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authorDaniel Thompson <daniel.thompson@linaro.org>2015-01-14 17:01:20 +0000
committerDaniel Thompson <daniel.thompson@linaro.org>2015-01-20 15:51:42 +0000
commit942ce6ffb99d3a015ea9ac9acd795e4009cb585d (patch)
tree61909beea5b92453435876229e4f82a01fca6748
parent681315604a3f35872205a5bb22850c2f5a6ded71 (diff)
downloadlinux-942ce6ffb99d3a015ea9ac9acd795e4009cb585d.tar.gz
misc: Add a lockup driver to get the CPUs wedged
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
-rw-r--r--drivers/misc/Makefile1
-rw-r--r--drivers/misc/lockup.c265
2 files changed, 266 insertions, 0 deletions
diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
index 37543479a741..d50db65642c7 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -57,3 +57,4 @@ obj-$(CONFIG_GENWQE) += genwqe/
obj-$(CONFIG_ECHO) += echo/
obj-$(CONFIG_VEXPRESS_SYSCFG) += vexpress-syscfg.o
obj-$(CONFIG_CXL_BASE) += cxl/
+obj-y += lockup.o
diff --git a/drivers/misc/lockup.c b/drivers/misc/lockup.c
new file mode 100644
index 000000000000..55d95dc83b3c
--- /dev/null
+++ b/drivers/misc/lockup.c
@@ -0,0 +1,265 @@
+/*
+ * lockup.c
+ *
+ * Deliberately do "stupid" things to see if we can debug them
+ * properly.
+ *
+ * The sole purpose of this module is to help with debugging of system
+ * debug tools.
+ *
+ * Copyright (C) 2014 Linaro Limited
+ * Daniel Thompson <daniel.thompson@linaro.org>
+ */
+
+#include <linux/module.h>
+#include <linux/debugfs.h>
+#include <linux/debug_locks.h>
+
+static DEFINE_SPINLOCK(lockup_lock);
+
+static int lockup_do_action_on_cpu(int cpu, long (*action)(void *))
+{
+ if (cpu == -1)
+ (void) action(NULL);
+
+ if (cpu < 0 || cpu > num_possible_cpus())
+ return -EINVAL;
+
+ /* work_on_cpu() ends up performing an uninterruptible
+ * wait-for-completion. This means we'll lose the prompt
+ * regardless of the CPU we send the work to.
+ */
+ work_on_cpu(cpu, action, NULL);
+
+ return 0;
+}
+
+#define DEFINE_LOCKUP_ATTRIBUTE(__fops, __action) \
+static int __fops ## _set(void *data, u64 val) \
+{ \
+ lockup_do_action_on_cpu(val, __action); \
+ return 0; \
+} \
+DEFINE_SIMPLE_ATTRIBUTE(__fops, NULL, __fops ## _set, "%llu\n")
+
+
+static long do_lockup_spin_lock(void *info)
+{
+ pr_warn("lockup[%u]: About to wedge in spin_lock\n", get_cpu());
+ spin_lock(&lockup_lock);
+ debug_locks_off();
+ spin_lock(&lockup_lock);
+ spin_unlock(&lockup_lock);
+ spin_unlock(&lockup_lock);
+ return 0;
+}
+DEFINE_LOCKUP_ATTRIBUTE(lockup_spin_lock_fops, do_lockup_spin_lock);
+
+static long do_lockup_spin_lock_irqsave(void *info)
+{
+ unsigned long flags1, flags2;
+
