From 9f8ac82452d8bb5eccc38a0c3c0a8f82e1774452 Mon Sep 17 00:00:00 2001
From: Paul Burton <paul.burton@imgtec.com>
Date: Mon, 16 May 2016 10:52:10 +0100
Subject: [PATCH] MIPS: Use unchecked immediate addition/subtraction

In MIPS assembly there have historically been 2 variants of immediate
addition - the standard "addi" which traps if an overflow occurs, and
the unchecked "addiu" which does not trap on overflow. In release 6 of
the MIPS architecture the trapping variants of immediate addition &
subtraction have been removed. In preparation for supporting MIPSr6,
stop using the trapping instructions from assembly & switch to their
unchecked variants.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
---
 arch/mips/cpu/start.S      | 22 ++++++++++++----------
 arch/mips/lib/cache_init.S |  2 +-
 2 files changed, 13 insertions(+), 11 deletions(-)

diff --git a/arch/mips/cpu/start.S b/arch/mips/cpu/start.S
index 1b56ca350a..fc6dd66aa6 100644
--- a/arch/mips/cpu/start.S
+++ b/arch/mips/cpu/start.S
@@ -164,12 +164,14 @@ reset:
 	li	t0, -16
 	PTR_LI	t1, CONFIG_SYS_INIT_SP_ADDR
 	and	sp, t1, t0		# force 16 byte alignment
-	PTR_SUB	sp, sp, GD_SIZE		# reserve space for gd
+	PTR_SUBU \
+		sp, sp, GD_SIZE		# reserve space for gd
 	and	sp, sp, t0		# force 16 byte alignment
 	move	k0, sp			# save gd pointer
 #ifdef CONFIG_SYS_MALLOC_F_LEN
 	li	t2, CONFIG_SYS_MALLOC_F_LEN
-	PTR_SUB	sp, sp, t2		# reserve space for early malloc
+	PTR_SUBU \
+		sp, sp, t2		# reserve space for early malloc
 	and	sp, sp, t0		# force 16 byte alignment
 #endif
 	move	fp, sp
@@ -179,7 +181,7 @@ reset:
 1:
 	PTR_S	zero, 0(t0)
 	blt	t0, t1, 1b
-	 PTR_ADDI t0, PTRSIZE
+	 PTR_ADDIU t0, PTRSIZE
 
 #ifdef CONFIG_SYS_MALLOC_F_LEN
 	PTR_S	sp, GD_MALLOC_BASE(k0)	# gd->malloc_base offset
@@ -237,7 +239,7 @@ ENTRY(relocate_code)
 	 move	a0, s2			# a0 <-- destination address
 
 	/* Jump to where we've relocated ourselves */
-	PTR_ADDI t0, s2, in_ram - _start
+	PTR_ADDIU t0, s2, in_ram - _start
 	jr	t0
 	 nop
 
@@ -257,7 +259,7 @@ in_ram:
 	PTR_L	t3, -(1 * PTRSIZE)(t0)	# t3 <-- num_got_entries
 	PTR_L	t8, -(2 * PTRSIZE)(t0)	# t8 <-- _GLOBAL_OFFSET_TABLE_
 	PTR_ADD	t8, s1			# t8 now holds relocated _G_O_T_
-	PTR_ADDI t8, t8, 2 * PTRSIZE	# skipping first two entries
+	PTR_ADDIU t8, t8, 2 * PTRSIZE	# skipping first two entries
 	PTR_LI	t2, 2
 1:
 	PTR_L	t1, 0(t8)
@@ -265,16 +267,16 @@ in_ram:
 	 PTR_ADD t1, s1
 	PTR_S	t1, 0(t8)
 2:
-	PTR_ADDI t2, 1
+	PTR_ADDIU t2, 1
 	blt	t2, t3, 1b
-	 PTR_ADDI t8, PTRSIZE
+	 PTR_ADDIU t8, PTRSIZE
 
 	/* Update dynamic relocations */
 	PTR_L	t1, -(4 * PTRSIZE)(t0)	# t1 <-- __rel_dyn_start
 	PTR_L	t2, -(5 * PTRSIZE)(t0)	# t2 <-- __rel_dyn_end
 
 	b	2f			# skip first reserved entry
-	 PTR_ADDI t1, 2 * PTRSIZE
+	 PTR_ADDIU t1, 2 * PTRSIZE
 
 1:
 	lw	t8, -4(t1)		# t8 <-- relocation info
@@ -293,7 +295,7 @@ in_ram:
 
 2:
 	blt	t1, t2, 1b
-	 PTR_ADDI t1, 2 * PTRSIZE	# each rel.dyn entry is 2*PTRSIZE bytes
+	 PTR_ADDIU t1, 2 * PTRSIZE	# each rel.dyn entry is 2*PTRSIZE bytes
 
 	/*
 	 * Clear BSS
@@ -307,7 +309,7 @@ in_ram:
 1:
 	PTR_S	zero, 0(t1)
 	blt	t1, t2, 1b
-	 PTR_ADDI t1, PTRSIZE
+	 PTR_ADDIU t1, PTRSIZE
 
 	move	a0, s0			# a0 <-- gd
 	move	a1, s2
diff --git a/arch/mips/lib/cache_init.S b/arch/mips/lib/cache_init.S
index 14cc2c49fd..08b7c3af52 100644
--- a/arch/mips/lib/cache_init.S
+++ b/arch/mips/lib/cache_init.S
@@ -64,7 +64,7 @@
 	/* detect associativity */
 	srl	\sz, $1, \off + MIPS_CONF1_DA_SHF - MIPS_CONF1_DA_SHF
 	andi	\sz, \sz, (MIPS_CONF1_DA >> MIPS_CONF1_DA_SHF)
-	addi	\sz, \sz, 1
+	addiu	\sz, \sz, 1
 
 	/* sz *= line_sz */
 	mul	\sz, \sz, \line_sz
-- 
2.25.1