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Subject[PATCH v3 33/44] metag: Stack unwinding
Date
Add stack unwinding support for metag.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
---
arch/metag/include/asm/stacktrace.h | 20 ++++
arch/metag/kernel/stacktrace.c | 187 +++++++++++++++++++++++++++++++++++
2 files changed, 207 insertions(+), 0 deletions(-)
create mode 100644 arch/metag/include/asm/stacktrace.h
create mode 100644 arch/metag/kernel/stacktrace.c

diff --git a/arch/metag/include/asm/stacktrace.h b/arch/metag/include/asm/stacktrace.h
new file mode 100644
index 0000000..2830a0f
--- /dev/null
+++ b/arch/metag/include/asm/stacktrace.h
@@ -0,0 +1,20 @@
+#ifndef __ASM_STACKTRACE_H
+#define __ASM_STACKTRACE_H
+
+struct stackframe {
+ unsigned long fp;
+ unsigned long sp;
+ unsigned long lr;
+ unsigned long pc;
+};
+
+struct metag_frame {
+ unsigned long fp;
+ unsigned long lr;
+};
+
+extern int unwind_frame(struct stackframe *frame);
+extern void walk_stackframe(struct stackframe *frame,
+ int (*fn)(struct stackframe *, void *), void *data);
+
+#endif /* __ASM_STACKTRACE_H */
diff --git a/arch/metag/kernel/stacktrace.c b/arch/metag/kernel/stacktrace.c
new file mode 100644
index 0000000..5510361
--- /dev/null
+++ b/arch/metag/kernel/stacktrace.c
@@ -0,0 +1,187 @@
+#include <linux/export.h>
+#include <linux/sched.h>
+#include <linux/stacktrace.h>
+
+#include <asm/stacktrace.h>
+
+#if defined(CONFIG_FRAME_POINTER)
+
+#ifdef CONFIG_KALLSYMS
+#include <linux/kallsyms.h>
+#include <linux/module.h>
+
+static unsigned long tbi_boing_addr;
+static unsigned long tbi_boing_size;
+
+static void tbi_boing_init(void)
+{
+ /* We need to know where TBIBoingVec is and it's size */
+ unsigned long size;
+ unsigned long offset;
+ char modname[MODULE_NAME_LEN];
+ char name[KSYM_NAME_LEN];
+ tbi_boing_addr = kallsyms_lookup_name("___TBIBoingVec");
+ if (!tbi_boing_addr)
+ tbi_boing_addr = 1;
+ else if (!lookup_symbol_attrs(tbi_boing_addr, &size,
+ &offset, modname, name))
+ tbi_boing_size = size;
+}
+#endif
+
+#define ALIGN_DOWN(addr, size) ((addr)&(~((size)-1)))
+
+/*
+ * Unwind the current stack frame and store the new register values in the
+ * structure passed as argument. Unwinding is equivalent to a function return,
+ * hence the new PC value rather than LR should be used for backtrace.
+ */
+int notrace unwind_frame(struct stackframe *frame)
+{
+ struct metag_frame *fp = (struct metag_frame *)frame->fp;
+ unsigned long lr;
+ unsigned long fpnew;
+
+ if (frame->fp & 0x7)
+ return -EINVAL;
+
+ fpnew = fp->fp;
+ lr = fp->lr - 4;
+
+#ifdef CONFIG_KALLSYMS
+ /* If we've reached TBIBoingVec then we're at an interrupt
+ * entry point or a syscall entry point. The frame pointer
+ * points to a pt_regs which can be used to continue tracing on
+ * the other side of the boing.
+ */
+ if (!tbi_boing_addr)
+ tbi_boing_init();
+ if (tbi_boing_size && lr >= tbi_boing_addr &&
+ lr < tbi_boing_addr + tbi_boing_size) {
+ struct pt_regs *regs = (struct pt_regs *)fpnew;
+ if (user_mode(regs))
+ return -EINVAL;
+ fpnew = regs->ctx.AX[1].U0;
+ lr = regs->ctx.DX[4].U1;
+ }
+#endif
+
+ /* stack grows up, so frame pointers must decrease */
+ if (fpnew < (ALIGN_DOWN((unsigned long)fp, THREAD_SIZE) +
+ sizeof(struct thread_info)) || fpnew >= (unsigned long)fp)
+ return -EINVAL;
+
+ /* restore the registers from the stack frame */
+ frame->fp = fpnew;
+ frame->pc = lr;
+
+ return 0;
+}
+#else
+int notrace unwind_frame(struct stackframe *frame)
+{
+ struct metag_frame *sp = (struct metag_frame *)frame->sp;
+
+ if (frame->sp & 0x7)
+ return -EINVAL;
+
+ while (!kstack_end(sp)) {
+ unsigned long addr = sp->lr - 4;
+ sp--;
+
+ if (__kernel_text_address(addr)) {
+ frame->sp = (unsigned long)sp;
+ frame->pc = addr;
+ return 0;
+ }
+ }
+ return -EINVAL;
+}
+#endif
+
+void notrace walk_stackframe(struct stackframe *frame,
+ int (*fn)(struct stackframe *, void *), void *data)
+{
+ while (1) {
+ int ret;
+
+ if (fn(frame, data))
+ break;
+ ret = unwind_frame(frame);
+ if (ret < 0)
+ break;
+ }
+}
+EXPORT_SYMBOL(walk_stackframe);
+
+#ifdef CONFIG_STACKTRACE
+struct stack_trace_data {
+ struct stack_trace *trace;
+ unsigned int no_sched_functions;
+ unsigned int skip;
+};
+
+static int save_trace(struct stackframe *frame, void *d)
+{
+ struct stack_trace_data *data = d;
+ struct stack_trace *trace = data->trace;
+ unsigned long addr = frame->pc;
+
+ if (data->no_sched_functions && in_sched_functions(addr))
+ return 0;
+ if (data->skip) {
+ data->skip--;
+ return 0;
+ }
+
+ trace->entries[trace->nr_entries++] = addr;
+
+ return trace->nr_entries >= trace->max_entries;
+}
+
+void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
+{
+ struct stack_trace_data data;
+ struct stackframe frame;
+
+ data.trace = trace;
+ data.skip = trace->skip;
+
+ if (tsk != current) {
+#ifdef CONFIG_SMP
+ /*
+ * What guarantees do we have here that 'tsk' is not
+ * running on another CPU? For now, ignore it as we
+ * can't guarantee we won't explode.
+ */
+ if (trace->nr_entries < trace->max_entries)
+ trace->entries[trace->nr_entries++] = ULONG_MAX;
+ return;
+#else
+ data.no_sched_functions = 1;
+ frame.fp = thread_saved_fp(tsk);
+ frame.sp = thread_saved_sp(tsk);
+ frame.lr = 0; /* recovered from the stack */
+ frame.pc = thread_saved_pc(tsk);
+#endif
+ } else {
+ register unsigned long current_sp asm ("A0StP");
+
+ data.no_sched_functions = 0;
+ frame.fp = (unsigned long)__builtin_frame_address(0);
+ frame.sp = current_sp;
+ frame.lr = (unsigned long)__builtin_return_address(0);
+ frame.pc = (unsigned long)save_stack_trace_tsk;
+ }
+
+ walk_stackframe(&frame, save_trace, &data);
+ if (trace->nr_entries < trace->max_entries)
+ trace->entries[trace->nr_entries++] = ULONG_MAX;
+}
+
+void save_stack_trace(struct stack_trace *trace)
+{
+ save_stack_trace_tsk(current, trace);
+}
+EXPORT_SYMBOL_GPL(save_stack_trace);
+#endif
--
1.7.7.6



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