[PATCH AUTOSEL 4.14 076/127] powerpc/83xx: handle machine check caused by watchdog timer

Sasha Levin
2019-11-22T06:09:25Z

From: Christophe Leroy <christophe.leroy@c-s.fr>

[ Upstream commit 0deae39cec6dab3a66794f3e9e83ca4dc30080f1 ]

When the watchdog timer is set in interrupt mode, it causes a
machine check when it times out. The purpose of this mode is to
ease debugging, not to crash the kernel and reboot the machine.

This patch implements a special handling for that, in order to not
crash the kernel if the watchdog times out while in interrupt or
within the idle task.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
[scottwood: added missing #include]
Signed-off-by: Scott Wood <oss@buserror.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/powerpc/include/asm/cputable.h | 1 +
arch/powerpc/include/asm/reg.h | 2 ++
arch/powerpc/kernel/cputable.c | 10 ++++++----
arch/powerpc/platforms/83xx/misc.c | 17 +++++++++++++++++
4 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/include/asm/cputable.h b/arch/powerpc/include/asm/cputable.h
index 7e3ccf21830e6..e4451b30d7e32 100644
--- a/arch/powerpc/include/asm/cputable.h
+++ b/arch/powerpc/include/asm/cputable.h
@@ -45,6 +45,7 @@ extern int machine_check_e500(struct pt_regs *regs);
extern int machine_check_e200(struct pt_regs *regs);
extern int machine_check_47x(struct pt_regs *regs);
int machine_check_8xx(struct pt_regs *regs);
+int machine_check_83xx(struct pt_regs *regs);

extern void cpu_down_flush_e500v2(void);
extern void cpu_down_flush_e500mc(void);
diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h
index b779f3ccd4126..05f3c2b3aa0ec 100644
--- a/arch/powerpc/include/asm/reg.h
+++ b/arch/powerpc/include/asm/reg.h
@@ -733,6 +733,8 @@
#define SRR1_PROGTRAP 0x00020000 /* Trap */
#define SRR1_PROGADDR 0x00010000 /* SRR0 contains subsequent addr */

+#define SRR1_MCE_MCP 0x00080000 /* Machine check signal caused interrupt */
+
#define SPRN_HSRR0 0x13A /* Save/Restore Register 0 */
#define SPRN_HSRR1 0x13B /* Save/Restore Register 1 */
#define HSRR1_DENORM 0x00100000 /* Denorm exception */
diff --git a/arch/powerpc/kernel/cputable.c b/arch/powerpc/kernel/cputable.c
index 760872916013d..da4b0e3792380 100644
--- a/arch/powerpc/kernel/cputable.c
+++ b/arch/powerpc/kernel/cputable.c
@@ -1185,6 +1185,7 @@ static struct cpu_spec __initdata cpu_specs[] = {
.machine_check = machine_check_generic,
.platform = "ppc603",
},
+#ifdef CONFIG_PPC_83xx
{ /* e300c1 (a 603e core, plus some) on 83xx */
.pvr_mask = 0x7fff0000,
.pvr_value = 0x00830000,
@@ -1195,7 +1196,7 @@ static struct cpu_spec __initdata cpu_specs[] = {
.icache_bsize = 32,
.dcache_bsize = 32,
.cpu_setup = __setup_cpu_603,
- .machine_check = machine_check_generic,
+ .machine_check = machine_check_83xx,
.platform = "ppc603",
},
{ /* e300c2 (an e300c1 core, plus some, minus FPU) on 83xx */
@@ -1209,7 +1210,7 @@ static struct cpu_spec __initdata cpu_specs[] = {
.icache_bsize = 32,
.dcache_bsize = 32,
.cpu_setup = __setup_cpu_603,
- .machine_check = machine_check_generic,
+ .machine_check = machine_check_83xx,
.platform = "ppc603",
},
{ /* e300c3 (e300c1, plus one IU, half cache size) on 83xx */
@@ -1223,7 +1224,7 @@ static struct cpu_spec __initdata cpu_specs[] = {
.icache_bsize = 32,
.dcache_bsize = 32,
.cpu_setup = __setup_cpu_603,
- .machine_check = machine_check_generic,
+ .machine_check = machine_check_83xx,
.num_pmcs = 4,
.oprofile_cpu_type = "ppc/e300",
.oprofile_type = PPC_OPROFILE_FSL_EMB,
@@ -1240,12 +1241,13 @@ static struct cpu_spec __initdata cpu_specs[] = {
.icache_bsize = 32,
.dcache_bsize = 32,
.cpu_setup = __setup_cpu_603,
- .machine_check = machine_check_generic,
+ .machine_check = machine_check_83xx,
.num_pmcs = 4,
.oprofile_cpu_type = "ppc/e300",
.oprofile_type = PPC_OPROFILE_FSL_EMB,
.platform = "ppc603",
},
+#endif
{ /* default match, we assume split I/D cache & TB (non-601)... */
.pvr_mask = 0x00000000,
.pvr_value = 0x00000000,
diff --git a/arch/powerpc/platforms/83xx/misc.c b/arch/powerpc/platforms/83xx/misc.c
index d75c9816a5c92..2b6589fe812dd 100644
--- a/arch/powerpc/platforms/83xx/misc.c
+++ b/arch/powerpc/platforms/83xx/misc.c
@@ -14,6 +14,7 @@
#include <linux/of_platform.h>
#include <linux/pci.h>

+#include <asm/debug.h>
#include <asm/io.h>
#include <asm/hw_irq.h>
#include <asm/ipic.h>
@@ -150,3 +151,19 @@ void __init mpc83xx_setup_arch(void)

mpc83xx_setup_pci();
}
+
+int machine_check_83xx(struct pt_regs *regs)
+{
+ u32 mask = 1 << (31 - IPIC_MCP_WDT);
+
+ if (!(regs->msr & SRR1_MCE_MCP) || !(ipic_get_mcp_status() & mask))
+ return machine_check_generic(regs);
+ ipic_clear_mcp_status(mask);
+
+ if (debugger_fault_handler(regs))
+ return 1;
+
+ die("Watchdog NMI Reset", regs, 0);
+
+ return 1;
+}
--
2.20.1