ARM: kprobes: Add emulate_rd12rn16rm0rs8_rwflags()

This is the emulation function for the instruction format used by the
ARM data-processing instructions.

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

1 files changed, 35 insertions, 0 deletions

diff --git a/arch/arm/kernel/kprobes-arm.c b/arch/arm/kernel/kprobes-arm.c
index 80a941100f8c..6e38bd4f7efd 100644
--- a/arch/arm/kernel/kprobes-arm.c
+++ b/arch/arm/kernel/kprobes-arm.c
@@ -893,6 +893,41 @@ prep_emulate_rdhi16rdlo12rs8rm0_wflags(kprobe_opcode_t insn,
         return INSN_GOOD;
 }
 
+static void __kprobes
+emulate_rd12rn16rm0rs8_rwflags(struct kprobe *p, struct pt_regs *regs)
+{
+        kprobe_opcode_t insn = p->opcode;
+        unsigned long pc = (unsigned long)p->addr + 8;
+        int rd = (insn >> 12) & 0xf;
+        int rn = (insn >> 16) & 0xf;
+        int rm = insn & 0xf;
+        int rs = (insn >> 8) & 0xf;
+
+        register unsigned long rdv asm("r0") = regs->uregs[rd];
+        register unsigned long rnv asm("r2") = (rn == 15) ? pc
+                                                          : regs->uregs[rn];
+        register unsigned long rmv asm("r3") = (rm == 15) ? pc
+                                                          : regs->uregs[rm];
+        register unsigned long rsv asm("r1") = regs->uregs[rs];
+        unsigned long cpsr = regs->ARM_cpsr;
+
+        __asm__ __volatile__ (
+                "msr    cpsr_fs, %[cpsr]        \n\t"
+                BLX("%[fn]")
+                "mrs    %[cpsr], cpsr           \n\t"
+                : "=r" (rdv), [cpsr] "=r" (cpsr)
+                : "0" (rdv), "r" (rnv), "r" (rmv), "r" (rsv),
+                  "1" (cpsr), [fn] "r" (p->ainsn.insn_fn)
+                : "lr", "memory", "cc"
+        );
+
+        if (rd == 15)
+                alu_write_pc(rdv, regs);
+        else
+                regs->uregs[rd] = rdv;
+        regs->ARM_cpsr = (regs->ARM_cpsr & ~APSR_MASK) | (cpsr & APSR_MASK);
+}
+
 /*
  * For the instruction masking and comparisons in all the "space_*"
  * functions below, Do _not_ rearrange the order of tests unless