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linux-stable/arch/alpha/math-emu/math.c
Ivan Kokshaysky 6b2d2cec10 alpha: fix conversion from denormal float to double 
The trap handler does properly update the fraction,
but not the exponent...

Thanks to Paolo Bonzini for the bug report and the testcase.

Signed-off-by: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Paolo Bonzini <bonzini@gnu.org>
Cc: Richard Henderson <rth@twiddle.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-01-17 15:38:59 -08:00

400 lines
9.6 KiB
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#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <asm/uaccess.h>
#include "sfp-util.h"
#include <math-emu/soft-fp.h>
#include <math-emu/single.h>
#include <math-emu/double.h>
#define OPC_PAL 0x00
#define OPC_INTA 0x10
#define OPC_INTL 0x11
#define OPC_INTS 0x12
#define OPC_INTM 0x13
#define OPC_FLTC 0x14
#define OPC_FLTV 0x15
#define OPC_FLTI 0x16
#define OPC_FLTL 0x17
#define OPC_MISC 0x18
#define OPC_JSR 0x1a
#define FOP_SRC_S 0
#define FOP_SRC_T 2
#define FOP_SRC_Q 3
#define FOP_FNC_ADDx 0
#define FOP_FNC_CVTQL 0
#define FOP_FNC_SUBx 1
#define FOP_FNC_MULx 2
#define FOP_FNC_DIVx 3
#define FOP_FNC_CMPxUN 4
#define FOP_FNC_CMPxEQ 5
#define FOP_FNC_CMPxLT 6
#define FOP_FNC_CMPxLE 7
#define FOP_FNC_SQRTx 11
#define FOP_FNC_CVTxS 12
#define FOP_FNC_CVTxT 14
#define FOP_FNC_CVTxQ 15
#define MISC_TRAPB 0x0000
#define MISC_EXCB 0x0400
extern unsigned long alpha_read_fp_reg (unsigned long reg);
extern void alpha_write_fp_reg (unsigned long reg, unsigned long val);
extern unsigned long alpha_read_fp_reg_s (unsigned long reg);
extern void alpha_write_fp_reg_s (unsigned long reg, unsigned long val);
#ifdef MODULE
MODULE_DESCRIPTION("FP Software completion module");
extern long (*alpha_fp_emul_imprecise)(struct pt_regs *, unsigned long);
extern long (*alpha_fp_emul) (unsigned long pc);
static long (*save_emul_imprecise)(struct pt_regs *, unsigned long);
static long (*save_emul) (unsigned long pc);
long do_alpha_fp_emul_imprecise(struct pt_regs *, unsigned long);
long do_alpha_fp_emul(unsigned long);
int init_module(void)
{
save_emul_imprecise = alpha_fp_emul_imprecise;
save_emul = alpha_fp_emul;
alpha_fp_emul_imprecise = do_alpha_fp_emul_imprecise;
alpha_fp_emul = do_alpha_fp_emul;
return 0;
}
void cleanup_module(void)
{
alpha_fp_emul_imprecise = save_emul_imprecise;
alpha_fp_emul = save_emul;
}
#undef alpha_fp_emul_imprecise
#define alpha_fp_emul_imprecise do_alpha_fp_emul_imprecise
#undef alpha_fp_emul
#define alpha_fp_emul do_alpha_fp_emul
#endif /* MODULE */
/*
* Emulate the floating point instruction at address PC. Returns -1 if the
* instruction to be emulated is illegal (such as with the opDEC trap), else
* the SI_CODE for a SIGFPE signal, else 0 if everything's ok.
*
* Notice that the kernel does not and cannot use FP regs. This is good
* because it means that instead of saving/restoring all fp regs, we simply
* stick the result of the operation into the appropriate register.
