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linux/arch/mips/math-emu/cp1emu.c
Maneesh Soni d8d4e3ae0b MIPS Kprobes: Refactor branch emulation 
This patch refactors MIPS branch emulation code so as to allow skipping
delay slot instruction in case of branch likely instructions when branch is
not taken. This is useful for keeping the code common for use cases like
kprobes where one would like to handle the branch instructions keeping the
delay slot instuction also in picture for branch likely instructions. Also
allow emulation when instruction to be decoded is not at pt_regs->cp0_epc
as in case of kprobes where pt_regs->cp0_epc points to the breakpoint
instruction.

The patch also exports the function for modules.

Signed-off-by: Maneesh Soni <manesoni@cisco.com>
Signed-off-by: Victor Kamensky <kamensky@cisco.com>
Cc: David Daney <david.daney@cavium.com>
Cc: ananth@in.ibm.com
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/2913/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2011-12-07 22:04:03 +00:00

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/*
* cp1emu.c: a MIPS coprocessor 1 (fpu) instruction emulator
*
* MIPS floating point support
* Copyright (C) 1994-2000 Algorithmics Ltd.
*
* Kevin D. Kissell, kevink@mips.com and Carsten Langgaard, carstenl@mips.com
* Copyright (C) 2000 MIPS Technologies, Inc.
*
* This program is free software; you can distribute it and/or modify it
* under the terms of the GNU General Public License (Version 2) as
* published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 59 Temple Place - Suite 330, Boston MA 02111-1307, USA.
*
* A complete emulator for MIPS coprocessor 1 instructions. This is
* required for #float(switch) or #float(trap), where it catches all
* COP1 instructions via the "CoProcessor Unusable" exception.
*
* More surprisingly it is also required for #float(ieee), to help out
* the hardware fpu at the boundaries of the IEEE-754 representation
* (denormalised values, infinities, underflow, etc). It is made
* quite nasty because emulation of some non-COP1 instructions is
* required, e.g. in branch delay slots.
*
* Note if you know that you won't have an fpu, then you'll get much
* better performance by compiling with -msoft-float!
*/
#include <linux/sched.h>
#include <linux/module.h>
#include <linux/debugfs.h>
#include <linux/perf_event.h>
#include <asm/inst.h>
#include <asm/bootinfo.h>
#include <asm/processor.h>
#include <asm/ptrace.h>
#include <asm/signal.h>
#include <asm/mipsregs.h>
#include <asm/fpu_emulator.h>
#include <asm/uaccess.h>
#include <asm/branch.h>
#include "ieee754.h"
/* Strap kernel emulator for full MIPS IV emulation */
#ifdef __mips
#undef __mips
#endif
#define __mips 4
/* Function which emulates a floating point instruction. */
static int fpu_emu(struct pt_regs *, struct mips_fpu_struct *,
mips_instruction);
#if __mips >= 4 && __mips != 32
static int fpux_emu(struct pt_regs *,
struct mips_fpu_struct *, mips_instruction, void *__user *);
#endif
/* Further private data for which no space exists in mips_fpu_struct */
#ifdef CONFIG_DEBUG_FS
DEFINE_PER_CPU(struct mips_fpu_emulator_stats, fpuemustats);
#endif
/* Control registers */
#define FPCREG_RID 0 /* $0 = revision id */
#define FPCREG_CSR 31 /* $31 = csr */
/* Determine rounding mode from the RM bits of the FCSR */
#define modeindex(v) ((v) & FPU_CSR_RM)
/* Convert Mips rounding mode (0..3) to IEEE library modes. */
static const unsigned char ieee_rm[4] = {
[FPU_CSR_RN] = IEEE754_RN,
[FPU_CSR_RZ] = IEEE754_RZ,
[FPU_CSR_RU] = IEEE754_RU,
[FPU_CSR_RD] = IEEE754_RD,
};
/* Convert IEEE library modes to Mips rounding mode (0..3). */
static const unsigned char mips_rm[4] = {
[IEEE754_RN] = FPU_CSR_RN,
[IEEE754_RZ] = FPU_CSR_RZ,
[IEEE754_RD] = FPU_CSR_RD,
[IEEE754_RU] = FPU_CSR_RU,
};
#if __mips >= 4
/* convert condition code register number to csr bit */
static const unsigned int fpucondbit[8] = {
FPU_CSR_COND0,
FPU_CSR_COND1,
FPU_CSR_COND2,
FPU_CSR_COND3,
FPU_CSR_COND4,
FPU_CSR_COND5,
FPU_CSR_COND6,
FPU_CSR_COND7
};
#endif
/*
* Redundant with logic already in kernel/branch.c,
* embedded in compute_return_epc. At some point,
* a single subroutine should be used across both
* modules.
*/
static int isBranchInstr(mips_instruction * i)
{
switch (MIPSInst_OPCODE(*i)) {
case spec_op:
switch (MIPSInst_FUNC(*i)) {
case jalr_op:
case jr_op:
return 1;
}
break;
case bcond_op:
switch (MIPSInst_RT(*i)) {
case bltz_op:
case bgez_op:
case bltzl_op:
case bgezl_op:
case bltzal_op:
case bgezal_op:
case bltzall_op:
case bgezall_op:
return 1;
}
break;
case j_op:
case jal_op:
case jalx_op:
case beq_op:
case bne_op:
case blez_op:
case bgtz_op:
case beql_op:
case bnel_op:
case blezl_op:
case bgtzl_op:
return 1;
case cop0_op:
case cop1_op:
case cop2_op:
case cop1x_op:
if (MIPSInst_RS(*i) == bc_op)
return 1;
break;
}
return 0;
}
/*
* In the Linux kernel, we support selection of FPR format on the
* basis of the Status.FR bit. If an FPU is not present, the FR bit
* is hardwired to zero, which would imply a 32-bit FPU even for
* 64-bit CPUs. For 64-bit kernels with no FPU we use TIF_32BIT_REGS
* as a proxy for the FR bit so that a 64-bit FPU is emulated. In any
* case, for a 32-bit kernel which uses the O32 MIPS ABI, only the
* even FPRs are used (Status.FR = 0).
