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-rw-r--r--arch/xtensa/kernel/stacktrace.c275
1 files changed, 275 insertions, 0 deletions
diff --git a/arch/xtensa/kernel/stacktrace.c b/arch/xtensa/kernel/stacktrace.c
new file mode 100644
index 000000000..7f7755cd2
--- /dev/null
+++ b/arch/xtensa/kernel/stacktrace.c
@@ -0,0 +1,275 @@
+/*
+ * Kernel and userspace stack tracing.
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 2001 - 2013 Tensilica Inc.
+ * Copyright (C) 2015 Cadence Design Systems Inc.
+ */
+#include <linux/export.h>
+#include <linux/sched.h>
+#include <linux/stacktrace.h>
+
+#include <asm/stacktrace.h>
+#include <asm/traps.h>
+#include <linux/uaccess.h>
+
+#if IS_ENABLED(CONFIG_PERF_EVENTS)
+
+/* Address of common_exception_return, used to check the
+ * transition from kernel to user space.
+ */
+extern int common_exception_return;
+
+void xtensa_backtrace_user(struct pt_regs *regs, unsigned int depth,
+ int (*ufn)(struct stackframe *frame, void *data),
+ void *data)
+{
+ unsigned long windowstart = regs->windowstart;
+ unsigned long windowbase = regs->windowbase;
+ unsigned long a0 = regs->areg[0];
+ unsigned long a1 = regs->areg[1];
+ unsigned long pc = regs->pc;
+ struct stackframe frame;
+ int index;
+
+ if (!depth--)
+ return;
+
+ frame.pc = pc;
+ frame.sp = a1;
+
+ if (pc == 0 || pc >= TASK_SIZE || ufn(&frame, data))
+ return;
+
+ if (IS_ENABLED(CONFIG_USER_ABI_CALL0_ONLY) ||
+ (IS_ENABLED(CONFIG_USER_ABI_CALL0_PROBE) &&
+ !(regs->ps & PS_WOE_MASK)))
+ return;
+
+ /* Two steps:
+ *
+ * 1. Look through the register window for the
+ * previous PCs in the call trace.
+ *
+ * 2. Look on the stack.
+ */
+
+ /* Step 1. */
+ /* Rotate WINDOWSTART to move the bit corresponding to
+ * the current window to the bit #0.
+ */
+ windowstart = (windowstart << WSBITS | windowstart) >> windowbase;
+
+ /* Look for bits that are set, they correspond to
+ * valid windows.
+ */
+ for (index = WSBITS - 1; (index > 0) && depth; depth--, index--)
+ if (windowstart & (1 << index)) {
+ /* Get the PC from a0 and a1. */
+ pc = MAKE_PC_FROM_RA(a0, pc);
+ /* Read a0 and a1 from the
+ * corresponding position in AREGs.
+ */
+ a0 = regs->areg[index * 4];
+ a1 = regs->areg[index * 4 + 1];
+
+ frame.pc = pc;
+ frame.sp = a1;
+
+ if (pc == 0 || pc >= TASK_SIZE || ufn(&frame, data))
+ return;
+ }
+
+ /* Step 2. */
+ /* We are done with the register window, we need to
+ * look through the stack.
+ */
+ if (!depth)
+ return;
+
+ /* Start from the a1 register. */
+ /* a1 = regs->areg[1]; */
+ while (a0 != 0 && depth--) {
+ pc = MAKE_PC_FROM_RA(a0, pc);
+
+ /* Check if the region is OK to access. */
+ if (!access_ok(&SPILL_SLOT(a1, 0), 8))
+ return;
+ /* Copy a1, a0 from user space stack frame. */
+ if (__get_user(a0, &SPILL_SLOT(a1, 0)) ||
+ __get_user(a1, &SPILL_SLOT(a1, 1)))
+ return;
+
+ frame.pc = pc;
+ frame.sp = a1;
+
+ if (pc == 0 || pc >= TASK_SIZE || ufn(&frame, data))
+ return;
+ }
+}
+EXPORT_SYMBOL(xtensa_backtrace_user);
+
+void xtensa_backtrace_kernel(struct pt_regs *regs, unsigned int depth,
+ int (*kfn)(struct stackframe *frame, void *data),
+ int (*ufn)(struct stackframe *frame, void *data),
+ void *data)
+{
+ unsigned long pc = regs->depc > VALID_DOUBLE_EXCEPTION_ADDRESS ?
