--- zzzz-none-000/linux-3.10.107/arch/arm/kernel/unwind.c	2017-06-27 09:49:32.000000000 +0000
+++ scorpion-7490-727/linux-3.10.107/arch/arm/kernel/unwind.c	2021-02-04 17:41:59.000000000 +0000
@@ -31,7 +31,7 @@
 #warning Your compiler does not have EABI support.
 #warning    ARM unwind is known to compile only with EABI compilers.
 #warning    Change compiler or disable ARM_UNWIND option.
-#elif (__GNUC__ == 4 && __GNUC_MINOR__ <= 2)
+#elif (__GNUC__ == 4 && __GNUC_MINOR__ <= 2) && !defined(__clang__)
 #warning Your compiler is too buggy; it is known to not compile ARM unwind support.
 #warning    Change compiler or disable ARM_UNWIND option.
 #endif
@@ -68,6 +68,12 @@
 struct unwind_ctrl_block {
 	unsigned long vrs[16];		/* virtual register set */
 	const unsigned long *insn;	/* pointer to the current instructions word */
+	unsigned long sp_high;		/* highest value of sp allowed */
+	/*
+	 * 1 : check for stack overflow for each register pop.
+	 * 0 : save overhead if there is plenty of stack remaining.
+	 */
+	int check_each_pop;
 	int entries;			/* number of entries left to interpret */
 	int byte;			/* current byte number in the instructions word */
 };
@@ -151,7 +157,7 @@
 	if (likely(start->addr_offset <= addr_prel31))
 		return start;
 	else {
-		pr_warning("unwind: Unknown symbol address %08lx\n", addr);
+		pr_warn("unwind: Unknown symbol address %08lx\n", addr);
 		return NULL;
 	}
 }
@@ -219,7 +225,7 @@
 	unsigned long ret;
 
 	if (ctrl->entries <= 0) {
-		pr_warning("unwind: Corrupt unwind table\n");
+		pr_warn("unwind: Corrupt unwind table\n");
 		return 0;
 	}
 
@@ -235,12 +241,85 @@
 	return ret;
 }
 
+/* Before poping a register check whether it is feasible or not */
+static int unwind_pop_register(struct unwind_ctrl_block *ctrl,
+				unsigned long **vsp, unsigned int reg)
+{
+	if (unlikely(ctrl->check_each_pop))
+		if (*vsp >= (unsigned long *)ctrl->sp_high)
+			return -URC_FAILURE;
+
+	ctrl->vrs[reg] = *(*vsp)++;
+	return URC_OK;
+}
+
+/* Helper functions to execute the instructions */
+static int unwind_exec_pop_subset_r4_to_r13(struct unwind_ctrl_block *ctrl,
+						unsigned long mask)
+{
+	unsigned long *vsp = (unsigned long *)ctrl->vrs[SP];
+	int load_sp, reg = 4;
+
+	load_sp = mask & (1 << (13 - 4));
+	while (mask) {
+		if (mask & 1)
+			if (unwind_pop_register(ctrl, &vsp, reg))
+				return -URC_FAILURE;
+		mask >>= 1;
+		reg++;
+	}
+	if (!load_sp)
+		ctrl->vrs[SP] = (unsigned long)vsp;
+
+	return URC_OK;
+}
+
+static int unwind_exec_pop_r4_to_rN(struct unwind_ctrl_block *ctrl,
+					unsigned long insn)
+{
+	unsigned long *vsp = (unsigned long *)ctrl->vrs[SP];
+	int reg;
+
+	/* pop R4-R[4+bbb] */
+	for (reg = 4; reg <= 4 + (insn & 7); reg++)
+		if (unwind_pop_register(ctrl, &vsp, reg))
+				return -URC_FAILURE;
+
+	if (insn & 0x8)
+		if (unwind_pop_register(ctrl, &vsp, 14))
+				return -URC_FAILURE;
+
+	ctrl->vrs[SP] = (unsigned long)vsp;
+
+	return URC_OK;
+}
+
+static int unwind_exec_pop_subset_r0_to_r3(struct unwind_ctrl_block *ctrl,
+						unsigned long mask)
+{
+	unsigned long *vsp = (unsigned long *)ctrl->vrs[SP];
+	int reg = 0;
+
+	/* pop R0-R3 according to mask */
+	while (mask) {
+		if (mask & 1)
+			if (unwind_pop_register(ctrl, &vsp, reg))
+				return -URC_FAILURE;
+		mask >>= 1;
+		reg++;
+	}
+	ctrl->vrs[SP] = (unsigned long)vsp;
+
+	return URC_OK;
+}
+
 /*
  * Execute the current unwind instruction.
  */
 static int unwind_exec_insn(struct unwind_ctrl_block *ctrl)
 {
 	unsigned long insn = unwind_get_byte(ctrl);
+	int ret = URC_OK;
 
