions, although it makes
nmi_console feature somewhat useless.
And for the cases when NMI connected to a dedicated button, the knocking
can be disabled altogether by setting kgdb_fiq.knock to -1.
Suggested-by: Colin Cross <ccross@android.com>
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
---
drivers/tty/serial/Kconfig | 19 ++
drivers/tty/serial/Makefile | 1 +
drivers/tty/serial/kgdb_nmi.c | 396 ++++++++++++++++++++++++++++++++++++++++++
drivers/tty/serial/kgdboc.c | 6 +
include/linux/kgdb.h | 10 ++
5 files changed, 432 insertions(+)
create mode 100644 drivers/tty/serial/kgdb_nmi.c
diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index 26907cf..b22e45b 100644
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig
@@ -141,6 +141,25 @@ config SERIAL_ATMEL_TTYAT
Say Y if you have an external 8250/16C550 UART. If unsure, say N.
+config SERIAL_KGDB_NMI
+ bool "Serial console over KGDB NMI debugger port"
+ depends on KGDB_SERIAL_CONSOLE
+ help
+ This special driver allows you to temporary use NMI debugger port
+ as a normal console (assuming that the port is attached to KGDB).
+
+ Unlike KDB's disable_nmi command, with this driver you are always
+ able to go back to the debugger using KGDB escape sequence ($3#33).
+ This is because this console driver processes the input in NMI
+ context, and thus is able to intercept the magic sequence.
+
+ Note that since the console interprets input and uses polling
+ communication methods, for things like PPP you still must fully
+ detach debugger port from the KGDB NMI (i.e. disable_nmi), and
+ use raw console.
+
+ If unsure, say N.
+
config SERIAL_KS8695
bool "Micrel KS8695 (Centaur) serial port support"
depends on ARCH_KS8695
diff --git a/drivers/tty/serial/Makefile b/drivers/tty/serial/Makefile
index ce88667..4f694da 100644
--- a/drivers/tty/serial/Makefile
+++ b/drivers/tty/serial/Makefile
@@ -61,6 +61,7 @@ obj-$(CONFIG_SERIAL_MSM_HS) += msm_serial_hs.o
obj-$(CONFIG_SERIAL_NETX) += netx-serial.o
obj-$(CONFIG_SERIAL_OF_PLATFORM) += of_serial.o
obj-$(CONFIG_SERIAL_OF_PLATFORM_NWPSERIAL) += nwpserial.o
+obj-$(CONFIG_SERIAL_KGDB_NMI) += kgdb_nmi.o
obj-$(CONFIG_SERIAL_KS8695) += serial_ks8695.o
obj-$(CONFIG_SERIAL_OMAP) += omap-serial.o
obj-$(CONFIG_SERIAL_ALTERA_UART) += altera_uart.o
diff --git a/drivers/tty/serial/kgdb_nmi.c b/drivers/tty/serial/kgdb_nmi.c
new file mode 100644
index 0000000..57bf744
--- /dev/null
+++ b/drivers/tty/serial/kgdb_nmi.c
@@ -0,0 +1,396 @@
+/*
+ * KGDB NMI serial console
+ *
+ * Copyright 2010 Google, Inc.
+ * Arve Hjønnevåg <arve@android.com>
+ * Colin Cross <ccross@android.com>
+ * Copyright 2012 Linaro Ltd.
+ * Anton Vorontsov <anton.vorontsov@linaro.org>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/compiler.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/errno.h>
+#include <linux/atomic.h>
+#include <linux/console.h>
+#include <linux/tty.h>
+#include <linux/tty_driver.h>
+#include <linux/tty_flip.h>
+#include <linux/interrupt.h>
+#include <linux/hrtimer.h>
+#include <linux/tick.h>
+#include <linux/kfifo.h>
+#include <linux/kgdb.h>
+#include <linux/kdb.h>
+
+static int kgdb_nmi_knock = 1;
+module_param_named(knock, kgdb_nmi_knock, int, 0600);
+MODULE_PARM_DESC(knock, "if set to 1 (default), the special '$3#33' command "
+ "must be used to enter the debugger; when set to 0, "
+ "hitting return key is enough to enter the debugger; "
+ "when set to -1, the debugger is entered immediately "
+ "upon NMI");
+
+static char *kgdb_nmi_magic = "$3#33";
+module_param_named(magic, kgdb_nmi_magic, charp, 0600);
+MODULE_PARM_DESC(magic, "magic sequence to enter NMI debugger (default $3#33)");
+
+static bool kgdb_nmi_tty_enabled;
+
+static void kgdb_nmi_console_write(struct console *co, const char *s, uint c)
+{
+ int i;
+
+ if (!kgdb_nmi_tty_enabled || atomic_read(&kgdb_active) >= 0)
+ return;
+
+ for (i = 0; i < c; i++)
+ dbg_io_ops->write_char(s[i]);
+}
+
+static struct tty_driver *kgdb_nmi_tty_driver;
+
+static struct tty_driver *kgdb_nmi_console_device(struct console *co, int *idx)
+{
+ *idx = co->index;
+ return kgdb_nmi_tty_driver;
+}
+
+static struct console kgdb_nmi_console = {
+ .name = "ttyNMI",
+ .write = kgdb_nmi_console_write,
+ .device = kgdb_nmi_console_device,
+ .flags = CON_PRINTBUFFER | CON_ANYTIME | CON_ENABLED,
+ .index = -1,
+};
+
+/*
+ * This is usually the maximum rate on debug ports. We make fifo large enough
+ * to make copy-pasting to the terminal usable.
+ */
+#define KGDB_NMI_BAUD 115200
+#define KGDB_NMI_FIFO_SIZE roundup_pow_of_two(KGDB_NMI_BAUD / 8 / HZ)
+
+struct kgdb_nmi_tty_priv {
+ struct tty_port port;
+ struct tasklet_struct tlet;
+ STRUCT_KFIFO(char, KGDB_NMI_FIFO_SIZE) fifo;
+};
+
+static struct kgdb_nmi_tty_priv *kgdb_nmi_port_to_priv(struct tty_port *port)
+{
+ return container_of(port, struct kgdb_nmi_tty_priv, port);
+}
+
+/*
+ * Our debugging console is polled in a tasklet, so we'll check for input
+ * every tick. In HZ-less mode, we should program the next tick. We have
+ * to use the lowlevel stuff as no locks should be grabbed.
+ */
+#ifdef CONFIG_HIGH_RES_TIMERS
+static void kgdb_tty_poke(void)
+{
+ tick_program_event(ktime_get(), 0);
+}
+#else
+static inline void kgdb_tty_poke(void) {}
+#endif
+
+static struct tty_port *kgdb_nmi_port;
+
+static void kgdb_tty_recv(int ch)
+{
+ struct kgdb_nmi_tty_priv *priv;
+ char c = ch;
+
+ if (!kgdb_nmi_port || ch < 0)
+ return;
+ /*
+ * Can't use port->tty->driver_data as tty might be not there. Tasklet
+ * will check for tty and will get the ref, but here we don't have to
+ * do that, and actually, we can't: we're in NMI context, no locks are
+ * possible.
+ */
+ priv = kgdb_nmi_port_to_priv(kgdb_nmi_port);
+ kfifo_in(&priv->fifo, &c, 1);
+ kgdb_tty_poke();
+}
+
+static int kgdb_nmi_poll_one_knock(void)
+{
+ static int n;
+ int c = -1;
+ const char *magic = kgdb_nmi_magic;
+ size_t m = strlen(magic);
+ bool printch = 0;
+
+ c = dbg_io_ops->read_char();
+ if (c == NO_POLL_CHAR)
+ return c;
+
+ if (!kgdb_nmi_knock && (c == '\r' || c == '\n')) {
+ return 1;
+ } else if (c == magic[n]) {
+ n = (n + 1) % m;
+ if (!n)
+ return 1;
+ printch = 1;
+ } else {
+ n = 0;
+ }
+
+ if (kgdb_nmi_tty_enabled) {
+ kgdb_tty_recv(c);
+ return 0;
+ }
+
+ if (printch) {
+ kdb_printf("%c", c);
+ return 0;
+ }
+
+ kdb_printf("\r%s %s to enter the debugger> %*s",
+ kgdb_nmi_knock ? "Type" : "Hit",
+ kgdb_nmi_knock ? magic : "<return>", m, "");
+ while (m--)
+ kdb_printf("\b");
+ return 0;
+}
+
+/**
+ * kgdb_nmi_poll_knock - Check if it is time to enter the debugger
+ *
+ * "Serial ports are often noisy, especially when muxed over another port (we
+ * often use serial over the headset connector). Noise on the async command
+ * line just causes characters that are ignored, on a command line that blocked
+ * execution noise would be catastrophic." -- Colin Cross
+ *
+ * So, this function implements KGDB/KDB knocking on the serial line: we won't
+ * enter the debugger until we receive a known magic phrase (which is actually
+ * "$3#33", known as "escape to KDB" command. There is also a relaxed variant
+ * of knocking, i.e. just pressing the return key is enough to enter the
+ * debugger. And if knocking is disabled, the function always returns 1.
+ */
+bool kgdb_nmi_poll_knock(void)
+{
+ if (kgdb_nmi_knock < 0)
+ return 1;
+
+ while (1) {
+ int ret;
+
+ ret = kgdb_nmi_poll_one_knock();
+ if (ret == NO_POLL_CHAR)
+ return 0;
+ else if (ret == 1)
+ break;
+ }
+ return 1;
+}
+
+/*
+ * The tasklet is cheap, it does not cause wakeups when reschedules itself,
+ * instead it waits for the next tick.
