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+/*
+ * arch/sparc/math-emu/math.c
+ *
+ * Copyright (C) 1998 Peter Maydell (pmaydell@chiark.greenend.org.uk)
+ * Copyright (C) 1997, 1999 Jakub Jelinek (jj@ultra.linux.cz)
+ * Copyright (C) 1999 David S. Miller (davem@redhat.com)
+ *
+ * This is a good place to start if you're trying to understand the
+ * emulation code, because it's pretty simple. What we do is
+ * essentially analyse the instruction to work out what the operation
+ * is and which registers are involved. We then execute the appropriate
+ * FXXXX function. [The floating point queue introduces a minor wrinkle;
+ * see below...]
+ * The fxxxxx.c files each emulate a single insn. They look relatively
+ * simple because the complexity is hidden away in an unholy tangle
+ * of preprocessor macros.
+ *
+ * The first layer of macros is single.h, double.h, quad.h. Generally
+ * these files define macros for working with floating point numbers
+ * of the three IEEE formats. FP_ADD_D(R,A,B) is for adding doubles,
+ * for instance. These macros are usually defined as calls to more
+ * generic macros (in this case _FP_ADD(D,2,R,X,Y) where the number
+ * of machine words required to store the given IEEE format is passed
+ * as a parameter. [double.h and co check the number of bits in a word
+ * and define FP_ADD_D & co appropriately].
+ * The generic macros are defined in op-common.h. This is where all
+ * the grotty stuff like handling NaNs is coded. To handle the possible
+ * word sizes macros in op-common.h use macros like _FP_FRAC_SLL_##wc()
+ * where wc is the 'number of machine words' parameter (here 2).
+ * These are defined in the third layer of macros: op-1.h, op-2.h
+ * and op-4.h. These handle operations on floating point numbers composed
+ * of 1,2 and 4 machine words respectively. [For example, on sparc64
+ * doubles are one machine word so macros in double.h eventually use
+ * constructs in op-1.h, but on sparc32 they use op-2.h definitions.]
+ * soft-fp.h is on the same level as op-common.h, and defines some
+ * macros which are independent of both word size and FP format.
+ * Finally, sfp-machine.h is the machine dependent part of the
+ * code: it defines the word size and what type a word is. It also
+ * defines how _FP_MUL_MEAT_t() maps to _FP_MUL_MEAT_n_* : op-n.h
+ * provide several possible flavours of multiply algorithm, most
+ * of which require that you supply some form of asm or C primitive to
+ * do the actual multiply. (such asm primitives should be defined
+ * in sfp-machine.h too). udivmodti4.c is the same sort of thing.
+ *
+ * There may be some errors here because I'm working from a
+ * SPARC architecture manual V9, and what I really want is V8...
+ * Also, the insns which can generate exceptions seem to be a
+ * greater subset of the FPops than for V9 (for example, FCMPED
+ * has to be emulated on V8). So I think I'm going to have
+ * to emulate them all just to be on the safe side...
+ *
+ * Emulation routines originate from soft-fp package, which is
+ * part of glibc and has appropriate copyrights in it (allegedly).
+ *
+ * NB: on sparc int == long == 4 bytes, long long == 8 bytes.
+ * Most bits of the kernel seem to go for long rather than int,
+ * so we follow that practice...
+ */
+
+/* TODO:
+ * fpsave() saves the FP queue but fpload() doesn't reload it.
+ * Therefore when we context switch or change FPU ownership
+ * we have to check to see if the queue had anything in it and
+ * emulate it if it did. This is going to be a pain.
