[Qemu-trivial] [PATCH] target-openrisc: Fix exception handling status registers

[Qemu-trivial] [PATCH] target-openrisc: Fix exception handling status registers

[Stafford Horne]

I am working on testing instruction emulation patches for the linux
kernel. During testing I found these 2 issues:

 - sets DSX (delay slot exception) but never clears it
 - EEAR for illegal insns should point to the bad exception (as per
   openrisc spec) but its not

This patch fixes these two issues by clearing the DSX flag when not in a
delay slot and by setting EEAR to exception PC when handling illegal
instruction exceptions.

After this patch the openrisc kernel with latest patches boots great on
qemu and instruction emulation works.

Cc: qemu-trivial@nongnu.org
Cc: openrisc@lists.librecores.org
Signed-off-by: Stafford Horne <shorne@gmail.com>
---
 target/openrisc/interrupt.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/target/openrisc/interrupt.c b/target/openrisc/interrupt.c
index 5fe3f11..e1b0142 100644
--- a/target/openrisc/interrupt.c
+++ b/target/openrisc/interrupt.c
@@ -38,10 +38,17 @@ void openrisc_cpu_do_interrupt(CPUState *cs)
         env->flags &= ~D_FLAG;
         env->sr |= SR_DSX;
         env->epcr -= 4;
+    } else {
+        env->sr &= ~SR_DSX;
     }
     if (cs->exception_index == EXCP_SYSCALL) {
         env->epcr += 4;
     }
+    /* When we have an illegal instruction the error effective address
+       shall be set to the illegal instruction address.  */
+    if (cs->exception_index == EXCP_ILLEGAL) {
+        env->eear = env->pc;
+    }
 
     /* For machine-state changed between user-mode and supervisor mode,
        we need flush TLB when we enter&exit EXCP.  */
-- 
2.9.3

[Qemu-trivial] [PATCH] target-openrisc: Fix exception handling status registers

[Stafford Horne]

I am working on testing instruction emulation patches for the linux
kernel. During testing I found these 2 issues:

 - sets DSX (delay slot exception) but never clears it
 - EEAR for illegal insns should point to the bad exception (as per
   openrisc spec) but its not

This patch fixes these two issues by clearing the DSX flag when not in a
delay slot and by setting EEAR to exception PC when handling illegal
instruction exceptions.

After this patch the openrisc kernel with latest patches boots great on
qemu and instruction emulation works.

Cc: qemu-trivial@nongnu.org
Cc: openrisc@lists.librecores.org
Signed-off-by: Stafford Horne <shorne@gmail.com>
---
 target/openrisc/interrupt.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/target/openrisc/interrupt.c b/target/openrisc/interrupt.c
index 5fe3f11..e1b0142 100644
--- a/target/openrisc/interrupt.c
+++ b/target/openrisc/interrupt.c
@@ -38,10 +38,17 @@ void openrisc_cpu_do_interrupt(CPUState *cs)
         env->flags &= ~D_FLAG;
         env->sr |= SR_DSX;
         env->epcr -= 4;
+    } else {
+        env->sr &= ~SR_DSX;
     }
     if (cs->exception_index == EXCP_SYSCALL) {
         env->epcr += 4;
     }
+    /* When we have an illegal instruction the error effective address
+       shall be set to the illegal instruction address.  */
+    if (cs->exception_index == EXCP_ILLEGAL) {
+        env->eear = env->pc;
+    }
 
     /* For machine-state changed between user-mode and supervisor mode,
        we need flush TLB when we enter&exit EXCP.  */
-- 
2.9.3

Re: [Qemu-trivial] [PATCH] target-openrisc: Fix exception handling status registers

[Stafford Horne]

Hello,

Sorry for the duplicate. There was an issue with my copy to qemu-devel
group.  Resent to everyone with proper cc to qemu-devel.

Please ignore this one.

-Stafford

On Sat, Jan 14, 2017 at 06:57:20AM +0900, Stafford Horne wrote:
> I am working on testing instruction emulation patches for the linux
> kernel. During testing I found these 2 issues:
> 
>  - sets DSX (delay slot exception) but never clears it
>  - EEAR for illegal insns should point to the bad exception (as per
>    openrisc spec) but its not
> 
> This patch fixes these two issues by clearing the DSX flag when not in a
> delay slot and by setting EEAR to exception PC when handling illegal
> instruction exceptions.
> 
> After this patch the openrisc kernel with latest patches boots great on
> qemu and instruction emulation works.
> 
> Cc: qemu-trivial@nongnu.org
> Cc: openrisc@lists.librecores.org
> Signed-off-by: Stafford Horne <shorne@gmail.com>
> ---
>  target/openrisc/interrupt.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/target/openrisc/interrupt.c b/target/openrisc/interrupt.c
> index 5fe3f11..e1b0142 100644
> --- a/target/openrisc/interrupt.c
> +++ b/target/openrisc/interrupt.c
> @@ -38,10 +38,17 @@ void openrisc_cpu_do_interrupt(CPUState *cs)
>          env->flags &= ~D_FLAG;
>          env->sr |= SR_DSX;
>          env->epcr -= 4;
> +    } else {
> +        env->sr &= ~SR_DSX;
>      }
>      if (cs->exception_index == EXCP_SYSCALL) {
>          env->epcr += 4;
>      }
> +    /* When we have an illegal instruction the error effective address
> +       shall be set to the illegal instruction address.  */
> +    if (cs->exception_index == EXCP_ILLEGAL) {
> +        env->eear = env->pc;
> +    }
>  
>      /* For machine-state changed between user-mode and supervisor mode,
>         we need flush TLB when we enter&exit EXCP.  */
> -- 
> 2.9.3
>