+ */
+static void kgdb_nmi_tty_receiver(unsigned long data)
+{
+ struct kgdb_nmi_tty_priv *priv = (void *)data;
+ struct tty_struct *tty;
+ char ch;
+
+ tasklet_schedule(&priv->tlet);
+
+ if (likely(!kgdb_nmi_tty_enabled || !kfifo_len(&priv->fifo)))
+ return;
+
+ /* Port is there, but tty might be hung up, check. */
+ tty = tty_port_tty_get(kgdb_nmi_port);
+ if (!tty)
+ return;
+
+ while (kfifo_out(&priv->fifo, &ch, 1))
+ tty_insert_flip_char(priv->port.tty, ch, TTY_NORMAL);
+ tty_flip_buffer_push(priv->port.tty);
+
+ tty_kref_put(tty);
+}
+
+static int kgdb_nmi_tty_activate(struct tty_port *port, struct tty_struct *tty)
+{
+ struct kgdb_nmi_tty_priv *priv = tty->driver_data;
+
+ kgdb_nmi_port = port;
+ tasklet_schedule(&priv->tlet);
+ return 0;
+}
+
+static void kgdb_nmi_tty_shutdown(struct tty_port *port)
+{
+ struct kgdb_nmi_tty_priv *priv = port->tty->driver_data;
+
+ tasklet_kill(&priv->tlet);
+ kgdb_nmi_port = NULL;
+}
+
+static const struct tty_port_operations kgdb_nmi_tty_port_ops = {
+ .activate = kgdb_nmi_tty_activate,
+ .shutdown = kgdb_nmi_tty_shutdown,
+};
+
+static int kgdb_nmi_tty_install(struct tty_driver *drv, struct tty_struct *tty)
+{
+ struct kgdb_nmi_tty_priv *priv;
+ int ret;
+
+ priv = kzalloc(sizeof(*priv), GFP_KERNEL);
+ if (!priv)
+ return -ENOMEM;
+
+ INIT_KFIFO(priv->fifo);
+ tasklet_init(&priv->tlet, kgdb_nmi_tty_receiver, (unsigned long)priv);
+ tty_port_init(&priv->port);
+ priv->port.ops = &kgdb_nmi_tty_port_ops;
+ tty->driver_data = priv;
+
+ ret = tty_port_install(&priv->port, drv, tty);
+ if (ret) {
+ pr_err("%s: can't nstall tty port: %d\n", __func__, ret);
+ goto err;
+ }
+ return 0;
+err:
+ kfree(priv);
+ return ret;
+}
+
+static void kgdb_nmi_tty_cleanup(struct tty_struct *tty)
+{
+ struct kgdb_nmi_tty_priv *priv = tty->driver_data;
+
+ tty->driver_data = NULL;
+ kfree(priv);
+}
+
+static int kgdb_nmi_tty_open(struct tty_struct *tty, struct file *file)
+{
+ struct kgdb_nmi_tty_priv *priv = tty->driver_data;
+
+ return tty_port_open(&priv->port, tty, file);
+}
+
+static void kgdb_nmi_tty_close(struct tty_struct *tty, struct file *file)
+{
+ struct kgdb_nmi_tty_priv *priv = tty->driver_data;
+
+ tty_port_close(&priv->port, tty, file);
+}
+
+static void kgdb_nmi_tty_hangup(struct tty_struct *tty)
+{
+ struct kgdb_nmi_tty_priv *priv = tty->driver_data;
+
+ tty_port_hangup(&priv->port);
+}
+
+static int kgdb_nmi_tty_write_room(struct tty_struct *tty)
+{
+ /* Actually, we can handle any amount as we use polled writes. */
+ return 2048;
+}
+
+static int kgdb_nmi_tty_write(struct tty_struct *tty, const unchar *buf, int c)
+{
+ int i;
+
+ for (i = 0; i < c; i++)
+ dbg_io_ops->write_char(buf[i]);
+ return c;
+}
+
+static const struct tty_operations kgdb_nmi_tty_ops = {
+ .open = kgdb_nmi_tty_open,
+ .close = kgdb_nmi_tty_close,
+ .install = kgdb_nmi_tty_install,
+ .cleanup = kgdb_nmi_tty_cleanup,
+ .hangup = kgdb_nmi_tty_hangup,
+ .write_room = kgdb_nmi_tty_write_room,
+ .write = kgdb_nmi_tty_write,
+};
+
+static int kgdb_nmi_enable_console(int argc, const char *argv[])
+{
+ kgdb_nmi_tty_enabled = !(argc == 1 && !strcmp(argv[1], "off"));
+ return 0;
+}
+
+int kgdb_register_nmi_console(void)
+{
+ int ret;
+
+ kgdb_nmi_tty_driver = alloc_tty_driver(1);
+ if (!kgdb_nmi_tty_driver) {
+ pr_err("%s: cannot allocate tty\n", __func__);
+ return -ENOMEM;
+ }
+ kgdb_nmi_tty_driver->driver_name = "ttyNMI";
+ kgdb_nmi_tty_driver->name = "ttyNMI";
+ kgdb_nmi_tty_driver->num = 1;
+ kgdb_nmi_tty_driver->type = TTY_DRIVER_TYPE_SERIAL;
+ kgdb_nmi_tty_driver->subtype = SERIAL_TYPE_NORMAL;
+ kgdb_nmi_tty_driver->flags = TTY_DRIVER_REAL_RAW;
+ kgdb_nmi_tty_driver->init_termios = tty_std_termios;
+ tty_termios_encode_baud_rate(&kgdb_nmi_tty_driver->init_termios,
+ KGDB_NMI_BAUD, KGDB_NMI_BAUD);
+ tty_set_operations(kgdb_nmi_tty_driver, &kgdb_nmi_tty_ops);
+
+ ret = tty_register_driver(kgdb_nmi_tty_driver);
+ if (ret) {
+ pr_err("%s: can't register tty driver: %d\n", __func__, ret);
+ goto err_drv_reg;
+ }
+
+ ret = kdb_register("nmi_console", kgdb_nmi_enable_console, "[off]",
+ "switch to Linux NMI console", 0);
+ if (ret) {
+ pr_err("%s: can't register kdb command: %d\n", __func__, ret);
+ goto err_kdb_reg;
+ }
+
+ register_console(&kgdb_nmi_console);
+ kgdb_enable_nmi(1);
+
+ return 0;
+err_kdb_reg:
+ tty_unregister_driver(kgdb_nmi_tty_driver);
+err_drv_reg:
+ put_tty_driver(kgdb_nmi_tty_driver);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(kgdb_register_nmi_console);
+
+int kgdb_unregister_nmi_console(void)
+{
+ int ret;
+
+ kgdb_enable_nmi(0);
+ kdb_unregister("nmi_console");
+
+ ret = unregister_console(&kgdb_nmi_console);
+ if (ret)
+ return ret;
+
+ ret = tty_unregister_driver(kgdb_nmi_tty_driver);
+ if (ret)
+ return ret;
+ put_tty_driver(kgdb_nmi_tty_driver);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(kgdb_unregister_nmi_console);
diff --git a/drivers/tty/serial/kgdboc.c b/drivers/tty/serial/kgdboc.c
index 2b42a01..ed97cfd 100644
--- a/drivers/tty/serial/kgdboc.c
+++ b/drivers/tty/serial/kgdboc.c
@@ -145,6 +145,8 @@ __setup("kgdboc=", kgdboc_option_setup);
static void cleanup_kgdboc(void)
{
+ if (kgdb_unregister_nmi_console())
+ return;
kgdboc_unregister_kbd();
if (configured == 1)
kgdb_unregister_io_module(&kgdboc_io_ops);
@@ -198,6 +200,10 @@ do_register:
if (err)
goto noconfig;
+ err = kgdb_register_nmi_console();
+ if (err)
+ goto noconfig;
+
configured = 1;
return 0;
diff --git a/include/linux/kgdb.h b/include/linux/kgdb.h
index 3b111a6..9bf888e 100644
--- a/include/linux/kgdb.h
+++ b/include/linux/kgdb.h
@@ -245,6 +245,16 @@ extern void kgdb_arch_enable_nmi(bool on);
*/
extern int kgdb_enable_nmi(bool on);
+#ifdef CONFIG_SERIAL_KGDB_NMI
+extern int kgdb_register_nmi_console(void);
+extern int kgdb_unregister_nmi_console(void);
+extern bool kgdb_nmi_poll_knock(void);
+#else
+static inline int kgdb_register_nmi_console(void) { return 0; }
+static inline int kgdb_unregister_nmi_console(void) { return 0; }
+static inline bool kgdb_nmi_poll_knock(void) { return 1; }
+#endif
+
/**
* struct kgdb_arch - Describe architecture specific values.
* @gdb_bpt_instr: The instruction to trigger a breakpoint.
--
1.7.11.5
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^ permalink raw reply related
* [PATCH 06/11] tty/serial/amba-pl011: Quiesce interrupts in poll_get_char
From: Anton Vorontsov @ 2012-09-13 15:03 UTC (permalink / raw)
To: Andrew Morton, Russell King, Jason Wessel, Greg Kroah-Hartman,
Alan Cox
Cc: Arve Hjønnevåg, Colin Cross, Brian Swetland,
John Stultz, Thomas Gleixner, linux-kernel, linux-arm-kernel,
linaro-kernel, patches, kernel-team, kgdb-bugreport, linux-serial
In-Reply-To: <20120913150133.GA16238@lizard>
We need to quiesce interrupts in the poll_get_char routine, otherwise,
if used with KGDB NMI debugger, we'll keep reentering the NMI.
Quiescing interrupts is pretty straightforward, except for TXIM
interrupt. The interrupt has "ready to transmit" meaning, so it's
almost always raised, and the only way to silence it is to mask it. But
that's OK, ops->start_tx will unmask it.
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
---
drivers/tty/serial/amba-pl011.c | 29 +++++++++++++++++++++++++++++
1 file changed, 29 insertions(+)
diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index 45137e4..459f8ba 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -1284,11 +1284,40 @@ static void pl011_break_ctl(struct uart_port *port, int break_state)
}
#ifdef CONFIG_CONSOLE_POLL
+
+static void pl011_quiesce_irqs(struct uart_port *port)
+{
+ struct uart_amba_port *uap = (struct uart_amba_port *)port;
+ unsigned char __iomem *regs = uap->port.membase;
+
+ writew(readw(regs + UART011_MIS), regs + UART011_ICR);
+ /*
+ * There is no way to clear TXIM as this is "ready to transmit IRQ", so
+ * we simply mask it. start_tx() will unmask it.
+ *
+ * Note we can race with start_tx(), and if the race happens, the
+ * polling user might get another interrupt just after we clear it.
+ * But it should be OK and can happen even w/o the race, e.g.
+ * controller immediately got some new data and raised the IRQ.
+ *
+ * And whoever uses polling routines assumes that it manages the device
+ * (including tx queue), so we're also fine with start_tx()'s caller
+ * side.
+ */
+ writew(readw(regs + UART011_IMSC) & ~UART011_TXIM, regs + UART011_IMSC);
+}
+
static int pl011_get_poll_char(struct uart_port *port)
{
struct uart_amba_port *uap = (struct uart_amba_port *)port;
unsigned int status;
+ /*
+ * The caller might need IRQs lowered, e.g. if used with KDB NMI
+ * debugger.
+ */
+ pl011_quiesce_irqs(port);
+
status = readw(uap->port.membase + UART01x_FR);
if (status & UART01x_FR_RXFE)
return NO_POLL_CHAR;
--
1.7.11.5
^ permalink raw reply related
* [PATCH v7 0/11] KGDB/KDB FIQ (NMI) debugger
From: Anton Vorontsov @ 2012-09-13 15:01 UTC (permalink / raw)
To: Andrew Morton, Russell King, Jason Wessel, Greg Kroah-Hartman,
Alan Cox
Cc: Arve Hjønnevåg, Colin Cross, Brian Swetland,
John Stultz, Thomas Gleixner, linux-kernel, linux-arm-kernel,
linaro-kernel, patches, kernel-team, kgdb-bugreport, linux-serial
Hi all,
Here comes the lucky v7:
- Per Alan Cox's suggestion added hangup method and removed a small
leftover;
- Per Colin Cross' suggestion moved IRQ quiescing logic into
poll_get_char routine. IIUC, Alan is less unhappy about it. As a
result, clear_irq() callback dropped.
These patches can be found in the following repo (based on tty-next):
git://git.infradead.org/users/cbou/linux-nmi-kdb.git master
Old changelogs and rationale for these patches can be found here:
v1-v5, rationale: http://lkml.org/lkml/2012/9/10/2
v6: http://lkml.org/lkml/2012/9/10/2
Thanks,
--
arch/arm/Kconfig | 19 ++
arch/arm/common/vic.c | 28 ++
arch/arm/include/asm/hardware/vic.h | 2 +
arch/arm/include/asm/kgdb.h | 8 +
arch/arm/kernel/Makefile | 1 +
arch/arm/kernel/entry-armv.S | 167 +-----------
arch/arm/kernel/entry-header.S | 170 +++++++++++++
arch/arm/kernel/kgdb_fiq.c | 99 ++++++++
arch/arm/kernel/kgdb_fiq_entry.S | 87 +++++++
arch/arm/mach-versatile/Makefile | 1 +
arch/arm/mach-versatile/kgdb_fiq.c | 31 +++
drivers/tty/serial/Kconfig | 19 ++
drivers/tty/serial/Makefile | 1 +
drivers/tty/serial/amba-pl011.c | 73 +++++-
drivers/tty/serial/kgdb_nmi.c | 396 +++++++++++++++++++++++++++++
drivers/tty/serial/kgdboc.c | 6 +
drivers/tty/serial/serial_core.c | 17 ++
include/linux/kdb.h | 29 ++-
include/linux/kgdb.h | 33 +++
include/linux/serial_core.h | 1 +
kernel/debug/debug_core.c | 36 ++-
kernel/debug/kdb/kdb_main.c | 29 +++
22 files changed, 1060 insertions(+), 193 deletions(-)
^ permalink raw reply
* [PATCH 11/11] ARM: versatile: Make able to use UART ports for KGDB FIQ debugger
From: Anton Vorontsov @ 2012-09-13 15:03 UTC (permalink / raw)
To: Andrew Morton, Russell King, Jason Wessel, Greg Kroah-Hartman,
Alan Cox
Cc: Arve Hjønnevåg, Colin Cross, Brian Swetland,
John Stultz, Thomas Gleixner, linux-kernel, linux-arm-kernel,
linaro-kernel, patches, kernel-team, kgdb-bugreport, linux-serial
In-Reply-To: <20120913150133.GA16238@lizard>
If enabled, kernel will able to enter KGDB upon serial line activity on
UART ports.
