ARM: probes: fix instruction fetch order with <asm/opcodes.h>

If we are running BE8, the data and instruction endianness do not
match, so use <asm/opcodes.h> to correctly translate memory accesses
into ARM instructions.

Acked-by: Jon Medhurst <tixy@linaro.org>
Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
[taras.kondratiuk@linaro.org: fixed Thumb instruction fetch order]
Signed-off-by: Taras Kondratiuk <taras.kondratiuk@linaro.org>

4 files changed, 28 insertions, 20 deletions

diff --git a/arch/arm/kernel/kprobes-common.c b/arch/arm/kernel/kprobes-common.c
index c311ed94ff1c..0bf5d64eba1d 100644
--- a/arch/arm/kernel/kprobes-common.c
+++ b/arch/arm/kernel/kprobes-common.c
@@ -13,6 +13,7 @@
 
 #include <linux/kernel.h>
 #include <linux/kprobes.h>
+#include <asm/opcodes.h>
 
 #include "kprobes.h"
 
@@ -153,7 +154,8 @@ kprobe_decode_ldmstm(probes_opcode_t insn, struct arch_probes_insn *asi,
 
         if (handler) {
                 /* We can emulate the instruction in (possibly) modified form */
-                asi->insn[0] = (insn & 0xfff00000) | (rn << 16) | reglist;
+                asi->insn[0] = __opcode_to_mem_arm((insn & 0xfff00000) |
+                                                   (rn << 16) | reglist);
                 asi->insn_handler = handler;
                 return INSN_GOOD;
         }
diff --git a/arch/arm/kernel/kprobes-thumb.c b/arch/arm/kernel/kprobes-thumb.c
index 6619188619ae..9495d7f3516f 100644
--- a/arch/arm/kernel/kprobes-thumb.c
+++ b/arch/arm/kernel/kprobes-thumb.c
@@ -149,9 +149,9 @@ t32_decode_ldmstm(probes_opcode_t insn, struct arch_probes_insn *asi,
         enum probes_insn ret = kprobe_decode_ldmstm(insn, asi, d);
 
         /* Fixup modified instruction to have halfwords in correct order...*/
-        insn = asi->insn[0];
-        ((u16 *)asi->insn)[0] = insn >> 16;
-        ((u16 *)asi->insn)[1] = insn & 0xffff;
+        insn = __mem_to_opcode_arm(asi->insn[0]);
+        ((u16 *)asi->insn)[0] = __opcode_to_mem_thumb16(insn >> 16);
+        ((u16 *)asi->insn)[1] = __opcode_to_mem_thumb16(insn & 0xffff);
 