+ regs->depc : regs->pc;
+ unsigned long sp_start, sp_end;
+ unsigned long a0 = regs->areg[0];
+ unsigned long a1 = regs->areg[1];
+
+ sp_start = a1 & ~(THREAD_SIZE - 1);
+ sp_end = sp_start + THREAD_SIZE;
+
+ /* Spill the register window to the stack first. */
+ spill_registers();
+
+ /* Read the stack frames one by one and create the PC
+ * from the a0 and a1 registers saved there.
+ */
+ while (a1 > sp_start && a1 < sp_end && depth--) {
+ struct stackframe frame;
+
+ frame.pc = pc;
+ frame.sp = a1;
+
+ if (kernel_text_address(pc) && kfn(&frame, data))
+ return;
+
+ if (pc == (unsigned long)&common_exception_return) {
+ regs = (struct pt_regs *)a1;
+ if (user_mode(regs)) {
+ if (ufn == NULL)
+ return;
+ xtensa_backtrace_user(regs, depth, ufn, data);
+ return;
+ }
+ a0 = regs->areg[0];
+ a1 = regs->areg[1];
+ continue;
+ }
+
+ sp_start = a1;
+
+ pc = MAKE_PC_FROM_RA(a0, pc);
+ a0 = SPILL_SLOT(a1, 0);
+ a1 = SPILL_SLOT(a1, 1);
+ }
+}
+EXPORT_SYMBOL(xtensa_backtrace_kernel);
+
+#endif
+
+void walk_stackframe(unsigned long *sp,
+ int (*fn)(struct stackframe *frame, void *data),
+ void *data)
+{
+ unsigned long a0, a1;
+ unsigned long sp_end;
+
+ a1 = (unsigned long)sp;
+ sp_end = ALIGN(a1, THREAD_SIZE);
+
+ spill_registers();
+
+ while (a1 < sp_end) {
+ struct stackframe frame;
+
+ sp = (unsigned long *)a1;
+
+ a0 = SPILL_SLOT(a1, 0);
+ a1 = SPILL_SLOT(a1, 1);
+
+ if (a1 <= (unsigned long)sp)
+ break;
+
+ frame.pc = MAKE_PC_FROM_RA(a0, a1);
+ frame.sp = a1;
+
+ if (fn(&frame, data))
+ return;
+ }
+}
+
+#ifdef CONFIG_STACKTRACE
+
+struct stack_trace_data {
+ struct stack_trace *trace;
+ unsigned skip;
+};
+
+static int stack_trace_cb(struct stackframe *frame, void *data)
+{
+ struct stack_trace_data *trace_data = data;
+ struct stack_trace *trace = trace_data->trace;
+
+ if (trace_data->skip) {
+ --trace_data->skip;
+ return 0;
+ }
+ if (!kernel_text_address(frame->pc))
+ return 0;
+
+ trace->entries[trace->nr_entries++] = frame->pc;
+ return trace->nr_entries >= trace->max_entries;
+}
+
+void save_stack_trace_tsk(struct task_struct *task, struct stack_trace *trace)
+{
+ struct stack_trace_data trace_data = {
+ .trace = trace,
+ .skip = trace->skip,
+ };
+ walk_stackframe(stack_pointer(task), stack_trace_cb, &trace_data);
+}
+EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
+
+void save_stack_trace(struct stack_trace *trace)
+{
+ save_stack_trace_tsk(current, trace);
+}
+EXPORT_SYMBOL_GPL(save_stack_trace);
+
+#endif
+
+#ifdef CONFIG_FRAME_POINTER
+
+struct return_addr_data {
+ unsigned long addr;
+ unsigned skip;
+};
+
+static int return_address_cb(struct stackframe *frame, void *data)
+{
+ struct return_addr_data *r = data;
+
+ if (r->skip) {
+ --r->skip;
+ return 0;
+ }
+ if (!kernel_text_address(frame->pc))
+ return 0;
+ r->addr = frame->pc;
+ return 1;
+}
+
+/*
+ * level == 0 is for the return address from the caller of this function,
+ * not from this function itself.
+ */
+unsigned long return_address(unsigned level)
+{
+ struct return_addr_data r = {
+ .skip = level,
+ };
+ walk_stackframe(stack_pointer(NULL), return_address_cb, &r);
+ return r.addr;
+}
+EXPORT_SYMBOL(return_address);
+
+#endif