MIPS: microMIPS: Add unaligned access support.

Add logic needed to handle unaligned accesses in microMIPS mode.

Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>
Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>

1 files changed, 101 insertions, 0 deletions

diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c
index 3be4405c2d14..ef533760d2c8 100644
--- a/arch/mips/kernel/process.c
+++ b/arch/mips/kernel/process.c
@@ -7,6 +7,7 @@
  * Copyright (C) 2005, 2006 by Ralf Baechle (ralf@linux-mips.org)
  * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
  * Copyright (C) 2004 Thiemo Seufer
+ * Copyright (C) 2013  Imagination Technologies Ltd.
  */
 #include <linux/errno.h>
 #include <linux/sched.h>
@@ -243,34 +244,115 @@ struct mips_frame_info {
 
 static inline int is_ra_save_ins(union mips_instruction *ip)
 {
+#ifdef CONFIG_CPU_MICROMIPS
+        union mips_instruction mmi;
+
+        /*
+         * swsp ra,offset
+         * swm16 reglist,offset(sp)
+         * swm32 reglist,offset(sp)
+         * sw32 ra,offset(sp)
+         * jradiussp - NOT SUPPORTED
+         *
+         * microMIPS is way more fun...
+         */
+        if (mm_insn_16bit(ip->halfword[0])) {
+                mmi.word = (ip->halfword[0] << 16);
+                return ((mmi.mm16_r5_format.opcode == mm_swsp16_op &&
+                         mmi.mm16_r5_format.rt == 31) ||
+                        (mmi.mm16_m_format.opcode == mm_pool16c_op &&
+                         mmi.mm16_m_format.func == mm_swm16_op));
+        }
+        else {
+                mmi.halfword[0] = ip->halfword[1];
+                mmi.halfword[1] = ip->halfword[0];
+                return ((mmi.mm_m_format.opcode == mm_pool32b_op &&
+                         mmi.mm_m_format.rd > 9 &&
+                         mmi.mm_m_format.base == 29 &&
+                         mmi.mm_m_format.func == mm_swm32_func) ||
+                        (mmi.i_format.opcode == mm_sw32_op &&
+                         mmi.i_format.rs == 29 &&
+                         mmi.i_format.rt == 31));
+        }
+#else
         /* sw / sd $ra, offset($sp) */
         return (ip->i_format.opcode == sw_op || ip->i_format.opcode == sd_op) &&
                 ip->i_format.rs == 29 &&
                 ip->i_format.rt == 31;
+#endif
 }
 
 static inline int is_jal_jalr_jr_ins(union mips_instruction *ip)
 {
+#ifdef CONFIG_CPU_MICROMIPS
+        /*
+         * jr16,jrc,jalr16,jalr16
+         * jal
+         * jalr/jr,jalr.hb/jr.hb,jalrs,jalrs.hb
+         * jraddiusp - NOT SUPPORTED
+         *
+         * microMIPS is kind of more fun...
+         */
+        union mips_instruction mmi;
+
+        mmi.word = (ip->halfword[0] << 16);
+
+        if ((mmi.mm16_r5_format.opcode == mm_pool16c_op &&
+            (mmi.mm16_r5_format.rt & mm_jr16_op) == mm_jr16_op) ||
+            ip->j_format.opcode == mm_jal32_op)
+                return 1;
+        if (ip->r_format.opcode != mm_pool32a_op ||
+                        ip->r_format.func != mm_pool32axf_op)
+                return 0;
+        return (((ip->u_format.uimmediate >> 6) & mm_jalr_op) == mm_jalr_op);
+#else
         if (ip->j_format.opcode == jal_op)
                 return 1;
         if (ip->r_format.opcode != spec_op)
                 return 0;
         return ip->r_format.func == jalr_op || ip->r_format.func == jr_op;
+#endif
 }
 
 static inline int is_sp_move_ins(union mips_instruction *ip)
 {
+#ifdef CONFIG_CPU_MICROMIPS
+        /*
+         * addiusp -imm
+         * addius5 sp,-imm
+         * addiu32 sp,sp,-imm
+         * jradiussp - NOT SUPPORTED
+         *
+         * microMIPS is not more fun...
+         */
+        if (mm_insn_16bit(ip->halfword[0])) {
+                union mips_instruction mmi;
+
+                mmi.word = (ip->halfword[0] << 16);
+                return ((mmi.mm16_r3_format.opcode == mm_pool16d_op &&
+                         mmi.mm16_r3_format.simmediate && mm_addiusp_func) ||
+                        (mmi.mm16_r5_format.opcode == mm_pool16d_op &&
+                         mmi.mm16_r5_format.rt == 29));
+        }
+        return (ip->mm_i_format.opcode == mm_addiu32_op &&
+                 ip->mm_i_format.rt == 29 && ip->mm_i_format.rs == 29);
+#else
         /* addiu/daddiu sp,sp,-imm */
         if (ip->i_format.rs != 29 || ip->i_format.rt != 29)
                 return 0;
         if (ip->i_format.opcode == addiu_op || ip->i_format.opcode == daddiu_op)
                 return 1;
+#endif
         return 0;
 }
 
 static int get_frame_info(struct mips_frame_info *info)
 {
+#ifdef CONFIG_CPU_MICROMIPS
+        union mips_instruction *ip = (void *) (((char *) info->func) - 1);
+#else
         union mips_instruction *ip = info->func;
+#endif
         unsigned max_insns = info->func_size / sizeof(union mips_instruction);
         unsigned i;
 
@@ -290,7 +372,26 @@ static int get_frame_info(struct mips_frame_info *info)
                         break;
                 if (!info->frame_size) {
                         if (is_sp_move_ins(ip))
+                        {
+#ifdef CONFIG_CPU_MICROMIPS
+                                if (mm_insn_16bit(ip->halfword[0]))
+                                {
+                                        unsigned short tmp;
+
+                                        if (ip->halfword[0] & mm_addiusp_func)
+                                        {
+                                                tmp = (((ip->halfword[0] >> 1) & 0x1ff) << 2);
+                                                info->frame_size = -(signed short)(tmp | ((tmp & 0x100) ? 0xfe00 : 0));
+                                        } else {
+                                                tmp = (ip->halfword[0] >> 1);
+                                                info->frame_size = -(signed short)(tmp & 0xf);
+                                        }
+                                        ip = (void *) &ip->halfword[1];
+                                        ip--;
+                                } else
+#endif
                                 info->frame_size = - ip->i_format.simmediate;
+                        }
                         continue;
                 }
                 if (info->pc_offset == -1 && is_ra_save_ins(ip)) {