+ */
+
+#include <linux/types.h>
+#include <linux/sched.h>
+#include <linux/mm.h>
+#include <asm/uaccess.h>
+
+#include "sfp-util_32.h"
+#include <math-emu/soft-fp.h>
+#include <math-emu/single.h>
+#include <math-emu/double.h>
+#include <math-emu/quad.h>
+
+#define FLOATFUNC(x) extern int x(void *,void *,void *)
+
+/* The Vn labels indicate what version of the SPARC architecture gas thinks
+ * each insn is. This is from the binutils source :->
+ */
+/* quadword instructions */
+#define FSQRTQ 0x02b /* v8 */
+#define FADDQ 0x043 /* v8 */
+#define FSUBQ 0x047 /* v8 */
+#define FMULQ 0x04b /* v8 */
+#define FDIVQ 0x04f /* v8 */
+#define FDMULQ 0x06e /* v8 */
+#define FQTOS 0x0c7 /* v8 */
+#define FQTOD 0x0cb /* v8 */
+#define FITOQ 0x0cc /* v8 */
+#define FSTOQ 0x0cd /* v8 */
+#define FDTOQ 0x0ce /* v8 */
+#define FQTOI 0x0d3 /* v8 */
+#define FCMPQ 0x053 /* v8 */
+#define FCMPEQ 0x057 /* v8 */
+/* single/double instructions (subnormal): should all work */
+#define FSQRTS 0x029 /* v7 */
+#define FSQRTD 0x02a /* v7 */
+#define FADDS 0x041 /* v6 */
+#define FADDD 0x042 /* v6 */
+#define FSUBS 0x045 /* v6 */
+#define FSUBD 0x046 /* v6 */
+#define FMULS 0x049 /* v6 */
+#define FMULD 0x04a /* v6 */
+#define FDIVS 0x04d /* v6 */
+#define FDIVD 0x04e /* v6 */
+#define FSMULD 0x069 /* v6 */
+#define FDTOS 0x0c6 /* v6 */
+#define FSTOD 0x0c9 /* v6 */
+#define FSTOI 0x0d1 /* v6 */
+#define FDTOI 0x0d2 /* v6 */
+#define FABSS 0x009 /* v6 */
+#define FCMPS 0x051 /* v6 */
+#define FCMPES 0x055 /* v6 */
+#define FCMPD 0x052 /* v6 */
+#define FCMPED 0x056 /* v6 */
+#define FMOVS 0x001 /* v6 */
+#define FNEGS 0x005 /* v6 */
+#define FITOS 0x0c4 /* v6 */
+#define FITOD 0x0c8 /* v6 */
+
+#define FSR_TEM_SHIFT 23UL
+#define FSR_TEM_MASK (0x1fUL << FSR_TEM_SHIFT)
+#define FSR_AEXC_SHIFT 5UL
+#define FSR_AEXC_MASK (0x1fUL << FSR_AEXC_SHIFT)
+#define FSR_CEXC_SHIFT 0UL
+#define FSR_CEXC_MASK (0x1fUL << FSR_CEXC_SHIFT)
+
+static int do_one_mathemu(u32 insn, unsigned long *fsr, unsigned long *fregs);
+
+/* Unlike the Sparc64 version (which has a struct fpustate), we
+ * pass the taskstruct corresponding to the task which currently owns the
+ * FPU. This is partly because we don't have the fpustate struct and
+ * partly because the task owning the FPU isn't always current (as is
+ * the case for the Sparc64 port). This is probably SMP-related...
+ * This function returns 1 if all queued insns were emulated successfully.
+ * The test for unimplemented FPop in kernel mode has been moved into
+ * kernel/traps.c for simplicity.
+ */
+int do_mathemu(struct pt_regs *regs, struct task_struct *fpt)
+{
+ /* regs->pc isn't necessarily the PC at which the offending insn is sitting.
+ * The FPU maintains a queue of FPops which cause traps.
+ * When it hits an instruction that requires that the trapped op succeeded
+ * (usually because it reads a reg. that the trapped op wrote) then it
+ * causes this exception. We need to emulate all the insns on the queue
+ * and then allow the op to proceed.
+ * This code should also handle the case where the trap was precise,
+ * in which case the queue length is zero and regs->pc points at the
+ * single FPop to be emulated. (this case is untested, though :->)
+ * You'll need this case if you want to be able to emulate all FPops
+ * because the FPU either doesn't exist or has been software-disabled.
+ * [The UltraSPARC makes FP a precise trap; this isn't as stupid as it
+ * might sound because the Ultra does funky things with a superscalar
+ * architecture.]
