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[PATCH v2 0/4] sparc64: Jump to boot prom from console on panic

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  [PATCH v2 0/4] sparc64: Jump to boot prom from console on panic Vijay Kumar <vijay.ac.kumar@oracle.com> - 2016-11-11 19:20 +0100
    [PATCH v2 4/4] Documentation/sparc: Steps for sending break on sunhv console Vijay Kumar <vijay.ac.kumar@oracle.com> - 2016-11-11 19:20 +0100
    [PATCH v2 3/4] sparc64: Send break twice from console to return to boot prom Vijay Kumar <vijay.ac.kumar@oracle.com> - 2016-11-11 19:20 +0100
    [PATCH v2 1/4] sparc64: Set cpu state to offline when stopped Vijay Kumar <vijay.ac.kumar@oracle.com> - 2016-11-11 19:20 +0100
    [PATCH v2 2/4] sparc64: Migrate hvcons irq to panicked cpu Vijay Kumar <vijay.ac.kumar@oracle.com> - 2016-11-11 19:20 +0100
      Re: [PATCH v2 2/4] sparc64: Migrate hvcons irq to panicked cpu David Miller <davem@davemloft.net> - 2016-11-19 16:50 +0100

#1519945 — [PATCH v2 0/4] sparc64: Jump to boot prom from console on panic

Currently Stop-A (L1A) does not make the kernel switch to OBP on panic. This
patchset addresses this issue. Also, now we can cause a jump to OBP by sending
'break' twice from sunhv console. On bare metal, one can send a break by
typing Esc + 'B' + Sysrq (or whatever). On LDOM, press Ctrl + ] in telnet,
and then "send break" at the telnet prompt.

      sparc64: Set cpu state to offline when stopped
      sparc64: Migrate hvcons irq to panicked cpu
      sparc64: Send break twice from console to return to boot prom
      Documentation/sparc: Steps for sending break on sunhv console

 Documentation/sparc/console.txt |    9 +++++++++
 arch/sparc/include/asm/setup.h  |    1 +
 arch/sparc/kernel/smp_64.c      |    9 ++++++++-
 drivers/tty/serial/sunhv.c      |   12 +++++++++++-
 kernel/panic.c                  |    3 ++-
 5 files changed, 31 insertions(+), 3 deletions(-)
 create mode 100644 Documentation/sparc/console.txt



--
1.7.1

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#1519946 — [PATCH v2 4/4] Documentation/sparc: Steps for sending break on sunhv console

Documented the steps for sending break on sunhv console.

Signed-off-by: Vijay Kumar <vijay.ac.kumar@oracle.com>
---
 Documentation/sparc/console.txt |    9 +++++++++
 1 files changed, 9 insertions(+), 0 deletions(-)

diff --git a/Documentation/sparc/console.txt b/Documentation/sparc/console.txt
new file mode 100644
index 0000000..ab55353
--- /dev/null
+++ b/Documentation/sparc/console.txt
@@ -0,0 +1,9 @@
+Steps for sending 'break' on sunhv console:
+===========================================
+
+On Baremetal:
+   1. press   Esc + 'B'
+
+On LDOM:
+   1. press    Ctrl + ']'
+   2. telnet> send  break	
-- 
1.7.1

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#1519951 — [PATCH v2 3/4] sparc64: Send break twice from console to return to boot prom

Now we can also jump to boot prom from sunhv console by sending
break twice on console for both running and panicked kernel
cases.

Signed-off-by: Vijay Kumar <vijay.ac.kumar@oracle.com>
---
 drivers/tty/serial/sunhv.c |    6 +++++-
 kernel/panic.c             |    3 ++-
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/sunhv.c b/drivers/tty/serial/sunhv.c
index 59828d8..33c35b4 100644
--- a/drivers/tty/serial/sunhv.c
+++ b/drivers/tty/serial/sunhv.c
@@ -116,7 +116,7 @@ static int receive_chars_getchar(struct uart_port *port)
 
 static int receive_chars_read(struct uart_port *port)
 {
-	int saw_console_brk = 0;
+	static int saw_console_brk;
 	int limit = 10000;
 
 	while (limit-- > 0) {
@@ -128,6 +128,9 @@ static int receive_chars_read(struct uart_port *port)
 			bytes_read = 0;
 
 			if (stat == CON_BREAK) {
+				if (saw_console_brk)
+					sun_do_break();
+
 				if (uart_handle_break(port))
 					continue;
 				saw_console_brk = 1;
@@ -151,6 +154,7 @@ static int receive_chars_read(struct uart_port *port)
 		if (port->sysrq != 0 &&  *con_read_page) {
 			for (i = 0; i < bytes_read; i++)
 				uart_handle_sysrq_char(port, con_read_page[i]);
+			saw_console_brk = 0;
 		}
 
 		if (port->state == NULL)
diff --git a/kernel/panic.c b/kernel/panic.c
index ca8cea1..4fe3b28 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -240,7 +240,8 @@ void panic(const char *fmt, ...)
 		extern int stop_a_enabled;
 		/* Make sure the user can actually press Stop-A (L1-A) */
 		stop_a_enabled = 1;
-		pr_emerg("Press Stop-A (L1-A) to return to the boot prom\n");
+		pr_emerg("Press Stop-A (L1-A) from sun keyboard or send break\n"
+			 "twice on console to return to the boot prom\n");
 	}
 #endif
 #if defined(CONFIG_S390)
-- 
1.7.1

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#1519952 — [PATCH v2 1/4] sparc64: Set cpu state to offline when stopped

CPU needs to be marked offline before stopping it. When not marked
offline, the xcall receives HV_EWOULDBLOCK and so assumes that not all
CPUs received the message, and retries. After 10000 retries, it finally
fails with fatal mondo timeout.

