ARM: 6412/1: kprobes-decode: add support for MOVW instruction

The MOVW instruction moves a 16-bit immediate into the bottom halfword
of the destination register.

This patch ensures that kprobes leaves the 16-bit immediate intact, rather
than assume a 12-bit immediate and mask out the upper 4 bits.

Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 4 insertions, 3 deletions

diff --git a/arch/arm/kernel/kprobes-decode.c b/arch/arm/kernel/kprobes-decode.c
index 8bccbfa693ff..2c1f0050c9c4 100644
--- a/arch/arm/kernel/kprobes-decode.c
+++ b/arch/arm/kernel/kprobes-decode.c
@@ -1162,11 +1162,12 @@ space_cccc_001x(kprobe_opcode_t insn, struct arch_specific_insn *asi)
 {
         /*
          * MSR   : cccc 0011 0x10 xxxx xxxx xxxx xxxx xxxx
-         * Undef : cccc 0011 0x00 xxxx xxxx xxxx xxxx xxxx
+         * Undef : cccc 0011 0100 xxxx xxxx xxxx xxxx xxxx
          * ALU op with S bit and Rd == 15 :
          *         cccc 001x xxx1 xxxx 1111 xxxx xxxx xxxx
          */
-        if ((insn & 0x0f900000) == 0x03200000 ||        /* MSR & Undef */
+        if ((insn & 0x0fb00000) == 0x03200000 ||        /* MSR */
+            (insn & 0x0ff00000) == 0x03400000 ||        /* Undef */
             (insn & 0x0e10f000) == 0x0210f000)          /* ALU s-bit, R15  */
                 return INSN_REJECTED;
 
@@ -1177,7 +1178,7 @@ space_cccc_001x(kprobe_opcode_t insn, struct arch_specific_insn *asi)
          * *S (bit 20) updates condition codes
          * ADC/SBC/RSC reads the C flag
          */
-        insn &= 0xfff00fff;     /* Rn = r0, Rd = r0 */
+        insn &= 0xffff0fff;     /* Rd = r0 */
         asi->insn[0] = insn;
         asi->insn_handler = (insn & (1 << 20)) ?  /* S-bit */
                         emulate_alu_imm_rwflags : emulate_alu_imm_rflags;