Note that even with this patch and CONFIG_KGDB_FIQ is enabled, you still
need to pass kgdb_fiq.enable=1 kernel command line option, otherwise UART
will behave in a normal way.
By default UART0 is used, but this can be changed via kgdb_fiq.uart_num
kernel command line option.
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
---
arch/arm/Kconfig | 1 +
arch/arm/mach-versatile/Makefile | 1 +
arch/arm/mach-versatile/kgdb_fiq.c | 31 +++++++++++++++++++++++++++++++
3 files changed, 33 insertions(+)
create mode 100644 arch/arm/mach-versatile/kgdb_fiq.c
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index c978c74..1a9881a 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -336,6 +336,7 @@ config ARCH_VERSATILE
select PLAT_VERSATILE_CLCD
select PLAT_VERSATILE_FPGA_IRQ
select ARM_TIMER_SP804
+ select ARCH_MIGHT_HAVE_KGDB_FIQ
help
This enables support for ARM Ltd Versatile board.
diff --git a/arch/arm/mach-versatile/Makefile b/arch/arm/mach-versatile/Makefile
index 81fa3fe..bfd761f 100644
--- a/arch/arm/mach-versatile/Makefile
+++ b/arch/arm/mach-versatile/Makefile
@@ -7,3 +7,4 @@ obj-$(CONFIG_ARCH_VERSATILE_PB) += versatile_pb.o
obj-$(CONFIG_MACH_VERSATILE_AB) += versatile_ab.o
obj-$(CONFIG_MACH_VERSATILE_DT) += versatile_dt.o
obj-$(CONFIG_PCI) += pci.o
+obj-$(CONFIG_KGDB_FIQ) += kgdb_fiq.o
diff --git a/arch/arm/mach-versatile/kgdb_fiq.c b/arch/arm/mach-versatile/kgdb_fiq.c
new file mode 100644
index 0000000..3cdf71d
--- /dev/null
+++ b/arch/arm/mach-versatile/kgdb_fiq.c
@@ -0,0 +1,31 @@
+/*
+ * KGDB FIQ board support
+ *
+ * Copyright 2012 Linaro Ltd.
+ * Anton Vorontsov <anton.vorontsov@linaro.org>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/kgdb.h>
+#include <mach/hardware.h>
+#include <mach/platform.h>
+#include <asm/hardware/vic.h>
+
+static int kgdb_fiq;
+module_param_named(uart_num, kgdb_fiq, int, 0600);
+MODULE_PARM_DESC(uart_num, "UART<number> port to use for KGDB FIQ");
+
+static int __init kgdb_fiq_init(void)
+{
+ WARN_ON(kgdb_fiq > INT_UARTINT2 - INT_UARTINT0);
+
+ return kgdb_register_fiq(INT_UARTINT0 + kgdb_fiq,
+ vic_fiq_select,
+ vic_is_fiq_rised);
+}
+console_initcall(kgdb_fiq_init);
--
1.7.11.5
^ permalink raw reply related
* [PATCH 10/11] ARM: VIC: Add a couple of low-level FIQ management helpers
From: Anton Vorontsov @ 2012-09-13 15:03 UTC (permalink / raw)
To: Andrew Morton, Russell King, Jason Wessel, Greg Kroah-Hartman,
Alan Cox
Cc: Arve Hjønnevåg, Colin Cross, Brian Swetland,
John Stultz, Thomas Gleixner, linux-kernel, linux-arm-kernel,
linaro-kernel, patches, kernel-team, kgdb-bugreport, linux-serial
In-Reply-To: <20120913150133.GA16238@lizard>
Just a couple of calls to manage VIC FIQ routing. We'll use them for
KGDB FIQ support on ARM Versatile machines.
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
---
arch/arm/common/vic.c | 28 ++++++++++++++++++++++++++++
arch/arm/include/asm/hardware/vic.h | 2 ++
2 files changed, 30 insertions(+)
diff --git a/arch/arm/common/vic.c b/arch/arm/common/vic.c
index e0d5388..df2fc82 100644
--- a/arch/arm/common/vic.c
+++ b/arch/arm/common/vic.c
@@ -66,6 +66,34 @@ static struct vic_device vic_devices[CONFIG_ARM_VIC_NR];
static int vic_id;
+static void __iomem *vic_base(struct irq_data *d)
+{
+ return (void __iomem *)irq_data_get_irq_chip_data(d);
+}
+
+void vic_fiq_select(unsigned int irq, bool on)
+{
+ void __iomem *base = vic_base(&irq_to_desc(irq)->irq_data);
+ void __iomem *sel = base + VIC_INT_SELECT;
+ u32 msk = 1 << irq;
+ u32 val;
+
+ pr_debug("rerouting VIC vector %d to %s\n", irq, on ? "FIQ" : "IRQ");
+
+ val = readl(sel);
+ val &= ~msk;
+ if (on)
+ val |= msk;
+ writel(val, sel);
+}
+
+bool vic_is_fiq_rised(unsigned int irq)
+{
+ void __iomem *base = vic_base(&irq_to_desc(irq)->irq_data);
+
+ return readl(base + VIC_FIQ_STATUS) & (1 << irq);
+}
+
/**
* vic_init2 - common initialisation code
* @base: Base of the VIC.
diff --git a/arch/arm/include/asm/hardware/vic.h b/arch/arm/include/asm/hardware/vic.h
index e14af1a..2728975 100644
--- a/arch/arm/include/asm/hardware/vic.h
+++ b/arch/arm/include/asm/hardware/vic.h
@@ -52,6 +52,8 @@ void __vic_init(void __iomem *base, unsigned int irq_start, u32 vic_sources,
void vic_init(void __iomem *base, unsigned int irq_start, u32 vic_sources, u32 resume_sources);
int vic_of_init(struct device_node *node, struct device_node *parent);
void vic_handle_irq(struct pt_regs *regs);
+void vic_fiq_select(unsigned int irq, bool on);
+bool vic_is_fiq_rised(unsigned int irq);
#endif /* __ASSEMBLY__ */
#endif
--
1.7.11.5
^ permalink raw reply related
* [PATCH 09/11] ARM: Add KGDB/KDB FIQ debugger generic code
From: Anton Vorontsov @ 2012-09-13 15:03 UTC (permalink / raw)
To: Andrew Morton, Russell King, Jason Wessel, Greg Kroah-Hartman,
Alan Cox
Cc: Arve Hjønnevåg, Colin Cross, Brian Swetland,
John Stultz, Thomas Gleixner, linux-kernel, linux-arm-kernel,
linaro-kernel, patches, kernel-team, kgdb-bugreport, linux-serial
In-Reply-To: <20120913150133.GA16238@lizard>
The FIQ debugger may be used to debug situations when the kernel stuck
in uninterruptable sections, e.g. the kernel infinitely loops or
deadlocked in an interrupt or with interrupts disabled.
By default KGDB FIQ is disabled in runtime, but can be enabled with
kgdb_fiq.enable=1 kernel command line option.
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
---
arch/arm/Kconfig | 18 ++++++++
arch/arm/include/asm/kgdb.h | 8 ++++
arch/arm/kernel/Makefile | 1 +
arch/arm/kernel/kgdb_fiq.c | 99 ++++++++++++++++++++++++++++++++++++++++
arch/arm/kernel/kgdb_fiq_entry.S | 87 +++++++++++++++++++++++++++++++++++
5 files changed, 213 insertions(+)
create mode 100644 arch/arm/kernel/kgdb_fiq.c
create mode 100644 arch/arm/kernel/kgdb_fiq_entry.S
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 6d6e18f..c978c74 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -171,6 +171,24 @@ config GENERIC_ISA_DMA
config FIQ
bool
+config ARCH_MIGHT_HAVE_KGDB_FIQ
+ bool
+
+config KGDB_FIQ
+ bool "KGDB/KDB FIQ debugger"
+ depends on KGDB_KDB && ARCH_MIGHT_HAVE_KGDB_FIQ && !THUMB2_KERNEL
+ select FIQ
+ help
+ The FIQ debugger may be used to debug situations when the
+ kernel stuck in uninterruptable sections, e.g. the kernel
+ infinitely loops or deadlocked in an interrupt or with
+ interrupts disabled.
+
+ By default KGDB FIQ is disabled in runtime, but can be
+ enabled with kgdb_fiq.enable=1 kernel command line option.
+
+ If unsure, say N.
+
config NEED_RET_TO_USER
bool
diff --git a/arch/arm/include/asm/kgdb.h b/arch/arm/include/asm/kgdb.h
index 48066ce..807e547 100644
--- a/arch/arm/include/asm/kgdb.h
+++ b/arch/arm/include/asm/kgdb.h
@@ -11,6 +11,8 @@
#define __ARM_KGDB_H__
#include <linux/ptrace.h>
+#include <linux/linkage.h>
+#include <asm/exception.h>
/*
* GDB assumes that we're a user process being debugged, so
@@ -47,6 +49,12 @@ static inline void arch_kgdb_breakpoint(void)
extern void kgdb_handle_bus_error(void);
extern int kgdb_fault_expected;
+extern char kgdb_fiq_handler;
+extern char kgdb_fiq_handler_end;
+asmlinkage void __exception_irq_entry kgdb_fiq_do_handle(struct pt_regs *regs);
+extern int __init kgdb_register_fiq(unsigned int mach_kgdb_fiq,
+ void (*mach_kgdb_enable_fiq)(unsigned int irq, bool on),
+ bool (*mach_is_kgdb_fiq)(unsigned int irq));
#endif /* !__ASSEMBLY__ */
/*
diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile
index 7ad2d5c..5aa079b 100644
--- a/arch/arm/kernel/Makefile
+++ b/arch/arm/kernel/Makefile
@@ -56,6 +56,7 @@ obj-$(CONFIG_ATAGS_PROC) += atags.o
obj-$(CONFIG_OABI_COMPAT) += sys_oabi-compat.o
obj-$(CONFIG_ARM_THUMBEE) += thumbee.o
obj-$(CONFIG_KGDB) += kgdb.o
+obj-$(CONFIG_KGDB_FIQ) += kgdb_fiq_entry.o kgdb_fiq.o
obj-$(CONFIG_ARM_UNWIND) += unwind.o
obj-$(CONFIG_HAVE_TCM) += tcm.o
obj-$(CONFIG_OF) += devtree.o
diff --git a/arch/arm/kernel/kgdb_fiq.c b/arch/arm/kernel/kgdb_fiq.c
new file mode 100644
index 0000000..8443af1
--- /dev/null
+++ b/arch/arm/kernel/kgdb_fiq.c
@@ -0,0 +1,99 @@
+/*
+ * KGDB FIQ
+ *
+ * Copyright 2010 Google, Inc.
+ * Arve Hjønnevåg <arve@android.com>
+ * Colin Cross <ccross@android.com>
+ * Copyright 2012 Linaro Ltd.
