ARM: kprobes: Add emulate_rd16rn12rm0rs8_rwflags_nopc()

This is the emulation function for the instruction format used by the
ARM multiply-accumulate instructions. These don't allow use of PC so we
don't have to add special cases for this.

This function is used to replace use of prep_emulate_rd16rs8rm0_wflags
and prep_emulate_rd16rn12rs8rm0_wflags.

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

1 files changed, 43 insertions, 7 deletions

diff --git a/arch/arm/kernel/kprobes-arm.c b/arch/arm/kernel/kprobes-arm.c
index f271212a7cd5..d3b0506df410 100644
--- a/arch/arm/kernel/kprobes-arm.c
+++ b/arch/arm/kernel/kprobes-arm.c
@@ -984,6 +984,35 @@ emulate_rd12rn16rm0_rwflags_nopc(struct kprobe *p, struct pt_regs *regs)
         regs->ARM_cpsr = (regs->ARM_cpsr & ~APSR_MASK) | (cpsr & APSR_MASK);
 }
 
+static void __kprobes
+emulate_rd16rn12rm0rs8_rwflags_nopc(struct kprobe *p, struct pt_regs *regs)
+{
+        kprobe_opcode_t insn = p->opcode;
+        int rd = (insn >> 16) & 0xf;
+        int rn = (insn >> 12) & 0xf;
+        int rm = insn & 0xf;
+        int rs = (insn >> 8) & 0xf;
+
+        register unsigned long rdv asm("r2") = regs->uregs[rd];
+        register unsigned long rnv asm("r0") = regs->uregs[rn];
+        register unsigned long rmv asm("r3") = 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"
+        );
+
+        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
@@ -1065,12 +1094,14 @@ static const union decode_item arm_cccc_0001_0xx0____1xx0_table[] = {
         /* SMULWy               cccc 0001 0010 xxxx xxxx xxxx 1x10 xxxx */
         DECODE_OR       (0x0ff000b0, 0x012000a0),
         /* SMULxy               cccc 0001 0110 xxxx xxxx xxxx 1xx0 xxxx */
-        DECODE_CUSTOM   (0x0ff00090, 0x01600080, prep_emulate_rd16rs8rm0_wflags),
+        DECODE_EMULATEX (0x0ff00090, 0x01600080, emulate_rd16rn12rm0rs8_rwflags_nopc,
+                                                 REGS(NOPC, 0, NOPC, 0, NOPC)),
 
         /* SMLAxy               cccc 0001 0000 xxxx xxxx xxxx 1xx0 xxxx */
         DECODE_OR       (0x0ff00090, 0x01000080),
         /* SMLAWy               cccc 0001 0010 xxxx xxxx xxxx 1x00 xxxx */
-        DECODE_CUSTOM   (0x0ff000b0, 0x01200080, prep_emulate_rd16rn12rs8rm0_wflags),
+        DECODE_EMULATEX (0x0ff000b0, 0x01200080, emulate_rd16rn12rm0rs8_rwflags_nopc,
+                                                 REGS(NOPC, NOPC, NOPC, 0, NOPC)),
 
         DECODE_END
 };
@@ -1080,13 +1111,15 @@ static const union decode_item arm_cccc_0000_____1001_table[] = {
 
         /* MUL                  cccc 0000 0000 xxxx xxxx xxxx 1001 xxxx */
         /* MULS                 cccc 0000 0001 xxxx xxxx xxxx 1001 xxxx */
-        DECODE_CUSTOM   (0x0fe000f0, 0x00000090, prep_emulate_rd16rs8rm0_wflags),
+        DECODE_EMULATEX (0x0fe000f0, 0x00000090, emulate_rd16rn12rm0rs8_rwflags_nopc,
+                                                 REGS(NOPC, 0, NOPC, 0, NOPC)),
 
         /* MLA                  cccc 0000 0010 xxxx xxxx xxxx 1001 xxxx */
         /* MLAS                 cccc 0000 0011 xxxx xxxx xxxx 1001 xxxx */
         DECODE_OR       (0x0fe000f0, 0x00200090),
         /* MLS                  cccc 0000 0110 xxxx xxxx xxxx 1001 xxxx */
-        DECODE_CUSTOM   (0x0ff000f0, 0x00600090, prep_emulate_rd16rn12rs8rm0_wflags),
+        DECODE_EMULATEX (0x0ff000f0, 0x00600090, emulate_rd16rn12rm0rs8_rwflags_nopc,
+                                                 REGS(NOPC, NOPC, NOPC, 0, NOPC)),
 
         /* UMAAL                cccc 0000 0100 xxxx xxxx xxxx 1001 xxxx */
         DECODE_OR       (0x0ff000f0, 0x00400090),
@@ -1368,7 +1401,8 @@ static const union decode_item arm_cccc_0111_____xxx1_table[] = {
         /* SMMUL                cccc 0111 0101 xxxx 1111 xxxx 00x1 xxxx */
         DECODE_OR       (0x0ff0f0d0, 0x0750f010),
         /* USAD8                cccc 0111 1000 xxxx 1111 xxxx 0001 xxxx */
-        DECODE_CUSTOM   (0x0ff0f0f0, 0x0780f010, prep_emulate_rd16rs8rm0_wflags),
+        DECODE_EMULATEX (0x0ff0f0f0, 0x0780f010, emulate_rd16rn12rm0rs8_rwflags_nopc,
+                                                 REGS(NOPC, 0, NOPC, 0, NOPC)),
 
         /* SMLAD                cccc 0111 0000 xxxx xxxx xxxx 00x1 xxxx */
         /* SMLSD                cccc 0111 0000 xxxx xxxx xxxx 01x1 xxxx */
@@ -1376,10 +1410,12 @@ static const union decode_item arm_cccc_0111_____xxx1_table[] = {
         /* SMMLA                cccc 0111 0101 xxxx xxxx xxxx 00x1 xxxx */
         DECODE_OR       (0x0ff000d0, 0x07500010),
         /* USADA8               cccc 0111 1000 xxxx xxxx xxxx 0001 xxxx */
-        DECODE_CUSTOM   (0x0ff000f0, 0x07800010, prep_emulate_rd16rn12rs8rm0_wflags),
+        DECODE_EMULATEX (0x0ff000f0, 0x07800010, emulate_rd16rn12rm0rs8_rwflags_nopc,
+                                                 REGS(NOPC, NOPCX, NOPC, 0, NOPC)),
 
         /* SMMLS                cccc 0111 0101 xxxx xxxx xxxx 11x1 xxxx */
-        DECODE_CUSTOM   (0x0ff000d0, 0x075000d0, prep_emulate_rd16rn12rs8rm0_wflags),
+        DECODE_EMULATEX (0x0ff000d0, 0x075000d0, emulate_rd16rn12rm0rs8_rwflags_nopc,
+                                                 REGS(NOPC, NOPC, NOPC, 0, NOPC)),
 
         /* SBFX                 cccc 0111 101x xxxx xxxx xxxx x101 xxxx */
         /* UBFX                 cccc 0111 111x xxxx xxxx xxxx x101 xxxx */