*/
long
alpha_fp_emul (unsigned long pc)
{
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);
unsigned long fa, fb, fc, func, mode, src;
unsigned long res, va, vb, vc, swcr, fpcr;
__u32 insn;
long si_code;
get_user(insn, (__u32 __user *)pc);
fc = (insn >> 0) & 0x1f; /* destination register */
fb = (insn >> 16) & 0x1f;
fa = (insn >> 21) & 0x1f;
func = (insn >> 5) & 0xf;
src = (insn >> 9) & 0x3;
mode = (insn >> 11) & 0x3;
fpcr = rdfpcr();
swcr = swcr_update_status(current_thread_info()->ieee_state, fpcr);
if (mode == 3) {
/* Dynamic -- get rounding mode from fpcr. */
mode = (fpcr >> FPCR_DYN_SHIFT) & 3;
}
switch (src) {
case FOP_SRC_S:
va = alpha_read_fp_reg_s(fa);
vb = alpha_read_fp_reg_s(fb);
FP_UNPACK_SP(SA, &va);
FP_UNPACK_SP(SB, &vb);
switch (func) {
case FOP_FNC_SUBx:
FP_SUB_S(SR, SA, SB);
goto pack_s;
case FOP_FNC_ADDx:
FP_ADD_S(SR, SA, SB);
goto pack_s;
case FOP_FNC_MULx:
FP_MUL_S(SR, SA, SB);
goto pack_s;
case FOP_FNC_DIVx:
FP_DIV_S(SR, SA, SB);
goto pack_s;
case FOP_FNC_SQRTx:
FP_SQRT_S(SR, SB);
goto pack_s;
}
goto bad_insn;
case FOP_SRC_T:
va = alpha_read_fp_reg(fa);
vb = alpha_read_fp_reg(fb);
if ((func & ~3) == FOP_FNC_CMPxUN) {
FP_UNPACK_RAW_DP(DA, &va);
FP_UNPACK_RAW_DP(DB, &vb);
if (!DA_e && !_FP_FRAC_ZEROP_1(DA)) {
FP_SET_EXCEPTION(FP_EX_DENORM);
if (FP_DENORM_ZERO)
_FP_FRAC_SET_1(DA, _FP_ZEROFRAC_1);
}
if (!DB_e && !_FP_FRAC_ZEROP_1(DB)) {
FP_SET_EXCEPTION(FP_EX_DENORM);
if (FP_DENORM_ZERO)
_FP_FRAC_SET_1(DB, _FP_ZEROFRAC_1);
}
FP_CMP_D(res, DA, DB, 3);
vc = 0x4000000000000000UL;
/* CMPTEQ, CMPTUN don't trap on QNaN,
while CMPTLT and CMPTLE do */
if (res == 3
&& ((func & 3) >= 2
|| FP_ISSIGNAN_D(DA)
|| FP_ISSIGNAN_D(DB))) {
FP_SET_EXCEPTION(FP_EX_INVALID);
}
switch (func) {
case FOP_FNC_CMPxUN: if (res != 3) vc = 0; break;
case FOP_FNC_CMPxEQ: if (res) vc = 0; break;
case FOP_FNC_CMPxLT: if (res != -1) vc = 0; break;
case FOP_FNC_CMPxLE: if ((long)res > 0) vc = 0; break;
}
goto done_d;
}
FP_UNPACK_DP(DA, &va);
FP_UNPACK_DP(DB, &vb);
switch (func) {
case FOP_FNC_SUBx:
FP_SUB_D(DR, DA, DB);
goto pack_d;
case FOP_FNC_ADDx:
FP_ADD_D(DR, DA, DB);
goto pack_d;
case FOP_FNC_MULx:
FP_MUL_D(DR, DA, DB);
goto pack_d;
case FOP_FNC_DIVx:
FP_DIV_D(DR, DA, DB);
goto pack_d;
case FOP_FNC_SQRTx:
FP_SQRT_D(DR, DB);
goto pack_d;
case FOP_FNC_CVTxS:
/* It is irritating that DEC encoded CVTST with
SRC == T_floating. It is also interesting that
the bit used to tell the two apart is /U... */
if (insn & 0x2000) {
FP_CONV(S,D,1,1,SR,DB);
goto pack_s;
} else {
vb = alpha_read_fp_reg_s(fb);
FP_UNPACK_SP(SB, &vb);
DR_c = DB_c;
DR_s = DB_s;
DR_e = DB_e + (1024 - 128);
DR_f = SB_f << (52 - 23);
goto pack_d;
}
case FOP_FNC_CVTxQ:
if (DB_c == FP_CLS_NAN
&& (_FP_FRAC_HIGH_RAW_D(DB) & _FP_QNANBIT_D)) {
/* AAHB Table B-2 says QNaN should not trigger INV */
vc = 0;
} else
FP_TO_INT_ROUND_D(vc, DB, 64, 2);
goto done_d;
}
goto bad_insn;
case FOP_SRC_Q:
vb = alpha_read_fp_reg(fb);
switch (func) {
case FOP_FNC_CVTQL:
/* Notice: We can get here only due to an integer
overflow. Such overflows are reported as invalid
ops. We return the result the hw would have
computed. */
vc = ((vb & 0xc0000000) << 32 | /* sign and msb */
(vb & 0x3fffffff) << 29); /* rest of the int */
FP_SET_EXCEPTION (FP_EX_INVALID);
goto done_d;
case FOP_FNC_CVTxS:
FP_FROM_INT_S(SR, ((long)vb), 64, long);
goto pack_s;
case FOP_FNC_CVTxT:
FP_FROM_INT_D(DR, ((long)vb), 64, long);
goto pack_d;
}
goto bad_insn;
}
goto bad_insn;
pack_s:
FP_PACK_SP(&vc, SR);
if ((_fex & FP_EX_UNDERFLOW) && (swcr & IEEE_MAP_UMZ))
vc = 0;
alpha_write_fp_reg_s(fc, vc);
goto done;
pack_d:
FP_PACK_DP(&vc, DR);
if ((_fex & FP_EX_UNDERFLOW) && (swcr & IEEE_MAP_UMZ))
vc = 0;
done_d:
alpha_write_fp_reg(fc, vc);
goto done;
/*
* Take the appropriate action for each possible
* floating-point result:
*
* - Set the appropriate bits in the FPCR
* - If the specified exception is enabled in the FPCR,
* return. The caller (entArith) will dispatch
* the appropriate signal to the translated program.