+ * Anton Vorontsov <anton.vorontsov@linaro.org>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/errno.h>
+#include <linux/hardirq.h>
+#include <linux/kdb.h>
+#include <linux/kgdb.h>
+#include <asm/fiq.h>
+#include <asm/exception.h>
+
+static int kgdb_fiq_enabled;
+module_param_named(enable, kgdb_fiq_enabled, int, 0600);
+MODULE_PARM_DESC(enable, "set to 1 to enable FIQ KGDB");
+
+static unsigned int kgdb_fiq;
+static bool (*is_kgdb_fiq)(unsigned int irq);
+
+asmlinkage void __exception_irq_entry kgdb_fiq_do_handle(struct pt_regs *regs)
+{
+ if (!is_kgdb_fiq(kgdb_fiq))
+ return;
+ if (!kgdb_nmi_poll_knock())
+ return;
+
+ nmi_enter();
+ kgdb_handle_exception(1, 0, 0, regs);
+ nmi_exit();
+}
+
+static struct fiq_handler kgdb_fiq_desc = {
+ .name = "kgdb",
+};
+
+static long kgdb_fiq_setup_stack(void *info)
+{
+ struct pt_regs regs;
+
+ regs.ARM_sp = __get_free_pages(GFP_KERNEL, THREAD_SIZE_ORDER) +
+ THREAD_START_SP;
+ WARN_ON(!regs.ARM_sp);
+
+ set_fiq_regs(®s);
+ return 0;
+}
+
+static void (*kgdb_enable_fiq)(unsigned int irq, bool on);
+
+void kgdb_arch_enable_nmi(bool on)
+{
+ if (!kgdb_enable_fiq)
+ return;
+ kgdb_enable_fiq(kgdb_fiq, on);
+}
+
+int __init kgdb_register_fiq(unsigned int mach_kgdb_fiq,
+ void (*mach_kgdb_enable_fiq)(unsigned int irq, bool on),
+ bool (*mach_is_kgdb_fiq)(unsigned int irq))
+{
+ int err;
+ int cpu;
+
+ if (!kgdb_fiq_enabled)
+ return -ENODEV;
+ if (kgdb_fiq)
+ return -EBUSY;
+
+ kgdb_fiq = mach_kgdb_fiq;
+ kgdb_enable_fiq = mach_kgdb_enable_fiq;
+ is_kgdb_fiq = mach_is_kgdb_fiq;
+
+ err = claim_fiq(&kgdb_fiq_desc);
+ if (err) {
+ pr_warn("%s: unable to claim fiq", __func__);
+ return err;
+ }
+
+ for_each_possible_cpu(cpu)
+ work_on_cpu(cpu, kgdb_fiq_setup_stack, NULL);
+
+ set_fiq_handler(&kgdb_fiq_handler,
+ &kgdb_fiq_handler_end - &kgdb_fiq_handler);
+
+ return 0;
+}
diff --git a/arch/arm/kernel/kgdb_fiq_entry.S b/arch/arm/kernel/kgdb_fiq_entry.S
new file mode 100644
index 0000000..d6becca
--- /dev/null
+++ b/arch/arm/kernel/kgdb_fiq_entry.S
@@ -0,0 +1,87 @@
+/*
+ * KGDB FIQ entry
+ *
+ * Copyright 1996,1997,1998 Russell King.
+ * Copyright 2012 Linaro Ltd.
+ * Anton Vorontsov <anton.vorontsov@linaro.org>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ */
+
+#include <linux/linkage.h>
+#include <asm/assembler.h>
+#include <asm/memory.h>
+#include <asm/unwind.h>
+#include "entry-header.S"
+
+ .text
+
+@ This is needed for usr_entry/alignment_trap
+.LCcralign:
+ .long cr_alignment
+.LCdohandle:
+ .long kgdb_fiq_do_handle
+
+ .macro fiq_handler
+ ldr r1, =.LCdohandle
+ mov r0, sp
+ adr lr, BSYM(9997f)
+ ldr pc, [r1]
+9997:
+ .endm
+
+ .align 5
+__fiq_svc:
+ svc_entry
+ fiq_handler
+ mov r0, sp
+ ldmib r0, {r1 - r14}
+ msr cpsr_c, #FIQ_MODE | PSR_I_BIT | PSR_F_BIT
+ add r8, r0, #S_PC
+ ldr r9, [r0, #S_PSR]
+ msr spsr_cxsf, r9
+ ldr r0, [r0, #S_R0]
+ ldmia r8, {pc}^
+
+ UNWIND(.fnend )
+ENDPROC(__fiq_svc)
+ .ltorg
+
+ .align 5
+__fiq_usr:
+ usr_entry
+ kuser_cmpxchg_check
+ fiq_handler
+ get_thread_info tsk
+ mov why, #0
+ b ret_to_user_from_irq
+ UNWIND(.fnend )
+ENDPROC(__fiq_usr)
+ .ltorg
+
+ .global kgdb_fiq_handler
+kgdb_fiq_handler:
+
+ vector_stub fiq, FIQ_MODE, 4
+
+ .long __fiq_usr @ 0 (USR_26 / USR_32)
+ .long __fiq_svc @ 1 (FIQ_26 / FIQ_32)
+ .long __fiq_svc @ 2 (IRQ_26 / IRQ_32)
+ .long __fiq_svc @ 3 (SVC_26 / SVC_32)
+ .long __fiq_svc @ 4
+ .long __fiq_svc @ 5
+ .long __fiq_svc @ 6
+ .long __fiq_svc @ 7
+ .long __fiq_svc @ 8
+ .long __fiq_svc @ 9
+ .long __fiq_svc @ a
+ .long __fiq_svc @ b
+ .long __fiq_svc @ c
+ .long __fiq_svc @ d
+ .long __fiq_svc @ e
+ .long __fiq_svc @ f
+
+ .global kgdb_fiq_handler_end
+kgdb_fiq_handler_end:
--
1.7.11.5
^ permalink raw reply related
* [PATCH 08/11] ARM: Move some macros from entry-armv to entry-header
From: Anton Vorontsov @ 2012-09-13 15:03 UTC (permalink / raw)
To: Andrew Morton, Russell King, Jason Wessel, Greg Kroah-Hartman,
Alan Cox
Cc: Arve Hjønnevåg, Colin Cross, Brian Swetland,
John Stultz, Thomas Gleixner, linux-kernel, linux-arm-kernel,
linaro-kernel, patches, kernel-team, kgdb-bugreport, linux-serial
In-Reply-To: <20120913150133.GA16238@lizard>
Just move the macros into header file as we would want to use them for
KGDB FIQ entry code.
The following macros were moved:
- svc_entry
- usr_entry
- kuser_cmpxchg_check
- vector_stub
To make kuser_cmpxchg_check actually work across different files, we
also have to make kuser_cmpxchg64_fixup global.
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
---
arch/arm/kernel/entry-armv.S | 167 +---------------------------------------
| 170 +++++++++++++++++++++++++++++++++++++++++
2 files changed, 171 insertions(+), 166 deletions(-)
diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index 0f82098..0f15368 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -136,57 +136,6 @@ common_invalid:
b bad_mode
ENDPROC(__und_invalid)
-/*
- * SVC mode handlers
- */
-
-#if defined(CONFIG_AEABI) && (__LINUX_ARM_ARCH__ >= 5)
-#define SPFIX(code...) code
-#else
-#define SPFIX(code...)
-#endif
-
- .macro svc_entry, stack_hole=0
- UNWIND(.fnstart )
- UNWIND(.save {r0 - pc} )
- sub sp, sp, #(S_FRAME_SIZE + \stack_hole - 4)
-#ifdef CONFIG_THUMB2_KERNEL
- SPFIX( str r0, [sp] ) @ temporarily saved
- SPFIX( mov r0, sp )
- SPFIX( tst r0, #4 ) @ test original stack alignment
- SPFIX( ldr r0, [sp] ) @ restored
-#else
- SPFIX( tst sp, #4 )
-#endif
- SPFIX( subeq sp, sp, #4 )
- stmia sp, {r1 - r12}
-
- ldmia r0, {r3 - r5}
- add r7, sp, #S_SP - 4 @ here for interlock avoidance
- mov r6, #-1 @ "" "" "" ""
- add r2, sp, #(S_FRAME_SIZE + \stack_hole - 4)
- SPFIX( addeq r2, r2, #4 )
- str r3, [sp, #-4]! @ save the "real" r0 copied
- @ from the exception stack
-
- mov r3, lr
-
- @
- @ We are now ready to fill in the remaining blanks on the stack:
- @
- @ r2 - sp_svc
- @ r3 - lr_svc
- @ r4 - lr_<exception>, already fixed up for correct return/restart
- @ r5 - spsr_<exception>
- @ r6 - orig_r0 (see pt_regs definition in ptrace.h)
- @
- stmia r7, {r2 - r6}
-
-#ifdef CONFIG_TRACE_IRQFLAGS
- bl trace_hardirqs_off
-#endif
- .endm
-
.align 5
__dabt_svc:
svc_entry
@@ -348,71 +297,8 @@ ENDPROC(__pabt_svc)
/*
* User mode handlers
- *
- * EABI note: sp_svc is always 64-bit aligned here, so should S_FRAME_SIZE
*/
-#if defined(CONFIG_AEABI) && (__LINUX_ARM_ARCH__ >= 5) && (S_FRAME_SIZE & 7)
-#error "sizeof(struct pt_regs) must be a multiple of 8"
-#endif
-
- .macro usr_entry
- UNWIND(.fnstart )
- UNWIND(.cantunwind ) @ don't unwind the user space
- sub sp, sp, #S_FRAME_SIZE
- ARM( stmib sp, {r1 - r12} )
- THUMB( stmia sp, {r0 - r12} )
-
- ldmia r0, {r3 - r5}
- add r0, sp, #S_PC @ here for interlock avoidance
- mov r6, #-1 @ "" "" "" ""
-
- str r3, [sp] @ save the "real" r0 copied
- @ from the exception stack
-
- @
- @ We are now ready to fill in the remaining blanks on the stack:
- @
- @ r4 - lr_<exception>, already fixed up for correct return/restart
- @ r5 - spsr_<exception>
- @ r6 - orig_r0 (see pt_regs definition in ptrace.h)
- @
- @ Also, separately save sp_usr and lr_usr
- @
- stmia r0, {r4 - r6}
- ARM( stmdb r0, {sp, lr}^ )
- THUMB( store_user_sp_lr r0, r1, S_SP - S_PC )
-
- @
- @ Enable the alignment trap while in kernel mode
- @
- alignment_trap r0
-
- @
- @ Clear FP to mark the first stack frame
- @
- zero_fp
-
-#ifdef CONFIG_IRQSOFF_TRACER
- bl trace_hardirqs_off
-#endif
- .endm
-
- .macro kuser_cmpxchg_check
-#if !defined(CONFIG_CPU_32v6K) && !defined(CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG)
-#ifndef CONFIG_MMU
-#warning "NPTL on non MMU needs fixing"
-#else
- @ Make sure our user space atomic helper is restarted
- @ if it was interrupted in a critical region. Here we
- @ perform a quick test inline since it should be false
- @ 99.9999% of the time. The rest is done out of line.
- cmp r4, #TASK_SIZE
- blhs kuser_cmpxchg64_fixup
-#endif
-#endif
- .endm
-
.align 5
__dabt_usr:
usr_entry
@@ -846,6 +732,7 @@ __kuser_cmpxchg64: @ 0xffff0f60
ldmfd sp!, {r4, r5, r6, pc}
.text
+ .global kuser_cmpxchg64_fixup
kuser_cmpxchg64_fixup:
@ Called from kuser_cmpxchg_fixup.