*/
static inline int cop1_64bit(struct pt_regs *xcp)
{
if (cpu_has_fpu)
return xcp->cp0_status & ST0_FR;
#ifdef CONFIG_64BIT
return !test_thread_flag(TIF_32BIT_REGS);
#else
return 0;
#endif
}
#define SIFROMREG(si, x) ((si) = cop1_64bit(xcp) || !(x & 1) ? \
(int)ctx->fpr[x] : (int)(ctx->fpr[x & ~1] >> 32))
#define SITOREG(si, x) (ctx->fpr[x & ~(cop1_64bit(xcp) == 0)] = \
cop1_64bit(xcp) || !(x & 1) ? \
ctx->fpr[x & ~1] >> 32 << 32 | (u32)(si) : \
ctx->fpr[x & ~1] << 32 >> 32 | (u64)(si) << 32)
#define DIFROMREG(di, x) ((di) = ctx->fpr[x & ~(cop1_64bit(xcp) == 0)])
#define DITOREG(di, x) (ctx->fpr[x & ~(cop1_64bit(xcp) == 0)] = (di))
#define SPFROMREG(sp, x) SIFROMREG((sp).bits, x)
#define SPTOREG(sp, x) SITOREG((sp).bits, x)
#define DPFROMREG(dp, x) DIFROMREG((dp).bits, x)
#define DPTOREG(dp, x) DITOREG((dp).bits, x)
/*
* Emulate the single floating point instruction pointed at by EPC.
* Two instructions if the instruction is in a branch delay slot.
*/
static int cop1Emulate(struct pt_regs *xcp, struct mips_fpu_struct *ctx,
void *__user *fault_addr)
{
mips_instruction ir;
unsigned long emulpc, contpc;
unsigned int cond;
if (!access_ok(VERIFY_READ, xcp->cp0_epc, sizeof(mips_instruction))) {
MIPS_FPU_EMU_INC_STATS(errors);
*fault_addr = (mips_instruction __user *)xcp->cp0_epc;
return SIGBUS;
}
if (__get_user(ir, (mips_instruction __user *) xcp->cp0_epc)) {
MIPS_FPU_EMU_INC_STATS(errors);
*fault_addr = (mips_instruction __user *)xcp->cp0_epc;
return SIGSEGV;
}
/* XXX NEC Vr54xx bug workaround */
if ((xcp->cp0_cause & CAUSEF_BD) && !isBranchInstr(&ir))
xcp->cp0_cause &= ~CAUSEF_BD;
if (xcp->cp0_cause & CAUSEF_BD) {
/*
* The instruction to be emulated is in a branch delay slot
* which means that we have to emulate the branch instruction
* BEFORE we do the cop1 instruction.
*
* This branch could be a COP1 branch, but in that case we
* would have had a trap for that instruction, and would not
* come through this route.
*
* Linux MIPS branch emulator operates on context, updating the
* cp0_epc.
*/
emulpc = xcp->cp0_epc + 4; /* Snapshot emulation target */
if (__compute_return_epc(xcp) < 0) {
#ifdef CP1DBG
printk("failed to emulate branch at %p\n",
(void *) (xcp->cp0_epc));
#endif
return SIGILL;
}
if (!access_ok(VERIFY_READ, emulpc, sizeof(mips_instruction))) {
MIPS_FPU_EMU_INC_STATS(errors);
*fault_addr = (mips_instruction __user *)emulpc;
return SIGBUS;
}
if (__get_user(ir, (mips_instruction __user *) emulpc)) {
MIPS_FPU_EMU_INC_STATS(errors);
*fault_addr = (mips_instruction __user *)emulpc;
return SIGSEGV;
}
/* __compute_return_epc() will have updated cp0_epc */
contpc = xcp->cp0_epc;
/* In order not to confuse ptrace() et al, tweak context */
xcp->cp0_epc = emulpc - 4;
} else {
emulpc = xcp->cp0_epc;
contpc = xcp->cp0_epc + 4;
}
emul:
perf_sw_event(PERF_COUNT_SW_EMULATION_FAULTS, 1, xcp, 0);
MIPS_FPU_EMU_INC_STATS(emulated);
switch (MIPSInst_OPCODE(ir)) {
case ldc1_op:{
u64 __user *va = (u64 __user *) (xcp->regs[MIPSInst_RS(ir)] +
MIPSInst_SIMM(ir));
u64 val;
MIPS_FPU_EMU_INC_STATS(loads);
if (!access_ok(VERIFY_READ, va, sizeof(u64))) {
MIPS_FPU_EMU_INC_STATS(errors);
*fault_addr = va;
return SIGBUS;
}
if (__get_user(val, va)) {
MIPS_FPU_EMU_INC_STATS(errors);
*fault_addr = va;
return SIGSEGV;
}
DITOREG(val, MIPSInst_RT(ir));
break;
}
case sdc1_op:{
u64 __user *va = (u64 __user *) (xcp->regs[MIPSInst_RS(ir)] +
MIPSInst_SIMM(ir));