+ pr_warn("lockup[%u]: About to wedge in spin_lock_irqsave\n", get_cpu());
+ spin_lock_irqsave(&lockup_lock, flags1);
+ debug_locks_off();
+ spin_lock_irqsave(&lockup_lock, flags2);
+ spin_unlock_irqrestore(&lockup_lock, flags2);
+ spin_unlock_irqrestore(&lockup_lock, flags1);
+ return 0;
+}
+DEFINE_LOCKUP_ATTRIBUTE(lockup_spin_lock_irqsave_fops,
+ do_lockup_spin_lock_irqsave);
+
+/* --- */
+
+#ifdef CONFIG_ARM64
+
+#include <asm/sysreg.h>
+
+#define DEFAULT_PMR_VALUE 0xf0
+
+#define DECLARE_RW_ACCESSOR(x) \
+static inline __maybe_unused void writeq_##x(u64 val) \
+{ \
+ asm volatile("msr_s " __stringify(x) ", %0" : : "r"(val)); \
+} \
+static inline __maybe_unused u64 readq_##x(void) \
+{ \
+ u64 val; \
+\
+ asm volatile("mrs_s %0, " __stringify(x) : "=r" (val)); \
+ return val; \
+}
+
+#define MIDR_EL1 sys_reg(3, 0, 0, 0, 0)
+#define MPIDR_EL1 sys_reg(3, 0, 0, 0, 5)
+#define VPIDR_EL2 sys_reg(3, 6, 0, 0, 0)
+
+#define ICC_PMR_EL1 sys_reg(3, 0, 4, 6, 0)
+#define ICC_SRE_EL1 sys_reg(3, 0, 12, 12, 5)
+#define ICC_SRE_EL2 sys_reg(3, 0, 12, 12, 5)
+
+DECLARE_RW_ACCESSOR(MIDR_EL1)
+DECLARE_RW_ACCESSOR(MPIDR_EL1)
+DECLARE_RW_ACCESSOR(VPIDR_EL2)
+DECLARE_RW_ACCESSOR(ICC_PMR_EL1)
+DECLARE_RW_ACCESSOR(ICC_SRE_EL1)
+
+#define PR_REG(x) pr_info("%20s %llx\n", #x, readq_##x())
+
+static long do_lockup_disable_interrupts(void *info)
+{
+ pr_warn("lockup[%u]: About to wedge by disabling interrupts\n",
+ get_cpu());
+
+ PR_REG(MIDR_EL1);
+ PR_REG(MPIDR_EL1);
+ PR_REG(ICC_SRE_EL1);
+ writeq_ICC_SRE_EL1(0x01);
+ PR_REG(ICC_SRE_EL1);
+ PR_REG(ICC_PMR_EL1);
+ /*PR_REG(VPIDR_EL2);*/
+ /*PR_REG(ICC_SRE_EL1);*/
+ /*PR_REG(ICC_PMR_EL1);*/
+ /*writeq_ICC_PMR_EL1(0x80);*/
+ /*PR_REG(ICC_PMR_EL1);*/
+
+ return 0;
+}
+DEFINE_LOCKUP_ATTRIBUTE(lockup_disable_interrupts_fops,
+ do_lockup_disable_interrupts);
+#endif
+
+unsigned long icc_pmr_el1_masked = 0xf0;
+EXPORT_SYMBOL(icc_pmr_el1_masked);
+
+#define PR_FN(x) ({pr_info("%s\n", #x); x; })
+
+static int __init lockup_init(void)
+{
+ unsigned long flags = 0;
+ unsigned long flags2 = 0;
+
+#define E(x) { #x, &lockup_##x##_fops }
+ const struct {
+ const char *name;
+ const struct file_operations *fops;
+ } fops_table[] = {
+ E(spin_lock),
+ E(spin_lock_irqsave),
+#ifdef CONFIG_ARM64
+ E(disable_interrupts),
+#endif
+ };
+#undef E
+
+ struct dentry *dir;
+ unsigned int i;
+
+ dir = debugfs_create_dir("lockup", NULL);
+ if (dir)
+ for (i = 0; i < ARRAY_SIZE(fops_table); i++)
+ (void)debugfs_create_file(fops_table[i].name,
+ S_IRUGO | S_IWUSR, dir, NULL,
+ fops_table[i].fops);
+
+
+ pr_info("lockup: create 'lockup' attribute\n");
+
+ PR_REG(ICC_PMR_EL1);
+ pr_info("irqs_disabled %d flags %lu flags2 %lu\n", irqs_disabled(),