*
* In addition, properly track the exception state in software
* as described in the Alpha Architecture Handbook section 4.7.7.3.
*/
done:
if (_fex) {
/* Record exceptions in software control word. */
swcr |= (_fex << IEEE_STATUS_TO_EXCSUM_SHIFT);
current_thread_info()->ieee_state
|= (_fex << IEEE_STATUS_TO_EXCSUM_SHIFT);
/* Update hardware control register. */
fpcr &= (~FPCR_MASK | FPCR_DYN_MASK);
fpcr |= ieee_swcr_to_fpcr(swcr);
wrfpcr(fpcr);
/* Do we generate a signal? */
_fex = _fex & swcr & IEEE_TRAP_ENABLE_MASK;
si_code = 0;
if (_fex) {
if (_fex & IEEE_TRAP_ENABLE_DNO) si_code = FPE_FLTUND;
if (_fex & IEEE_TRAP_ENABLE_INE) si_code = FPE_FLTRES;
if (_fex & IEEE_TRAP_ENABLE_UNF) si_code = FPE_FLTUND;
if (_fex & IEEE_TRAP_ENABLE_OVF) si_code = FPE_FLTOVF;
if (_fex & IEEE_TRAP_ENABLE_DZE) si_code = FPE_FLTDIV;
if (_fex & IEEE_TRAP_ENABLE_INV) si_code = FPE_FLTINV;
}
return si_code;
}
/* We used to write the destination register here, but DEC FORTRAN
requires that the result *always* be written... so we do the write
immediately after the operations above. */
return 0;
bad_insn:
printk(KERN_ERR "alpha_fp_emul: Invalid FP insn %#x at %#lx\n",
insn, pc);
return -1;
}
long
alpha_fp_emul_imprecise (struct pt_regs *regs, unsigned long write_mask)
{
unsigned long trigger_pc = regs->pc - 4;
unsigned long insn, opcode, rc, si_code = 0;
/*
* Turn off the bits corresponding to registers that are the
* target of instructions that set bits in the exception
* summary register. We have some slack doing this because a
* register that is the target of a trapping instruction can
* be written at most once in the trap shadow.
*
* Branches, jumps, TRAPBs, EXCBs and calls to PALcode all
* bound the trap shadow, so we need not look any further than
* up to the first occurrence of such an instruction.
*/
while (write_mask) {
get_user(insn, (__u32 __user *)(trigger_pc));
opcode = insn >> 26;
rc = insn & 0x1f;
switch (opcode) {
case OPC_PAL:
case OPC_JSR:
case 0x30 ... 0x3f: /* branches */
goto egress;
case OPC_MISC:
switch (insn & 0xffff) {
case MISC_TRAPB:
case MISC_EXCB:
goto egress;
default:
break;
}
break;
case OPC_INTA:
case OPC_INTL:
case OPC_INTS:
case OPC_INTM:
write_mask &= ~(1UL << rc);
break;
case OPC_FLTC:
case OPC_FLTV:
case OPC_FLTI:
case OPC_FLTL:
write_mask &= ~(1UL << (rc + 32));
break;
}
if (!write_mask) {
/* Re-execute insns in the trap-shadow. */
regs->pc = trigger_pc + 4;
si_code = alpha_fp_emul(trigger_pc);
goto egress;
}
trigger_pc -= 4;
}
egress:
return si_code;
}
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