u64 val;
MIPS_FPU_EMU_INC_STATS(stores);
DIFROMREG(val, MIPSInst_RT(ir));
if (!access_ok(VERIFY_WRITE, va, sizeof(u64))) {
MIPS_FPU_EMU_INC_STATS(errors);
*fault_addr = va;
return SIGBUS;
}
if (__put_user(val, va)) {
MIPS_FPU_EMU_INC_STATS(errors);
*fault_addr = va;
return SIGSEGV;
}
break;
}
case lwc1_op:{
u32 __user *va = (u32 __user *) (xcp->regs[MIPSInst_RS(ir)] +
MIPSInst_SIMM(ir));
u32 val;
MIPS_FPU_EMU_INC_STATS(loads);
if (!access_ok(VERIFY_READ, va, sizeof(u32))) {
MIPS_FPU_EMU_INC_STATS(errors);
*fault_addr = va;
return SIGBUS;
}
if (__get_user(val, va)) {
MIPS_FPU_EMU_INC_STATS(errors);
*fault_addr = va;
return SIGSEGV;
}
SITOREG(val, MIPSInst_RT(ir));
break;
}
case swc1_op:{
u32 __user *va = (u32 __user *) (xcp->regs[MIPSInst_RS(ir)] +
MIPSInst_SIMM(ir));
u32 val;
MIPS_FPU_EMU_INC_STATS(stores);
SIFROMREG(val, MIPSInst_RT(ir));
if (!access_ok(VERIFY_WRITE, va, sizeof(u32))) {
MIPS_FPU_EMU_INC_STATS(errors);
*fault_addr = va;
return SIGBUS;
}
if (__put_user(val, va)) {
MIPS_FPU_EMU_INC_STATS(errors);
*fault_addr = va;
return SIGSEGV;
}
break;
}
case cop1_op:
switch (MIPSInst_RS(ir)) {
#if defined(__mips64)
case dmfc_op:
/* copregister fs -> gpr[rt] */
if (MIPSInst_RT(ir) != 0) {
DIFROMREG(xcp->regs[MIPSInst_RT(ir)],
MIPSInst_RD(ir));
}
break;
case dmtc_op:
/* copregister fs <- rt */
DITOREG(xcp->regs[MIPSInst_RT(ir)], MIPSInst_RD(ir));
break;
#endif
case mfc_op:
/* copregister rd -> gpr[rt] */
if (MIPSInst_RT(ir) != 0) {
SIFROMREG(xcp->regs[MIPSInst_RT(ir)],
MIPSInst_RD(ir));
}
break;
case mtc_op:
/* copregister rd <- rt */
SITOREG(xcp->regs[MIPSInst_RT(ir)], MIPSInst_RD(ir));
break;
case cfc_op:{
/* cop control register rd -> gpr[rt] */
u32 value;
if (MIPSInst_RD(ir) == FPCREG_CSR) {
value = ctx->fcr31;
value = (value & ~FPU_CSR_RM) |
mips_rm[modeindex(value)];
#ifdef CSRTRACE
printk("%p gpr[%d]<-csr=%08x\n",
(void *) (xcp->cp0_epc),
MIPSInst_RT(ir), value);
#endif
}
else if (MIPSInst_RD(ir) == FPCREG_RID)
value = 0;
else
value = 0;
if (MIPSInst_RT(ir))
xcp->regs[MIPSInst_RT(ir)] = value;
break;
}
case ctc_op:{
/* copregister rd <- rt */
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) {
#ifdef CSRTRACE
printk("%p gpr[%d]->csr=%08x\n",
(void *) (xcp->cp0_epc),
MIPSInst_RT(ir), value);
#endif
/*
* Don't write reserved bits,
* and convert to ieee library modes
*/
ctx->fcr31 = (value &
~(FPU_CSR_RSVD | FPU_CSR_RM)) |
ieee_rm[modeindex(value)];
}
if ((ctx->fcr31 >> 5) & ctx->fcr31 & FPU_CSR_ALL_E) {
return SIGFPE;
}
break;
}
case bc_op:{
int likely = 0;
if (xcp->cp0_cause & CAUSEF_BD)
return SIGILL;
#if __mips >= 4
cond = ctx->fcr31 & fpucondbit[MIPSInst_RT(ir) >> 2];
#else
cond = ctx->fcr31 & FPU_CSR_COND;
#endif
switch (MIPSInst_RT(ir) & 3) {
case bcfl_op:
likely = 1;
case bcf_op:
cond = !cond;
break;
case bctl_op:
likely = 1;
case bct_op:
break;
default:
/* thats an illegal instruction */
return SIGILL;
}
xcp->cp0_cause |= CAUSEF_BD;
if (cond) {
/* branch taken: emulate dslot
* instruction
*/
xcp->cp0_epc += 4;
contpc = (xcp->cp0_epc +
(MIPSInst_SIMM(ir) << 2));
if (!access_ok(VERIFY_READ, xcp->cp0_epc,
sizeof(mips_instruction))) {
MIPS_FPU_EMU_INC_STATS(errors);
*fault_addr = (mips_instruction __user *)xcp->cp0_epc;
return SIGBUS;
}
if (__get_user(ir,
(mips_instruction __user *) xcp->cp0_epc)) {
MIPS_FPU_EMU_INC_STATS(errors);
*fault_addr = (mips_instruction __user *)xcp->cp0_epc;
return SIGSEGV;
}
