ARM: kprobes: Add new versions of emulate_ldr() and emulate_str()

These use the register calling conventions required by the new decoding
table framework for calling simulated instructions.

We rename the old versions of these functions to *_old for now.

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

1 files changed, 60 insertions, 3 deletions

diff --git a/arch/arm/kernel/kprobes-arm.c b/arch/arm/kernel/kprobes-arm.c
index bb38ae3601c8..d252e7821fcc 100644
--- a/arch/arm/kernel/kprobes-arm.c
+++ b/arch/arm/kernel/kprobes-arm.c
@@ -502,7 +502,7 @@ static void __kprobes emulate_strd(struct kprobe *p, struct pt_regs *regs)
                 regs->uregs[rn] = rnv_wb;
 }
 
-static void __kprobes emulate_ldr(struct kprobe *p, struct pt_regs *regs)
+static void __kprobes emulate_ldr_old(struct kprobe *p, struct pt_regs *regs)
 {
         insn_llret_3arg_fn_t *i_fn = (insn_llret_3arg_fn_t *)&p->ainsn.insn[0];
         kprobe_opcode_t insn = p->opcode;
@@ -535,7 +535,7 @@ static void __kprobes emulate_ldr(struct kprobe *p, struct pt_regs *regs)
         regs->uregs[rd] = rdv;
 }
 
-static void __kprobes emulate_str(struct kprobe *p, struct pt_regs *regs)
+static void __kprobes emulate_str_old(struct kprobe *p, struct pt_regs *regs)
 {
         insn_3arg_fn_t *i_fn = (insn_3arg_fn_t *)&p->ainsn.insn[0];
         kprobe_opcode_t insn = p->opcode;
@@ -795,7 +795,7 @@ prep_emulate_ldr_str(kprobe_opcode_t insn, struct arch_specific_insn *asi)
                 insn |= 2;      /* Rm = r2 */
         }
         asi->insn[0] = insn;
-        asi->insn_handler = (insn & (1 << 20)) ? emulate_ldr : emulate_str;
+        asi->insn_handler = (insn & (1 << 20)) ? emulate_ldr_old : emulate_str_old;
         return INSN_GOOD;
 }
 
@@ -923,6 +923,63 @@ emulate_ldrdstrd(struct kprobe *p, struct pt_regs *regs)
 }
 
 static void __kprobes
+emulate_ldr(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");
+        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" (rnv)
+                : "1" (rnv), "r" (rmv), [fn] "r" (p->ainsn.insn_fn)
+                : "lr", "memory", "cc"
+        );
+
+        if (rt == 15)
+                load_write_pc(rtv, regs);
+        else
+                regs->uregs[rt] = rtv;
+
+        if (is_writeback(insn))
+                regs->uregs[rn] = rnv;
+}
+
+static void __kprobes
+emulate_str(struct kprobe *p, struct pt_regs *regs)
+{
+        kprobe_opcode_t insn = p->opcode;
+        unsigned long rtpc = (unsigned long)p->addr + str_pc_offset;
+        unsigned long rnpc = (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") = (rt == 15) ? rtpc
+                                                          : regs->uregs[rt];
+        register unsigned long rnv asm("r2") = (rn == 15) ? rnpc
+                                                          : regs->uregs[rn];
+        register unsigned long rmv asm("r3") = regs->uregs[rm];
+
+        __asm__ __volatile__ (
+                BLX("%[fn]")
+                : "=r" (rnv)
+                : "r" (rtv), "0" (rnv), "r" (rmv), [fn] "r" (p->ainsn.insn_fn)
+                : "lr", "memory", "cc"
+        );
+
+        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;