+ flags, flags2);
+
+ PR_FN(local_irq_disable());
+ PR_REG(ICC_PMR_EL1);
+ pr_info("irqs_disabled %d flags %lu flags2 %lu\n", irqs_disabled(),
+ flags, flags2);
+
+ PR_FN(local_irq_enable());
+ PR_REG(ICC_PMR_EL1);
+ pr_info("irqs_disabled %d flags %lu flags2 %lu\n", irqs_disabled(),
+ flags, flags2);
+
+ PR_FN(local_irq_save(flags));
+ PR_REG(ICC_PMR_EL1);
+ pr_info("irqs_disabled %d flags %lu flags2 %lu\n", irqs_disabled(),
+ flags, flags2);
+
+ PR_FN(local_irq_restore(flags));
+ PR_REG(ICC_PMR_EL1);
+ pr_info("irqs_disabled %d flags %lu flags2 %lu\n", irqs_disabled(),
+ flags, flags2);
+
+ PR_FN(local_irq_save(flags));
+ PR_REG(ICC_PMR_EL1);
+ pr_info("irqs_disabled %d flags %lu flags2 %lu\n", irqs_disabled(),
+ flags, flags2);
+
+ PR_FN(local_irq_save(flags2));
+ PR_REG(ICC_PMR_EL1);
+ pr_info("irqs_disabled %d flags %lu flags2 %lu\n", irqs_disabled(),
+ flags, flags2);
+
+ PR_FN(local_irq_restore(flags2));
+ PR_REG(ICC_PMR_EL1);
+ pr_info("irqs_disabled %d flags %lu flags2 %lu\n", irqs_disabled(),
+ flags, flags2);
+
+ PR_FN(local_irq_restore(flags));
+ PR_REG(ICC_PMR_EL1);
+ pr_info("irqs_disabled %d flags %lu flags2 %lu\n", irqs_disabled(),
+ flags, flags2);
+
+ PR_FN(icc_pmr_el1_masked = 0x70);
+
+ PR_REG(ICC_PMR_EL1);
+ pr_info("irqs_disabled %d flags %lu flags2 %lu\n", irqs_disabled(),
+ flags, flags2);
+
+ PR_FN(local_irq_disable());
+ PR_REG(ICC_PMR_EL1);
+ pr_info("irqs_disabled %d flags %lu flags2 %lu\n", irqs_disabled(),
+ flags, flags2);
+
+ PR_FN(local_irq_enable());
+ PR_REG(ICC_PMR_EL1);
+ pr_info("irqs_disabled %d flags %lu flags2 %lu\n", irqs_disabled(),
+ flags, flags2);
+
+ PR_FN(local_irq_save(flags));
+ PR_REG(ICC_PMR_EL1);
+ pr_info("irqs_disabled %d flags %lu flags2 %lu\n", irqs_disabled(),
+ flags, flags2);
+
+ PR_FN(local_irq_restore(flags));
+ PR_REG(ICC_PMR_EL1);
+ pr_info("irqs_disabled %d flags %lu flags2 %lu\n", irqs_disabled(),
+ flags, flags2);
+
+ PR_FN(local_irq_save(flags));
+ PR_REG(ICC_PMR_EL1);
+ pr_info("irqs_disabled %d flags %lu flags2 %lu\n", irqs_disabled(),
+ flags, flags2);
+
+ PR_FN(local_irq_save(flags2));
+ PR_REG(ICC_PMR_EL1);
+ pr_info("irqs_disabled %d flags %lu flags2 %lu\n", irqs_disabled(),
+ flags, flags2);
+
+ PR_FN(local_irq_restore(flags2));
+ PR_REG(ICC_PMR_EL1);
+ pr_info("irqs_disabled %d flags %lu flags2 %lu\n", irqs_disabled(),
+ flags, flags2);
+
+ PR_FN(local_irq_restore(flags));
+ PR_REG(ICC_PMR_EL1);
+ pr_info("irqs_disabled %d flags %lu flags2 %lu\n", irqs_disabled(),
+ flags, flags2);
+
+ return 0;
+}
+
+module_init(lockup_init);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Daniel Thompson");