switch (MIPSInst_OPCODE(ir)) {
case lwc1_op:
case swc1_op:
#if (__mips >= 2 || defined(__mips64))
case ldc1_op:
case sdc1_op:
#endif
case cop1_op:
#if __mips >= 4 && __mips != 32
case cop1x_op:
#endif
/* its one of ours */
goto emul;
#if __mips >= 4
case spec_op:
if (MIPSInst_FUNC(ir) == movc_op)
goto emul;
break;
#endif
}
/*
* Single step the non-cp1
* instruction in the dslot
*/
return mips_dsemul(xcp, ir, contpc);
}
else {
/* branch not taken */
if (likely) {
/*
* branch likely nullifies
* dslot if not taken
*/
xcp->cp0_epc += 4;
contpc += 4;
/*
* else continue & execute
* dslot as normal insn
*/
}
}
break;
}
default:
if (!(MIPSInst_RS(ir) & 0x10))
return SIGILL;
{
int sig;
/* a real fpu computation instruction */
if ((sig = fpu_emu(xcp, ctx, ir)))
return sig;
}
}
break;
#if __mips >= 4 && __mips != 32
case cop1x_op:{
int sig = fpux_emu(xcp, ctx, ir, fault_addr);
if (sig)
return sig;
break;
}
#endif
#if __mips >= 4
case spec_op:
if (MIPSInst_FUNC(ir) != movc_op)
return SIGILL;
cond = fpucondbit[MIPSInst_RT(ir) >> 2];
if (((ctx->fcr31 & cond) != 0) == ((MIPSInst_RT(ir) & 1) != 0))
xcp->regs[MIPSInst_RD(ir)] =
xcp->regs[MIPSInst_RS(ir)];
break;
#endif
default:
return SIGILL;
}
/* we did it !! */
xcp->cp0_epc = contpc;
xcp->cp0_cause &= ~CAUSEF_BD;
return 0;
}
/*
* Conversion table from MIPS compare ops 48-63
* cond = ieee754dp_cmp(x,y,IEEE754_UN,sig);
*/
static const unsigned char cmptab[8] = {
0, /* cmp_0 (sig) cmp_sf */
IEEE754_CUN, /* cmp_un (sig) cmp_ngle */
IEEE754_CEQ, /* cmp_eq (sig) cmp_seq */
IEEE754_CEQ | IEEE754_CUN, /* cmp_ueq (sig) cmp_ngl */
IEEE754_CLT, /* cmp_olt (sig) cmp_lt */
IEEE754_CLT | IEEE754_CUN, /* cmp_ult (sig) cmp_nge */
IEEE754_CLT | IEEE754_CEQ, /* cmp_ole (sig) cmp_le */
IEEE754_CLT | IEEE754_CEQ | IEEE754_CUN, /* cmp_ule (sig) cmp_ngt */
};
#if __mips >= 4 && __mips != 32
/*
* Additional MIPS4 instructions
*/
#define DEF3OP(name, p, f1, f2, f3) \
static ieee754##p fpemu_##p##_##name(ieee754##p r, ieee754##p s, \
ieee754##p t) \
{ \
struct _ieee754_csr ieee754_csr_save; \
s = f1(s, t); \
ieee754_csr_save = ieee754_csr; \
s = f2(s, r); \
ieee754_csr_save.cx |= ieee754_csr.cx; \
ieee754_csr_save.sx |= ieee754_csr.sx; \
s = f3(s); \
ieee754_csr.cx |= ieee754_csr_save.cx; \
ieee754_csr.sx |= ieee754_csr_save.sx; \
return s; \
}
static ieee754dp fpemu_dp_recip(ieee754dp d)
{
return ieee754dp_div(ieee754dp_one(0), d);
}
static ieee754dp fpemu_dp_rsqrt(ieee754dp d)
{
return ieee754dp_div(ieee754dp_one(0), ieee754dp_sqrt(d));
}
static ieee754sp fpemu_sp_recip(ieee754sp s)
{
return ieee754sp_div(ieee754sp_one(0), s);
}
static ieee754sp fpemu_sp_rsqrt(ieee754sp s)
{
return ieee754sp_div(ieee754sp_one(0), ieee754sp_sqrt(s));
}
DEF3OP(madd, sp, ieee754sp_mul, ieee754sp_add, );
DEF3OP(msub, sp, ieee754sp_mul, ieee754sp_sub, );
DEF3OP(nmadd, sp, ieee754sp_mul, ieee754sp_add, ieee754sp_neg);
DEF3OP(nmsub, sp, ieee754sp_mul, ieee754sp_sub, ieee754sp_neg);
DEF3OP(madd, dp, ieee754dp_mul, ieee754dp_add, );
DEF3OP(msub, dp, ieee754dp_mul, ieee754dp_sub, );
DEF3OP(nmadd, dp, ieee754dp_mul, ieee754dp_add, ieee754dp_neg);
DEF3OP(nmsub, dp, ieee754dp_mul, ieee754dp_sub, ieee754dp_neg);
static int fpux_emu(struct pt_regs *xcp, struct mips_fpu_struct *ctx,
mips_instruction ir, void *__user *fault_addr)
{
unsigned rcsr = 0; /* resulting csr */
MIPS_FPU_EMU_INC_STATS(cp1xops);
switch (MIPSInst_FMA_FFMT(ir)) {
