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Diffstat (limited to 'arch/parisc/math-emu/decode_exc.c')
| -rw-r--r-- | arch/parisc/math-emu/decode_exc.c | 357 |
1 files changed, 357 insertions, 0 deletions
diff --git a/arch/parisc/math-emu/decode_exc.c b/arch/parisc/math-emu/decode_exc.c new file mode 100644 index 000000000..d41ddb343 --- /dev/null +++ b/arch/parisc/math-emu/decode_exc.c @@ -0,0 +1,357 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Linux/PA-RISC Project (http://www.parisc-linux.org/) + * + * Floating-point emulation code + * Copyright (C) 2001 Hewlett-Packard (Paul Bame) <bame@debian.org> + */ +/* + * BEGIN_DESC + * + * File: + * @(#) pa/fp/decode_exc.c $ Revision: $ + * + * Purpose: + * <<please update with a synopsis of the functionality provided by this file>> + * + * External Interfaces: + * <<the following list was autogenerated, please review>> + * decode_fpu(Fpu_register, trap_counts) + * + * Internal Interfaces: + * <<please update>> + * + * Theory: + * <<please update with a overview of the operation of this file>> + * + * END_DESC +*/ + +#include <linux/kernel.h> +#include "float.h" +#include "sgl_float.h" +#include "dbl_float.h" +#include "cnv_float.h" +/* #include "types.h" */ +#include <asm/signal.h> +#include <asm/siginfo.h> +/* #include <machine/sys/mdep_private.h> */ + +#undef Fpustatus_register +#define Fpustatus_register Fpu_register[0] + +/* General definitions */ +#define DOESTRAP 1 +#define NOTRAP 0 +#define SIGNALCODE(signal, code) ((signal) << 24 | (code)) +#define copropbit 1<<31-2 /* bit position 2 */ +#define opclass 9 /* bits 21 & 22 */ +#define fmtbits 11 /* bits 19 & 20 */ +#define df 13 /* bits 17 & 18 */ +#define twobits 3 /* mask low-order 2 bits */ +#define fivebits 31 /* mask low-order 5 bits */ +#define MAX_EXCP_REG 7 /* number of excpeption registers to check */ + +/* Exception register definitions */ +#define Excp_type(index) Exceptiontype(Fpu_register[index]) +#define Excp_instr(index) Instructionfield(Fpu_register[index]) +#define Clear_excp_register(index) Allexception(Fpu_register[index]) = 0 +#define Excp_format() \ + (current_ir >> ((current_ir>>opclass & twobits) == 1 ? df : fmtbits) & twobits) + +/* Miscellaneous definitions */ +#define Fpu_sgl(index) Fpu_register[index*2] + +#define Fpu_dblp1(index) Fpu_register[index*2] +#define Fpu_dblp2(index) Fpu_register[(index*2)+1] + +#define Fpu_quadp1(index) Fpu_register[index*2] +#define Fpu_quadp2(index) Fpu_register[(index*2)+1] +#define Fpu_quadp3(index) Fpu_register[(index*2)+2] +#define Fpu_quadp4(index) Fpu_register[(index*2)+3] + +/* Single precision floating-point definitions */ +#ifndef Sgl_decrement +# define Sgl_decrement(sgl_value) Sall(sgl_value)-- +#endif + +/* Double precision floating-point definitions */ +#ifndef Dbl_decrement +# define Dbl_decrement(dbl_valuep1,dbl_valuep2) \ + if ((Dallp2(dbl_valuep2)--) == 0) Dallp1(dbl_valuep1)-- +#endif + + +#define update_trap_counts(Fpu_register, aflags, bflags, trap_counts) { \ + aflags=(Fpu_register[0])>>27; /* assumes zero fill. 32 bit */ \ + Fpu_register[0] |= bflags; \ +} + +u_int +decode_fpu(unsigned int Fpu_register[], unsigned int trap_counts[]) +{ + unsigned int current_ir, excp; + int target, exception_index = 1; + boolean inexact; + unsigned int aflags; + unsigned int bflags; + unsigned int excptype; + + + /* Keep stats on how many floating point exceptions (based on type) + * that happen. Want to keep this overhead low, but still provide + * some information to the customer. All exits from this routine + * need to restore Fpu_register[0] + */ + + bflags=(Fpu_register[0] & 0xf8000000); + Fpu_register[0] &= 0x07ffffff; + + /* exception_index is used to index the exception register queue. It + * always points at the last register that contains a valid exception. A + * zero value implies no exceptions (also the initialized value). Setting + * the T-bit resets the exception_index to zero. + */ + + /* + * Check for reserved-op exception. A reserved-op exception does not + * set any exception registers nor does it set the T-bit. If the T-bit + * is not set then a reserved-op exception occurred. + * + * At some point, we may want to report reserved op exceptions as + * illegal instructions. + */ + + if (!Is_tbit_set()) { + update_trap_counts(Fpu_register, aflags, bflags, trap_counts); + return SIGNALCODE(SIGILL, ILL_COPROC); + } + + /* + * Is a coprocessor op. + * + * Now we need to determine what type of exception occurred. + */ + for (exception_index=1; exception_index<=MAX_EXCP_REG; exception_index++) { + current_ir = Excp_instr(exception_index); + /* + * On PA89: there are 5 different unimplemented exception + * codes: 0x1, 0x9, 0xb, 0x3, and 0x23. PA-RISC 2.0 adds + * another, 0x2b. Only these have the low order bit set. + */ + excptype = Excp_type(exception_index); + if (excptype & UNIMPLEMENTEDEXCEPTION) { + /* + * Clear T-bit and exception register so that + * we can tell if a trap really occurs while + * emulating the instruction. + */ + Clear_tbit(); + Clear_excp_register(exception_index); + /* + * Now emulate this instruction. If a trap occurs, + * fpudispatch will return a non-zero number + */ + excp = fpudispatch(current_ir,excptype,0,Fpu_register); + /* accumulate the status flags, don't lose them as in hpux */ + if (excp) { + /* + * We now need to make sure that the T-bit and the + * exception register contain the correct values + * before continuing. + */ + /* + * Set t-bit since it might still be needed for a + * subsequent real trap (I don't understand fully -PB) + */ + Set_tbit(); + /* some of the following code uses + * Excp_type(exception_index) so fix that up */ + Set_exceptiontype_and_instr_field(excp,current_ir, + Fpu_register[exception_index]); + if (excp == UNIMPLEMENTEDEXCEPTION) { + /* + * it is really unimplemented, so restore the + * TIMEX extended unimplemented exception code + */ + excp = excptype; + update_trap_counts(Fpu_register, aflags, bflags, + trap_counts); + return SIGNALCODE(SIGILL, ILL_COPROC); + } + /* some of the following code uses excptype, so + * fix that up too */ + excptype = excp; + } + /* handle exceptions other than the real UNIMPLIMENTED the + * same way as if the hardware had caused them */ + if (excp == NOEXCEPTION) + /* For now use 'break', should technically be 'continue' */ + break; + } + + /* + * In PA89, the underflow exception has been extended to encode + * additional information. The exception looks like pp01x0, + * where x is 1 if inexact and pp represent the inexact bit (I) + * and the round away bit (RA) + */ + if (excptype & UNDERFLOWEXCEPTION) { + /* check for underflow trap enabled */ + if (Is_underflowtrap_enabled()) { + update_trap_counts(Fpu_register, aflags, bflags, + trap_counts); + return SIGNALCODE(SIGFPE, FPE_FLTUND); + } else { + /* + * Isn't a real trap; we need to + * return the default value. + */ + target = current_ir & fivebits; +#ifndef lint + if (Ibit(Fpu_register[exception_index])) inexact = TRUE; + else inexact = FALSE; +#endif + switch (Excp_format()) { + case SGL: + /* + * If ra (round-away) is set, will + * want to undo the rounding done + * by the hardware. + */ + if (Rabit(Fpu_register[exception_index])) + Sgl_decrement(Fpu_sgl(target)); + + /* now denormalize */ + sgl_denormalize(&Fpu_sgl(target),&inexact,Rounding_mode()); + break; + case DBL: + /* + * If ra (round-away) is set, will + * want to undo the rounding done + * by the hardware. + */ + if (Rabit(Fpu_register[exception_index])) + Dbl_decrement(Fpu_dblp1(target),Fpu_dblp2(target)); + + /* now denormalize */ + dbl_denormalize(&Fpu_dblp1(target),&Fpu_dblp2(target), + &inexact,Rounding_mode()); + break; + } + if (inexact) Set_underflowflag(); + /* + * Underflow can generate an inexact + * exception. If inexact trap is enabled, + * want to do an inexact trap, otherwise + * set inexact flag. + */ + if (inexact && Is_inexacttrap_enabled()) { + /* + * Set exception field of exception register + * to inexact, parm field to zero. + * Underflow bit should be cleared. + */ + Set_exceptiontype(Fpu_register[exception_index], + INEXACTEXCEPTION); + Set_parmfield(Fpu_register[exception_index],0); + update_trap_counts(Fpu_register, aflags, bflags, + trap_counts); + return SIGNALCODE(SIGFPE, FPE_FLTRES); + } + else { + /* + * Exception register needs to be cleared. + * Inexact flag needs to be set if inexact. + */ + Clear_excp_register(exception_index); + if (inexact) Set_inexactflag(); + } + } + continue; + } + switch(Excp_type(exception_index)) { + case OVERFLOWEXCEPTION: + case OVERFLOWEXCEPTION | INEXACTEXCEPTION: + /* check for overflow trap enabled */ + update_trap_counts(Fpu_register, aflags, bflags, + trap_counts); + if (Is_overflowtrap_enabled()) { + update_trap_counts(Fpu_register, aflags, bflags, + trap_counts); + return SIGNALCODE(SIGFPE, FPE_FLTOVF); + } else { + /* + * Isn't a real trap; we need to + * return the default value. + */ + target = current_ir & fivebits; + switch (Excp_format()) { + case SGL: + Sgl_setoverflow(Fpu_sgl(target)); + break; + case DBL: + Dbl_setoverflow(Fpu_dblp1(target),Fpu_dblp2(target)); + break; + } + Set_overflowflag(); + /* + * Overflow always generates an inexact + * exception. If inexact trap is enabled, + * want to do an inexact trap, otherwise + * set inexact flag. + */ + if (Is_inexacttrap_enabled()) { + /* + * Set exception field of exception + * register to inexact. Overflow + * bit should be cleared. + */ + Set_exceptiontype(Fpu_register[exception_index], + INEXACTEXCEPTION); + update_trap_counts(Fpu_register, aflags, bflags, + trap_counts); + return SIGNALCODE(SIGFPE, FPE_FLTRES); + } + else { + /* + * Exception register needs to be cleared. + * Inexact flag needs to be set. + */ + Clear_excp_register(exception_index); + Set_inexactflag(); + } + } + break; + case INVALIDEXCEPTION: + case OPC_2E_INVALIDEXCEPTION: + update_trap_counts(Fpu_register, aflags, bflags, trap_counts); + return SIGNALCODE(SIGFPE, FPE_FLTINV); + case DIVISIONBYZEROEXCEPTION: + update_trap_counts(Fpu_register, aflags, bflags, trap_counts); + Clear_excp_register(exception_index); + return SIGNALCODE(SIGFPE, FPE_FLTDIV); + case INEXACTEXCEPTION: + update_trap_counts(Fpu_register, aflags, bflags, trap_counts); + return SIGNALCODE(SIGFPE, FPE_FLTRES); + default: + update_trap_counts(Fpu_register, aflags, bflags, trap_counts); + printk("%s(%d) Unknown FPU exception 0x%x\n", __FILE__, + __LINE__, Excp_type(exception_index)); + return SIGNALCODE(SIGILL, ILL_COPROC); + case NOEXCEPTION: /* no exception */ + /* + * Clear exception register in case + * other fields are non-zero. + */ + Clear_excp_register(exception_index); + break; + } + } + /* + * No real exceptions occurred. + */ + Clear_tbit(); + update_trap_counts(Fpu_register, aflags, bflags, trap_counts); + return(NOTRAP); +} |