 	pr_debug("%s: insn = %08lx\n", __func__, insn);
 
@@ -250,40 +329,25 @@
 		ctrl->vrs[SP] -= ((insn & 0x3f) << 2) + 4;
 	else if ((insn & 0xf0) == 0x80) {
 		unsigned long mask;
-		unsigned long *vsp = (unsigned long *)ctrl->vrs[SP];
-		int load_sp, reg = 4;
 
 		insn = (insn << 8) | unwind_get_byte(ctrl);
 		mask = insn & 0x0fff;
 		if (mask == 0) {
-			pr_warning("unwind: 'Refuse to unwind' instruction %04lx\n",
-				   insn);
+			pr_warn("unwind: 'Refuse to unwind' instruction %04lx\n",
+				insn);
 			return -URC_FAILURE;
 		}
 
-		/* pop R4-R15 according to mask */
-		load_sp = mask & (1 << (13 - 4));
-		while (mask) {
-			if (mask & 1)
-				ctrl->vrs[reg] = *vsp++;
-			mask >>= 1;
-			reg++;
-		}
-		if (!load_sp)
-			ctrl->vrs[SP] = (unsigned long)vsp;
+		ret = unwind_exec_pop_subset_r4_to_r13(ctrl, mask);
+		if (ret)
+			goto error;
 	} else if ((insn & 0xf0) == 0x90 &&
 		   (insn & 0x0d) != 0x0d)
 		ctrl->vrs[SP] = ctrl->vrs[insn & 0x0f];
 	else if ((insn & 0xf0) == 0xa0) {
-		unsigned long *vsp = (unsigned long *)ctrl->vrs[SP];
-		int reg;
-
-		/* pop R4-R[4+bbb] */
-		for (reg = 4; reg <= 4 + (insn & 7); reg++)
-			ctrl->vrs[reg] = *vsp++;
-		if (insn & 0x80)
-			ctrl->vrs[14] = *vsp++;
-		ctrl->vrs[SP] = (unsigned long)vsp;
+		ret = unwind_exec_pop_r4_to_rN(ctrl, insn);
+		if (ret)
+			goto error;
 	} else if (insn == 0xb0) {
 		if (ctrl->vrs[PC] == 0)
 			ctrl->vrs[PC] = ctrl->vrs[LR];
@@ -291,36 +355,30 @@
 		ctrl->entries = 0;
 	} else if (insn == 0xb1) {
 		unsigned long mask = unwind_get_byte(ctrl);
-		unsigned long *vsp = (unsigned long *)ctrl->vrs[SP];
-		int reg = 0;
 
 		if (mask == 0 || mask & 0xf0) {
-			pr_warning("unwind: Spare encoding %04lx\n",
-			       (insn << 8) | mask);
+			pr_warn("unwind: Spare encoding %04lx\n",
+				(insn << 8) | mask);
 			return -URC_FAILURE;
 		}
 
-		/* pop R0-R3 according to mask */
-		while (mask) {
-			if (mask & 1)
-				ctrl->vrs[reg] = *vsp++;
-			mask >>= 1;
-			reg++;
-		}
-		ctrl->vrs[SP] = (unsigned long)vsp;
+		ret = unwind_exec_pop_subset_r0_to_r3(ctrl, mask);
+		if (ret)
+			goto error;
 	} else if (insn == 0xb2) {
 		unsigned long uleb128 = unwind_get_byte(ctrl);
 
 		ctrl->vrs[SP] += 0x204 + (uleb128 << 2);
 	} else {
-		pr_warning("unwind: Unhandled instruction %02lx\n", insn);
+		pr_warn("unwind: Unhandled instruction %02lx\n", insn);
 		return -URC_FAILURE;
 	}
 
 	pr_debug("%s: fp = %08lx sp = %08lx lr = %08lx pc = %08lx\n", __func__,
 		 ctrl->vrs[FP], ctrl->vrs[SP], ctrl->vrs[LR], ctrl->vrs[PC]);
 
