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[Qemu-devel] [PATCH v16 5/5] linux-user: Handle EXCP_FPE properly for MIPS

Aleksandar Markovic posted 5 patches 6 years, 7 months ago
Maintainers: Laurent Vivier <laurent@vivier.eu>, Riku Voipio <riku.voipio@iki.fi>
[Qemu-devel] [PATCH v16 5/5] linux-user: Handle EXCP_FPE properly for MIPS
Posted by Aleksandar Markovic 6 years, 7 months ago 
From: Aleksandar Markovic <amarkovic@wavecomp.com>

Handle EXCP_FPE properly for MIPS in cpu loop.

Note that a vast majority of FP instructions are not affected by
the absence of the code in this patch, as they use alternative code
paths for handling floating point exceptions (see, for example,
invocations of update_fcr31()) - they rely on softfloat library for
keeping track on exceptions that needs to be raised. However, there
are few MIPS FP instructions (an example is CTC1) that use function
do_raise_exception() directly, and they need the case that is added
in this patch to propagate the FPE exception as designed.

The code is based on kernel's function force_fcr31_sig() in
arch/mips/kernel.traps.c.

Reported-by: Yunqiang Su <ysu@wavecomp.com>
Signed-off-by: Aleksandar Markovic <amarkovic@wavecomp.com>
---
 linux-user/mips/cpu_loop.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/linux-user/mips/cpu_loop.c b/linux-user/mips/cpu_loop.c
index 43ba267..0ba894f 100644
--- a/linux-user/mips/cpu_loop.c
+++ b/linux-user/mips/cpu_loop.c
@@ -540,6 +540,23 @@ done_syscall:
             info.si_code = TARGET_ILL_ILLOPC;
             queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
             break;
+        case EXCP_FPE:
+            info.si_signo = TARGET_SIGFPE;
+            info.si_errno = 0;
+            info.si_code = TARGET_FPE_FLTUNK;
+            if (GET_FP_CAUSE(env->active_fpu.fcr31) & FP_INVALID) {
+                info.si_code = TARGET_FPE_FLTINV;
+            } else if (GET_FP_CAUSE(env->active_fpu.fcr31) & FP_DIV0) {
+                info.si_code = TARGET_FPE_FLTDIV;
+            } else if (GET_FP_CAUSE(env->active_fpu.fcr31) & FP_OVERFLOW) {
+                info.si_code = TARGET_FPE_FLTOVF;
+            } else if (GET_FP_CAUSE(env->active_fpu.fcr31) & FP_UNDERFLOW) {
+                info.si_code = TARGET_FPE_FLTUND;
+            } else if (GET_FP_CAUSE(env->active_fpu.fcr31) & FP_INEXACT) {
+                info.si_code = TARGET_FPE_FLTRES;
+            }
+            queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
+            break;
         /* The code below was inspired by the MIPS Linux kernel trap
          * handling code in arch/mips/kernel/traps.c.
          */
-- 
2.7.4
Re: [Qemu-devel] [PATCH v16 5/5] linux-user: Handle EXCP_FPE properly for MIPS
Posted by Laurent Vivier 6 years, 7 months ago 
Le 28/06/2019 à 12:43, Aleksandar Markovic a écrit :
> From: Aleksandar Markovic <amarkovic@wavecomp.com>
> 
> Handle EXCP_FPE properly for MIPS in cpu loop.
> 
> Note that a vast majority of FP instructions are not affected by
> the absence of the code in this patch, as they use alternative code
> paths for handling floating point exceptions (see, for example,
> invocations of update_fcr31()) - they rely on softfloat library for
> keeping track on exceptions that needs to be raised. However, there
> are few MIPS FP instructions (an example is CTC1) that use function
> do_raise_exception() directly, and they need the case that is added
> in this patch to propagate the FPE exception as designed.
> 
> The code is based on kernel's function force_fcr31_sig() in
> arch/mips/kernel.traps.c.
> 
> Reported-by: Yunqiang Su <ysu@wavecomp.com>
> Signed-off-by: Aleksandar Markovic <amarkovic@wavecomp.com>
> ---
>  linux-user/mips/cpu_loop.c | 17 +++++++++++++++++
>  1 file changed, 17 insertions(+)
> 
> diff --git a/linux-user/mips/cpu_loop.c b/linux-user/mips/cpu_loop.c
> index 43ba267..0ba894f 100644
> --- a/linux-user/mips/cpu_loop.c
> +++ b/linux-user/mips/cpu_loop.c
> @@ -540,6 +540,23 @@ done_syscall:
>              info.si_code = TARGET_ILL_ILLOPC;
>              queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
>              break;
> +        case EXCP_FPE:
> +            info.si_signo = TARGET_SIGFPE;
> +            info.si_errno = 0;
> +            info.si_code = TARGET_FPE_FLTUNK;
> +            if (GET_FP_CAUSE(env->active_fpu.fcr31) & FP_INVALID) {
> +                info.si_code = TARGET_FPE_FLTINV;
> +            } else if (GET_FP_CAUSE(env->active_fpu.fcr31) & FP_DIV0) {
> +                info.si_code = TARGET_FPE_FLTDIV;
> +            } else if (GET_FP_CAUSE(env->active_fpu.fcr31) & FP_OVERFLOW) {
> +                info.si_code = TARGET_FPE_FLTOVF;
> +            } else if (GET_FP_CAUSE(env->active_fpu.fcr31) & FP_UNDERFLOW) {
> +                info.si_code = TARGET_FPE_FLTUND;
> +            } else if (GET_FP_CAUSE(env->active_fpu.fcr31) & FP_INEXACT) {
> +                info.si_code = TARGET_FPE_FLTRES;
> +            }
> +            queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
> +            break;
>          /* The code below was inspired by the MIPS Linux kernel trap
>           * handling code in arch/mips/kernel/traps.c.
>           */
> 

Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Re: [Qemu-devel] [PATCH v16 5/5] linux-user: Handle EXCP_FPE properly for MIPS
Posted by Laurent Vivier 6 years, 7 months ago 
Le 28/06/2019 à 12:43, Aleksandar Markovic a écrit :
> From: Aleksandar Markovic <amarkovic@wavecomp.com>
> 
> Handle EXCP_FPE properly for MIPS in cpu loop.
> 
> Note that a vast majority of FP instructions are not affected by
> the absence of the code in this patch, as they use alternative code
> paths for handling floating point exceptions (see, for example,
> invocations of update_fcr31()) - they rely on softfloat library for
> keeping track on exceptions that needs to be raised. However, there
> are few MIPS FP instructions (an example is CTC1) that use function
> do_raise_exception() directly, and they need the case that is added
> in this patch to propagate the FPE exception as designed.
> 
> The code is based on kernel's function force_fcr31_sig() in
> arch/mips/kernel.traps.c.
> 
> Reported-by: Yunqiang Su <ysu@wavecomp.com>
> Signed-off-by: Aleksandar Markovic <amarkovic@wavecomp.com>
> ---
>  linux-user/mips/cpu_loop.c | 17 +++++++++++++++++
>  1 file changed, 17 insertions(+)
> 
> diff --git a/linux-user/mips/cpu_loop.c b/linux-user/mips/cpu_loop.c
> index 43ba267..0ba894f 100644
> --- a/linux-user/mips/cpu_loop.c
> +++ b/linux-user/mips/cpu_loop.c
> @@ -540,6 +540,23 @@ done_syscall:
>              info.si_code = TARGET_ILL_ILLOPC;
>              queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
>              break;
> +        case EXCP_FPE:
> +            info.si_signo = TARGET_SIGFPE;
> +            info.si_errno = 0;
> +            info.si_code = TARGET_FPE_FLTUNK;
> +            if (GET_FP_CAUSE(env->active_fpu.fcr31) & FP_INVALID) {
> +                info.si_code = TARGET_FPE_FLTINV;
> +            } else if (GET_FP_CAUSE(env->active_fpu.fcr31) & FP_DIV0) {
> +                info.si_code = TARGET_FPE_FLTDIV;
> +            } else if (GET_FP_CAUSE(env->active_fpu.fcr31) & FP_OVERFLOW) {
> +                info.si_code = TARGET_FPE_FLTOVF;
> +            } else if (GET_FP_CAUSE(env->active_fpu.fcr31) & FP_UNDERFLOW) {
> +                info.si_code = TARGET_FPE_FLTUND;
> +            } else if (GET_FP_CAUSE(env->active_fpu.fcr31) & FP_INEXACT) {
> +                info.si_code = TARGET_FPE_FLTRES;
> +            }
> +            queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
> +            break;
>          /* The code below was inspired by the MIPS Linux kernel trap
>           * handling code in arch/mips/kernel/traps.c.
>           */
> 

Applied to my linux-user branch.

Thanks,
Laurent

Patchew 2.1-devel-b67e4c2

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