MIPS: Emulate the new MIPS R6 B{L,G}T{Z,}{AL,}C instructions

MIPS R6 added the following four instructions which share the
BGTZ and BGTZL opcode:

BLTZALC: Compact branch-and-link if GPR rt is < to zero
BGTZALC: Compact branch-and-link if GPR rt is > to zero
BLTZL  : Compact branch if GPR rt is < to zero
BGTZL  : Compact branch if GPR rt is > to zero
BLTC   : Compact branch if GPR rs is less than GPR rt
BLTUC  : Similar to BLTC but unsigned

Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>

diff --git a/arch/mips/kernel/branch.c b/arch/mips/kernel/branch.c
index a1fd878..cd880b9 100644 (file)
--- a/arch/mips/kernel/branch.c
+++ b/arch/mips/kernel/branch.c
@@ -635,6 +635,28 @@ int __compute_return_epc_for_insn(struct pt_regs *regs,
                if (NO_R6EMU)
                        goto sigill_r6;
        case bgtz_op:
+               /*
+                * Compact branches for R6 for the
+                * bgtz and bgtzl opcodes.
+                * BGTZ  | rs = 0 | rt != 0  == BGTZALC
+                * BGTZ  | rs = rt != 0      == BLTZALC
+                * BGTZ  | rs != 0 | rt != 0 == BLTUC
+                * BGTZL | rs = 0 | rt != 0  == BGTZC
+                * BGTZL | rs = rt != 0      == BLTZC
+                * BGTZL | rs != 0 | rt != 0 == BLTC
+                *
+                * *ZALC varint for BGTZ &&& rt != 0
+                * For real GTZ{,L}, rt is always 0.
+                */
+               if (cpu_has_mips_r6 && insn.i_format.rt) {
+                       if ((insn.i_format.opcode == blez_op) &&
+                           ((!insn.i_format.rs && insn.i_format.rt) ||
+                           (insn.i_format.rs == insn.i_format.rt)))
+                               regs->regs[31] = epc + 4;
+                       regs->cp0_epc += 8;
+                       break;
+               }
+
                /* rt field assumed to be zero */
                if ((long)regs->regs[insn.i_format.rs] > 0) {
                        epc = epc + 4 + (insn.i_format.simmediate << 2);

diff --git a/arch/mips/math-emu/cp1emu.c b/arch/mips/math-emu/cp1emu.c
index c770617..d6d67e2 100644 (file)
--- a/arch/mips/math-emu/cp1emu.c
+++ b/arch/mips/math-emu/cp1emu.c
@@ -589,6 +589,31 @@ static int isBranchInstr(struct pt_regs *regs, struct mm_decoded_insn dec_insn,
                if (NO_R6EMU)
                        break;
        case bgtz_op:
+               /*
+                * Compact branches for R6 for the
+                * bgtz and bgtzl opcodes.
+                * BGTZ  | rs = 0 | rt != 0  == BGTZALC
+                * BGTZ  | rs = rt != 0      == BLTZALC
+                * BGTZ  | rs != 0 | rt != 0 == BLTUC
+                * BGTZL | rs = 0 | rt != 0  == BGTZC
+                * BGTZL | rs = rt != 0      == BLTZC
+                * BGTZL | rs != 0 | rt != 0 == BLTC
+                *
+                * *ZALC varint for BGTZ &&& rt != 0
+                * For real GTZ{,L}, rt is always 0.
+                */
+               if (cpu_has_mips_r6 && insn.i_format.rt) {
+                       if ((insn.i_format.opcode == blez_op) &&
+                           ((!insn.i_format.rs && insn.i_format.rt) ||
+                            (insn.i_format.rs == insn.i_format.rt)))
+                               regs->regs[31] = regs->cp0_epc +
+                                       dec_insn.pc_inc;
+                       *contpc = regs->cp0_epc + dec_insn.pc_inc +
+                               dec_insn.next_pc_inc;
+
+                       return 1;
+               }
+
                if ((long)regs->regs[insn.i_format.rs] > 0)
                        *contpc = regs->cp0_epc +
                                dec_insn.pc_inc +