@ r4 = address of interrupted insn (must be preserved).
@@ -976,58 +863,6 @@ __kuser_helper_end:
THUMB( .thumb )
-/*
- * Vector stubs.
- *
- * This code is copied to 0xffff0200 so we can use branches in the
- * vectors, rather than ldr's. Note that this code must not
- * exceed 0x300 bytes.
- *
- * Common stub entry macro:
- * Enter in IRQ mode, spsr = SVC/USR CPSR, lr = SVC/USR PC
- *
- * SP points to a minimal amount of processor-private memory, the address
- * of which is copied into r0 for the mode specific abort handler.
- */
- .macro vector_stub, name, mode, correction=0
- .align 5
-
-vector_\name:
- .if \correction
- sub lr, lr, #\correction
- .endif
-
- @
- @ Save r0, lr_<exception> (parent PC) and spsr_<exception>
- @ (parent CPSR)
- @
- stmia sp, {r0, lr} @ save r0, lr
- mrs lr, spsr
- str lr, [sp, #8] @ save spsr
-
- @
- @ Prepare for SVC32 mode. IRQs remain disabled.
- @
- mrs r0, cpsr
- eor r0, r0, #(\mode ^ SVC_MODE | PSR_ISETSTATE)
- msr spsr_cxsf, r0
-
- @
- @ the branch table must immediately follow this code
- @
- and lr, lr, #0x0f
- THUMB( adr r0, 1f )
- THUMB( ldr lr, [r0, lr, lsl #2] )
- mov r0, sp
- ARM( ldr lr, [pc, lr, lsl #2] )
- movs pc, lr @ branch to handler in SVC mode
-ENDPROC(vector_\name)
-
- .align 2
- @ handler addresses follow this label
-1:
- .endm
-
.globl __stubs_start
__stubs_start:
/*
--git a/arch/arm/kernel/entry-header.S b/arch/arm/kernel/entry-header.S
index 9a8531e..c3c09ac 100644
--- a/arch/arm/kernel/entry-header.S
+++ b/arch/arm/kernel/entry-header.S
@@ -73,6 +73,109 @@
msr cpsr_c, \rtemp @ switch back to the SVC mode
.endm
+/*
+ * Vector stubs.
+ *
+ * This code is copied to 0xffff0200 so we can use branches in the
+ * vectors, rather than ldr's. Note that this code must not
+ * exceed 0x300 bytes.
+ *
+ * Common stub entry macro:
+ * Enter in IRQ mode, spsr = SVC/USR CPSR, lr = SVC/USR PC
+ *
+ * SP points to a minimal amount of processor-private memory, the address
+ * of which is copied into r0 for the mode specific abort handler.
+ */
+ .macro vector_stub, name, mode, correction=0
+ .align 5
+
+vector_\name:
+ .if \correction
+ sub lr, lr, #\correction
+ .endif
+
+ @
+ @ Save r0, lr_<exception> (parent PC) and spsr_<exception>
+ @ (parent CPSR)
+ @
+ stmia sp, {r0, lr} @ save r0, lr
+ mrs lr, spsr
+ str lr, [sp, #8] @ save spsr
+
+ @
+ @ Prepare for SVC32 mode. IRQs remain disabled.
+ @
+ mrs r0, cpsr
+ eor r0, r0, #(\mode ^ SVC_MODE | PSR_ISETSTATE)
+ msr spsr_cxsf, r0
+
+ @
+ @ the branch table must immediately follow this code
+ @
+ and lr, lr, #0x0f
+ THUMB( adr r0, 1f )
+ THUMB( ldr lr, [r0, lr, lsl #2] )
+ mov r0, sp
+ ARM( ldr lr, [pc, lr, lsl #2] )
+ movs pc, lr @ branch to handler in SVC mode
+ENDPROC(vector_\name)
+
+ .align 2
+ @ handler addresses follow this label
+1:
+ .endm
+
+/*
+ * SVC mode handlers
+ */
+
+#if defined(CONFIG_AEABI) && (__LINUX_ARM_ARCH__ >= 5)
+#define SPFIX(code...) code
+#else
+#define SPFIX(code...)
+#endif
+
+ .macro svc_entry, stack_hole=0
+ UNWIND(.fnstart )
+ UNWIND(.save {r0 - pc} )
+ sub sp, sp, #(S_FRAME_SIZE + \stack_hole - 4)
+#ifdef CONFIG_THUMB2_KERNEL
+ SPFIX( str r0, [sp] ) @ temporarily saved
+ SPFIX( mov r0, sp )
+ SPFIX( tst r0, #4 ) @ test original stack alignment
+ SPFIX( ldr r0, [sp] ) @ restored
+#else
+ SPFIX( tst sp, #4 )
+#endif
+ SPFIX( subeq sp, sp, #4 )
+ stmia sp, {r1 - r12}
+
+ ldmia r0, {r3 - r5}
+ add r7, sp, #S_SP - 4 @ here for interlock avoidance
+ mov r6, #-1 @ "" "" "" ""
+ add r2, sp, #(S_FRAME_SIZE + \stack_hole - 4)
+ SPFIX( addeq r2, r2, #4 )
+ str r3, [sp, #-4]! @ save the "real" r0 copied
+ @ from the exception stack
+
+ mov r3, lr
+
+ @
+ @ We are now ready to fill in the remaining blanks on the stack:
+ @
+ @ r2 - sp_svc
+ @ r3 - lr_svc
+ @ r4 - lr_<exception>, already fixed up for correct return/restart
+ @ r5 - spsr_<exception>
+ @ r6 - orig_r0 (see pt_regs definition in ptrace.h)
+ @
+ stmia r7, {r2 - r6}
+
+#ifdef CONFIG_TRACE_IRQFLAGS
+ bl trace_hardirqs_off
+#endif
+ .endm
+
#ifndef CONFIG_THUMB2_KERNEL
.macro svc_exit, rpsr
msr spsr_cxsf, \rpsr
@@ -164,6 +267,73 @@
#endif /* !CONFIG_THUMB2_KERNEL */
/*
+ * User mode handlers
+ *
+ * EABI note: sp_svc is always 64-bit aligned here, so should S_FRAME_SIZE
+ */
+
+#if defined(CONFIG_AEABI) && (__LINUX_ARM_ARCH__ >= 5) && (S_FRAME_SIZE & 7)
+#error "sizeof(struct pt_regs) must be a multiple of 8"
+#endif
+
+ .macro usr_entry
+ UNWIND(.fnstart )
+ UNWIND(.cantunwind ) @ don't unwind the user space
+ sub sp, sp, #S_FRAME_SIZE
+ ARM( stmib sp, {r1 - r12} )
+ THUMB( stmia sp, {r0 - r12} )
+
+ ldmia r0, {r3 - r5}
+ add r0, sp, #S_PC @ here for interlock avoidance
+ mov r6, #-1 @ "" "" "" ""
+
+ str r3, [sp] @ save the "real" r0 copied
+ @ from the exception stack
+
+ @
+ @ We are now ready to fill in the remaining blanks on the stack:
+ @
+ @ r4 - lr_<exception>, already fixed up for correct return/restart
+ @ r5 - spsr_<exception>
+ @ r6 - orig_r0 (see pt_regs definition in ptrace.h)
+ @
+ @ Also, separately save sp_usr and lr_usr
+ @
+ stmia r0, {r4 - r6}
+ ARM( stmdb r0, {sp, lr}^ )
+ THUMB( store_user_sp_lr r0, r1, S_SP - S_PC )
+
+ @
+ @ Enable the alignment trap while in kernel mode
+ @
+ alignment_trap r0
+
+ @
+ @ Clear FP to mark the first stack frame
+ @
+ zero_fp
+
+#ifdef CONFIG_IRQSOFF_TRACER
+ bl trace_hardirqs_off
+#endif
+ .endm
+
+ .macro kuser_cmpxchg_check
+#if !defined(CONFIG_CPU_32v6K) && !defined(CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG)
+#ifndef CONFIG_MMU
+#warning "NPTL on non MMU needs fixing"
+#else
+ @ Make sure our user space atomic helper is restarted
+ @ if it was interrupted in a critical region. Here we
+ @ perform a quick test inline since it should be false
+ @ 99.9999% of the time. The rest is done out of line.
+ cmp r4, #TASK_SIZE
+ blhs kuser_cmpxchg64_fixup
+#endif
+#endif
+ .endm
+
+/*
* These are the registers used in the syscall handler, and allow us to
* have in theory up to 7 arguments to a function - r0 to r6.
*
--
1.7.11.5
^ permalink raw reply related
* [PATCH 05/11] tty/serial/amba-pl011: Implement poll_init callback
From: Anton Vorontsov @ 2012-09-13 15:03 UTC (permalink / raw)
To: Andrew Morton, Russell King, Jason Wessel, Greg Kroah-Hartman,
Alan Cox
Cc: Arve Hjønnevåg, Colin Cross, Brian Swetland,
John Stultz, Thomas Gleixner, linux-kernel, linux-arm-kernel,
linaro-kernel, patches, kernel-team, kgdb-bugreport, linux-serial
In-Reply-To: <20120913150133.GA16238@lizard>
The callback is used to initialize the hardware, nothing else should be
done, i.e. we should not request interrupts (but we can and do unmask
some of them, as they might be useful for NMI entry).
As a side-effect, the patch also fixes a division by zero[1] when booting
with kgdboc options specified (e.g. kgdboc=ttyAMA0,115200n8). The issue
happens because serial core calls set_termios callback, but the driver
doesn't know clock frequency, and thus cannot calculate proper baud rate
values.
[1]
WARNING: at drivers/tty/serial/serial_core.c:400 uart_get_baud_rate+0xe8/0x14c()
Modules linked in:
[<c0018e50>] (unwind_backtrace+0x0/0xf0) from [<c0020ae8>] (warn_slowpath_common+0x4c/0x64)
[<c0020ae8>] (warn_slowpath_common+0x4c/0x64) from [<c0020b1c>] (warn_slowpath_null+0x1c/0x24)
[<c0020b1c>] (warn_slowpath_null+0x1c/0x24) from [<c0185ed8>] (uart_get_baud_rate+0xe8/0x14c)
[<c0185ed8>] (uart_get_baud_rate+0xe8/0x14c) from [<c0187078>] (pl011_set_termios+0x48/0x278)
[<c0187078>] (pl011_set_termios+0x48/0x278) from [<c01850b0>] (uart_set_options+0xe8/0x114)
[<c01850b0>] (uart_set_options+0xe8/0x114) from [<c0185de4>] (uart_poll_init+0xd4/0xe0)
[<c0185de4>] (uart_poll_init+0xd4/0xe0) from [<c016da8c>] (tty_find_polling_driver+0x100/0x17c)
[<c016da8c>] (tty_find_polling_driver+0x100/0x17c) from [<c0188538>] (configure_kgdboc+0xc8/0x1b8)
[<c0188538>] (configure_kgdboc+0xc8/0x1b8) from [<c00088a4>] (do_one_initcall+0x30/0x168)
[<c00088a4>] (do_one_initcall+0x30/0x168) from [<c033784c>] (do_basic_setup+0x94/0xc8)
[<c033784c>] (do_basic_setup+0x94/0xc8) from [<c03378e0>] (kernel_init+0x60/0xf4)
[<c03378e0>] (kernel_init+0x60/0xf4) from [<c00144a0>] (kernel_thread_exit+0x0/0x8)
---[ end trace 7d41c9186f342c40 ]---
Division by zero in kernel.