case s_fmt:{ /* 0 */
ieee754sp(*handler) (ieee754sp, ieee754sp, ieee754sp);
ieee754sp fd, fr, fs, ft;
u32 __user *va;
u32 val;
switch (MIPSInst_FUNC(ir)) {
case lwxc1_op:
va = (void __user *) (xcp->regs[MIPSInst_FR(ir)] +
xcp->regs[MIPSInst_FT(ir)]);
MIPS_FPU_EMU_INC_STATS(loads);
if (!access_ok(VERIFY_READ, va, sizeof(u32))) {
MIPS_FPU_EMU_INC_STATS(errors);
*fault_addr = va;
return SIGBUS;
}
if (__get_user(val, va)) {
MIPS_FPU_EMU_INC_STATS(errors);
*fault_addr = va;
return SIGSEGV;
}
SITOREG(val, MIPSInst_FD(ir));
break;
case swxc1_op:
va = (void __user *) (xcp->regs[MIPSInst_FR(ir)] +
xcp->regs[MIPSInst_FT(ir)]);
MIPS_FPU_EMU_INC_STATS(stores);
SIFROMREG(val, MIPSInst_FS(ir));
if (!access_ok(VERIFY_WRITE, va, sizeof(u32))) {
MIPS_FPU_EMU_INC_STATS(errors);
*fault_addr = va;
return SIGBUS;
}
if (put_user(val, va)) {
MIPS_FPU_EMU_INC_STATS(errors);
*fault_addr = va;
return SIGSEGV;
}
break;
case madd_s_op:
handler = fpemu_sp_madd;
goto scoptop;
case msub_s_op:
handler = fpemu_sp_msub;
goto scoptop;
case nmadd_s_op:
handler = fpemu_sp_nmadd;
goto scoptop;
case nmsub_s_op:
handler = fpemu_sp_nmsub;
goto scoptop;
scoptop:
SPFROMREG(fr, MIPSInst_FR(ir));
SPFROMREG(fs, MIPSInst_FS(ir));
SPFROMREG(ft, MIPSInst_FT(ir));
fd = (*handler) (fr, fs, ft);
SPTOREG(fd, MIPSInst_FD(ir));
copcsr:
if (ieee754_cxtest(IEEE754_INEXACT))
rcsr |= FPU_CSR_INE_X | FPU_CSR_INE_S;
if (ieee754_cxtest(IEEE754_UNDERFLOW))
rcsr |= FPU_CSR_UDF_X | FPU_CSR_UDF_S;
if (ieee754_cxtest(IEEE754_OVERFLOW))
rcsr |= FPU_CSR_OVF_X | FPU_CSR_OVF_S;
if (ieee754_cxtest(IEEE754_INVALID_OPERATION))
rcsr |= FPU_CSR_INV_X | FPU_CSR_INV_S;
ctx->fcr31 = (ctx->fcr31 & ~FPU_CSR_ALL_X) | rcsr;
if ((ctx->fcr31 >> 5) & ctx->fcr31 & FPU_CSR_ALL_E) {
/*printk ("SIGFPE: fpu csr = %08x\n",
ctx->fcr31); */
return SIGFPE;
}
break;
default:
return SIGILL;
}
break;
}
case d_fmt:{ /* 1 */
ieee754dp(*handler) (ieee754dp, ieee754dp, ieee754dp);
ieee754dp fd, fr, fs, ft;
u64 __user *va;
u64 val;
switch (MIPSInst_FUNC(ir)) {
case ldxc1_op:
va = (void __user *) (xcp->regs[MIPSInst_FR(ir)] +
xcp->regs[MIPSInst_FT(ir)]);
MIPS_FPU_EMU_INC_STATS(loads);
if (!access_ok(VERIFY_READ, va, sizeof(u64))) {
MIPS_FPU_EMU_INC_STATS(errors);
*fault_addr = va;
return SIGBUS;
}
if (__get_user(val, va)) {
MIPS_FPU_EMU_INC_STATS(errors);
*fault_addr = va;
return SIGSEGV;
}
DITOREG(val, MIPSInst_FD(ir));
break;
case sdxc1_op:
va = (void __user *) (xcp->regs[MIPSInst_FR(ir)] +
xcp->regs[MIPSInst_FT(ir)]);
MIPS_FPU_EMU_INC_STATS(stores);
DIFROMREG(val, MIPSInst_FS(ir));
if (!access_ok(VERIFY_WRITE, va, sizeof(u64))) {
MIPS_FPU_EMU_INC_STATS(errors);
*fault_addr = va;
return SIGBUS;
}
if (__put_user(val, va)) {
MIPS_FPU_EMU_INC_STATS(errors);
*fault_addr = va;
return SIGSEGV;
}
break;
case madd_d_op:
handler = fpemu_dp_madd;
goto dcoptop;
case msub_d_op:
handler = fpemu_dp_msub;
goto dcoptop;
case nmadd_d_op:
handler = fpemu_dp_nmadd;
goto dcoptop;
case nmsub_d_op:
handler = fpemu_dp_nmsub;
goto dcoptop;
dcoptop:
DPFROMREG(fr, MIPSInst_FR(ir));
DPFROMREG(fs, MIPSInst_FS(ir));
DPFROMREG(ft, MIPSInst_FT(ir));
fd = (*handler) (fr, fs, ft);
DPTOREG(fd, MIPSInst_FD(ir));
goto copcsr;
default:
return SIGILL;
}
break;
}
case 0x7: /* 7 */
if (MIPSInst_FUNC(ir) != pfetch_op) {
return SIGILL;
}
/* ignore prefx operation */
break;
default:
return SIGILL;
}
return 0;
}
#endif
/*
* Emulate a single COP1 arithmetic instruction.