+ */
+
+ /* You wouldn't believe how often I typed 'ftp' when I meant 'fpt' :-> */
+
+ int i;
+ int retcode = 0; /* assume all succeed */
+ unsigned long insn;
+
+#ifdef DEBUG_MATHEMU
+ printk("In do_mathemu()... pc is %08lx\n", regs->pc);
+ printk("fpqdepth is %ld\n", fpt->thread.fpqdepth);
+ for (i = 0; i < fpt->thread.fpqdepth; i++)
+ printk("%d: %08lx at %08lx\n", i, fpt->thread.fpqueue[i].insn,
+ (unsigned long)fpt->thread.fpqueue[i].insn_addr);
+#endif
+
+ if (fpt->thread.fpqdepth == 0) { /* no queue, guilty insn is at regs->pc */
+#ifdef DEBUG_MATHEMU
+ printk("precise trap at %08lx\n", regs->pc);
+#endif
+ if (!get_user(insn, (u32 __user *) regs->pc)) {
+ retcode = do_one_mathemu(insn, &fpt->thread.fsr, fpt->thread.float_regs);
+ if (retcode) {
+ /* in this case we need to fix up PC & nPC */
+ regs->pc = regs->npc;
+ regs->npc += 4;
+ }
+ }
+ return retcode;
+ }
+
+ /* Normal case: need to empty the queue... */
+ for (i = 0; i < fpt->thread.fpqdepth; i++) {
+ retcode = do_one_mathemu(fpt->thread.fpqueue[i].insn, &(fpt->thread.fsr), fpt->thread.float_regs);
+ if (!retcode) /* insn failed, no point doing any more */
+ break;
+ }
+ /* Now empty the queue and clear the queue_not_empty flag */
+ if (retcode)
+ fpt->thread.fsr &= ~(0x3000 | FSR_CEXC_MASK);
+ else
+ fpt->thread.fsr &= ~0x3000;
+ fpt->thread.fpqdepth = 0;
+
+ return retcode;
+}
+
+/* All routines returning an exception to raise should detect
+ * such exceptions _before_ rounding to be consistent with
+ * the behavior of the hardware in the implemented cases
+ * (and thus with the recommendations in the V9 architecture
+ * manual).
+ *
+ * We return 0 if a SIGFPE should be sent, 1 otherwise.
+ */
+static inline int record_exception(unsigned long *pfsr, int eflag)
+{
+ unsigned long fsr = *pfsr;
+ int would_trap;
+
+ /* Determine if this exception would have generated a trap. */
+ would_trap = (fsr & ((long)eflag << FSR_TEM_SHIFT)) != 0UL;
+
+ /* If trapping, we only want to signal one bit. */
+ if (would_trap != 0) {
+ eflag &= ((fsr & FSR_TEM_MASK) >> FSR_TEM_SHIFT);
+ if ((eflag & (eflag - 1)) != 0) {
+ if (eflag & FP_EX_INVALID)
+ eflag = FP_EX_INVALID;
+ else if (eflag & FP_EX_OVERFLOW)
+ eflag = FP_EX_OVERFLOW;
+ else if (eflag & FP_EX_UNDERFLOW)
+ eflag = FP_EX_UNDERFLOW;
+ else if (eflag & FP_EX_DIVZERO)
+ eflag = FP_EX_DIVZERO;
+ else if (eflag & FP_EX_INEXACT)
+ eflag = FP_EX_INEXACT;
+ }
+ }
+
+ /* Set CEXC, here is the rule:
+ *
+ * In general all FPU ops will set one and only one
+ * bit in the CEXC field, this is always the case
+ * when the IEEE exception trap is enabled in TEM.
+ */
+ fsr &= ~(FSR_CEXC_MASK);
+ fsr |= ((long)eflag << FSR_CEXC_SHIFT);
+
+ /* Set the AEXC field, rule is:
+ *
+ * If a trap would not be generated, the
+ * CEXC just generated is OR'd into the
+ * existing value of AEXC.