[<c0018e50>] (unwind_backtrace+0x0/0xf0) from [<c014546c>] (Ldiv0+0x8/0x10)
[<c014546c>] (Ldiv0+0x8/0x10) from [<c0187098>] (pl011_set_termios+0x68/0x278)
[<c0187098>] (pl011_set_termios+0x68/0x278) from [<c01850b0>] (uart_set_options+0xe8/0x114)
[<c01850b0>] (uart_set_options+0xe8/0x114) from [<c0185de4>] (uart_poll_init+0xd4/0xe0)
[<c0185de4>] (uart_poll_init+0xd4/0xe0) from [<c016da8c>] (tty_find_polling_driver+0x100/0x17c)
[<c016da8c>] (tty_find_polling_driver+0x100/0x17c) from [<c0188538>] (configure_kgdboc+0xc8/0x1b8)
[<c0188538>] (configure_kgdboc+0xc8/0x1b8) from [<c00088a4>] (do_one_initcall+0x30/0x168)
[<c00088a4>] (do_one_initcall+0x30/0x168) from [<c033784c>] (do_basic_setup+0x94/0xc8)
[<c033784c>] (do_basic_setup+0x94/0xc8) from [<c03378e0>] (kernel_init+0x60/0xf4)
[<c03378e0>] (kernel_init+0x60/0xf4) from [<c00144a0>] (kernel_thread_exit+0x0/0x8)
Division by zero in kernel.
[<c0018e50>] (unwind_backtrace+0x0/0xf0) from [<c014546c>] (Ldiv0+0x8/0x10)
[<c014546c>] (Ldiv0+0x8/0x10) from [<c0183a98>] (uart_update_timeout+0x4c/0x5c)
[<c0183a98>] (uart_update_timeout+0x4c/0x5c) from [<c01870f8>] (pl011_set_termios+0xc8/0x278)
[<c01870f8>] (pl011_set_termios+0xc8/0x278) from [<c01850b0>] (uart_set_options+0xe8/0x114)
[<c01850b0>] (uart_set_options+0xe8/0x114) from [<c0185de4>] (uart_poll_init+0xd4/0xe0)
[<c0185de4>] (uart_poll_init+0xd4/0xe0) from [<c016da8c>] (tty_find_polling_driver+0x100/0x17c)
[<c016da8c>] (tty_find_polling_driver+0x100/0x17c) from [<c0188538>] (configure_kgdboc+0xc8/0x1b8)
[<c0188538>] (configure_kgdboc+0xc8/0x1b8) from [<c00088a4>] (do_one_initcall+0x30/0x168)
[<c00088a4>] (do_one_initcall+0x30/0x168) from [<c033784c>] (do_basic_setup+0x94/0xc8)
[<c033784c>] (do_basic_setup+0x94/0xc8) from [<c03378e0>] (kernel_init+0x60/0xf4)
[<c03378e0>] (kernel_init+0x60/0xf4) from [<c00144a0>] (kernel_thread_exit+0x0/0x8)
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
---
drivers/tty/serial/amba-pl011.c | 44 ++++++++++++++++++++++++++++++-----------
1 file changed, 33 insertions(+), 11 deletions(-)
diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index cede938..45137e4 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -1309,10 +1309,9 @@ static void pl011_put_poll_char(struct uart_port *port,
#endif /* CONFIG_CONSOLE_POLL */
-static int pl011_startup(struct uart_port *port)
+static int pl011_hwinit(struct uart_port *port)
{
struct uart_amba_port *uap = (struct uart_amba_port *)port;
- unsigned int cr;
int retval;
/* Optionaly enable pins to be muxed in and configured */
@@ -1337,6 +1336,37 @@ static int pl011_startup(struct uart_port *port)
UART011_RTIS | UART011_RXIS, uap->port.membase + UART011_ICR);
/*
+ * Save interrupts enable mask, and enable RX interrupts in case if
+ * the interrupt is used for NMI entry.
+ */
+ uap->im = readw(uap->port.membase + UART011_IMSC);
+ writew(UART011_RTIM | UART011_RXIM, uap->port.membase + UART011_IMSC);
+
+ if (uap->port.dev->platform_data) {
+ struct amba_pl011_data *plat;
+
+ plat = uap->port.dev->platform_data;
+ if (plat->init)
+ plat->init();
+ }
+ return 0;
+ out:
+ return retval;
+}
+
+static int pl011_startup(struct uart_port *port)
+{
+ struct uart_amba_port *uap = (struct uart_amba_port *)port;
+ unsigned int cr;
+ int retval;
+
+ retval = pl011_hwinit(port);
+ if (retval)
+ goto clk_dis;
+
+ writew(uap->im, uap->port.membase + UART011_IMSC);
+
+ /*
* Allocate the IRQ
*/
retval = request_irq(uap->port.irq, pl011_int, 0, "uart-pl011", uap);
@@ -1395,19 +1425,10 @@ static int pl011_startup(struct uart_port *port)
writew(uap->im, uap->port.membase + UART011_IMSC);
spin_unlock_irq(&uap->port.lock);
- if (uap->port.dev->platform_data) {
- struct amba_pl011_data *plat;
-
- plat = uap->port.dev->platform_data;
- if (plat->init)
- plat->init();
- }
-
return 0;
clk_dis:
clk_disable_unprepare(uap->clk);
- out:
return retval;
}
@@ -1688,6 +1709,7 @@ static struct uart_ops amba_pl011_pops = {
.config_port = pl011_config_port,
.verify_port = pl011_verify_port,
#ifdef CONFIG_CONSOLE_POLL
+ .poll_init = pl011_hwinit,
.poll_get_char = pl011_get_poll_char,
.poll_put_char = pl011_put_poll_char,
#endif
--
1.7.11.5
^ permalink raw reply related
* [PATCH 04/11] tty/serial/core: Introduce poll_init callback
From: Anton Vorontsov @ 2012-09-13 15:03 UTC (permalink / raw)
To: Andrew Morton, Russell King, Jason Wessel, Greg Kroah-Hartman,
Alan Cox
Cc: Arve Hjønnevåg, Colin Cross, Brian Swetland,
John Stultz, Thomas Gleixner, linux-kernel, linux-arm-kernel,
linaro-kernel, patches, kernel-team, kgdb-bugreport, linux-serial
In-Reply-To: <20120913150133.GA16238@lizard>
It was noticed that polling drivers (like KGDB) are not able to use
serial ports if the ports were not previously initialized via console.
I.e. when booting with console=ttyAMA0 kgdboc=ttyAMA0, everything works
fine, but with console=ttyFOO kgdboc=ttyAMA0, the kgdboc doesn't work.
This is because we don't initialize the hardware. Calling ->startup() is
not an option, because drivers request interrupts there, and drivers
fail to handle situations when tty isn't opened with interrupts enabled.
So, we have to implement a new callback (actually, tty_ops already have
a similar callback), which does everything needed to initialize just the
hardware.
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
---
drivers/tty/serial/serial_core.c | 17 +++++++++++++++++
include/linux/serial_core.h | 1 +
2 files changed, 18 insertions(+)
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 046279c..dcb2d5a 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -2129,6 +2129,7 @@ static int uart_poll_init(struct tty_driver *driver, int line, char *options)
int bits = 8;
int parity = 'n';
int flow = 'n';
+ int ret;
if (!state || !state->uart_port)
return -1;
@@ -2137,6 +2138,22 @@ static int uart_poll_init(struct tty_driver *driver, int line, char *options)
if (!(port->ops->poll_get_char && port->ops->poll_put_char))
return -1;
+ if (port->ops->poll_init) {
+ struct tty_port *tport = &state->port;
+
+ ret = 0;
+ mutex_lock(&tport->mutex);
+ /*
+ * We don't set ASYNCB_INITIALIZED as we only initialized the
+ * hw, e.g. state->xmit is still uninitialized.
+ */
+ if (!test_bit(ASYNCB_INITIALIZED, &tport->flags))
+ ret = port->ops->poll_init(port);
+ mutex_unlock(&tport->mutex);
+ if (ret)
+ return ret;
+ }
+
if (options) {
uart_parse_options(options, &baud, &parity, &bits, &flow);
return uart_set_options(port, NULL, baud, parity, bits, flow);
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index 7cf0b68..822c887 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -274,6 +274,7 @@ struct uart_ops {
int (*verify_port)(struct uart_port *, struct serial_struct *);
int (*ioctl)(struct uart_port *, unsigned int, unsigned long);
#ifdef CONFIG_CONSOLE_POLL
+ int (*poll_init)(struct uart_port *);
void (*poll_put_char)(struct uart_port *, unsigned char);
int (*poll_get_char)(struct uart_port *);
#endif
--
1.7.11.5
^ permalink raw reply related
* [PATCH 03/11] kdb: Turn KGDB_KDB=n stubs into static inlines
From: Anton Vorontsov @ 2012-09-13 15:03 UTC (permalink / raw)
To: Andrew Morton, Russell King, Jason Wessel, Greg Kroah-Hartman,
Alan Cox
Cc: Arve Hjønnevåg, Colin Cross, Brian Swetland,
John Stultz, Thomas Gleixner, linux-kernel, linux-arm-kernel,
linaro-kernel, patches, kernel-team, kgdb-bugreport, linux-serial
In-Reply-To: <20120913150133.GA16238@lizard>
This makes the stubs actually usable, since e.g. 'foo = kdb_register();'
leads to build errors in !KGDB_KDB case. Plus, with static inlines we
do type checking.
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
---
include/linux/kdb.h | 29 ++++++++++++++++-------------
1 file changed, 16 insertions(+), 13 deletions(-)
diff --git a/include/linux/kdb.h b/include/linux/kdb.h
index 42d9e86..7f6fe6e 100644
--- a/include/linux/kdb.h
+++ b/include/linux/kdb.h
@@ -13,6 +13,14 @@
* Copyright (C) 2009 Jason Wessel <jason.wessel@windriver.com>
*/
+typedef enum {
+ KDB_REPEAT_NONE = 0, /* Do not repeat this command */
+ KDB_REPEAT_NO_ARGS, /* Repeat the command without arguments */
+ KDB_REPEAT_WITH_ARGS, /* Repeat the command including its arguments */
+} kdb_repeat_t;
+
+typedef int (*kdb_func_t)(int, const char **);
+
#ifdef CONFIG_KGDB_KDB
#include <linux/init.h>
#include <linux/sched.h>
@@ -32,14 +40,6 @@ extern atomic_t kdb_event;
#define KDB_MAXARGS 16 /* Maximum number of arguments to a function */
-typedef enum {
- KDB_REPEAT_NONE = 0, /* Do not repeat this command */
- KDB_REPEAT_NO_ARGS, /* Repeat the command without arguments */
- KDB_REPEAT_WITH_ARGS, /* Repeat the command including its arguments */
-} kdb_repeat_t;
-
-typedef int (*kdb_func_t)(int, const char **);
-
/* KDB return codes from a command or internal kdb function */
#define KDB_NOTFOUND (-1)
#define KDB_ARGCOUNT (-2)
@@ -149,11 +149,14 @@ extern int kdb_register_repeat(char *, kdb_func_t, char *, char *,
short, kdb_repeat_t);
extern int kdb_unregister(char *);
#else /* ! CONFIG_KGDB_KDB */
-#define kdb_printf(...)
-#define kdb_init(x)
-#define kdb_register(...)
-#define kdb_register_repeat(...)
