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

Browse source 
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>
This commit is contained in:
Markos Chandras 2014-11-26 13:05:09 +00:00
commit f1b44067c1
2 changed files with 47 additions and 0 deletions
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22
arch/mips/kernel/branch.c
View file

@ -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);

25
arch/mips/math-emu/cp1emu.c
View file

@ -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 +