MN10300: Handle misaligned postinc-with-imm addressing mode correctly

Correctly handle misalignment in MOV instructions with postinc-with-immediate
addressing mode operands.  In these, the immediate value is the increment to
be applied the address register, not the displacement to the address.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 56 insertions, 51 deletions

diff --git a/arch/mn10300/mm/misalignment.c b/arch/mn10300/mm/misalignment.c
index d5b45bb7d108..61e65ec47db8 100644
--- a/arch/mn10300/mm/misalignment.c
+++ b/arch/mn10300/mm/misalignment.c
@@ -44,7 +44,8 @@
 
 static int misalignment_addr(unsigned long *registers, unsigned params,
                              unsigned opcode, unsigned long disp,
-                             void **_address, unsigned long **_postinc);
+                             void **_address, unsigned long **_postinc,
+                             unsigned long *_inc);
 
 static int misalignment_reg(unsigned long *registers, unsigned params,
                             unsigned opcode, unsigned long disp,
@@ -150,7 +151,7 @@ enum value_id {
 };
 
 struct mn10300_opcode {
-        const char      *name;
+        const char      name[8];
         u_int32_t       opcode;
         u_int32_t       opmask;
         unsigned        exclusion;
@@ -310,7 +311,7 @@ static const struct mn10300_opcode mn10300_opcodes[] = {
 { "mov_lne",    0xf7e00009,  0xffff000f,  0x22, FMT_D10, AM33,   {MEMINC2 (RN4,SIMM4_2), RM6}},
 { "mov_lra",    0xf7e0000a,  0xffff000f,  0x22, FMT_D10, AM33,   {MEMINC2 (RN4,SIMM4_2), RM6}},
 
-{ 0, 0, 0, 0, 0, 0, {0}},
+{ "", 0, 0, 0, 0, 0, {0}},
 };
 
 /*
@@ -321,11 +322,11 @@ asmlinkage void misalignment(struct pt_regs *regs, enum exception_code code)
         const struct exception_table_entry *fixup;
         const struct mn10300_opcode *pop;
         unsigned long *registers = (unsigned long *) regs;
-        unsigned long data, *store, *postinc, disp;
+        unsigned long data, *store, *postinc, disp, inc;
         mm_segment_t seg;
         siginfo_t info;
         uint32_t opcode, noc, xo, xm;
-        uint8_t *pc, byte;
+        uint8_t *pc, byte, datasz;
         void *address;
         unsigned tmp, npop, dispsz, loop;
 
@@ -347,7 +348,7 @@ asmlinkage void misalignment(struct pt_regs *regs, enum exception_code code)
         opcode = byte;
         noc = 8;
 
-        for (pop = mn10300_opcodes; pop->name; pop++) {
+        for (pop = mn10300_opcodes; pop->name[0]; pop++) {
                 npop = ilog2(pop->opcode | pop->opmask);
                 if (npop <= 0 || npop > 31)
                         continue;
@@ -484,32 +485,31 @@ found_opcode:
                 goto failed;
         }
 
+        /* determine the data transfer size of the move */
+        if (pop->name[3] == 0 || /* "mov" */
+            pop->name[4] == 'l') /* mov_lcc */
+                inc = datasz = 4;
+        else if (pop->name[3] == 'h') /* movhu */
+                inc = datasz = 2;
+        else
+                goto unsupported_instruction;
+
         if (pop->params[0] & 0x80000000) {
                 /* move memory to register */
                 if (!misalignment_addr(registers, pop->params[0], opcode, disp,
-                                       &address, &postinc))
+                                       &address, &postinc, &inc))
                         goto bad_addr_mode;
 
                 if (!misalignment_reg(registers, pop->params[1], opcode, disp,
                                       &store))
                         goto bad_reg_mode;
 
-                if (strcmp(pop->name, "mov") == 0 ||
-                    memcmp(pop->name, "mov_l", 5) == 0) {
-                        kdebug("mov (%p),DARn", address);
-                        if (copy_from_user(&data, (void *) address, 4) != 0)
-                                goto transfer_failed;
-                        if (pop->params[0] & 0x1000000)
-                                *postinc += 4;
-                } else if (strcmp(pop->name, "movhu") == 0) {
-                        kdebug("movhu (%p),DARn", address);
-                        data = 0;
-                        if (copy_from_user(&data, (void *) address, 2) != 0)
-                                goto transfer_failed;
-                        if (pop->params[0] & 0x1000000)
-                                *postinc += 2;
-                } else {
-                        goto unsupported_instruction;
+                kdebug("mov%u (%p),DARn", datasz, address);
+                if (copy_from_user(&data, (void *) address, datasz) != 0)
+                        goto transfer_failed;
+                if (pop->params[0] & 0x1000000) {
+                        kdebug("inc=%lx", inc);
+                        *postinc += inc;
                 }
 
