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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>
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Maciej W. Rozycki authored and Ralf Baechle committed Apr 7, 2015
1 parent 80cbfad commit 2d83fea
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Showing 3 changed files with 43 additions and 42 deletions.
7 changes: 5 additions & 2 deletions arch/mips/include/asm/cpu-features.h
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Original file line number Diff line number Diff line change
Expand Up @@ -221,8 +221,11 @@
#define cpu_has_mips_4_5_r (cpu_has_mips_4 | cpu_has_mips_5_r)
#define cpu_has_mips_5_r (cpu_has_mips_5 | cpu_has_mips_r)

#define cpu_has_mips_4_5_r2_r6 (cpu_has_mips_4_5 | cpu_has_mips_r2 | \
cpu_has_mips_r6)
#define cpu_has_mips_3_4_5_64_r2_r6 \
(cpu_has_mips_3 | cpu_has_mips_4_5_64_r2_r6)
#define cpu_has_mips_4_5_64_r2_r6 \
(cpu_has_mips_4_5 | cpu_has_mips64r1 | \
cpu_has_mips_r2 | cpu_has_mips_r6)

#define cpu_has_mips32 (cpu_has_mips32r1 | cpu_has_mips32r2 | cpu_has_mips32r6)
#define cpu_has_mips64 (cpu_has_mips64r1 | cpu_has_mips64r2 | cpu_has_mips64r6)
Expand Down
23 changes: 11 additions & 12 deletions arch/mips/kernel/traps.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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;
}
Expand Down
55 changes: 27 additions & 28 deletions arch/mips/math-emu/cp1emu.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1115,17 +1115,18 @@ static int cop1Emulate(struct pt_regs *xcp, struct mips_fpu_struct *ctx,
likely = 0;
switch (MIPSInst_RT(ir) & 3) {
case bcfl_op:
likely = 1;
if (cpu_has_mips_2_3_4_5_r)
likely = 1;
/* Fall through */
case bcf_op:
cond = !cond;
break;
case bctl_op:
likely = 1;
if (cpu_has_mips_2_3_4_5_r)
likely = 1;
/* Fall through */
case bct_op:
break;
default:
/* thats an illegal instruction */
return SIGILL;
}

set_delay_slot(xcp);
Expand Down Expand Up @@ -1165,36 +1166,34 @@ static int cop1Emulate(struct pt_regs *xcp, struct mips_fpu_struct *ctx,

switch (MIPSInst_OPCODE(ir)) {
case lwc1_op:
goto emul;

case swc1_op:
goto emul;

case ldc1_op:
case sdc1_op:
if (cpu_has_mips_2_3_4_5 ||
cpu_has_mips64)
if (cpu_has_mips_2_3_4_5_r)
goto emul;

return SIGILL;
goto emul;

case cop1_op:
goto emul;

case cop1x_op:
if (cpu_has_mips_4_5 || cpu_has_mips64 || cpu_has_mips32r2)
if (cpu_has_mips_4_5_64_r2_r6)
/* its one of ours */
goto emul;

return SIGILL;

case spec_op:
if (!cpu_has_mips_4_5_r)
return SIGILL;
switch (MIPSInst_FUNC(ir)) {
case movc_op:
if (cpu_has_mips_4_5_r)
goto emul;

if (MIPSInst_FUNC(ir) == movc_op)
goto emul;
return SIGILL;
}
break;
}

Expand Down Expand Up @@ -1228,7 +1227,7 @@ static int cop1Emulate(struct pt_regs *xcp, struct mips_fpu_struct *ctx,
break;

case cop1x_op:
if (!cpu_has_mips_4_5 && !cpu_has_mips64 && !cpu_has_mips32r2)
if (!cpu_has_mips_4_5_64_r2_r6)
return SIGILL;

sig = fpux_emu(xcp, ctx, ir, fault_addr);
Expand Down Expand Up @@ -1561,7 +1560,7 @@ static int fpu_emu(struct pt_regs *xcp, struct mips_fpu_struct *ctx,