*/
static int fpu_emu(struct pt_regs *xcp, struct mips_fpu_struct *ctx,
mips_instruction ir)
{
int rfmt; /* resulting format */
unsigned rcsr = 0; /* resulting csr */
unsigned cond;
union {
ieee754dp d;
ieee754sp s;
int w;
#ifdef __mips64
s64 l;
#endif
} rv; /* resulting value */
MIPS_FPU_EMU_INC_STATS(cp1ops);
switch (rfmt = (MIPSInst_FFMT(ir) & 0xf)) {
case s_fmt:{ /* 0 */
union {
ieee754sp(*b) (ieee754sp, ieee754sp);
ieee754sp(*u) (ieee754sp);
} handler;
switch (MIPSInst_FUNC(ir)) {
/* binary ops */
case fadd_op:
handler.b = ieee754sp_add;
goto scopbop;
case fsub_op:
handler.b = ieee754sp_sub;
goto scopbop;
case fmul_op:
handler.b = ieee754sp_mul;
goto scopbop;
case fdiv_op:
handler.b = ieee754sp_div;
goto scopbop;
/* unary ops */
#if __mips >= 2 || defined(__mips64)
case fsqrt_op:
handler.u = ieee754sp_sqrt;
goto scopuop;
#endif
#if __mips >= 4 && __mips != 32
case frsqrt_op:
handler.u = fpemu_sp_rsqrt;
goto scopuop;
case frecip_op:
handler.u = fpemu_sp_recip;
goto scopuop;
#endif
#if __mips >= 4
case fmovc_op:
cond = fpucondbit[MIPSInst_FT(ir) >> 2];
if (((ctx->fcr31 & cond) != 0) !=
((MIPSInst_FT(ir) & 1) != 0))
return 0;
SPFROMREG(rv.s, MIPSInst_FS(ir));
break;
case fmovz_op:
if (xcp->regs[MIPSInst_FT(ir)] != 0)
return 0;
SPFROMREG(rv.s, MIPSInst_FS(ir));
break;
case fmovn_op:
if (xcp->regs[MIPSInst_FT(ir)] == 0)
return 0;
SPFROMREG(rv.s, MIPSInst_FS(ir));
break;
#endif
case fabs_op:
handler.u = ieee754sp_abs;
goto scopuop;
case fneg_op:
handler.u = ieee754sp_neg;
goto scopuop;
case fmov_op:
/* an easy one */
SPFROMREG(rv.s, MIPSInst_FS(ir));
goto copcsr;
/* binary op on handler */
scopbop:
{
ieee754sp fs, ft;
SPFROMREG(fs, MIPSInst_FS(ir));
SPFROMREG(ft, MIPSInst_FT(ir));
rv.s = (*handler.b) (fs, ft);
goto copcsr;
}
scopuop:
{
ieee754sp fs;
SPFROMREG(fs, MIPSInst_FS(ir));
rv.s = (*handler.u) (fs);
goto copcsr;
}
copcsr:
if (ieee754_cxtest(IEEE754_INEXACT))
rcsr |= FPU_CSR_INE_X | FPU_CSR_INE_S;
if (ieee754_cxtest(IEEE754_UNDERFLOW))
rcsr |= FPU_CSR_UDF_X | FPU_CSR_UDF_S;
if (ieee754_cxtest(IEEE754_OVERFLOW))
rcsr |= FPU_CSR_OVF_X | FPU_CSR_OVF_S;
if (ieee754_cxtest(IEEE754_ZERO_DIVIDE))
rcsr |= FPU_CSR_DIV_X | FPU_CSR_DIV_S;
if (ieee754_cxtest(IEEE754_INVALID_OPERATION))
rcsr |= FPU_CSR_INV_X | FPU_CSR_INV_S;
break;
/* unary conv ops */
case fcvts_op:
return SIGILL; /* not defined */
case fcvtd_op:{
ieee754sp fs;
SPFROMREG(fs, MIPSInst_FS(ir));
rv.d = ieee754dp_fsp(fs);
rfmt = d_fmt;
goto copcsr;
}
case fcvtw_op:{
ieee754sp fs;
SPFROMREG(fs, MIPSInst_FS(ir));
rv.w = ieee754sp_tint(fs);
rfmt = w_fmt;
goto copcsr;
}
#if __mips >= 2 || defined(__mips64)
case fround_op:
case ftrunc_op:
case fceil_op:
case ffloor_op:{
unsigned int oldrm = ieee754_csr.rm;
ieee754sp fs;
SPFROMREG(fs, MIPSInst_FS(ir));
ieee754_csr.rm = ieee_rm[modeindex(MIPSInst_FUNC(ir))];
rv.w = ieee754sp_tint(fs);
ieee754_csr.rm = oldrm;
rfmt = w_fmt;
goto copcsr;
}
#endif /* __mips >= 2 */
#if defined(__mips64)
case fcvtl_op:{
ieee754sp fs;
SPFROMREG(fs, MIPSInst_FS(ir));
rv.l = ieee754sp_tlong(fs);
rfmt = l_fmt;
goto copcsr;
}
case froundl_op:
case ftruncl_op:
case fceill_op:
case ffloorl_op:{
unsigned int oldrm = ieee754_csr.rm;
ieee754sp fs;
SPFROMREG(fs, MIPSInst_FS(ir));
ieee754_csr.rm = ieee_rm[modeindex(MIPSInst_FUNC(ir))];
rv.l = ieee754sp_tlong(fs);
ieee754_csr.rm = oldrm;
rfmt = l_fmt;
goto copcsr;
}
#endif /* defined(__mips64) */
default:
if (MIPSInst_FUNC(ir) >= fcmp_op) {
unsigned cmpop = MIPSInst_FUNC(ir) - fcmp_op;
ieee754sp fs, ft;
SPFROMREG(fs, MIPSInst_FS(ir));
SPFROMREG(ft, MIPSInst_FT(ir));
rv.w = ieee754sp_cmp(fs, ft,
cmptab[cmpop & 0x7], cmpop & 0x8);
rfmt = -1;
if ((cmpop & 0x8) && ieee754_cxtest
(IEEE754_INVALID_OPERATION))
rcsr = FPU_CSR_INV_X | FPU_CSR_INV_S;
else
goto copcsr;
}
else {
return SIGILL;
}
break;
}
break;
}
case d_fmt:{
union {