-#define kdb_uregister(x)
+static inline __printf(1, 2) int kdb_printf(const char *fmt, ...) { return 0; }
+static inline void kdb_init(int level) {}
+static inline int kdb_register(char *cmd, kdb_func_t func, char *usage,
+ char *help, short minlen) { return 0; }
+static inline int kdb_register_repeat(char *cmd, kdb_func_t func, char *usage,
+ char *help, short minlen,
+ kdb_repeat_t repeat) { return 0; }
+static inline int kdb_unregister(char *cmd) { return 0; }
#endif /* CONFIG_KGDB_KDB */
enum {
KDB_NOT_INITIALIZED,
--
1.7.11.5
^ permalink raw reply related
* [PATCH 02/11] kdb: Implement disable_nmi command
From: Anton Vorontsov @ 2012-09-13 15:03 UTC (permalink / raw)
To: Andrew Morton, Russell King, Jason Wessel, Greg Kroah-Hartman,
Alan Cox
Cc: linaro-kernel, patches, Brian Swetland, linux-kernel,
Arve Hjønnevåg, John Stultz, linux-serial, Colin Cross,
kgdb-bugreport, Thomas Gleixner, kernel-team, linux-arm-kernel
In-Reply-To: <20120913150133.GA16238@lizard>
This command disables NMI-entry. If NMI source has been previously shared
with a serial console ("debug port"), this effectively releases the port
from KDB exclusive use, and makes the console available for normal use.
Of course, NMI can be reenabled, enable_nmi modparam is used for that:
echo 1 > /sys/module/kdb/parameters/enable_nmi
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
---
kernel/debug/kdb/kdb_main.c | 29 +++++++++++++++++++++++++++++
1 file changed, 29 insertions(+)
diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c
index 31df170..9fadff1 100644
--- a/kernel/debug/kdb/kdb_main.c
+++ b/kernel/debug/kdb/kdb_main.c
@@ -21,6 +21,7 @@
#include <linux/smp.h>
#include <linux/utsname.h>
#include <linux/vmalloc.h>
+#include <linux/atomic.h>
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/init.h>
@@ -2107,6 +2108,32 @@ static int kdb_dmesg(int argc, const char **argv)
return 0;
}
#endif /* CONFIG_PRINTK */
+
+/* Make sure we balance enable/disable calls, must disable first. */
+static atomic_t kdb_nmi_disabled;
+
+static int kdb_disable_nmi(int argc, const char *argv[])
+{
+ if (atomic_read(&kdb_nmi_disabled))
+ return 0;
+ atomic_set(&kdb_nmi_disabled, 1);
+ kgdb_enable_nmi(0);
+ return 0;
+}
+
+static int kdb_param_enable_nmi(const char *val, const struct kernel_param *kp)
+{
+ if (!atomic_add_unless(&kdb_nmi_disabled, -1, 0))
+ return -EINVAL;
+ kgdb_enable_nmi(1);
+ return 0;
+}
+
+static const struct kernel_param_ops kdb_param_ops_enable_nmi = {
+ .set = kdb_param_enable_nmi,
+};
+module_param_cb(enable_nmi, &kdb_param_ops_enable_nmi, NULL, 0600);
+
/*
* kdb_cpu - This function implements the 'cpu' command.
* cpu [<cpunum>]
@@ -2851,6 +2878,8 @@ static void __init kdb_inittab(void)
kdb_register_repeat("dmesg", kdb_dmesg, "[lines]",
"Display syslog buffer", 0, KDB_REPEAT_NONE);
#endif
+ kdb_register_repeat("disable_nmi", kdb_disable_nmi, "",
+ "Disable NMI entry to KDB", 0, KDB_REPEAT_NONE);
kdb_register_repeat("defcmd", kdb_defcmd, "name \"usage\" \"help\"",
"Define a set of commands, down to endefcmd", 0, KDB_REPEAT_NONE);
kdb_register_repeat("kill", kdb_kill, "<-signal> <pid>",
--
1.7.11.5
^ permalink raw reply related
* [PATCH 01/11] kernel/debug: Mask KGDB NMI upon entry
From: Anton Vorontsov @ 2012-09-13 15:03 UTC (permalink / raw)
To: Andrew Morton, Russell King, Jason Wessel, Greg Kroah-Hartman,
Alan Cox
Cc: Arve Hjønnevåg, Colin Cross, Brian Swetland,
John Stultz, Thomas Gleixner, linux-kernel, linux-arm-kernel,
linaro-kernel, patches, kernel-team, kgdb-bugreport, linux-serial
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
^ permalink raw reply related
* Re: [PATCH 1/2] serial: mxs-auart: fix the wrong setting order
From: Huang Shijie @ 2012-09-13 5:45 UTC (permalink / raw)
To: Lauri Hintsala; +Cc: Huang Shijie, linux-serial, linux-arm-kernel
In-Reply-To: <50516EF6.7070306@bluegiga.com>
于 2012年09月13日 13:28, Lauri Hintsala 写道:
> Hi Huang,
>
> On 09/07/2012 05:43 AM, Huang Shijie wrote:
>> I found this bug when i tried to add DMA support for MXS-AUART.
>
> What is the status of DMA support? We could help you testing your
> patches.
thanks.
I maybe send out the new patch set in next week. I resume this work
recently.
BR
Huang Shijie
>
> Best regards,
> Lauri Hintsala
>
--
To unsubscribe from this list: send the line "unsubscribe linux-serial" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
^ permalink raw reply
* Re: [PATCH 1/2] serial: mxs-auart: fix the wrong setting order
From: Lauri Hintsala @ 2012-09-13 5:28 UTC (permalink / raw)
To: Huang Shijie; +Cc: Huang Shijie, linux-arm-kernel, linux-serial
In-Reply-To: <50495F6F.4040800@freescale.com>
Hi Huang,
On 09/07/2012 05:43 AM, Huang Shijie wrote:
> I found this bug when i tried to add DMA support for MXS-AUART.
What is the status of DMA support? We could help you testing your patches.
Best regards,
Lauri Hintsala
^ permalink raw reply
* Re: [PATCH v4 00/21] OMAP UART Patches
From: Felipe Balbi @ 2012-09-13 5:01 UTC (permalink / raw)
To: Paul Walmsley
Cc: Felipe Balbi, Greg KH, alan, Tony Lindgren, Kevin Hilman,
Linux OMAP Mailing List, Linux ARM Kernel Mailing List,
linux-serial, Linux Kernel Mailing List, Santosh Shilimkar,
Shubhrajyoti Datta, Sourav Poddar
In-Reply-To: <alpine.DEB.2.00.1209122025020.17903@utopia.booyaka.com>
[-- Attachment #1: Type: text/plain, Size: 805 bytes --]
On Wed, Sep 12, 2012 at 08:25:30PM +0000, Paul Walmsley wrote:
> Hi
>
> On Wed, 12 Sep 2012, Felipe Balbi wrote:
>
> > On Tue, Sep 11, 2012 at 10:02:48PM +0000, Paul Walmsley wrote:
> >
> > > The bad news is that N800 no longer boots -- or the UART dies during
> > > serial init:
> > >
> > > http://www.pwsan.com/omap/testlogs/test_tty_next_e36851d0/20120910020323/boot/2420n800/2420n800_log.txt
> > >
> > > The problem doesn't seem to affect the 2430SDP.
> > >
> > > Could you put together a patch to fix N800?
> >
> > I'll see what I can do. BTW, is that log with DEBUG_LL enabled ?
>
> Yes. Here's the .config that was used on N800:
>
> http://www.pwsan.com/omap/testlogs/test_tty_next_e36851d0/20120910020323/build/n800_b_testconfig/Kconfig
Thanks :-)
--
balbi
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^ permalink raw reply
* Re: [PATCH v4 00/21] OMAP UART Patches
From: Paul Walmsley @ 2012-09-12 20:25 UTC (permalink / raw)
To: Felipe Balbi
Cc: Greg KH, alan, Tony Lindgren, Kevin Hilman,
Linux OMAP Mailing List, Linux ARM Kernel Mailing List,
linux-serial, Linux Kernel Mailing List, Santosh Shilimkar,
Shubhrajyoti Datta, Sourav Poddar
In-Reply-To: <20120912062259.GC18563@arwen.pp.htv.fi>
Hi
On Wed, 12 Sep 2012, Felipe Balbi wrote:
> On Tue, Sep 11, 2012 at 10:02:48PM +0000, Paul Walmsley wrote:
>
> > The bad news is that N800 no longer boots -- or the UART dies during
> > serial init:
> >
> > http://www.pwsan.com/omap/testlogs/test_tty_next_e36851d0/20120910020323/boot/2420n800/2420n800_log.txt
> >
> > The problem doesn't seem to affect the 2430SDP.
> >
> > Could you put together a patch to fix N800?
>
> I'll see what I can do. BTW, is that log with DEBUG_LL enabled ?
Yes. Here's the .config that was used on N800:
http://www.pwsan.com/omap/testlogs/test_tty_next_e36851d0/20120910020323/build/n800_b_testconfig/Kconfig
- Paul
^ permalink raw reply
* Re: [RFC] tty/serial/kgdboc: Add and wire up clear_irqs callback
From: Anton Vorontsov @ 2012-09-12 10:32 UTC (permalink / raw)
To: Alan Cox
Cc: Colin Cross, Thomas Gleixner, Alan Cox, Andrew Morton,
Russell King, Jason Wessel, Greg Kroah-Hartman,
Arve Hjønnevåg, Brian Swetland, John Stultz,
linux-kernel, linux-arm-kernel, linaro-kernel, patches,
kernel-team, kgdb-bugreport, linux-serial
In-Reply-To: <20120912104420.06a88957@bob.linux.org.uk>
On Wed, Sep 12, 2012 at 10:44:20AM +0100, Alan Cox wrote:
> > Of course, if Alan is OK with this, I'm more than OK too. :-)
>
> It may well be better.
>
> > (But the polling routines would need to clear all interrupts, not
> > just rx/tx. For example, if the controller indicated some error, and
> > nobody clears it, then we'll start reentering infinitely.)
>
> For a lot of devices and platforms you'd probably mask them instead ?
If there is no way to clear them, yes, we obviously would want to
mask them before using the port for NMI debugger. Then we'd need
three callbacks:
- mask_all_irqs_but_rx() -- used before we want to start using the port
for the NMI debugger;
- clear_rx_irq() -- (optional) clears rx IRQ for controllers that need
it;
- restore_irqs() -- unmasks interrupts that were previously masked.
If we ever encounter a case when just clearing interrupts doesn't work,
we can surely implement the above scheme... It's just so far I don't
see any need to over-design this, but again, it's your call, I told my
opinion on this, but I'll do whatever you guys like more. :-)
> > > If you use a clear_irqs callback, you can drop characters if
> > > one arrives between the last character buffer read and calling
> > > clear_irqs.
> >
> > Only if we call clear_irqs() after reading the characters, but we do
> > it before. So if new characters are available, we will reenter NMI,
> > which is OK.
>
> Recursively or not... again you get platform specific magic in places
> we don't want.
I really really don't see how this is platform-specific. All we ask the
serial driver is to quiesce its interrupt. Whether we can handle
NMIs/IRQs recursively or not is not serial driver's worry, since its
IRQ handler is not going to fire anyway. The polling routines already
gave us the power to steal/inject the data, so now we're stealing the
interrupt too.
How we use the callback is indeed platform-specific, but so is the
whole KGDB, and that knowledge is hidden there.
For serial driver it's all pretty much clear: lower the interrupt, but
don't turn off rx detection.
Thanks!
Anton.
^ permalink raw reply
* Re: [RFC] tty/serial/kgdboc: Add and wire up clear_irqs callback
From: Alan Cox @ 2012-09-12 9:44 UTC (permalink / raw)
To: Anton Vorontsov
Cc: Colin Cross, Thomas Gleixner, Alan Cox, Andrew Morton,
Russell King, Jason Wessel, Greg Kroah-Hartman,
Arve Hjønnevåg, Brian Swetland, John Stultz,
linux-kernel, linux-arm-kernel, linaro-kernel, patches,
kernel-team, kgdb-bugreport, linux-serial
In-Reply-To: <20120912040657.GA3880@lizard>
> Of course, if Alan is OK with this, I'm more than OK too. :-)
It may well be better.