+ */
+ if (would_trap == 0)
+ fsr |= ((long)eflag << FSR_AEXC_SHIFT);
+
+ /* If trapping, indicate fault trap type IEEE. */
+ if (would_trap != 0)
+ fsr |= (1UL << 14);
+
+ *pfsr = fsr;
+
+ return (would_trap ? 0 : 1);
+}
+
+typedef union {
+ u32 s;
+ u64 d;
+ u64 q[2];
+} *argp;
+
+static int do_one_mathemu(u32 insn, unsigned long *pfsr, unsigned long *fregs)
+{
+ /* Emulate the given insn, updating fsr and fregs appropriately. */
+ int type = 0;
+ /* r is rd, b is rs2 and a is rs1. The *u arg tells
+ whether the argument should be packed/unpacked (0 - do not unpack/pack, 1 - unpack/pack)
+ non-u args tells the size of the argument (0 - no argument, 1 - single, 2 - double, 3 - quad */
+#define TYPE(dummy, r, ru, b, bu, a, au) type = (au << 2) | (a << 0) | (bu << 5) | (b << 3) | (ru << 8) | (r << 6)
+ int freg;
+ argp rs1 = NULL, rs2 = NULL, rd = NULL;
+ FP_DECL_EX;
+ FP_DECL_S(SA); FP_DECL_S(SB); FP_DECL_S(SR);
+ FP_DECL_D(DA); FP_DECL_D(DB); FP_DECL_D(DR);
+ FP_DECL_Q(QA); FP_DECL_Q(QB); FP_DECL_Q(QR);
+ int IR;
+ long fsr;
+
+#ifdef DEBUG_MATHEMU
+ printk("In do_mathemu(), emulating %08lx\n", insn);
+#endif
+
+ if ((insn & 0xc1f80000) == 0x81a00000) /* FPOP1 */ {
+ switch ((insn >> 5) & 0x1ff) {
+ case FSQRTQ: TYPE(3,3,1,3,1,0,0); break;
+ case FADDQ:
+ case FSUBQ:
+ case FMULQ:
+ case FDIVQ: TYPE(3,3,1,3,1,3,1); break;
+ case FDMULQ: TYPE(3,3,1,2,1,2,1); break;
+ case FQTOS: TYPE(3,1,1,3,1,0,0); break;
+ case FQTOD: TYPE(3,2,1,3,1,0,0); break;
+ case FITOQ: TYPE(3,3,1,1,0,0,0); break;
+ case FSTOQ: TYPE(3,3,1,1,1,0,0); break;
+ case FDTOQ: TYPE(3,3,1,2,1,0,0); break;
+ case FQTOI: TYPE(3,1,0,3,1,0,0); break;
+ case FSQRTS: TYPE(2,1,1,1,1,0,0); break;
+ case FSQRTD: TYPE(2,2,1,2,1,0,0); break;
+ case FADDD:
+ case FSUBD:
+ case FMULD:
+ case FDIVD: TYPE(2,2,1,2,1,2,1); break;
+ case FADDS:
+ case FSUBS:
+ case FMULS:
+ case FDIVS: TYPE(2,1,1,1,1,1,1); break;
+ case FSMULD: TYPE(2,2,1,1,1,1,1); break;
+ case FDTOS: TYPE(2,1,1,2,1,0,0); break;
+ case FSTOD: TYPE(2,2,1,1,1,0,0); break;
+ case FSTOI: TYPE(2,1,0,1,1,0,0); break;
+ case FDTOI: TYPE(2,1,0,2,1,0,0); break;
+ case FITOS: TYPE(2,1,1,1,0,0,0); break;
+ case FITOD: TYPE(2,2,1,1,0,0,0); break;
+ case FMOVS:
+ case FABSS:
+ case FNEGS: TYPE(2,1,0,1,0,0,0); break;
+ }
+ } else if ((insn & 0xc1f80000) == 0x81a80000) /* FPOP2 */ {
+ switch ((insn >> 5) & 0x1ff) {
+ case FCMPS: TYPE(3,0,0,1,1,1,1); break;
+ case FCMPES: TYPE(3,0,0,1,1,1,1); break;
+ case FCMPD: TYPE(3,0,0,2,1,2,1); break;
+ case FCMPED: TYPE(3,0,0,2,1,2,1); break;
+ case FCMPQ: TYPE(3,0,0,3,1,3,1); break;
+ case FCMPEQ: TYPE(3,0,0,3,1,3,1); break;
+ }
+ }
