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[Qemu-devel] [PATCH] Implement ARM floating point exception emulation
From: |
Aurelien Jarno |
Subject: |
[Qemu-devel] [PATCH] Implement ARM floating point exception emulation |
Date: |
Sun, 6 Jan 2008 23:51:27 +0100 |
User-agent: |
Mutt/1.5.13 (2006-08-11) |
The patch below, written by Ulrich Hecht implements ARM floating point
exception emulation. It is in the Debian qemu package for more than 2
years, and looks good enough to be committed upsteam.
Index: linux-user/main.c
===================================================================
RCS file: /sources/qemu/qemu/linux-user/main.c,v
retrieving revision 1.159
diff -u -d -p -r1.159 main.c
--- linux-user/main.c 6 Jan 2008 17:21:48 -0000 1.159
+++ linux-user/main.c 6 Jan 2008 22:35:49 -0000
@@ -377,19 +377,68 @@ void cpu_loop(CPUARMState *env)
{
TaskState *ts = env->opaque;
uint32_t opcode;
+ int rc;
/* we handle the FPU emulation here, as Linux */
/* we get the opcode */
/* FIXME - what to do if get_user() fails? */
get_user_u32(opcode, env->regs[15]);
- if (EmulateAll(opcode, &ts->fpa, env) == 0) {
+ rc = EmulateAll(opcode, &ts->fpa, env);
+ if (rc == 0) { /* illegal instruction */
info.si_signo = SIGILL;
info.si_errno = 0;
info.si_code = TARGET_ILL_ILLOPN;
info._sifields._sigfault._addr = env->regs[15];
queue_signal(info.si_signo, &info);
- } else {
+ } else if (rc < 0) { /* FP exception */
+ int arm_fpe=0;
+
+ /* translate softfloat flags to FPSR flags */
+ if (-rc & float_flag_invalid)
+ arm_fpe |= BIT_IOC;
+ if (-rc & float_flag_divbyzero)
+ arm_fpe |= BIT_DZC;
+ if (-rc & float_flag_overflow)
+ arm_fpe |= BIT_OFC;
+ if (-rc & float_flag_underflow)
+ arm_fpe |= BIT_UFC;
+ if (-rc & float_flag_inexact)
+ arm_fpe |= BIT_IXC;
+
+ FPSR fpsr = ts->fpa.fpsr;
+ //printf("fpsr 0x%x, arm_fpe 0x%x\n",fpsr,arm_fpe);
+
+ if (fpsr & (arm_fpe << 16)) { /* exception enabled? */
+ info.si_signo = SIGFPE;
+ info.si_errno = 0;
+
+ /* ordered by priority, least first */
+ if (arm_fpe & BIT_IXC) info.si_code = TARGET_FPE_FLTRES;
+ if (arm_fpe & BIT_UFC) info.si_code = TARGET_FPE_FLTUND;
+ if (arm_fpe & BIT_OFC) info.si_code = TARGET_FPE_FLTOVF;
+ if (arm_fpe & BIT_DZC) info.si_code = TARGET_FPE_FLTDIV;
+ if (arm_fpe & BIT_IOC) info.si_code = TARGET_FPE_FLTINV;
+
+ info._sifields._sigfault._addr = env->regs[15];
+ queue_signal(info.si_signo, &info);
+ } else {
+ env->regs[15] += 4;
+ }
+
+ /* accumulate unenabled exceptions */
+ if ((!(fpsr & BIT_IXE)) && (arm_fpe & BIT_IXC))
+ fpsr |= BIT_IXC;
+ if ((!(fpsr & BIT_UFE)) && (arm_fpe & BIT_UFC))
+ fpsr |= BIT_UFC;
+ if ((!(fpsr & BIT_OFE)) && (arm_fpe & BIT_OFC))
+ fpsr |= BIT_OFC;
+ if ((!(fpsr & BIT_DZE)) && (arm_fpe & BIT_DZC))
+ fpsr |= BIT_DZC;
+ if ((!(fpsr & BIT_IOE)) && (arm_fpe & BIT_IOC))
+ fpsr |= BIT_IOC;
+ ts->fpa.fpsr=fpsr;
+ } else { /* everything OK */
/* increment PC */
env->regs[15] += 4;
}
Index: target-arm/nwfpe/fpa11.c
===================================================================
RCS file: /sources/qemu/qemu/target-arm/nwfpe/fpa11.c,v
retrieving revision 1.5
diff -u -d -p -r1.5 fpa11.c
--- target-arm/nwfpe/fpa11.c 17 Sep 2007 08:09:52 -0000 1.5
+++ target-arm/nwfpe/fpa11.c 6 Jan 2008 22:35:49 -0000
@@ -162,6 +162,8 @@ unsigned int EmulateAll(unsigned int opc
fpa11->initflag = 1;
}
+ set_float_exception_flags(0, &fpa11->fp_status);
+
if (TEST_OPCODE(opcode,MASK_CPRT))
{
//fprintf(stderr,"emulating CPRT\n");
@@ -191,6 +193,11 @@ unsigned int EmulateAll(unsigned int opc
}
// restore_flags(flags);
+ if(nRc == 1 && get_float_exception_flags(&fpa11->fp_status))
+ {
+ //printf("fef 0x%x\n",float_exception_flags);
+ nRc=-get_float_exception_flags(&fpa11->fp_status);
+ }
//printf("returning %d\n",nRc);
return(nRc);
--
.''`. Aurelien Jarno | GPG: 1024D/F1BCDB73
: :' : Debian developer | Electrical Engineer
`. `' address@hidden | address@hidden
`- people.debian.org/~aurel32 | www.aurel32.net
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