> (But the polling routines would need to clear all interrupts, not
> just rx/tx. For example, if the controller indicated some error, and
> nobody clears it, then we'll start reentering infinitely.)
For a lot of devices and platforms you'd probably mask them instead ?
>
> > If you use a clear_irqs callback, you can drop characters if
> > one arrives between the last character buffer read and calling
> > clear_irqs.
>
> Only if we call clear_irqs() after reading the characters, but we do
> it before. So if new characters are available, we will reenter NMI,
> which is OK.
Recursively or not... again you get platform specific magic in places
we don't want.
In the driver poll method for most uarts is going to be at least buried
in what is usually arch specific uarts.
^ permalink raw reply
* Re: [RFC] tty/serial/kgdboc: Add and wire up clear_irqs callback
From: Anton Vorontsov @ 2012-09-12 7:01 UTC (permalink / raw)
To: Colin Cross
Cc: Thomas Gleixner, Alan Cox, Andrew Morton, Russell King,
Jason Wessel, Greg Kroah-Hartman, Alan Cox,
Arve Hjønnevåg, Brian Swetland, John Stultz,
linux-kernel, linux-arm-kernel, linaro-kernel, patches,
kernel-team, kgdb-bugreport, linux-serial
In-Reply-To: <CAMbhsRT+JR9-qzADiPXo9e59oHFCY4g6HNObKNMeciC5Xj6m6g@mail.gmail.com>
On Tue, Sep 11, 2012 at 09:40:35PM -0700, Colin Cross wrote:
[..]
> >> the polling rx function should clear the interrupt
> >> for you.
> >
> > Yes, that's an option. But that way we add a new semantic for the
> > polling routines, and effecitvely we just merge the two callbacks.
> >
> > Of course, if Alan is OK with this, I'm more than OK too. :-)
> >
> > (But the polling routines would need to clear all interrupts, not
> > just rx/tx. For example, if the controller indicated some error, and
> > nobody clears it, then we'll start reentering infinitely.)
>
> For exynos5, the only non-8250 based serial port I've come across, we
> clear all interrupts in the rx poll function (see
> https://android.googlesource.com/kernel/exynos/+/ef427aafffb7153dde59745e440fd7ec41ea969d/arch/arm/mach-exynos/exynos_fiq_debugger.c).
Yes, but if you'd like to merge your code, some might ask you: why?
You'd answer that you need to clear the interrupts, otherwise you'll
keep reentering NMI. The next that you might get is this: "this does
not belong to the getc callback, it's better to factor it out". :-) And
here comes clear_irq() (or alike, see below).
> >> If you use a clear_irqs callback, you can drop characters if
> >> one arrives between the last character buffer read and calling
> >> clear_irqs.
> >
> > Only if we call clear_irqs() after reading the characters, but we do
> > it before. So if new characters are available, we will reenter NMI,
> > which is OK.
> >
> > But if used incorrectly, it truly can cause dropping (or staling) of
> > characters, so I'd better add some comments about this.
>
> What does clear_irqs() mean for a status or tx interrupt? The tx
> interrupt will generally re-assert as long as the tx fifo is empty,
> which would require disabling it.
Yup, and that's exactly what we do: http://lkml.org/lkml/2012/9/11/119
Your words made me think that clear_irq() might be indeed a somewhat
inappropriate name. We have to be even stricter on its definition and
behaviour.
So, returning to your question "What does clear_irqs() mean", I'd
answer that: the function must do whatever needed to lower the IRQ
line, plus the function must leave the port in the state that it's
still able to throw RX interrupts after the call.
So, the 100% proper name for this function would be this:
quiesce_irqs_but_rx()
It's a bit long, but does exactly what the name states.
Thanks!
Anton.
^ permalink raw reply
* [PATCH] serial: Samsung: Fix return value
From: Sachin Kamat @ 2012-09-12 6:30 UTC (permalink / raw)
To: linux-serial; +Cc: alan, gregkh, sachin.kamat, patches
Return the value returned by the failing function instead
of -1 (which does not convey the right error information).
Fixes the following smatch warning:
drivers/tty/serial/samsung.c:1687 s3c24xx_serial_modinit() info:
why not propagate 'ret' from uart_register_driver() instead of -1?
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
---
drivers/tty/serial/samsung.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/drivers/tty/serial/samsung.c b/drivers/tty/serial/samsung.c
index bdaa06f..8eef114 100644
--- a/drivers/tty/serial/samsung.c
+++ b/drivers/tty/serial/samsung.c
@@ -1684,7 +1684,7 @@ static int __init s3c24xx_serial_modinit(void)
ret = uart_register_driver(&s3c24xx_uart_drv);
if (ret < 0) {
pr_err("Failed to register Samsung UART driver\n");
- return -1;
+ return ret;
}
return platform_driver_register(&samsung_serial_driver);
--
1.7.4.1
^ permalink raw reply related
* Re: [PATCH v4 00/21] OMAP UART Patches
From: Felipe Balbi @ 2012-09-12 6:23 UTC (permalink / raw)
To: Paul Walmsley
Cc: Felipe Balbi, Greg KH, alan, Tony Lindgren, Kevin Hilman,
Linux OMAP Mailing List, Linux ARM Kernel Mailing List,
linux-serial, Linux Kernel Mailing List, Santosh Shilimkar,
Shubhrajyoti Datta, Sourav Poddar
In-Reply-To: <alpine.DEB.2.00.1209112141220.9444@utopia.booyaka.com>
[-- Attachment #1: Type: text/plain, Size: 1533 bytes --]
Hi,
On Tue, Sep 11, 2012 at 10:02:48PM +0000, Paul Walmsley wrote:
>
> Hi Felipe
>
> Just tested these OMAP serial changes at commit
> e36851d0fa94b0f7802b3cc80406dbd3ef4f2f16 ("serial: omap: fix compile
> breakage"). There's good news and bad news...
>
> The good news is that after applying this series, the 'OMAP4 UART garbage
> on long transmit buffers when PM is enabled' bug:
>
> http://www.pwsan.com/omap/testlogs/test_v3.6-rc5/20120908202511/pm/4430es2panda/4430es2panda_log.txt
>
> ... goes away. (Unclear if it's because the underlying bug was fixed, or
> if unrelated changes are masking it.) Not sure what caused the problem to
> go away exactly, but it's one of the changes between d37c6ceb and bf63a08.
> So that's good!
I'd point the finger at sticking to put_autosuspend() as that would give
HW enough time to actually unload all bytes from its FIFO through the
UART lines. can you check if forcing the autosuspend_delay to -1
triggers the issue again ? If it does, it's some help from autosuspend,
which would mean we still have the problem and needs to be properly
fixed.
> The bad news is that N800 no longer boots -- or the UART dies during
> serial init:
>
> http://www.pwsan.com/omap/testlogs/test_tty_next_e36851d0/20120910020323/boot/2420n800/2420n800_log.txt
>
> The problem doesn't seem to affect the 2430SDP.
>
> Could you put together a patch to fix N800?
I'll see what I can do. BTW, is that log with DEBUG_LL enabled ?
cheers
--
balbi
[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 836 bytes --]
^ permalink raw reply
* Re: [RFC] tty/serial/kgdboc: Add and wire up clear_irqs callback
From: Colin Cross @ 2012-09-12 4:40 UTC (permalink / raw)
To: Anton Vorontsov
Cc: Thomas Gleixner, Alan Cox, Andrew Morton, Russell King,
Jason Wessel, Greg Kroah-Hartman, Alan Cox,
Arve Hjønnevåg, Brian Swetland, John Stultz,
linux-kernel, linux-arm-kernel, linaro-kernel, patches,
kernel-team, kgdb-bugreport, linux-serial
In-Reply-To: <20120912040657.GA3880@lizard>
On Tue, Sep 11, 2012 at 9:06 PM, Anton Vorontsov
<anton.vorontsov@linaro.org> wrote:
> On Tue, Sep 11, 2012 at 08:42:46PM -0700, Colin Cross wrote:
> [...]
>> > The "problem" is in the last step. If we exit NMI without making UART
>> > know that we're done with the interrupt, we will reenter the NMI
>> > immediately, even without any new characters from the UART.
>>
>> The UART irq line should go low when you read the character out of the
>
> Probably some controllers may lower the line by themselves, but not
> all, and probably most of them need an explicit clear.
Anything 8250-based will clear the interrupt automatically, assuming
you read the status registers as well as the character register.
>> receive buffer, or the polling rx function should clear the interrupt
>> for you.
>
> Yes, that's an option. But that way we add a new semantic for the
> polling routines, and effecitvely we just merge the two callbacks.
>
> Of course, if Alan is OK with this, I'm more than OK too. :-)
>
> (But the polling routines would need to clear all interrupts, not
> just rx/tx. For example, if the controller indicated some error, and
> nobody clears it, then we'll start reentering infinitely.)
For exynos5, the only non-8250 based serial port I've come across, we
clear all interrupts in the rx poll function (see
https://android.googlesource.com/kernel/exynos/+/ef427aafffb7153dde59745e440fd7ec41ea969d/arch/arm/mach-exynos/exynos_fiq_debugger.c).
>> If you use a clear_irqs callback, you can drop characters if
>> one arrives between the last character buffer read and calling
>> clear_irqs.
>
> Only if we call clear_irqs() after reading the characters, but we do
> it before. So if new characters are available, we will reenter NMI,
> which is OK.
>
> But if used incorrectly, it truly can cause dropping (or staling) of
> characters, so I'd better add some comments about this.
What does clear_irqs() mean for a status or tx interrupt? The tx
interrupt will generally re-assert as long as the tx fifo is empty,
which would require disabling it. On 8250 ports, status interrupts
will re-assert until the corresponding status register is read.
^ permalink raw reply
* Re: [RFC] tty/serial/kgdboc: Add and wire up clear_irqs callback
From: Anton Vorontsov @ 2012-09-12 4:06 UTC (permalink / raw)
To: Colin Cross
Cc: Thomas Gleixner, Alan Cox, Andrew Morton, Russell King,
Jason Wessel, Greg Kroah-Hartman, Alan Cox,
Arve Hjønnevåg, Brian Swetland, John Stultz,
linux-kernel, linux-arm-kernel, linaro-kernel, patches,
kernel-team, kgdb-bugreport, linux-serial
In-Reply-To: <CAMbhsRTmZyxFE-vAa-UvNE8KJ2f0cfXP7mncXKcpUiNF6C9PUQ@mail.gmail.com>
On Tue, Sep 11, 2012 at 08:42:46PM -0700, Colin Cross wrote:
[...]
> > The "problem" is in the last step. If we exit NMI without making UART
> > know that we're done with the interrupt, we will reenter the NMI
> > immediately, even without any new characters from the UART.
>
> The UART irq line should go low when you read the character out of the
Probably some controllers may lower the line by themselves, but not
all, and probably most of them need an explicit clear.
> receive buffer, or the polling rx function should clear the interrupt
> for you.
Yes, that's an option. But that way we add a new semantic for the
polling routines, and effecitvely we just merge the two callbacks.
Of course, if Alan is OK with this, I'm more than OK too. :-)
(But the polling routines would need to clear all interrupts, not
just rx/tx. For example, if the controller indicated some error, and
nobody clears it, then we'll start reentering infinitely.)
> If you use a clear_irqs callback, you can drop characters if
> one arrives between the last character buffer read and calling
> clear_irqs.
Only if we call clear_irqs() after reading the characters, but we do
it before. So if new characters are available, we will reenter NMI,
which is OK.
But if used incorrectly, it truly can cause dropping (or staling) of
characters, so I'd better add some comments about this.
Thanks!
Anton.
^ permalink raw reply
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