Skip to content

Commit

Permalink
MIPS: math-emu: Implement the FCCR, FEXR and FENR registers
Browse files Browse the repository at this point in the history 
Implement the FCCR, FEXR and FENR "shadow" FPU registers for the
architecture levels that include them, for the CFC1 and CTC1
instructions in the full emulation mode.

For completeness add macros for the CP1 UFR and UNFR registers too, no
actual implementation though.

Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9708/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
  • Loading branch information
Maciej W. Rozycki authored and Ralf Baechle committed Apr 7, 2015
1 parent f684362 commit c491cfa
Show file tree
Hide file tree
Showing 2 changed files with 148 additions and 27 deletions.
69 changes: 57 additions & 12 deletions arch/mips/include/asm/mipsregs.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -689,8 +689,13 @@
/*
* Coprocessor 1 (FPU) register names
*/
#define CP1_REVISION $0
#define CP1_STATUS $31
#define CP1_REVISION $0
#define CP1_UFR $1
#define CP1_UNFR $4
#define CP1_FCCR $25
#define CP1_FEXR $26
#define CP1_FENR $28
#define CP1_STATUS $31


/*
Expand All @@ -705,19 +710,59 @@
#define MIPS_FPIR_F64 (_ULCAST_(1) << 22)
#define MIPS_FPIR_FREP (_ULCAST_(1) << 29)

/*
* Bits in the MIPS32/64 coprocessor 1 (FPU) condition codes register.
*/
#define MIPS_FCCR_CONDX_S 0
#define MIPS_FCCR_CONDX (_ULCAST_(255) << MIPS_FCCR_CONDX_S)
#define MIPS_FCCR_COND0_S 0
#define MIPS_FCCR_COND0 (_ULCAST_(1) << MIPS_FCCR_COND0_S)
#define MIPS_FCCR_COND1_S 1
#define MIPS_FCCR_COND1 (_ULCAST_(1) << MIPS_FCCR_COND1_S)
#define MIPS_FCCR_COND2_S 2
#define MIPS_FCCR_COND2 (_ULCAST_(1) << MIPS_FCCR_COND2_S)
#define MIPS_FCCR_COND3_S 3
#define MIPS_FCCR_COND3 (_ULCAST_(1) << MIPS_FCCR_COND3_S)
#define MIPS_FCCR_COND4_S 4
#define MIPS_FCCR_COND4 (_ULCAST_(1) << MIPS_FCCR_COND4_S)
#define MIPS_FCCR_COND5_S 5
#define MIPS_FCCR_COND5 (_ULCAST_(1) << MIPS_FCCR_COND5_S)
#define MIPS_FCCR_COND6_S 6
#define MIPS_FCCR_COND6 (_ULCAST_(1) << MIPS_FCCR_COND6_S)
#define MIPS_FCCR_COND7_S 7
#define MIPS_FCCR_COND7 (_ULCAST_(1) << MIPS_FCCR_COND7_S)

/*
* Bits in the MIPS32/64 coprocessor 1 (FPU) enables register.
*/
#define MIPS_FENR_FS_S 2
#define MIPS_FENR_FS (_ULCAST_(1) << MIPS_FENR_FS_S)

/*
* FPU Status Register Values
*/
#define FPU_CSR_FLUSH 0x01000000 /* flush denormalised results to 0 */
#define FPU_CSR_COND 0x00800000 /* $fcc0 */
#define FPU_CSR_COND0 0x00800000 /* $fcc0 */
#define FPU_CSR_COND1 0x02000000 /* $fcc1 */
#define FPU_CSR_COND2 0x04000000 /* $fcc2 */
#define FPU_CSR_COND3 0x08000000 /* $fcc3 */
#define FPU_CSR_COND4 0x10000000 /* $fcc4 */
#define FPU_CSR_COND5 0x20000000 /* $fcc5 */
#define FPU_CSR_COND6 0x40000000 /* $fcc6 */
#define FPU_CSR_COND7 0x80000000 /* $fcc7 */
#define FPU_CSR_COND_S 23 /* $fcc0 */
#define FPU_CSR_COND (_ULCAST_(1) << FPU_CSR_COND_S)

