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-rw-r--r--arch/unicore32/lib/backtrace.S163
1 files changed, 163 insertions, 0 deletions
diff --git a/arch/unicore32/lib/backtrace.S b/arch/unicore32/lib/backtrace.S
new file mode 100644
index 000000000000..ef01d77f2f65
--- /dev/null
+++ b/arch/unicore32/lib/backtrace.S
@@ -0,0 +1,163 @@
+/*
+ * linux/arch/unicore32/lib/backtrace.S
+ *
+ * Code specific to PKUnity SoC and UniCore ISA
+ *
+ * Copyright (C) 2001-2010 GUAN Xue-tao
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/linkage.h>
+#include <asm/assembler.h>
+ .text
+
+@ fp is 0 or stack frame
+
+#define frame v4
+#define sv_fp v5
+#define sv_pc v6
+#define offset v8
+
+ENTRY(__backtrace)
+ mov r0, fp
+
+ENTRY(c_backtrace)
+
+#if !defined(CONFIG_FRAME_POINTER) || !defined(CONFIG_PRINTK)
+ mov pc, lr
+ENDPROC(__backtrace)
+ENDPROC(c_backtrace)
+#else
+ stm.w (v4 - v8, lr), [sp-] @ Save an extra register
+ @ so we have a location...
+ mov.a frame, r0 @ if frame pointer is zero
+ beq no_frame @ we have no stack frames
+
+1: stm.w (pc), [sp-] @ calculate offset of PC stored
+ ldw.w r0, [sp]+, #4 @ by stmfd for this CPU
+ adr r1, 1b
+ sub offset, r0, r1
+
+/*
+ * Stack frame layout:
+ * optionally saved caller registers (r4 - r10)
+ * saved fp
+ * saved sp
+ * saved lr
+ * frame => saved pc
+ * optionally saved arguments (r0 - r3)
+ * saved sp => <next word>
+ *
+ * Functions start with the following code sequence:
+ * mov ip, sp
+ * stm.w (r0 - r3), [sp-] (optional)
+ * corrected pc => stm.w sp, (..., fp, ip, lr, pc)
+ */
+for_each_frame:
+
+1001: ldw sv_pc, [frame+], #0 @ get saved pc
+1002: ldw sv_fp, [frame+], #-12 @ get saved fp
+
+ sub sv_pc, sv_pc, offset @ Correct PC for prefetching
+
+1003: ldw r2, [sv_pc+], #-4 @ if stmfd sp, {args} exists,
+ ldw r3, .Ldsi+4 @ adjust saved 'pc' back one
+ cxor.a r3, r2 >> #14 @ instruction
+ beq 201f
+ sub r0, sv_pc, #4 @ allow for mov
+ b 202f
+201:
+ sub r0, sv_pc, #8 @ allow for mov + stmia
+202:
+ ldw r1, [frame+], #-4 @ get saved lr
+ mov r2, frame
+ b.l dump_backtrace_entry
+
+ ldw r1, [sv_pc+], #-4 @ if stmfd sp, {args} exists,
+ ldw r3, .Ldsi+4
+ cxor.a r3, r1 >> #14
+ bne 1004f
+ ldw r0, [frame+], #-8 @ get sp
+ sub r0, r0, #4 @ point at the last arg
+ b.l .Ldumpstm @ dump saved registers
+
+1004: ldw r1, [sv_pc+], #0 @ if stmfd {, fp, ip, lr, pc}
+ ldw r3, .Ldsi @ instruction exists,
+ cxor.a r3, r1 >> #14
+ bne 201f
+ sub r0, frame, #16
+ b.l .Ldumpstm @ dump saved registers
+201:
+ cxor.a sv_fp, #0 @ zero saved fp means
+ beq no_frame @ no further frames
+
+ csub.a sv_fp, frame @ next frame must be
+ mov frame, sv_fp @ above the current frame
+ bua for_each_frame
+
+1006: adr r0, .Lbad
+ mov r1, frame
+ b.l printk
+no_frame: ldm.w (v4 - v8, pc), [sp]+
+ENDPROC(__backtrace)
+ENDPROC(c_backtrace)
+
+ .pushsection __ex_table,"a"
+ .align 3
+ .long 1001b, 1006b
+ .long 1002b, 1006b
+ .long 1003b, 1006b
+ .long 1004b, 1006b
+ .popsection
+
+#define instr v4
+#define reg v5
+#define stack v6
+
+.Ldumpstm: stm.w (instr, reg, stack, v7, lr), [sp-]
+ mov stack, r0
+ mov instr, r1
+ mov reg, #14
+ mov v7, #0
+1: mov r3, #1
+ csub.a reg, #8
+ bne 201f
+ sub reg, reg, #3
+201:
+ cand.a instr, r3 << reg
+ beq 2f
+ add v7, v7, #1
+ cxor.a v7, #6
+ cmoveq v7, #1
+ cmoveq r1, #'\n'
+ cmovne r1, #' '
+ ldw.w r3, [stack]+, #-4
+ mov r2, reg
+ csub.a r2, #8
+ bsl 201f
+ sub r2, r2, #3
+201:
+ cand.a instr, #0x40 @ if H is 1, high 16 regs
+ beq 201f
+ add r2, r2, #0x10 @ so r2 need add 16
+201:
+ adr r0, .Lfp
+ b.l printk
+2: sub.a reg, reg, #1
+ bns 1b
+ cxor.a v7, #0
+ beq 201f
+ adr r0, .Lcr
+ b.l printk
+201: ldm.w (instr, reg, stack, v7, pc), [sp]+
+
+.Lfp: .asciz "%cr%d:%08x"
+.Lcr: .asciz "\n"
+.Lbad: .asciz "Backtrace aborted due to bad frame pointer <%p>\n"
+ .align
+.Ldsi: .word 0x92eec000 >> 14 @ stm.w sp, (... fp, ip, lr, pc)
+ .word 0x92e10000 >> 14 @ stm.w sp, ()
+
+#endif