-	return URC_OK;
+error:
+	return ret;
 }
 
 /*
@@ -329,13 +387,13 @@
  */
 int unwind_frame(struct stackframe *frame)
 {
-	unsigned long high, low;
+	unsigned long low;
 	const struct unwind_idx *idx;
 	struct unwind_ctrl_block ctrl;
 
-	/* only go to a higher address on the stack */
+	/* store the highest address on the stack to avoid crossing it*/
 	low = frame->sp;
-	high = ALIGN(low, THREAD_SIZE);
+	ctrl.sp_high = ALIGN(low, THREAD_SIZE);
 
 	pr_debug("%s(pc = %08lx lr = %08lx sp = %08lx)\n", __func__,
 		 frame->pc, frame->lr, frame->sp);
@@ -345,7 +403,6 @@
 
 	idx = unwind_find_idx(frame->pc);
 	if (!idx) {
-		pr_warning("unwind: Index not found %08lx\n", frame->pc);
 		return -URC_FAILURE;
 	}
 
@@ -364,8 +421,8 @@
 		/* only personality routine 0 supported in the index */
 		ctrl.insn = &idx->insn;
 	else {
-		pr_warning("unwind: Unsupported personality routine %08lx in the index at %p\n",
-			   idx->insn, idx);
+		pr_warn("unwind: Unsupported personality routine %08lx in the index at %p\n",
+			idx->insn, idx);
 		return -URC_FAILURE;
 	}
 
@@ -377,16 +434,21 @@
 		ctrl.byte = 1;
 		ctrl.entries = 1 + ((*ctrl.insn & 0x00ff0000) >> 16);
 	} else {
-		pr_warning("unwind: Unsupported personality routine %08lx at %p\n",
-			   *ctrl.insn, ctrl.insn);
+		pr_warn("unwind: Unsupported personality routine %08lx at %p\n",
+			*ctrl.insn, ctrl.insn);
 		return -URC_FAILURE;
 	}
 
+	ctrl.check_each_pop = 0;
+
 	while (ctrl.entries > 0) {
-		int urc = unwind_exec_insn(&ctrl);
+		int urc;
+		if ((ctrl.sp_high - ctrl.vrs[SP]) < sizeof(ctrl.vrs))
+			ctrl.check_each_pop = 1;
+		urc = unwind_exec_insn(&ctrl);
 		if (urc < 0)
 			return urc;
-		if (ctrl.vrs[SP] < low || ctrl.vrs[SP] >= high)
+		if (ctrl.vrs[SP] < low || ctrl.vrs[SP] >= ctrl.sp_high)
 			return -URC_FAILURE;
 	}
 
@@ -408,7 +470,6 @@
 void unwind_backtrace(struct pt_regs *regs, struct task_struct *tsk)
 {
 	struct stackframe frame;
-	register unsigned long current_sp asm ("sp");
 
 	pr_debug("%s(regs = %p tsk = %p)\n", __func__, regs, tsk);
 
@@ -416,15 +477,13 @@
 		tsk = current;
 
 	if (regs) {
-		frame.fp = regs->ARM_fp;
-		frame.sp = regs->ARM_sp;
-		frame.lr = regs->ARM_lr;
+		arm_get_current_stackframe(regs, &frame);
 		/* PC might be corrupted, use LR in that case. */
-		frame.pc = kernel_text_address(regs->ARM_pc)
-			 ? regs->ARM_pc : regs->ARM_lr;
+		if (!kernel_text_address(regs->ARM_pc))
+			frame.pc = regs->ARM_lr;
 	} else if (tsk == current) {
 		frame.fp = (unsigned long)__builtin_frame_address(0);
-		frame.sp = current_sp;
+		frame.sp = current_stack_pointer;
 		frame.lr = (unsigned long)__builtin_return_address(0);
 		frame.pc = (unsigned long)unwind_backtrace;
 	} else {