summaryrefslogtreecommitdiffstats
path: root/arch/s390/include/asm/unwind.h
diff options
context:
space:
mode:
Diffstat (limited to 'arch/s390/include/asm/unwind.h')
-rw-r--r--arch/s390/include/asm/unwind.h101
1 files changed, 101 insertions, 0 deletions
diff --git a/arch/s390/include/asm/unwind.h b/arch/s390/include/asm/unwind.h
new file mode 100644
index 000000000000..6eb2ef105d87
--- /dev/null
+++ b/arch/s390/include/asm/unwind.h
@@ -0,0 +1,101 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_S390_UNWIND_H
+#define _ASM_S390_UNWIND_H
+
+#include <linux/sched.h>
+#include <linux/ftrace.h>
+#include <asm/ptrace.h>
+#include <asm/stacktrace.h>
+
+/*
+ * To use the stack unwinder it has to be initialized with unwind_start.
+ * There four combinations for task and regs:
+ * 1) task==NULL, regs==NULL: the unwind starts for the task that is currently
+ * running, sp/ip picked up from the CPU registers
+ * 2) task==NULL, regs!=NULL: the unwind starts from the sp/ip found in
+ * the struct pt_regs of an interrupt frame for the current task
+ * 3) task!=NULL, regs==NULL: the unwind starts for an inactive task with
+ * the sp picked up from task->thread.ksp and the ip picked up from the
+ * return address stored by __switch_to
+ * 4) task!=NULL, regs!=NULL: the sp/ip are picked up from the interrupt
+ * frame 'regs' of a inactive task
+ * If 'first_frame' is not zero unwind_start skips unwind frames until it
+ * reaches the specified stack pointer.
+ * The end of the unwinding is indicated with unwind_done, this can be true
+ * right after unwind_start, e.g. with first_frame!=0 that can not be found.
+ * unwind_next_frame skips to the next frame.
+ * Once the unwind is completed unwind_error() can be used to check if there
+ * has been a situation where the unwinder could not correctly understand
+ * the tasks call chain.
+ */
+
+struct unwind_state {
+ struct stack_info stack_info;
+ unsigned long stack_mask;
+ struct task_struct *task;
+ struct pt_regs *regs;
+ unsigned long sp, ip;
+ int graph_idx;
+ bool reliable;
+ bool error;
+};
+
+void __unwind_start(struct unwind_state *state, struct task_struct *task,
+ struct pt_regs *regs, unsigned long first_frame);
+bool unwind_next_frame(struct unwind_state *state);
+unsigned long unwind_get_return_address(struct unwind_state *state);
+
+static inline bool unwind_done(struct unwind_state *state)
+{
+ return state->stack_info.type == STACK_TYPE_UNKNOWN;
+}
+
+static inline bool unwind_error(struct unwind_state *state)
+{
+ return state->error;
+}
+
+static inline void unwind_start(struct unwind_state *state,
+ struct task_struct *task,
+ struct pt_regs *regs,
+ unsigned long sp)
+{
+ sp = sp ? : get_stack_pointer(task, regs);
+ __unwind_start(state, task, regs, sp);
+}
+
+static inline struct pt_regs *unwind_get_entry_regs(struct unwind_state *state)
+{
+ return unwind_done(state) ? NULL : state->regs;
+}
+
+#define unwind_for_each_frame(state, task, regs, first_frame) \
+ for (unwind_start(state, task, regs, first_frame); \
+ !unwind_done(state); \
+ unwind_next_frame(state))
+
+static inline void unwind_init(void) {}
+static inline void unwind_module_init(struct module *mod, void *orc_ip,
+ size_t orc_ip_size, void *orc,
+ size_t orc_size) {}
+
+#ifdef CONFIG_KASAN
+/*
+ * This disables KASAN checking when reading a value from another task's stack,
+ * since the other task could be running on another CPU and could have poisoned
+ * the stack in the meantime.
+ */
+#define READ_ONCE_TASK_STACK(task, x) \
+({ \
+ unsigned long val; \
+ if (task == current) \
+ val = READ_ONCE(x); \
+ else \
+ val = READ_ONCE_NOCHECK(x); \
+ val; \
+})
+#else
+#define READ_ONCE_TASK_STACK(task, x) READ_ONCE(x)
+#endif
+
+#endif /* _ASM_S390_UNWIND_H */