microblaze: Add stack unwinder
Implement intelligent backtracing by searching for stack frame creation,
and emitting only return addresses. Use print_hex_dump() to display the
entire binary kernel stack.
Limitation: MMU kernels are not currently able to trace beyond a system trap
(interrupt, syscall, etc.). It is the intent of this patch to provide
infrastructure that can be extended to add this capability later.
Changes from V1:
* Removed checks in find_frame_creation() that prevented location of the frame
creation instruction in heavily optimized code
* Various formatting/commenting/file location tweaks per review comments
* Dropped Kconfig option to enable STACKTRACE as something logically separate
Signed-off-by: Steven J. Magnani <steve@digidescorp.com>
diff --git a/arch/microblaze/kernel/entry.S b/arch/microblaze/kernel/entry.S
index 077377a..7a19d89 100644
--- a/arch/microblaze/kernel/entry.S
+++ b/arch/microblaze/kernel/entry.S
@@ -1127,3 +1127,30 @@
syscall_table_size=(.-sys_call_table)
+type_SYSCALL:
+ .ascii "SYSCALL\0"
+type_IRQ:
+ .ascii "IRQ\0"
+type_IRQ_PREEMPT:
+ .ascii "IRQ (PREEMPTED)\0"
+type_SYSCALL_PREEMPT:
+ .ascii " SYSCALL (PREEMPTED)\0"
+
+ /*
+ * Trap decoding for stack unwinder
+ * Tuples are (start addr, end addr, string)
+ * If return address lies on [start addr, end addr],
+ * unwinder displays 'string'
+ */
+
+ .align 4
+.global microblaze_trap_handlers
+microblaze_trap_handlers:
+ /* Exact matches come first */
+ .word ret_from_trap; .word ret_from_trap ; .word type_SYSCALL
+ .word ret_from_irq ; .word ret_from_irq ; .word type_IRQ
+ /* Fuzzy matches go here */
+ .word ret_from_irq ; .word no_intr_resched ; .word type_IRQ_PREEMPT
+ .word ret_from_trap; .word TRAP_return ; .word type_SYSCALL_PREEMPT
+ /* End of table */
+ .word 0 ; .word 0 ; .word 0