Signed-off-by: Vijay Kumar <vijay.ac.kumar@oracle.com>
---
 arch/sparc/kernel/smp_64.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/arch/sparc/kernel/smp_64.c b/arch/sparc/kernel/smp_64.c
index d3035ba..14138ad 100644
--- a/arch/sparc/kernel/smp_64.c
+++ b/arch/sparc/kernel/smp_64.c
@@ -1435,6 +1435,7 @@ void __irq_entry smp_receive_signal_client(int irq, struct pt_regs *regs)
 
 static void stop_this_cpu(void *dummy)
 {
+	set_cpu_online(smp_processor_id(), false);
 	prom_stopself();
 }
 
@@ -1446,6 +1447,8 @@ void smp_send_stop(void)
 		for_each_online_cpu(cpu) {
 			if (cpu == smp_processor_id())
 				continue;
+
+			set_cpu_online(cpu, false);
 #ifdef CONFIG_SUN_LDOMS
 			if (ldom_domaining_enabled) {
 				unsigned long hv_err;
-- 
1.7.1

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#1519953 — [PATCH v2 2/4] sparc64: Migrate hvcons irq to panicked cpu

On panic, all other CPUs are stopped except the one which had
hit panic. To keep console alive, we need to migrate hvcons irq
to panicked CPU.

Signed-off-by: Vijay Kumar <vijay.ac.kumar@oracle.com>
---
 arch/sparc/include/asm/setup.h |    1 +
 arch/sparc/kernel/smp_64.c     |    6 +++++-
 drivers/tty/serial/sunhv.c     |    6 ++++++
 3 files changed, 12 insertions(+), 1 deletions(-)

diff --git a/arch/sparc/include/asm/setup.h b/arch/sparc/include/asm/setup.h
index 29d64b1..41691a5 100644
--- a/arch/sparc/include/asm/setup.h
+++ b/arch/sparc/include/asm/setup.h
@@ -61,6 +61,7 @@ extern atomic_t dcpage_flushes_xcall;
 extern int sysctl_tsb_ratio;
 #endif
 
+void sunhv_migrate_hvcons_irq(int cpu);
 void sun_do_break(void);
 extern int stop_a_enabled;
 extern int scons_pwroff;
diff --git a/arch/sparc/kernel/smp_64.c b/arch/sparc/kernel/smp_64.c
index 14138ad..52dc4b7 100644
--- a/arch/sparc/kernel/smp_64.c
+++ b/arch/sparc/kernel/smp_64.c
@@ -1444,8 +1444,12 @@ void smp_send_stop(void)
 	int cpu;
 
 	if (tlb_type == hypervisor) {
+		int this_cpu = smp_processor_id();
+
+		sunhv_migrate_hvcons_irq(this_cpu);
+
 		for_each_online_cpu(cpu) {
-			if (cpu == smp_processor_id())
+			if (cpu == this_cpu)
 				continue;
 
 			set_cpu_online(cpu, false);
diff --git a/drivers/tty/serial/sunhv.c b/drivers/tty/serial/sunhv.c
index 4e603d0..59828d8 100644
--- a/drivers/tty/serial/sunhv.c
+++ b/drivers/tty/serial/sunhv.c
@@ -398,6 +398,12 @@ static struct uart_driver sunhv_reg = {
 
 static struct uart_port *sunhv_port;
 
+void sunhv_migrate_hvcons_irq(int cpu)
+{
+	/* Migrate hvcons irq to param cpu */
+	irq_force_affinity(sunhv_port->irq, cpumask_of(cpu));
+}
+
 /* Copy 's' into the con_write_page, decoding "\n" into
  * "\r\n" along the way.  We have to return two lengths
  * because the caller needs to know how much to advance
-- 
1.7.1

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#1526022 — Re: [PATCH v2 2/4] sparc64: Migrate hvcons irq to panicked cpu

From: Vijay Kumar <vijay.ac.kumar@oracle.com>
Date: Fri, 11 Nov 2016 10:11:57 -0800

> @@ -1444,8 +1444,12 @@ void smp_send_stop(void)
>  	int cpu;
>  
>  	if (tlb_type == hypervisor) {
> +		int this_cpu = smp_processor_id();
> +
> +		sunhv_migrate_hvcons_irq(this_cpu);
> +

You can't unconditionally call into code that might be configured
out by a Kconfig option, as you are doing here.

If SERIAL_SUNHV=n this change will thus result in a build error.

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