ARM: kprobes: Add emulate_ldrdstrd()

This is an emulation function for the LDRD and STRD instructions.

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

1 files changed, 29 insertions, 0 deletions

diff --git a/arch/arm/kernel/kprobes-arm.c b/arch/arm/kernel/kprobes-arm.c
index 8e4b7185f9fb..2b43d056fff5 100644
--- a/arch/arm/kernel/kprobes-arm.c
+++ b/arch/arm/kernel/kprobes-arm.c
@@ -894,6 +894,35 @@ prep_emulate_rdhi16rdlo12rs8rm0_wflags(kprobe_opcode_t insn,
 }
 
 static void __kprobes
+emulate_ldrdstrd(struct kprobe *p, struct pt_regs *regs)
+{
+        kprobe_opcode_t insn = p->opcode;
+        unsigned long pc = (unsigned long)p->addr + 8;
+        int rt = (insn >> 12) & 0xf;
+        int rn = (insn >> 16) & 0xf;
+        int rm = insn & 0xf;
+
+        register unsigned long rtv asm("r0") = regs->uregs[rt];
+        register unsigned long rt2v asm("r1") = regs->uregs[rt+1];
+        register unsigned long rnv asm("r2") = (rn == 15) ? pc
+                                                          : regs->uregs[rn];
+        register unsigned long rmv asm("r3") = regs->uregs[rm];
+
+        __asm__ __volatile__ (
+                BLX("%[fn]")
+                : "=r" (rtv), "=r" (rt2v), "=r" (rnv)
+                : "0" (rtv), "1" (rt2v), "2" (rnv), "r" (rmv),
+                  [fn] "r" (p->ainsn.insn_fn)
+                : "lr", "memory", "cc"
+        );
+
+        regs->uregs[rt] = rtv;
+        regs->uregs[rt+1] = rt2v;
+        if (is_writeback(insn))
+                regs->uregs[rn] = rnv;
+}
+
+static void __kprobes
 emulate_rd12rn16rm0rs8_rwflags(struct kprobe *p, struct pt_regs *regs)
 {
         kprobe_opcode_t insn = p->opcode;