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MIPS: Correct FP ISA requirements

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Correct ISA requirements for floating-point instructions:

* the CU3 exception signifies a real COP3 instruction in MIPS I & II,

* the BC1FL and BC1TL instructions are not supported in MIPS I,

* the SQRT.fmt instructions are indeed supported in MIPS II,

* the LDC1 and SDC1 instructions are indeed supported in MIPS32r1,

* the CEIL.W.fmt, FLOOR.W.fmt, ROUND.W.fmt and TRUNC.W.fmt instructions
  are indeed supported in MIPS32,

* the CVT.L.fmt and CVT.fmt.L instructions are indeed supported in
  MIPS32r2 and MIPS32r6,

* the CEIL.L.fmt, FLOOR.L.fmt, ROUND.L.fmt and TRUNC.L.fmt instructions
  are indeed supported in MIPS32r2 and MIPS32r6,

* the RSQRT.fmt and RECIP.fmt instructions are indeed supported in
  MIPS64r1,

Also simplify conditionals for MIPS III and MIPS IV FPU instructions and
the handling of the MOVCI minor opcode.

Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9700/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This commit is contained in:
Maciej W. Rozycki 2015-04-03 23:26:49 +01:00 • committed by Ralf Baechle
parent 80cbfad790
commit 2d83fea786
3 changed files with 43 additions and 42 deletions
Download patch file Download diff file Expand all files Collapse all files

23
arch/mips/kernel/traps.c
View file

@ -1349,19 +1349,18 @@ asmlinkage void do_cpu(struct pt_regs *regs)
case 3:
/*
* Old (MIPS I and MIPS II) processors will set this code
* for COP1X opcode instructions that replaced the original
* COP3 space. We don't limit COP1 space instructions in
* the emulator according to the CPU ISA, so we want to
* treat COP1X instructions consistently regardless of which
* code the CPU chose. Therefore we redirect this trap to
* the FP emulator too.
*
* Then some newer FPU-less processors use this code
* erroneously too, so they are covered by this choice
* as well.
* The COP3 opcode space and consequently the CP0.Status.CU3
* bit and the CP0.Cause.CE=3 encoding have been removed as
* of the MIPS III ISA. From the MIPS IV and MIPS32r2 ISAs
* up the space has been reused for COP1X instructions, that
* are enabled by the CP0.Status.CU1 bit and consequently
* use the CP0.Cause.CE=1 encoding for Coprocessor Unusable
* exceptions. Some FPU-less processors that implement one
* of these ISAs however use this code erroneously for COP1X
* instructions. Therefore we redirect this trap to the FP
* emulator too.
*/
if (raw_cpu_has_fpu) {
if (raw_cpu_has_fpu || !cpu_has_mips_4_5_64_r2_r6) {
force_sig(SIGILL, current);
break;
}