         return ret;
 }
@@ -516,7 +516,7 @@ t16_decode_hiregs(probes_opcode_t insn, struct arch_probes_insn *asi,
 {
         insn &= ~0x00ff;
         insn |= 0x001; /* Set Rdn = R1 and Rm = R0 */
-        ((u16 *)asi->insn)[0] = insn;
+        ((u16 *)asi->insn)[0] = __opcode_to_mem_thumb16(insn);
         asi->insn_handler = t16_emulate_hiregs;
         return INSN_GOOD;
 }
@@ -547,8 +547,10 @@ t16_decode_push(probes_opcode_t insn, struct arch_probes_insn *asi,
          * and call it with R9=SP and LR in the register list represented
          * by R8.
          */
-        ((u16 *)asi->insn)[0] = 0xe929;         /* 1st half STMDB R9!,{} */
-        ((u16 *)asi->insn)[1] = insn & 0x1ff;   /* 2nd half (register list) */
+        /* 1st half STMDB R9!,{} */
+        ((u16 *)asi->insn)[0] = __opcode_to_mem_thumb16(0xe929);
+        /* 2nd half (register list) */
+        ((u16 *)asi->insn)[1] = __opcode_to_mem_thumb16(insn & 0x1ff);
         asi->insn_handler = t16_emulate_push;
         return INSN_GOOD;
 }
@@ -600,8 +602,10 @@ t16_decode_pop(probes_opcode_t insn, struct arch_probes_insn *asi,
          * and call it with R9=SP and PC in the register list represented
          * by R8.
          */
-        ((u16 *)asi->insn)[0] = 0xe8b9;         /* 1st half LDMIA R9!,{} */
-        ((u16 *)asi->insn)[1] = insn & 0x1ff;   /* 2nd half (register list) */
+        /* 1st half LDMIA R9!,{} */
+        ((u16 *)asi->insn)[0] = __opcode_to_mem_thumb16(0xe8b9);
+        /* 2nd half (register list) */
+        ((u16 *)asi->insn)[1] = __opcode_to_mem_thumb16(insn & 0x1ff);
         asi->insn_handler = insn & 0x100 ? t16_emulate_pop_pc
                                          : t16_emulate_pop_nopc;
         return INSN_GOOD;
diff --git a/arch/arm/kernel/kprobes.c b/arch/arm/kernel/kprobes.c
index 8795f9f819d5..6d644202c8dc 100644
--- a/arch/arm/kernel/kprobes.c
+++ b/arch/arm/kernel/kprobes.c
@@ -26,6 +26,7 @@
 #include <linux/stop_machine.h>
 #include <linux/stringify.h>
 #include <asm/traps.h>
+#include <asm/opcodes.h>
 #include <asm/cacheflush.h>
 #include <linux/percpu.h>
 #include <linux/bug.h>
@@ -67,10 +68,10 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p)
 #ifdef CONFIG_THUMB2_KERNEL
         thumb = true;
         addr &= ~1; /* Bit 0 would normally be set to indicate Thumb code */
-        insn = ((u16 *)addr)[0];
+        insn = __mem_to_opcode_thumb16(((u16 *)addr)[0]);
         if (is_wide_instruction(insn)) {
-                insn <<= 16;
-                insn |= ((u16 *)addr)[1];
+                u16 inst2 = __mem_to_opcode_thumb16(((u16 *)addr)[1]);
+                insn = __opcode_thumb32_compose(insn, inst2);
                 decode_insn = thumb32_probes_decode_insn;
                 actions = kprobes_t32_actions;
         } else {
@@ -81,7 +82,7 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p)
         thumb = false;
         if (addr & 0x3)
                 return -EINVAL;
-        insn = *p->addr;
+        insn = __mem_to_opcode_arm(*p->addr);
         decode_insn = arm_probes_decode_insn;
         actions = kprobes_arm_actions;
 #endif
diff --git a/arch/arm/kernel/probes.c b/arch/arm/kernel/probes.c
index b41873f33e69..a8ab540d7e73 100644
--- a/arch/arm/kernel/probes.c
+++ b/arch/arm/kernel/probes.c
@@ -202,13 +202,14 @@ prepare_emulated_insn(probes_opcode_t insn, struct arch_probes_insn *asi,
 #ifdef CONFIG_THUMB2_KERNEL
         if (thumb) {
                 u16 *thumb_insn = (u16 *)asi->insn;
-                thumb_insn[1] = 0x4770; /* Thumb bx lr */
-                thumb_insn[2] = 0x4770; /* Thumb bx lr */
+                /* Thumb bx lr */
+                thumb_insn[1] = __opcode_to_mem_thumb16(0x4770);
+                thumb_insn[2] = __opcode_to_mem_thumb16(0x4770);
                 return insn;
         }
-        asi->insn[1] = 0xe12fff1e; /* ARM bx lr */
+        asi->insn[1] = __opcode_to_mem_arm(0xe12fff1e); /* ARM bx lr */
 #else
-        asi->insn[1] = 0xe1a0f00e; /* mov pc, lr */
+        asi->insn[1] = __opcode_to_mem_arm(0xe1a0f00e); /* mov pc, lr */
 #endif
         /* Make an ARM instruction unconditional */
         if (insn < 0xe0000000)
@@ -228,12 +229,12 @@ set_emulated_insn(probes_opcode_t insn, struct arch_probes_insn *asi,
         if (thumb) {
                 u16 *ip = (u16 *)asi->insn;
                 if (is_wide_instruction(insn))
-                        *ip++ = insn >> 16;
-                *ip++ = insn;
+                        *ip++ = __opcode_to_mem_thumb16(insn >> 16);
+                *ip++ = __opcode_to_mem_thumb16(insn);
                 return;
         }
 #endif
-        asi->insn[0] = insn;
+        asi->insn[0] = __opcode_to_mem_arm(insn);
 }
 
 /*