+
+ if (!type) { /* oops, didn't recognise that FPop */
+#ifdef DEBUG_MATHEMU
+ printk("attempt to emulate unrecognised FPop!\n");
+#endif
+ return 0;
+ }
+
+ /* Decode the registers to be used */
+ freg = (*pfsr >> 14) & 0xf;
+
+ *pfsr &= ~0x1c000; /* clear the traptype bits */
+
+ freg = ((insn >> 14) & 0x1f);
+ switch (type & 0x3) { /* is rs1 single, double or quad? */
+ case 3:
+ if (freg & 3) { /* quadwords must have bits 4&5 of the */
+ /* encoded reg. number set to zero. */
+ *pfsr |= (6 << 14);
+ return 0; /* simulate invalid_fp_register exception */
+ }
+ /* fall through */
+ case 2:
+ if (freg & 1) { /* doublewords must have bit 5 zeroed */
+ *pfsr |= (6 << 14);
+ return 0;
+ }
+ }
+ rs1 = (argp)&fregs[freg];
+ switch (type & 0x7) {
+ case 7: FP_UNPACK_QP (QA, rs1); break;
+ case 6: FP_UNPACK_DP (DA, rs1); break;
+ case 5: FP_UNPACK_SP (SA, rs1); break;
+ }
+ freg = (insn & 0x1f);
+ switch ((type >> 3) & 0x3) { /* same again for rs2 */
+ case 3:
+ if (freg & 3) { /* quadwords must have bits 4&5 of the */
+ /* encoded reg. number set to zero. */
+ *pfsr |= (6 << 14);
+ return 0; /* simulate invalid_fp_register exception */
+ }
+ /* fall through */
+ case 2:
+ if (freg & 1) { /* doublewords must have bit 5 zeroed */
+ *pfsr |= (6 << 14);
+ return 0;
+ }
+ }
+ rs2 = (argp)&fregs[freg];
+ switch ((type >> 3) & 0x7) {
+ case 7: FP_UNPACK_QP (QB, rs2); break;
+ case 6: FP_UNPACK_DP (DB, rs2); break;
+ case 5: FP_UNPACK_SP (SB, rs2); break;
+ }
+ freg = ((insn >> 25) & 0x1f);
+ switch ((type >> 6) & 0x3) { /* and finally rd. This one's a bit different */
+ case 0: /* dest is fcc. (this must be FCMPQ or FCMPEQ) */
+ if (freg) { /* V8 has only one set of condition codes, so */
+ /* anything but 0 in the rd field is an error */
+ *pfsr |= (6 << 14); /* (should probably flag as invalid opcode */
+ return 0; /* but SIGFPE will do :-> ) */
+ }
+ break;
+ case 3:
+ if (freg & 3) { /* quadwords must have bits 4&5 of the */
+ /* encoded reg. number set to zero. */
+ *pfsr |= (6 << 14);
+ return 0; /* simulate invalid_fp_register exception */
+ }
+ /* fall through */
+ case 2:
+ if (freg & 1) { /* doublewords must have bit 5 zeroed */
+ *pfsr |= (6 << 14);
+ return 0;
+ }
+ /* fall through */
+ case 1:
+ rd = (void *)&fregs[freg];
+ break;
+ }
+#ifdef DEBUG_MATHEMU
+ printk("executing insn...\n");
+#endif
+ /* do the Right Thing */
+ switch ((insn >> 5) & 0x1ff) {
+ /* + */
+ case FADDS: FP_ADD_S (SR, SA, SB); break;
+ case FADDD: FP_ADD_D (DR, DA, DB); break;
+ case FADDQ: FP_ADD_Q (QR, QA, QB); break;
+ /* - */
+ case FSUBS: FP_SUB_S (SR, SA, SB); break;
+ case FSUBD: FP_SUB_D (DR, DA, DB); break;