#define FPU_CSR_FS_S 24 /* flush denormalised results to 0 */
#define FPU_CSR_FS (_ULCAST_(1) << FPU_CSR_FS_S)

#define FPU_CSR_CONDX_S 25 /* $fcc[7:1] */
#define FPU_CSR_CONDX (_ULCAST_(127) << FPU_CSR_CONDX_S)
#define FPU_CSR_COND1_S 25 /* $fcc1 */
#define FPU_CSR_COND1 (_ULCAST_(1) << FPU_CSR_COND1_S)
#define FPU_CSR_COND2_S 26 /* $fcc2 */
#define FPU_CSR_COND2 (_ULCAST_(1) << FPU_CSR_COND2_S)
#define FPU_CSR_COND3_S 27 /* $fcc3 */
#define FPU_CSR_COND3 (_ULCAST_(1) << FPU_CSR_COND3_S)
#define FPU_CSR_COND4_S 28 /* $fcc4 */
#define FPU_CSR_COND4 (_ULCAST_(1) << FPU_CSR_COND4_S)
#define FPU_CSR_COND5_S 29 /* $fcc5 */
#define FPU_CSR_COND5 (_ULCAST_(1) << FPU_CSR_COND5_S)
#define FPU_CSR_COND6_S 30 /* $fcc6 */
#define FPU_CSR_COND6 (_ULCAST_(1) << FPU_CSR_COND6_S)
#define FPU_CSR_COND7_S 31 /* $fcc7 */
#define FPU_CSR_COND7 (_ULCAST_(1) << FPU_CSR_COND7_S)

/*
* Bits 18 - 20 of the FPU Status Register will be read as 0,
Expand Down
106 changes: 91 additions & 15 deletions arch/mips/math-emu/cp1emu.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -64,11 +64,14 @@ static int fpux_emu(struct pt_regs *,
/* Control registers */

#define FPCREG_RID 0 /* $0 = revision id */
#define FPCREG_FCCR 25 /* $25 = fccr */
#define FPCREG_FEXR 26 /* $26 = fexr */
#define FPCREG_FENR 28 /* $28 = fenr */
#define FPCREG_CSR 31 /* $31 = csr */

/* convert condition code register number to csr bit */
const unsigned int fpucondbit[8] = {
FPU_CSR_COND0,
FPU_CSR_COND,
FPU_CSR_COND1,
FPU_CSR_COND2,
FPU_CSR_COND3,
Expand Down Expand Up @@ -846,17 +849,53 @@ do { \
static inline void cop1_cfc(struct pt_regs *xcp, struct mips_fpu_struct *ctx,
mips_instruction ir)
{
u32 value;
u32 fcr31 = ctx->fcr31;
u32 value = 0;

if (MIPSInst_RD(ir) == FPCREG_CSR) {
value = ctx->fcr31;
switch (MIPSInst_RD(ir)) {
case FPCREG_CSR:
value = fcr31;
pr_debug("%p gpr[%d]<-csr=%08x\n",
(void *)xcp->cp0_epc,
MIPSInst_RT(ir), value);
} else if (MIPSInst_RD(ir) == FPCREG_RID)
(void *)xcp->cp0_epc, MIPSInst_RT(ir), value);
break;

case FPCREG_FENR:
if (!cpu_has_mips_r)
break;
value = (fcr31 >> (FPU_CSR_FS_S - MIPS_FENR_FS_S)) &
MIPS_FENR_FS;
value |= fcr31 & (FPU_CSR_ALL_E | FPU_CSR_RM);
pr_debug("%p gpr[%d]<-enr=%08x\n",
(void *)xcp->cp0_epc, MIPSInst_RT(ir), value);
break;