/* unary ops */
case fsqrt_op:
if (!cpu_has_mips_4_5_r)
if (!cpu_has_mips_2_3_4_5_r)
return SIGILL;

handler.u = ieee754sp_sqrt;
Expand All @@ -1573,14 +1572,14 @@ static int fpu_emu(struct pt_regs *xcp, struct mips_fpu_struct *ctx,
* achieve full IEEE-754 accuracy - however this emulator does.
*/
case frsqrt_op:
if (!cpu_has_mips_4_5_r2_r6)
if (!cpu_has_mips_4_5_64_r2_r6)
return SIGILL;

handler.u = fpemu_sp_rsqrt;
goto scopuop;

case frecip_op:
if (!cpu_has_mips_4_5_r2_r6)
if (!cpu_has_mips_4_5_64_r2_r6)
return SIGILL;

handler.u = fpemu_sp_recip;
Expand Down Expand Up @@ -1682,7 +1681,7 @@ static int fpu_emu(struct pt_regs *xcp, struct mips_fpu_struct *ctx,
case ftrunc_op:
case fceil_op:
case ffloor_op:
if (!cpu_has_mips_2_3_4_5 && !cpu_has_mips64)
if (!cpu_has_mips_2_3_4_5_r)
return SIGILL;

oldrm = ieee754_csr.rm;
Expand All @@ -1694,7 +1693,7 @@ static int fpu_emu(struct pt_regs *xcp, struct mips_fpu_struct *ctx,
goto copcsr;

case fcvtl_op:
if (!cpu_has_mips_3_4_5 && !cpu_has_mips64)
if (!cpu_has_mips_3_4_5_64_r2_r6)
return SIGILL;

SPFROMREG(fs, MIPSInst_FS(ir));
Expand All @@ -1706,7 +1705,7 @@ static int fpu_emu(struct pt_regs *xcp, struct mips_fpu_struct *ctx,
case ftruncl_op:
case fceill_op:
case ffloorl_op:
if (!cpu_has_mips_3_4_5 && !cpu_has_mips64)
if (!cpu_has_mips_3_4_5_64_r2_r6)
return SIGILL;

oldrm = ieee754_csr.rm;
Expand Down Expand Up @@ -1775,13 +1774,13 @@ static int fpu_emu(struct pt_regs *xcp, struct mips_fpu_struct *ctx,
* achieve full IEEE-754 accuracy - however this emulator does.
*/
case frsqrt_op:
if (!cpu_has_mips_4_5_r2_r6)
if (!cpu_has_mips_4_5_64_r2_r6)
return SIGILL;

handler.u = fpemu_dp_rsqrt;
goto dcopuop;
case frecip_op:
if (!cpu_has_mips_4_5_r2_r6)
if (!cpu_has_mips_4_5_64_r2_r6)
return SIGILL;

handler.u = fpemu_dp_recip;
Expand Down Expand Up @@ -1871,7 +1870,7 @@ static int fpu_emu(struct pt_regs *xcp, struct mips_fpu_struct *ctx,
goto copcsr;

case fcvtl_op:
if (!cpu_has_mips_3_4_5 && !cpu_has_mips64)
if (!cpu_has_mips_3_4_5_64_r2_r6)
return SIGILL;

DPFROMREG(fs, MIPSInst_FS(ir));
Expand All @@ -1883,7 +1882,7 @@ static int fpu_emu(struct pt_regs *xcp, struct mips_fpu_struct *ctx,
case ftruncl_op:
case fceill_op:
case ffloorl_op:
if (!cpu_has_mips_3_4_5 && !cpu_has_mips64)
if (!cpu_has_mips_3_4_5_64_r2_r6)
return SIGILL;

oldrm = ieee754_csr.rm;
Expand Down Expand Up @@ -1942,7 +1941,7 @@ static int fpu_emu(struct pt_regs *xcp, struct mips_fpu_struct *ctx,

case l_fmt:

if (!cpu_has_mips_3_4_5 && !cpu_has_mips64)
if (!cpu_has_mips_3_4_5_64_r2_r6)
return SIGILL;

DIFROMREG(bits, MIPSInst_FS(ir));
Expand Down Expand Up @@ -2006,7 +2005,7 @@ static int fpu_emu(struct pt_regs *xcp, struct mips_fpu_struct *ctx,
SITOREG(rv.w, MIPSInst_FD(ir));
break;
case l_fmt:
if (!cpu_has_mips_3_4_5 && !cpu_has_mips64)
if (!cpu_has_mips_3_4_5_64_r2_r6)
return SIGILL;

DITOREG(rv.l, MIPSInst_FD(ir));
Expand Down

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