                 *store = data;
@@ -521,26 +521,16 @@ found_opcode:
                         goto bad_reg_mode;
 
                 if (!misalignment_addr(registers, pop->params[1], opcode, disp,
-                                       &address, &postinc))
+                                       &address, &postinc, &inc))
                         goto bad_addr_mode;
 
                 data = *store;
 
-                if (strcmp(pop->name, "mov") == 0) {
-                        kdebug("mov %lx,(%p)", data, address);
-                        if (copy_to_user((void *) address, &data, 4) != 0)
-                                goto transfer_failed;
-                        if (pop->params[1] & 0x1000000)
-                                *postinc += 4;
-                } else if (strcmp(pop->name, "movhu") == 0) {
-                        kdebug("movhu %hx,(%p)", (uint16_t) data, address);
-                        if (copy_to_user((void *) address, &data, 2) != 0)
-                                goto transfer_failed;
-                        if (pop->params[1] & 0x1000000)
-                                *postinc += 2;
-                } else {
-                        goto unsupported_instruction;
-                }
+                kdebug("mov%u %lx,(%p)", datasz, data, address);
+                if (copy_to_user((void *) address, &data, datasz) != 0)
+                        goto transfer_failed;
+                if (pop->params[1] & 0x1000000)
+                        *postinc += inc;
         }
 
         tmp = format_tbl[pop->format].opsz + format_tbl[pop->format].dispsz;
@@ -560,10 +550,17 @@ found_opcode:
  */
 static int misalignment_addr(unsigned long *registers, unsigned params,
                              unsigned opcode, unsigned long disp,
-                             void **_address, unsigned long **_postinc)
+                             void **_address, unsigned long **_postinc,
+                             unsigned long *_inc)
 {
         unsigned long *postinc = NULL, address = 0, tmp;
 
+        if (!(params & 0x1000000)) {
+                kdebug("noinc");
+                *_inc = 0;
+                _inc = NULL;
+        }
+
         params &= 0x00ffffff;
 
         do {
@@ -624,32 +621,40 @@ static int misalignment_addr(unsigned long *registers, unsigned params,
                         address += registers[REG_SP >> 2];
                         break;
 
+                        /* displacements are either to be added to the address
+                         * before use, or, in the case of post-inc addressing,
+                         * to be added into the base register after use */
                 case SD8:
                 case SIMM8:
-                        address += (int32_t) (int8_t) (disp & 0xff);
-                        break;
+                        disp = (long) (int8_t) (disp & 0xff);
+                        goto displace_or_inc;
                 case SD16:
-                        address += (int32_t) (int16_t) (disp & 0xffff);
-                        break;
+                        disp = (long) (int16_t) (disp & 0xffff);
+                        goto displace_or_inc;
                 case SD24:
                         tmp = disp << 8;
                         asm("asr 8,%0" : "=r"(tmp) : "0"(tmp));
-                        address += tmp;
-                        break;
+                        disp = (long) tmp;
+                        goto displace_or_inc;
                 case SIMM4_2:
                         tmp = opcode >> 4 & 0x0f;
                         tmp <<= 28;
                         asm("asr 28,%0" : "=r"(tmp) : "0"(tmp));
-                        address += tmp;
-                        break;
+                        disp = (long) tmp;
+                        goto displace_or_inc;
                 case IMM24:
-                        address += disp & 0x00ffffff;
-                        break;
+                        disp &= 0x00ffffff;
+                        goto displace_or_inc;
                 case IMM32:
                 case IMM32_MEM:
                 case IMM32_HIGH8:
                 case IMM32_HIGH8_MEM:
-                        address += disp;
+                displace_or_inc:
+                        kdebug("%s %lx", _inc ? "incr" : "disp", disp);
+                        if (!_inc)
+                                address += disp;
+                        else
+                                *_inc = disp;
                         break;
                 default:
                         BUG();