| Message ID | 1592835984-28613-5-git-send-email-sumit.garg@linaro.org |
|---|---|
| State | New |
| Headers | show |
| Series | Enable support for kgdb NMI console feature | expand |
On Mon, Jun 22, 2020 at 07:56:21PM +0530, Sumit Garg wrote: > From: Daniel Thompson <daniel.thompson@linaro.org> > > Add a generic NMI fallback to support kgdb NMI console feature which can > be overridden by arch specific implementation. arch_kgdb_ops.enable_nmi should probably be killed off. Given we now have request_nmi() I'm dubious there are any good reasons to use this API. Daniel. > This common fallback mechanism utilizes kgdb IO based interrupt in order > to support entry into kgdb if a user types in kgdb_nmi_magic sequence. So > during NMI console init, NMI handler is installed corresponding to kgdb > IO based NMI which is invoked when a character is pending and that can be > cleared by calling @read_char until it returns NO_POLL_CHAR. > > Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org> > Co-developed-by: Sumit Garg <sumit.garg@linaro.org> > Signed-off-by: Sumit Garg <sumit.garg@linaro.org> > --- > drivers/tty/serial/kgdb_nmi.c | 47 ++++++++++++++++++++++++++++++++++++------- > 1 file changed, 40 insertions(+), 7 deletions(-) > > diff --git a/drivers/tty/serial/kgdb_nmi.c b/drivers/tty/serial/kgdb_nmi.c > index b32c6b1..2580f39 100644 > --- a/drivers/tty/serial/kgdb_nmi.c > +++ b/drivers/tty/serial/kgdb_nmi.c > @@ -42,9 +42,46 @@ MODULE_PARM_DESC(magic, "magic sequence to enter NMI debugger (default $3#33)"); > static atomic_t kgdb_nmi_num_readers = ATOMIC_INIT(0); > static struct console *orig_dbg_cons; > > +static int kgdb_nmi_poll_one_knock(void); > + > +static irqreturn_t kgdb_handle_nmi(int irq, void *dev_id) > +{ > + int ret; > + > + if (kgdb_nmi_knock < 0) { > + kgdb_breakpoint(); > + return IRQ_HANDLED; > + } > + > + ret = kgdb_nmi_poll_one_knock(); > + if (ret == NO_POLL_CHAR) > + return IRQ_NONE; > + > + while (ret != 1) { > + ret = kgdb_nmi_poll_one_knock(); > + if (ret == NO_POLL_CHAR) > + return IRQ_HANDLED; > + } > + > + kgdb_breakpoint(); > + return IRQ_HANDLED; > +} > + > static int kgdb_nmi_console_setup(struct console *co, char *options) > { > - arch_kgdb_ops.enable_nmi(1); > + int res; > + > + if (arch_kgdb_ops.enable_nmi) { > + arch_kgdb_ops.enable_nmi(1); > + } else if (dbg_io_ops->request_nmi) { > + res = dbg_io_ops->request_nmi(kgdb_handle_nmi, co); > + if (res) { > + pr_err("ttyNMI0: Cannot request nmi/irq\n"); > + return res; > + } > + } else { > + return -ENODEV; > + } > > /* The NMI console uses the dbg_io_ops to issue console messages. To > * avoid duplicate messages during kdb sessions we must inform kdb's > @@ -328,9 +365,6 @@ int kgdb_register_nmi_console(void) > { > int ret; > > - if (!arch_kgdb_ops.enable_nmi) > - return 0; > - > kgdb_nmi_tty_driver = alloc_tty_driver(1); > if (!kgdb_nmi_tty_driver) { > pr_err("%s: cannot allocate tty\n", __func__); > @@ -380,9 +414,8 @@ int kgdb_unregister_nmi_console(void) > { > int ret; > > - if (!arch_kgdb_ops.enable_nmi) > - return 0; > - arch_kgdb_ops.enable_nmi(0); > + if (arch_kgdb_ops.enable_nmi) > + arch_kgdb_ops.enable_nmi(0); > > ret = unregister_console(&kgdb_nmi_console); > if (ret) > -- > 2.7.4 >
On Mon, 22 Jun 2020 at 22:06, Daniel Thompson <daniel.thompson@linaro.org> wrote: > > On Mon, Jun 22, 2020 at 07:56:21PM +0530, Sumit Garg wrote: > > From: Daniel Thompson <daniel.thompson@linaro.org> > > > > Add a generic NMI fallback to support kgdb NMI console feature which can > > be overridden by arch specific implementation. > > arch_kgdb_ops.enable_nmi should probably be killed off. Given we now > have request_nmi() I'm dubious there are any good reasons to use this > API. > Sounds reasonable. Along with this, kgdb_nmi_poll_knock() seems to be unused and can be removed as well. -Sumit > > Daniel. > > > > This common fallback mechanism utilizes kgdb IO based interrupt in order > > to support entry into kgdb if a user types in kgdb_nmi_magic sequence. So > > during NMI console init, NMI handler is installed corresponding to kgdb > > IO based NMI which is invoked when a character is pending and that can be > > cleared by calling @read_char until it returns