From 04dd17822334871b23ea2862f7798fb0e0007777 Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Sat, 11 May 2024 08:53:19 +0000
Subject: [PATCH] change otg to host mode

---
 kernel/arch/arm/kernel/unwind.c |   47 +++++++++++++++++++++++++++++------------------
 1 files changed, 29 insertions(+), 18 deletions(-)

diff --git a/kernel/arch/arm/kernel/unwind.c b/kernel/arch/arm/kernel/unwind.c
index 314cfb2..7e90f17 100644
--- a/kernel/arch/arm/kernel/unwind.c
+++ b/kernel/arch/arm/kernel/unwind.c
@@ -1,21 +1,8 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * arch/arm/kernel/unwind.c
  *
  * Copyright (C) 2008 ARM Limited
- *
- * 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.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
- *
  *
  * Stack unwinding support for ARM
  *
@@ -313,6 +300,29 @@
 	return URC_OK;
 }
 
+static unsigned long unwind_decode_uleb128(struct unwind_ctrl_block *ctrl)
+{
+	unsigned long bytes = 0;
+	unsigned long insn;
+	unsigned long result = 0;
+
+	/*
+	 * unwind_get_byte() will advance `ctrl` one instruction at a time, so
+	 * loop until we get an instruction byte where bit 7 is not set.
+	 *
+	 * Note: This decodes a maximum of 4 bytes to output 28 bits data where
+	 * max is 0xfffffff: that will cover a vsp increment of 1073742336, hence
+	 * it is sufficient for unwinding the stack.
+	 */
+	do {
+		insn = unwind_get_byte(ctrl);
+		result |= (insn & 0x7f) << (bytes * 7);
+		bytes++;
+	} while (!!(insn & 0x80) && (bytes != sizeof(result)));
+
+	return result;
+}
+
 /*
  * Execute the current unwind instruction.
  */
@@ -366,7 +376,7 @@
 		if (ret)
 			goto error;
 	} else if (insn == 0xb2) {
-		unsigned long uleb128 = unwind_get_byte(ctrl);
+		unsigned long uleb128 = unwind_decode_uleb128(ctrl);
 
 		ctrl->vrs[SP] += 0x204 + (uleb128 << 2);
 	} else {
@@ -457,7 +467,7 @@
 		ctrl.vrs[PC] = ctrl.vrs[LR];
 
 	/* check for infinite loop */
-	if (frame->pc == ctrl.vrs[PC])
+	if (frame->pc == ctrl.vrs[PC] && frame->sp == ctrl.vrs[SP])
 		return -URC_FAILURE;
 
 	frame->fp = ctrl.vrs[FP];
@@ -468,7 +478,8 @@
 	return URC_OK;
 }
 
-void unwind_backtrace(struct pt_regs *regs, struct task_struct *tsk)
+void unwind_backtrace(struct pt_regs *regs, struct task_struct *tsk,
+		      const char *loglvl)
 {
 	struct stackframe frame;
 
@@ -506,7 +517,7 @@
 		urc = unwind_frame(&frame);
 		if (urc < 0)
 			break;
-		dump_backtrace_entry(where, frame.pc, frame.sp - 4);
+		dump_backtrace_entry(where, frame.pc, frame.sp - 4, loglvl);
 	}
 }
 

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