+ case FSUBQ: FP_SUB_Q (QR, QA, QB); break;
+ /* * */
+ case FMULS: FP_MUL_S (SR, SA, SB); break;
+ case FSMULD: FP_CONV (D, S, 2, 1, DA, SA);
+ FP_CONV (D, S, 2, 1, DB, SB);
+ case FMULD: FP_MUL_D (DR, DA, DB); break;
+ case FDMULQ: FP_CONV (Q, D, 4, 2, QA, DA);
+ FP_CONV (Q, D, 4, 2, QB, DB);
+ case FMULQ: FP_MUL_Q (QR, QA, QB); break;
+ /* / */
+ case FDIVS: FP_DIV_S (SR, SA, SB); break;
+ case FDIVD: FP_DIV_D (DR, DA, DB); break;
+ case FDIVQ: FP_DIV_Q (QR, QA, QB); break;
+ /* sqrt */
+ case FSQRTS: FP_SQRT_S (SR, SB); break;
+ case FSQRTD: FP_SQRT_D (DR, DB); break;
+ case FSQRTQ: FP_SQRT_Q (QR, QB); break;
+ /* mov */
+ case FMOVS: rd->s = rs2->s; break;
+ case FABSS: rd->s = rs2->s & 0x7fffffff; break;
+ case FNEGS: rd->s = rs2->s ^ 0x80000000; break;
+ /* float to int */
+ case FSTOI: FP_TO_INT_S (IR, SB, 32, 1); break;
+ case FDTOI: FP_TO_INT_D (IR, DB, 32, 1); break;
+ case FQTOI: FP_TO_INT_Q (IR, QB, 32, 1); break;
+ /* int to float */
+ case FITOS: IR = rs2->s; FP_FROM_INT_S (SR, IR, 32, int); break;
+ case FITOD: IR = rs2->s; FP_FROM_INT_D (DR, IR, 32, int); break;
+ case FITOQ: IR = rs2->s; FP_FROM_INT_Q (QR, IR, 32, int); break;
+ /* float to float */
+ case FSTOD: FP_CONV (D, S, 2, 1, DR, SB); break;
+ case FSTOQ: FP_CONV (Q, S, 4, 1, QR, SB); break;
+ case FDTOQ: FP_CONV (Q, D, 4, 2, QR, DB); break;
+ case FDTOS: FP_CONV (S, D, 1, 2, SR, DB); break;
+ case FQTOS: FP_CONV (S, Q, 1, 4, SR, QB); break;
+ case FQTOD: FP_CONV (D, Q, 2, 4, DR, QB); break;
+ /* comparison */
+ case FCMPS:
+ case FCMPES:
+ FP_CMP_S(IR, SB, SA, 3);
+ if (IR == 3 &&
+ (((insn >> 5) & 0x1ff) == FCMPES ||
+ FP_ISSIGNAN_S(SA) ||
+ FP_ISSIGNAN_S(SB)))
+ FP_SET_EXCEPTION (FP_EX_INVALID);
+ break;
+ case FCMPD:
+ case FCMPED:
+ FP_CMP_D(IR, DB, DA, 3);
+ if (IR == 3 &&
+ (((insn >> 5) & 0x1ff) == FCMPED ||
+ FP_ISSIGNAN_D(DA) ||
+ FP_ISSIGNAN_D(DB)))
+ FP_SET_EXCEPTION (FP_EX_INVALID);
+ break;
+ case FCMPQ:
+ case FCMPEQ:
+ FP_CMP_Q(IR, QB, QA, 3);
+ if (IR == 3 &&
+ (((insn >> 5) & 0x1ff) == FCMPEQ ||
+ FP_ISSIGNAN_Q(QA) ||
+ FP_ISSIGNAN_Q(QB)))
+ FP_SET_EXCEPTION (FP_EX_INVALID);
+ }
+ if (!FP_INHIBIT_RESULTS) {
+ switch ((type >> 6) & 0x7) {
+ case 0: fsr = *pfsr;
+ if (IR == -1) IR = 2;
+ /* fcc is always fcc0 */
+ fsr &= ~0xc00; fsr |= (IR << 10); break;
+ *pfsr = fsr;
+ break;
+ case 1: rd->s = IR; break;
+ case 5: FP_PACK_SP (rd, SR); break;
+ case 6: FP_PACK_DP (rd, DR); break;
+ case 7: FP_PACK_QP (rd, QR); break;
+ }
+ }
+ if (_fex == 0)
+ return 1; /* success! */
+ return record_exception(pfsr, _fex);
+}
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