ARM: kprobes: Decode 32-bit Thumb data-processing (plain binary immediate) instructions

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

1 files changed, 95 insertions, 0 deletions

diff --git a/arch/arm/kernel/kprobes-thumb.c b/arch/arm/kernel/kprobes-thumb.c
index cf834484fb58..1fbeba8093f1 100644
--- a/arch/arm/kernel/kprobes-thumb.c
+++ b/arch/arm/kernel/kprobes-thumb.c
@@ -124,6 +124,46 @@ t32_emulate_rd8rn16rm0_rwflags(struct kprobe *p, struct pt_regs *regs)
         regs->ARM_cpsr = (regs->ARM_cpsr & ~APSR_MASK) | (cpsr & APSR_MASK);
 }
 
+static void __kprobes
+t32_emulate_rd8pc16_noflags(struct kprobe *p, struct pt_regs *regs)
+{
+        kprobe_opcode_t insn = p->opcode;
+        unsigned long pc = thumb_probe_pc(p);
+        int rd = (insn >> 8) & 0xf;
+
+        register unsigned long rdv asm("r1") = regs->uregs[rd];
+        register unsigned long rnv asm("r2") = pc & ~3;
+
+        __asm__ __volatile__ (
+                "blx    %[fn]"
+                : "=r" (rdv)
+                : "0" (rdv), "r" (rnv), [fn] "r" (p->ainsn.insn_fn)
+                : "lr", "memory", "cc"
+        );
+
+        regs->uregs[rd] = rdv;
+}
+
+static void __kprobes
+t32_emulate_rd8rn16_noflags(struct kprobe *p, struct pt_regs *regs)
+{
+        kprobe_opcode_t insn = p->opcode;
+        int rd = (insn >> 8) & 0xf;
+        int rn = (insn >> 16) & 0xf;
+
+        register unsigned long rdv asm("r1") = regs->uregs[rd];
+        register unsigned long rnv asm("r2") = regs->uregs[rn];
+
+        __asm__ __volatile__ (
+                "blx    %[fn]"
+                : "=r" (rdv)
+                : "0" (rdv), "r" (rnv), [fn] "r" (p->ainsn.insn_fn)
+                : "lr", "memory", "cc"
+        );
+
+        regs->uregs[rd] = rdv;
+}
+
 static const union decode_item t32_table_1110_100x_x0xx[] = {
         /* Load/store multiple instructions */
 
@@ -293,6 +333,55 @@ static const union decode_item t32_table_1111_0x0x___0[] = {
         DECODE_END
 };
 
+static const union decode_item t32_table_1111_0x1x___0[] = {
+        /* Data-processing (plain binary immediate)                     */
+
+        /* ADDW Rd, PC, #imm    1111 0x10 0000 1111 0xxx xxxx xxxx xxxx */
+        DECODE_OR       (0xfbff8000, 0xf20f0000),
+        /* SUBW Rd, PC, #imm    1111 0x10 1010 1111 0xxx xxxx xxxx xxxx */
+        DECODE_EMULATEX (0xfbff8000, 0xf2af0000, t32_emulate_rd8pc16_noflags,
+                                                 REGS(PC, 0, NOSPPC, 0, 0)),
+
+        /* ADDW SP, SP, #imm    1111 0x10 0000 1101 0xxx 1101 xxxx xxxx */
+        DECODE_OR       (0xfbff8f00, 0xf20d0d00),
+        /* SUBW SP, SP, #imm    1111 0x10 1010 1101 0xxx 1101 xxxx xxxx */
+        DECODE_EMULATEX (0xfbff8f00, 0xf2ad0d00, t32_emulate_rd8rn16_noflags,
+                                                 REGS(SP, 0, SP, 0, 0)),
+
+        /* ADDW                 1111 0x10 0000 xxxx 0xxx xxxx xxxx xxxx */
+        DECODE_OR       (0xfbf08000, 0xf2000000),
+        /* SUBW                 1111 0x10 1010 xxxx 0xxx xxxx xxxx xxxx */
+        DECODE_EMULATEX (0xfbf08000, 0xf2a00000, t32_emulate_rd8rn16_noflags,
+                                                 REGS(NOPCX, 0, NOSPPC, 0, 0)),
+
+        /* MOVW                 1111 0x10 0100 xxxx 0xxx xxxx xxxx xxxx */
+        /* MOVT                 1111 0x10 1100 xxxx 0xxx xxxx xxxx xxxx */
+        DECODE_EMULATEX (0xfb708000, 0xf2400000, t32_emulate_rd8rn16_noflags,
+                                                 REGS(0, 0, NOSPPC, 0, 0)),
+
+        /* SSAT16               1111 0x11 0010 xxxx 0000 xxxx 00xx xxxx */
+        /* SSAT                 1111 0x11 00x0 xxxx 0xxx xxxx xxxx xxxx */
+        /* USAT16               1111 0x11 1010 xxxx 0000 xxxx 00xx xxxx */
+        /* USAT                 1111 0x11 10x0 xxxx 0xxx xxxx xxxx xxxx */
+        DECODE_EMULATEX (0xfb508000, 0xf3000000, t32_emulate_rd8rn16rm0_rwflags,
+                                                 REGS(NOSPPC, 0, NOSPPC, 0, 0)),
+
+        /* SFBX                 1111 0x11 0100 xxxx 0xxx xxxx xxxx xxxx */
+        /* UFBX                 1111 0x11 1100 xxxx 0xxx xxxx xxxx xxxx */
+        DECODE_EMULATEX (0xfb708000, 0xf3400000, t32_emulate_rd8rn16_noflags,
+                                                 REGS(NOSPPC, 0, NOSPPC, 0, 0)),
+
+        /* BFC                  1111 0x11 0110 1111 0xxx xxxx xxxx xxxx */
+        DECODE_EMULATEX (0xfbff8000, 0xf36f0000, t32_emulate_rd8rn16_noflags,
+                                                 REGS(0, 0, NOSPPC, 0, 0)),
+
+        /* BFI                  1111 0x11 0110 xxxx 0xxx xxxx xxxx xxxx */
+        DECODE_EMULATEX (0xfbf08000, 0xf3600000, t32_emulate_rd8rn16_noflags,
+                                                 REGS(NOSPPCX, 0, NOSPPC, 0, 0)),
+
+        DECODE_END
+};
+
 static const union decode_item t32_table_1111_0xxx___1[] = {
         /* Branches and miscellaneous control                           */
 
@@ -335,6 +424,12 @@ const union decode_item kprobe_decode_thumb32_table[] = {
         DECODE_TABLE    (0xfa008000, 0xf0000000, t32_table_1111_0x0x___0),
 
         /*
+         * Data-processing (plain binary immediate)
+         *                      1111 0x1x xxxx xxxx 0xxx xxxx xxxx xxxx
+         */
+        DECODE_TABLE    (0xfa008000, 0xf2000000, t32_table_1111_0x1x___0),
+
+        /*
          * Branches and miscellaneous control
          *                      1111 0xxx xxxx xxxx 1xxx xxxx xxxx xxxx
          */