ieee754dp(*b) (ieee754dp, ieee754dp);
ieee754dp(*u) (ieee754dp);
} handler;
switch (MIPSInst_FUNC(ir)) {
/* binary ops */
case fadd_op:
handler.b = ieee754dp_add;
goto dcopbop;
case fsub_op:
handler.b = ieee754dp_sub;
goto dcopbop;
case fmul_op:
handler.b = ieee754dp_mul;
goto dcopbop;
case fdiv_op:
handler.b = ieee754dp_div;
goto dcopbop;
/* unary ops */
#if __mips >= 2 || defined(__mips64)
case fsqrt_op:
handler.u = ieee754dp_sqrt;
goto dcopuop;
#endif
#if __mips >= 4 && __mips != 32
case frsqrt_op:
handler.u = fpemu_dp_rsqrt;
goto dcopuop;
case frecip_op:
handler.u = fpemu_dp_recip;
goto dcopuop;
#endif
#if __mips >= 4
case fmovc_op:
cond = fpucondbit[MIPSInst_FT(ir) >> 2];
if (((ctx->fcr31 & cond) != 0) !=
((MIPSInst_FT(ir) & 1) != 0))
return 0;
DPFROMREG(rv.d, MIPSInst_FS(ir));
break;
case fmovz_op:
if (xcp->regs[MIPSInst_FT(ir)] != 0)
return 0;
DPFROMREG(rv.d, MIPSInst_FS(ir));
break;
case fmovn_op:
if (xcp->regs[MIPSInst_FT(ir)] == 0)
return 0;
DPFROMREG(rv.d, MIPSInst_FS(ir));
break;
#endif
case fabs_op:
handler.u = ieee754dp_abs;
goto dcopuop;
case fneg_op:
handler.u = ieee754dp_neg;
goto dcopuop;
case fmov_op:
/* an easy one */
DPFROMREG(rv.d, MIPSInst_FS(ir));
goto copcsr;
/* binary op on handler */
dcopbop:{
ieee754dp fs, ft;
DPFROMREG(fs, MIPSInst_FS(ir));
DPFROMREG(ft, MIPSInst_FT(ir));
rv.d = (*handler.b) (fs, ft);
goto copcsr;
}
dcopuop:{
ieee754dp fs;
DPFROMREG(fs, MIPSInst_FS(ir));
rv.d = (*handler.u) (fs);
goto copcsr;
}
/* unary conv ops */
case fcvts_op:{
ieee754dp fs;
DPFROMREG(fs, MIPSInst_FS(ir));
rv.s = ieee754sp_fdp(fs);
rfmt = s_fmt;
goto copcsr;
}
case fcvtd_op:
return SIGILL; /* not defined */
case fcvtw_op:{
ieee754dp fs;
DPFROMREG(fs, MIPSInst_FS(ir));
rv.w = ieee754dp_tint(fs); /* wrong */
rfmt = w_fmt;
goto copcsr;
}
#if __mips >= 2 || defined(__mips64)
case fround_op:
case ftrunc_op:
case fceil_op:
case ffloor_op:{
unsigned int oldrm = ieee754_csr.rm;
ieee754dp fs;
DPFROMREG(fs, MIPSInst_FS(ir));
ieee754_csr.rm = ieee_rm[modeindex(MIPSInst_FUNC(ir))];
rv.w = ieee754dp_tint(fs);
ieee754_csr.rm = oldrm;
rfmt = w_fmt;
goto copcsr;
}
#endif
#if defined(__mips64)
case fcvtl_op:{
ieee754dp fs;
DPFROMREG(fs, MIPSInst_FS(ir));
rv.l = ieee754dp_tlong(fs);
rfmt = l_fmt;
goto copcsr;
}
case froundl_op:
case ftruncl_op:
case fceill_op:
case ffloorl_op:{
unsigned int oldrm = ieee754_csr.rm;
ieee754dp fs;
DPFROMREG(fs, MIPSInst_FS(ir));
ieee754_csr.rm = ieee_rm[modeindex(MIPSInst_FUNC(ir))];
rv.l = ieee754dp_tlong(fs);
ieee754_csr.rm = oldrm;
rfmt = l_fmt;
goto copcsr;
}
#endif /* __mips >= 3 */
default:
if (MIPSInst_FUNC(ir) >= fcmp_op) {
unsigned cmpop = MIPSInst_FUNC(ir) - fcmp_op;
ieee754dp fs, ft;
DPFROMREG(fs, MIPSInst_FS(ir));
DPFROMREG(ft, MIPSInst_FT(ir));
rv.w = ieee754dp_cmp(fs, ft,
cmptab[cmpop & 0x7], cmpop & 0x8);
rfmt = -1;
if ((cmpop & 0x8)
&&
ieee754_cxtest
(IEEE754_INVALID_OPERATION))
rcsr = FPU_CSR_INV_X | FPU_CSR_INV_S;
else
goto copcsr;
}
else {
return SIGILL;
}
break;
}
break;
}
case w_fmt:{
ieee754sp fs;
switch (MIPSInst_FUNC(ir)) {
case fcvts_op:
/* convert word to single precision real */
SPFROMREG(fs, MIPSInst_FS(ir));
rv.s = ieee754sp_fint(fs.bits);
rfmt = s_fmt;
goto copcsr;
case fcvtd_op:
/* convert word to double precision real */
SPFROMREG(fs, MIPSInst_FS(ir));
rv.d = ieee754dp_fint(fs.bits);
rfmt = d_fmt;
goto copcsr;
default:
return SIGILL;
}
break;
}
#if defined(__mips64)
case l_fmt:{
switch (MIPSInst_FUNC(ir)) {
case fcvts_op:
/* convert long to single precision real */
rv.s = ieee754sp_flong(ctx->fpr[MIPSInst_FS(ir)]);
rfmt = s_fmt;
goto copcsr;
case fcvtd_op:
/* convert long to double precision real */
rv.d = ieee754dp_flong(ctx->fpr[MIPSInst_FS(ir)]);
rfmt = d_fmt;
goto copcsr;
default:
return SIGILL;
}
break;
}
#endif
default:
return SIGILL;
}
/*
* Update the fpu CSR register for this operation.
