/*
- * arch/xtensa/kernel/stacktrace.c
+ * 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 <asm/stacktrace.h>
#include <asm/traps.h>
+#include <asm/uaccess.h>
+
+#if IS_ENABLED(CONFIG_OPROFILE) || 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;
+
+/* A struct that maps to the part of the frame containing the a0 and
+ * a1 registers.
+ */
+struct frame_start {
+ unsigned long a0;
+ unsigned long a1;
+};
+
+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;
+
+ /* 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--) {
+ struct frame_start frame_start;
+ /* Get the location for a1, a0 for the
+ * previous frame from the current a1.
+ */
+ unsigned long *psp = (unsigned long *)a1;
+
+ psp -= 4;
+
+ /* Check if the region is OK to access. */
+ if (!access_ok(VERIFY_READ, psp, sizeof(frame_start)))
+ return;
+ /* Copy a1, a0 from user space stack frame. */
+ if (__copy_from_user_inatomic(&frame_start, psp,
+ sizeof(frame_start)))
+ return;
+
+ pc = MAKE_PC_FROM_RA(a0, pc);
+ a0 = frame_start.a0;
+ a1 = frame_start.a1;
+
+ 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;
+ unsigned long *psp = (unsigned long *)a1;
+
+ 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 = *(psp - 4);
+ a1 = *(psp - 3);
+ }
+}
+EXPORT_SYMBOL(xtensa_backtrace_kernel);
+
+#endif
void walk_stackframe(unsigned long *sp,
int (*fn)(struct stackframe *frame, void *data),
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