ARM: kprobes: Migrate ARM LDRD and STRD to decoding tables

Signed-off-by: Jon Medhurst <tixy@yxit.co.uk>
Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>

1 files changed, 20 insertions, 17 deletions

diff --git a/arch/arm/kernel/kprobes-arm.c b/arch/arm/kernel/kprobes-arm.c
index 2b43d056fff5..e590ff6603c2 100644
--- a/arch/arm/kernel/kprobes-arm.c
+++ b/arch/arm/kernel/kprobes-arm.c
@@ -997,6 +997,23 @@ static const union decode_item arm_1111_table[] = {
         DECODE_END
 };
 
+static const union decode_item arm_cccc_000x_____1xx1_table[] = {
+        /* LDRD/STRD lr,pc,{... cccc 000x x0x0 xxxx 111x xxxx 1101 xxxx */
+        DECODE_REJECT   (0x0e10e0d0, 0x0000e0d0),
+
+        /* LDRD (register)      cccc 000x x0x0 xxxx xxxx xxxx 1101 xxxx */
+        /* STRD (register)      cccc 000x x0x0 xxxx xxxx xxxx 1111 xxxx */
+        DECODE_EMULATEX (0x0e5000d0, 0x000000d0, emulate_ldrdstrd,
+                                                 REGS(NOPCWB, NOPCX, 0, 0, NOPC)),
+
+        /* LDRD (immediate)     cccc 000x x1x0 xxxx xxxx xxxx 1101 xxxx */
+        /* STRD (immediate)     cccc 000x x1x0 xxxx xxxx xxxx 1111 xxxx */
+        DECODE_EMULATEX (0x0e5000d0, 0x004000d0, emulate_ldrdstrd,
+                                                 REGS(NOPCWB, NOPCX, 0, 0, 0)),
+
+        DECODE_END
+};
+
 static const union decode_item arm_cccc_000x_table[] = {
         /* Data-processing (register)                                   */
 
@@ -1192,23 +1209,9 @@ space_cccc_000x(kprobe_opcode_t insn, struct arch_specific_insn *asi)
                         }
 
                 } else if ((insn & 0x0e1000d0) == 0x00000d0) {
-                        /* STRD/LDRD */
-                        if ((insn & 0x0000e000) == 0x0000e000)
-                                return INSN_REJECTED;   /* Rd is LR or PC */
-                        if (is_writeback(insn) && is_r15(insn, 16))
-                                return INSN_REJECTED;   /* Writeback to PC */
-
-                        insn &= 0xfff00fff;
-                        insn |= 0x00002000;     /* Rn = r0, Rd = r2 */
-                        if (!(insn & (1 << 22))) {
-                                /* Register index */
-                                insn &= ~0xf;
-                                insn |= 1;      /* Rm = r1 */
-                        }
-                        asi->insn[0] = insn;
-                        asi->insn_handler =
-                                (insn & (1 << 5)) ? emulate_strd : emulate_ldrd;
-                        return INSN_GOOD;
+
+                        return kprobe_decode_insn(insn, asi, arm_cccc_000x_____1xx1_table,
+                                                                        false);
                 }
 
                 /* LDRH/STRH/LDRSB/LDRSH */