case FPCREG_FEXR:
if (!cpu_has_mips_r)
break;
value = fcr31 & (FPU_CSR_ALL_X | FPU_CSR_ALL_S);
pr_debug("%p gpr[%d]<-exr=%08x\n",
(void *)xcp->cp0_epc, MIPSInst_RT(ir), value);
break;

case FPCREG_FCCR:
if (!cpu_has_mips_r)
break;
value = (fcr31 >> (FPU_CSR_COND_S - MIPS_FCCR_COND0_S)) &
MIPS_FCCR_COND0;
value |= (fcr31 >> (FPU_CSR_COND1_S - MIPS_FCCR_COND1_S)) &
(MIPS_FCCR_CONDX & ~MIPS_FCCR_COND0);
pr_debug("%p gpr[%d]<-ccr=%08x\n",
(void *)xcp->cp0_epc, MIPSInst_RT(ir), value);
break;

case FPCREG_RID:
value = current_cpu_data.fpu_id;
else
value = 0;
break;

default:
break;
}

if (MIPSInst_RT(ir))
xcp->regs[MIPSInst_RT(ir)] = value;
}
Expand All @@ -867,23 +906,60 @@ static inline void cop1_cfc(struct pt_regs *xcp, struct mips_fpu_struct *ctx,
static inline void cop1_ctc(struct pt_regs *xcp, struct mips_fpu_struct *ctx,
mips_instruction ir)
{
u32 fcr31 = ctx->fcr31;
u32 value;

if (MIPSInst_RT(ir) == 0)
value = 0;
else
value = xcp->regs[MIPSInst_RT(ir)];

/* we only have one writable control reg
*/
if (MIPSInst_RD(ir) == FPCREG_CSR) {
switch (MIPSInst_RD(ir)) {
case FPCREG_CSR:
pr_debug("%p gpr[%d]->csr=%08x\n",
(void *)xcp->cp0_epc,
MIPSInst_RT(ir), value);
(void *)xcp->cp0_epc, MIPSInst_RT(ir), value);

/* Don't write reserved bits. */
ctx->fcr31 = value & ~FPU_CSR_RSVD;
fcr31 = value & ~FPU_CSR_RSVD;
break;

case FPCREG_FENR:
if (!cpu_has_mips_r)
break;
pr_debug("%p gpr[%d]->enr=%08x\n",
(void *)xcp->cp0_epc, MIPSInst_RT(ir), value);
fcr31 &= ~(FPU_CSR_FS | FPU_CSR_ALL_E | FPU_CSR_RM);
fcr31 |= (value << (FPU_CSR_FS_S - MIPS_FENR_FS_S)) &
FPU_CSR_FS;
fcr31 |= value & (FPU_CSR_ALL_E | FPU_CSR_RM);
break;

case FPCREG_FEXR:
if (!cpu_has_mips_r)
break;
pr_debug("%p gpr[%d]->exr=%08x\n",
(void *)xcp->cp0_epc, MIPSInst_RT(ir), value);
fcr31 &= ~(FPU_CSR_ALL_X | FPU_CSR_ALL_S);
fcr31 |= value & (FPU_CSR_ALL_X | FPU_CSR_ALL_S);
break;

case FPCREG_FCCR:
if (!cpu_has_mips_r)
break;
pr_debug("%p gpr[%d]->ccr=%08x\n",
(void *)xcp->cp0_epc, MIPSInst_RT(ir), value);
fcr31 &= ~(FPU_CSR_CONDX | FPU_CSR_COND);
fcr31 |= (value << (FPU_CSR_COND_S - MIPS_FCCR_COND0_S)) &
FPU_CSR_COND;
fcr31 |= (value << (FPU_CSR_COND1_S - MIPS_FCCR_COND1_S)) &
FPU_CSR_CONDX;
break;

default:
break;
}

ctx->fcr31 = fcr31;
}

/*
Expand Down

0 comments on commit c491cfa

Please sign in to comment.