NO_POLL_CHAR. > > > > Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org> > > Co-developed-by: Sumit Garg <sumit.garg@linaro.org> > > Signed-off-by: Sumit Garg <sumit.garg@linaro.org> > > --- > > drivers/tty/serial/kgdb_nmi.c | 47 ++++++++++++++++++++++++++++++++++++------- > > 1 file changed, 40 insertions(+), 7 deletions(-) > > > > diff --git a/drivers/tty/serial/kgdb_nmi.c b/drivers/tty/serial/kgdb_nmi.c > > index b32c6b1..2580f39 100644 > > --- a/drivers/tty/serial/kgdb_nmi.c > > +++ b/drivers/tty/serial/kgdb_nmi.c > > @@ -42,9 +42,46 @@ MODULE_PARM_DESC(magic, "magic sequence to enter NMI debugger (default $3#33)"); > > static atomic_t kgdb_nmi_num_readers = ATOMIC_INIT(0); > > static struct console *orig_dbg_cons; > > > > +static int kgdb_nmi_poll_one_knock(void); > > + > > +static irqreturn_t kgdb_handle_nmi(int irq, void *dev_id) > > +{ > > + int ret; > > + > > + if (kgdb_nmi_knock < 0) { > > + kgdb_breakpoint(); > > + return IRQ_HANDLED; > > + } > > + > > + ret = kgdb_nmi_poll_one_knock(); > > + if (ret == NO_POLL_CHAR) > > + return IRQ_NONE; > > + > > + while (ret != 1) { > > + ret = kgdb_nmi_poll_one_knock(); > > + if (ret == NO_POLL_CHAR) > > + return IRQ_HANDLED; > > + } > > + > > + kgdb_breakpoint(); > > + return IRQ_HANDLED; > > +} > > + > > static int kgdb_nmi_console_setup(struct console *co, char *options) > > { > > - arch_kgdb_ops.enable_nmi(1); > > + int res; > > + > > + if (arch_kgdb_ops.enable_nmi) { > > + arch_kgdb_ops.enable_nmi(1); > > + } else if (dbg_io_ops->request_nmi) { > > + res = dbg_io_ops->request_nmi(kgdb_handle_nmi, co); > > + if (res) { > > + pr_err("ttyNMI0: Cannot request nmi/irq\n"); > > + return res; > > + } > > + } else { > > + return -ENODEV; > > + } > > > > /* The NMI console uses the dbg_io_ops to issue console messages. To > > * avoid duplicate messages during kdb sessions we must inform kdb's > > @@ -328,9 +365,6 @@ int kgdb_register_nmi_console(void) > > { > > int ret; > > > > - if (!arch_kgdb_ops.enable_nmi) > > - return 0; > > - > > kgdb_nmi_tty_driver = alloc_tty_driver(1); > > if (!kgdb_nmi_tty_driver) { > > pr_err("%s: cannot allocate tty\n", __func__); > > @@ -380,9 +414,8 @@ int kgdb_unregister_nmi_console(void) > > { > > int ret; > > > > - if (!arch_kgdb_ops.enable_nmi) > > - return 0; > > - arch_kgdb_ops.enable_nmi(0); > > + if (arch_kgdb_ops.enable_nmi) > > + arch_kgdb_ops.enable_nmi(0); > > > > ret = unregister_console(&kgdb_nmi_console); > > if (ret) > > -- > > 2.7.4 > >
diff --git a/drivers/tty/serial/kgdb_nmi.c b/drivers/tty/serial/kgdb_nmi.c index b32c6b1..2580f39 100644 --- a/drivers/tty/serial/kgdb_nmi.c +++ b/drivers/tty/serial/kgdb_nmi.c @@ -42,9 +42,46 @@ MODULE_PARM_DESC(magic, "magic sequence to enter NMI debugger (default $3#33)"); static atomic_t kgdb_nmi_num_readers = ATOMIC_INIT(0); static struct console *orig_dbg_cons; +static int kgdb_nmi_poll_one_knock(void); + +static irqreturn_t kgdb_handle_nmi(int irq, void *dev_id) +{ + int ret; + + if (kgdb_nmi_knock < 0) { + kgdb_breakpoint(); + return IRQ_HANDLED; + } + + ret = kgdb_nmi_poll_one_knock(); + if (ret == NO_POLL_CHAR) + return IRQ_NONE; + + while (ret != 1) { + ret = kgdb_nmi_poll_one_knock(); + if (ret == NO_POLL_CHAR) + return IRQ_HANDLED; + } + + kgdb_breakpoint(); + return IRQ_HANDLED; +} + static int kgdb_nmi_console_setup(struct console *co, char *options) { - arch_kgdb_ops.enable_nmi(1); + int res; + + if (arch_kgdb_ops.enable_nmi) { + arch_kgdb_ops.enable_nmi(1); + } else if (dbg_io_ops->request_nmi) { + res = dbg_io_ops->request_nmi(kgdb_handle_nmi, co); + if (res) { + pr_err("ttyNMI0: Cannot request nmi/irq\n"); + return res; + } + } else { + return -ENODEV; + } /* The NMI console uses the dbg_io_ops to issue console messages. To * avoid duplicate messages during kdb sessions we must inform kdb's @@ -328,9 +365,6 @@ int kgdb_register_nmi_console(void) { int ret; - if (!arch_kgdb_ops.enable_nmi) - return 0; - kgdb_nmi_tty_driver = alloc_tty_driver(1); if (!kgdb_nmi_tty_driver) { pr_err("%s: cannot allocate tty\n", __func__); @@ -380,9 +414,8 @@ int kgdb_unregister_nmi_console(void) { int ret; - if (!arch_kgdb_ops.enable_nmi) - return 0; - arch_kgdb_ops.enable_nmi(0); + if (arch_kgdb_ops.enable_nmi) + arch_kgdb_ops.enable_nmi(0); ret = unregister_console(&kgdb_nmi_console); if (ret)