44e92e0364
Currently, the nds32 FPU dose not support the arithmetic of denormalized
number. When the nds32 FPU finds the result of the instruction is a
denormlized number, the nds32 FPU considers it to be an underflow condition
and rounds the result to an appropriate number. It may causes some loss
of precision. This commit proposes a solution to re-execute the
instruction by the FPU emulator to enhance the precision. To transfer
calculations from user space to kernel space, this feature will enable
the underflow exception trap by default. Enabling this feature may cause
some side effects:
1. Performance loss due to extra FPU exception
2. Need another scheme to control real underflow trap
A new parameter, UDF_trap, which is belong to FPU context is used
to control underflow trap.
User can configure this feature via CONFIG_SUPPORT_DENORMAL_ARITHMETIC
Signed-off-by: Vincent Chen <vincentc@andestech.com>
Acked-by: Greentime Hu <greentime@andestech.com>
Signed-off-by: Greentime Hu <greentime@andestech.com>
74 lines
2 KiB
C
74 lines
2 KiB
C
// SPDX-License-Identifier: GPL-2.0
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// Copyright (C) 2005-2017 Andes Technology Corporation
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#ifndef _ASMNDS32_SIGCONTEXT_H
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#define _ASMNDS32_SIGCONTEXT_H
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/*
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* Signal context structure - contains all info to do with the state
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* before the signal handler was invoked. Note: only add new entries
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* to the end of the structure.
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*/
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struct fpu_struct {
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unsigned long long fd_regs[32];
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unsigned long fpcsr;
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/*
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* UDF_trap is used to recognize whether underflow trap is enabled
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* or not. When UDF_trap == 1, this process will be traped and then
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* get a SIGFPE signal when encountering an underflow exception.
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* UDF_trap is only modified through setfputrap syscall. Therefore,
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* UDF_trap needn't be saved or loaded to context in each context
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* switch.
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*/
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unsigned long UDF_trap;
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};
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struct zol_struct {
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unsigned long nds32_lc; /* $LC */
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unsigned long nds32_le; /* $LE */
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unsigned long nds32_lb; /* $LB */
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};
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struct sigcontext {
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unsigned long trap_no;
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unsigned long error_code;
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unsigned long oldmask;
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unsigned long nds32_r0;
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unsigned long nds32_r1;
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unsigned long nds32_r2;
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unsigned long nds32_r3;
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unsigned long nds32_r4;
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unsigned long nds32_r5;
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unsigned long nds32_r6;
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unsigned long nds32_r7;
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unsigned long nds32_r8;
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unsigned long nds32_r9;
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unsigned long nds32_r10;
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unsigned long nds32_r11;
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unsigned long nds32_r12;
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unsigned long nds32_r13;
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unsigned long nds32_r14;
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unsigned long nds32_r15;
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unsigned long nds32_r16;
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unsigned long nds32_r17;
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unsigned long nds32_r18;
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unsigned long nds32_r19;
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unsigned long nds32_r20;
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unsigned long nds32_r21;
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unsigned long nds32_r22;
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unsigned long nds32_r23;
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unsigned long nds32_r24;
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unsigned long nds32_r25;
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unsigned long nds32_fp; /* $r28 */
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unsigned long nds32_gp; /* $r29 */
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unsigned long nds32_lp; /* $r30 */
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unsigned long nds32_sp; /* $r31 */
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unsigned long nds32_ipc;
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unsigned long fault_address;
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unsigned long used_math_flag;
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/* FPU Registers */
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struct fpu_struct fpu;
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struct zol_struct zol;
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};
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#endif
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