--- zzzz-none-000/linux-3.10.107/arch/mips/kernel/kgdb.c	2017-06-27 09:49:32.000000000 +0000
+++ scorpion-7490-727/linux-3.10.107/arch/mips/kernel/kgdb.c	2021-02-04 17:41:59.000000000 +0000
@@ -32,6 +32,7 @@
 #include <asm/cacheflush.h>
 #include <asm/processor.h>
 #include <asm/sigcontext.h>
+#include <asm/uaccess.h>
 
 static struct hard_trap_info {
 	unsigned char tt;	/* Trap type code for MIPS R3xxx and R4xxx */
@@ -208,7 +209,14 @@
 
 static void kgdb_call_nmi_hook(void *ignored)
 {
+	mm_segment_t old_fs;
+
+	old_fs = get_fs();
+	set_fs(get_ds());
+
 	kgdb_nmicallback(raw_smp_processor_id(), NULL);
+
+	set_fs(old_fs);
 }
 
 void kgdb_roundup_cpus(unsigned long flags)
@@ -236,6 +244,9 @@
 void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *p)
 {
 	int reg;
+	struct thread_info *ti = task_thread_info(p);
+	unsigned long ksp = (unsigned long)ti + THREAD_SIZE - 32;
+	struct pt_regs *regs = (struct pt_regs *)ksp - 1;
 #if (KGDB_GDB_REG_SIZE == 32)
 	u32 *ptr = (u32 *)gdb_regs;
 #else
@@ -243,46 +254,25 @@
 #endif
 
 	for (reg = 0; reg < 16; reg++)
-		*(ptr++) = 0;
+		*(ptr++) = regs->regs[reg];
 
 	/* S0 - S7 */
-	*(ptr++) = p->thread.reg16;
-	*(ptr++) = p->thread.reg17;
-	*(ptr++) = p->thread.reg18;
-	*(ptr++) = p->thread.reg19;
-	*(ptr++) = p->thread.reg20;
-	*(ptr++) = p->thread.reg21;
-	*(ptr++) = p->thread.reg22;
-	*(ptr++) = p->thread.reg23;
+	for (reg = 16; reg < 24; reg++)
+		*(ptr++) = regs->regs[reg];
 
 	for (reg = 24; reg < 28; reg++)
 		*(ptr++) = 0;
 
 	/* GP, SP, FP, RA */
-	*(ptr++) = (long)p;
-	*(ptr++) = p->thread.reg29;
-	*(ptr++) = p->thread.reg30;
-	*(ptr++) = p->thread.reg31;
-
-	*(ptr++) = p->thread.cp0_status;
-
-	/* lo, hi */
-	*(ptr++) = 0;
-	*(ptr++) = 0;
-
-	/*
-	 * BadVAddr, Cause
-	 * Ideally these would come from the last exception frame up the stack
-	 * but that requires unwinding, otherwise we can't know much for sure.
-	 */
-	*(ptr++) = 0;
-	*(ptr++) = 0;
+	for (reg = 28; reg < 32; reg++)
+		*(ptr++) = regs->regs[reg];
 
-	/*
-	 * PC
-	 * use return address (RA), i.e. the moment after return from resume()
-	 */
-	*(ptr++) = p->thread.reg31;
+	*(ptr++) = regs->cp0_status;
+	*(ptr++) = regs->lo;
+	*(ptr++) = regs->hi;
+	*(ptr++) = regs->cp0_badvaddr;
+	*(ptr++) = regs->cp0_cause;
+	*(ptr++) = regs->cp0_epc;
 }
 
 void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc)
@@ -300,6 +290,7 @@
 	struct die_args *args = (struct die_args *)ptr;
 	struct pt_regs *regs = args->regs;
 	int trap = (regs->cp0_cause & 0x7c) >> 2;
+	mm_segment_t old_fs;
 
 #ifdef CONFIG_KPROBES
 	/*
@@ -314,11 +305,17 @@
 	if (user_mode(regs))
 		return NOTIFY_DONE;
 
+	/* Kernel mode. Set correct address limit */
+	old_fs = get_fs();
+	set_fs(get_ds());
+
 	if (atomic_read(&kgdb_active) != -1)
 		kgdb_nmicallback(smp_processor_id(), regs);
 
-	if (kgdb_handle_exception(trap, compute_signal(trap), cmd, regs))
+	if (kgdb_handle_exception(trap, compute_signal(trap), cmd, regs)) {
+		set_fs(old_fs);
 		return NOTIFY_DONE;
+	}
 
 	if (atomic_read(&kgdb_setting_breakpoint))
 		if ((trap == 9) && (regs->cp0_epc == (unsigned long)breakinst))
@@ -328,6 +325,7 @@
 	local_irq_enable();
 	__flush_cache_all();
 
+	set_fs(old_fs);
 	return NOTIFY_STOP;
 }
 
@@ -380,10 +378,6 @@
 
 struct kgdb_arch arch_kgdb_ops;
 
-/*
- * We use kgdb_early_setup so that functions we need to call now don't
- * cause trouble when called again later.
- */
 int kgdb_arch_init(void)
 {
 	union mips_instruction insn = {