* If an exception is required, generate a tidy SIGFPE exception,
* without updating the result register.
* Note: cause exception bits do not accumulate, they are rewritten
* for each op; only the flag/sticky bits accumulate.
*/
ctx->fcr31 = (ctx->fcr31 & ~FPU_CSR_ALL_X) | rcsr;
if ((ctx->fcr31 >> 5) & ctx->fcr31 & FPU_CSR_ALL_E) {
/*printk ("SIGFPE: fpu csr = %08x\n",ctx->fcr31); */
return SIGFPE;
}
/*
* Now we can safely write the result back to the register file.
*/
switch (rfmt) {
case -1:{
#if __mips >= 4
cond = fpucondbit[MIPSInst_FD(ir) >> 2];
#else
cond = FPU_CSR_COND;
#endif
if (rv.w)
ctx->fcr31 |= cond;
else
ctx->fcr31 &= ~cond;
break;
}
case d_fmt:
DPTOREG(rv.d, MIPSInst_FD(ir));
break;
case s_fmt:
SPTOREG(rv.s, MIPSInst_FD(ir));
break;
case w_fmt:
SITOREG(rv.w, MIPSInst_FD(ir));
break;
#if defined(__mips64)
case l_fmt:
DITOREG(rv.l, MIPSInst_FD(ir));
break;
#endif
default:
return SIGILL;
}
return 0;
}
int fpu_emulator_cop1Handler(struct pt_regs *xcp, struct mips_fpu_struct *ctx,
int has_fpu, void *__user *fault_addr)
{
unsigned long oldepc, prevepc;
mips_instruction insn;
int sig = 0;
oldepc = xcp->cp0_epc;
do {
prevepc = xcp->cp0_epc;
if (!access_ok(VERIFY_READ, xcp->cp0_epc, sizeof(mips_instruction))) {
MIPS_FPU_EMU_INC_STATS(errors);
*fault_addr = (mips_instruction __user *)xcp->cp0_epc;
return SIGBUS;
}
if (__get_user(insn, (mips_instruction __user *) xcp->cp0_epc)) {
MIPS_FPU_EMU_INC_STATS(errors);
*fault_addr = (mips_instruction __user *)xcp->cp0_epc;
return SIGSEGV;
}
if (insn == 0)
xcp->cp0_epc += 4; /* skip nops */
else {
/*
* The 'ieee754_csr' is an alias of
* ctx->fcr31. No need to copy ctx->fcr31 to
* ieee754_csr. But ieee754_csr.rm is ieee
* library modes. (not mips rounding mode)
*/
/* convert to ieee library modes */
ieee754_csr.rm = ieee_rm[ieee754_csr.rm];
sig = cop1Emulate(xcp, ctx, fault_addr);
/* revert to mips rounding mode */
ieee754_csr.rm = mips_rm[ieee754_csr.rm];
}
if (has_fpu)
break;
if (sig)
break;
cond_resched();
} while (xcp->cp0_epc > prevepc);
/* SIGILL indicates a non-fpu instruction */
if (sig == SIGILL && xcp->cp0_epc != oldepc)
/* but if epc has advanced, then ignore it */
sig = 0;
return sig;
}
#ifdef CONFIG_DEBUG_FS
static int fpuemu_stat_get(void *data, u64 *val)
{
int cpu;
unsigned long sum = 0;
for_each_online_cpu(cpu) {
struct mips_fpu_emulator_stats *ps;
local_t *pv;
ps = &per_cpu(fpuemustats, cpu);
pv = (void *)ps + (unsigned long)data;
sum += local_read(pv);
}
*val = sum;
return 0;
}
DEFINE_SIMPLE_ATTRIBUTE(fops_fpuemu_stat, fpuemu_stat_get, NULL, "%llu\n");
extern struct dentry *mips_debugfs_dir;
static int __init debugfs_fpuemu(void)
{
struct dentry *d, *dir;
if (!mips_debugfs_dir)
return -ENODEV;
dir = debugfs_create_dir("fpuemustats", mips_debugfs_dir);
if (!dir)
return -ENOMEM;
#define FPU_STAT_CREATE(M) \
do { \
d = debugfs_create_file(#M , S_IRUGO, dir, \
(void *)offsetof(struct mips_fpu_emulator_stats, M), \
&fops_fpuemu_stat); \
if (!d) \
return -ENOMEM; \
} while (0)
FPU_STAT_CREATE(emulated);
FPU_STAT_CREATE(loads);
FPU_STAT_CREATE(stores);
FPU_STAT_CREATE(cp1ops);
FPU_STAT_CREATE(cp1xops);
FPU_STAT_CREATE(errors);
return 0;
}
__initcall(debugfs_fpuemu);
#endif
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