ARM: kprobes: Decode 32-bit Thumb long multiply and divide instructions

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

1 files changed, 55 insertions, 0 deletions

diff --git a/arch/arm/kernel/kprobes-thumb.c b/arch/arm/kernel/kprobes-thumb.c
index 7c32e5b03cee..4ef12d13c7d0 100644
--- a/arch/arm/kernel/kprobes-thumb.c
+++ b/arch/arm/kernel/kprobes-thumb.c
@@ -289,6 +289,32 @@ t32_emulate_rd8rn16_noflags(struct kprobe *p, struct pt_regs *regs)
         regs->uregs[rd] = rdv;
 }
 
+static void __kprobes
+t32_emulate_rdlo12rdhi8rn16rm0_noflags(struct kprobe *p, struct pt_regs *regs)
+{
+        kprobe_opcode_t insn = p->opcode;
+        int rdlo = (insn >> 12) & 0xf;
+        int rdhi = (insn >> 8) & 0xf;
+        int rn = (insn >> 16) & 0xf;
+        int rm = insn & 0xf;
+
+        register unsigned long rdlov asm("r0") = regs->uregs[rdlo];
+        register unsigned long rdhiv asm("r1") = regs->uregs[rdhi];
+        register unsigned long rnv asm("r2") = regs->uregs[rn];
+        register unsigned long rmv asm("r3") = regs->uregs[rm];
+
+        __asm__ __volatile__ (
+                "blx    %[fn]"
+                : "=r" (rdlov), "=r" (rdhiv)
+                : "0" (rdlov), "1" (rdhiv), "r" (rnv), "r" (rmv),
+                  [fn] "r" (p->ainsn.insn_fn)
+                : "lr", "memory", "cc"
+        );
+
+        regs->uregs[rdlo] = rdlov;
+        regs->uregs[rdhi] = rdhiv;
+}
+
 static const union decode_item t32_table_1110_100x_x0xx[] = {
         /* Load/store multiple instructions */
 
@@ -763,6 +789,29 @@ static const union decode_item t32_table_1111_1010___1111[] = {
         DECODE_END
 };
 
+static const union decode_item t32_table_1111_1011_1[] = {
+        /* Long multiply, long multiply accumulate, and divide          */
+
+        /* UMAAL                1111 1011 1110 xxxx xxxx xxxx 0110 xxxx */
+        DECODE_OR       (0xfff000f0, 0xfbe00060),
+        /* SMLALxy              1111 1011 1100 xxxx xxxx xxxx 10xx xxxx */
+        DECODE_OR       (0xfff000c0, 0xfbc00080),
+        /* SMLALD{X}            1111 1011 1100 xxxx xxxx xxxx 110x xxxx */
+        /* SMLSLD{X}            1111 1011 1101 xxxx xxxx xxxx 110x xxxx */
+        DECODE_OR       (0xffe000e0, 0xfbc000c0),
+        /* SMULL                1111 1011 1000 xxxx xxxx xxxx 0000 xxxx */
+        /* UMULL                1111 1011 1010 xxxx xxxx xxxx 0000 xxxx */
+        /* SMLAL                1111 1011 1100 xxxx xxxx xxxx 0000 xxxx */
+        /* UMLAL                1111 1011 1110 xxxx xxxx xxxx 0000 xxxx */
+        DECODE_EMULATEX (0xff9000f0, 0xfb800000, t32_emulate_rdlo12rdhi8rn16rm0_noflags,
+                                                 REGS(NOSPPC, NOSPPC, NOSPPC, 0, NOSPPC)),
+
+        /* SDIV                 1111 1011 1001 xxxx xxxx xxxx 1111 xxxx */
+        /* UDIV                 1111 1011 1011 xxxx xxxx xxxx 1111 xxxx */
+        /* Other unallocated instructions...                            */
+        DECODE_END
+};
+
 const union decode_item kprobe_decode_thumb32_table[] = {
 
         /*
@@ -834,6 +883,12 @@ const union decode_item kprobe_decode_thumb32_table[] = {
         DECODE_TABLE    (0xff00f000, 0xfa00f000, t32_table_1111_1010___1111),
 
         /*
+         * Long multiply, long multiply accumulate, and divide
+         *                      1111 1011 1xxx xxxx xxxx xxxx xxxx xxxx
+         */
+        DECODE_TABLE    (0xff800000, 0xfb800000, t32_table_1111_1011_1),
+
+        /*
          * Coprocessor instructions
          *                      1111 11xx xxxx xxxx xxxx xxxx xxxx xxxx
          */