[ARM] 2867/2: unaligned ldrd/strd fixups

Patch from Steve Longerbeam

Adds an implementation of unaligned LDRD and STRD fixups.
Also fixes a bug where do_alignment() would misinterpret and
fixup an unaligned LDRD/STRD as LDRH/STRH, causing memory
corruption.
This is the same as Patch #2867/1, but with minor whitespace
and comments changes, plus a check for arch-level >= v5TE
before printing ai_dword count in proc_alignment_read().

Signed-off-by: Steve Longerbeam <stevel@mwwireless.net>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 56 insertions, 14 deletions

diff --git a/arch/arm/mm/alignment.c b/arch/arm/mm/alignment.c
index 81f4a8a2d34b..4b39d867ac14 100644
--- a/arch/arm/mm/alignment.c
+++ b/arch/arm/mm/alignment.c
@@ -45,7 +45,7 @@
 
 #define LDST_P_EQ_U(i)  ((((i) ^ ((i) >> 1)) & (1 << 23)) == 0)
 
-#define LDSTH_I_BIT(i)  (i & (1 << 22))         /* half-word immed      */
+#define LDSTHD_I_BIT(i) (i & (1 << 22))         /* double/half-word immed */
 #define LDM_S_BIT(i)    (i & (1 << 22))         /* write CPSR from SPSR */
 
 #define RN_BITS(i)      ((i >> 16) & 15)        /* Rn                   */
@@ -68,6 +68,7 @@ static unsigned long ai_sys;
 static unsigned long ai_skipped;
 static unsigned long ai_half;
 static unsigned long ai_word;
+static unsigned long ai_dword;
 static unsigned long ai_multi;
 static int ai_usermode;
 
@@ -93,6 +94,8 @@ proc_alignment_read(char *page, char **start, off_t off, int count, int *eof,
         p += sprintf(p, "Skipped:\t%lu\n", ai_skipped);
         p += sprintf(p, "Half:\t\t%lu\n", ai_half);
         p += sprintf(p, "Word:\t\t%lu\n", ai_word);
+        if (cpu_architecture() >= CPU_ARCH_ARMv5TE)
+                p += sprintf(p, "DWord:\t\t%lu\n", ai_dword);
         p += sprintf(p, "Multi:\t\t%lu\n", ai_multi);
         p += sprintf(p, "User faults:\t%i (%s)\n", ai_usermode,
                         usermode_action[ai_usermode]);
@@ -283,12 +286,6 @@ do_alignment_ldrhstrh(unsigned long addr, unsigned long instr, struct pt_regs *r
 {
         unsigned int rd = RD_BITS(instr);
 
-        if ((instr & 0x01f00ff0) == 0x01000090)
-                goto swp;
-
-        if ((instr & 0x90) != 0x90 || (instr & 0x60) == 0)
-                goto bad;
-
         ai_half += 1;
 
         if (user_mode(regs))
@@ -323,10 +320,47 @@ do_alignment_ldrhstrh(unsigned long addr, unsigned long instr, struct pt_regs *r
 
         return TYPE_LDST;
 
- swp:
-        printk(KERN_ERR "Alignment trap: not handling swp instruction\n");
- bad:
-        return TYPE_ERROR;
+ fault:
+        return TYPE_FAULT;
+}
+
+static int
+do_alignment_ldrdstrd(unsigned long addr, unsigned long instr,
+                      struct pt_regs *regs)
+{
+        unsigned int rd = RD_BITS(instr);
+
+        ai_dword += 1;
+
+        if (user_mode(regs))
+                goto user;
+
+        if ((instr & 0xf0) == 0xd0) {
+                unsigned long val;
+                get32_unaligned_check(val, addr);
+                regs->uregs[rd] = val;
+                get32_unaligned_check(val, addr+4);
+                regs->uregs[rd+1] = val;
+        } else {
+                put32_unaligned_check(regs->uregs[rd], addr);
+                put32_unaligned_check(regs->uregs[rd+1], addr+4);
+        }
+
+        return TYPE_LDST;
+
+ user:
+        if ((instr & 0xf0) == 0xd0) {
+                unsigned long val;
+                get32t_unaligned_check(val, addr);
+                regs->uregs[rd] = val;
+                get32t_unaligned_check(val, addr+4);
+                regs->uregs[rd+1] = val;
+        } else {
+                put32t_unaligned_check(regs->uregs[rd], addr);
+                put32t_unaligned_check(regs->uregs[rd+1], addr+4);
+        }
+
+        return TYPE_LDST;
 
  fault:
         return TYPE_FAULT;
@@ -617,12 +651,20 @@ do_alignment(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
         regs->ARM_pc += thumb_mode(regs) ? 2 : 4;
 
         switch (CODING_BITS(instr)) {
-        case 0x00000000:        /* ldrh or strh */
-                if (LDSTH_I_BIT(instr))
+        case 0x00000000:        /* 3.13.4 load/store instruction extensions */
+                if (LDSTHD_I_BIT(instr))
                         offset.un = (instr & 0xf00) >> 4 | (instr & 15);
                 else
                         offset.un = regs->uregs[RM_BITS(instr)];
-                handler = do_alignment_ldrhstrh;
+
+                if ((instr & 0x000000f0) == 0x000000b0 || /* LDRH, STRH */
+                    (instr & 0x001000f0) == 0x001000f0)   /* LDRSH */
+                        handler = do_alignment_ldrhstrh;
+                else if ((instr & 0x001000f0) == 0x000000d0 || /* LDRD */
+                         (instr & 0x001000f0) == 0x000000f0)   /* STRD */
+                        handler = do_alignment_ldrdstrd;
+                else
+                        goto bad;
                 break;
 
         case 0x04000000:        /* ldr or str immediate */