diff mbox series

[kvm-unit-tests,v3,03/13] powerpc: Add some checking to exception handler install

Message ID 20230327124520.2707537-4-npiggin@gmail.com (mailing list archive)
State New, archived
Headers show
Series powerpc: updates, P10, PNV support | expand

Commit Message

Nicholas Piggin March 27, 2023, 12:45 p.m. UTC
Check to ensure exception handlers are not being overwritten or
invalid exception numbers are used.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
Since v2:
- New patch

 lib/powerpc/processor.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

Comments

Thomas Huth March 27, 2023, 2:39 p.m. UTC | #1
On 27/03/2023 14.45, Nicholas Piggin wrote:
> Check to ensure exception handlers are not being overwritten or
> invalid exception numbers are used.
> 
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
> ---
> Since v2:
> - New patch
> 
>   lib/powerpc/processor.c | 12 ++++++++++++
>   1 file changed, 12 insertions(+)
> 
> diff --git a/lib/powerpc/processor.c b/lib/powerpc/processor.c
> index ec85b9d..70391aa 100644
> --- a/lib/powerpc/processor.c
> +++ b/lib/powerpc/processor.c
> @@ -19,11 +19,23 @@ static struct {
>   void handle_exception(int trap, void (*func)(struct pt_regs *, void *),
>   		      void * data)
>   {
> +	if (trap & 0xff) {

You could check for the other "invalid exception handler" condition here 
already, i.e. if (trap & ~0xf00) ...

I'd maybe simply do an "assert(!(trap & ~0xf00))" here.

> +		printf("invalid exception handler %#x\n", trap);
> +		abort();
> +	}
> +
>   	trap >>= 8;
>   
>   	if (trap < 16) {

... then you could get rid of the if-statement here and remove one level of 
indentation in the code below.

> +		if (func && handlers[trap].func) {
> +			printf("exception handler installed twice %#x\n", trap);
> +			abort();
> +		}
>   		handlers[trap].func = func;
>   		handlers[trap].data = data;
> +	} else {
> +		printf("invalid exception handler %#x\n", trap);
> +		abort();
>   	}
>   }
>   

  Thomas
Nicholas Piggin March 28, 2023, 6:53 a.m. UTC | #2
On Tue Mar 28, 2023 at 12:39 AM AEST, Thomas Huth wrote:
> On 27/03/2023 14.45, Nicholas Piggin wrote:
> > Check to ensure exception handlers are not being overwritten or
> > invalid exception numbers are used.
> > 
> > Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
> > ---
> > Since v2:
> > - New patch
> > 
> >   lib/powerpc/processor.c | 12 ++++++++++++
> >   1 file changed, 12 insertions(+)
> > 
> > diff --git a/lib/powerpc/processor.c b/lib/powerpc/processor.c
> > index ec85b9d..70391aa 100644
> > --- a/lib/powerpc/processor.c
> > +++ b/lib/powerpc/processor.c
> > @@ -19,11 +19,23 @@ static struct {
> >   void handle_exception(int trap, void (*func)(struct pt_regs *, void *),
> >   		      void * data)
> >   {
> > +	if (trap & 0xff) {
>
> You could check for the other "invalid exception handler" condition here 
> already, i.e. if (trap & ~0xf00) ...
>
> I'd maybe simply do an "assert(!(trap & ~0xf00))" here.
>
> > +		printf("invalid exception handler %#x\n", trap);
> > +		abort();
> > +	}
> > +
> >   	trap >>= 8;
> >   
> >   	if (trap < 16) {
>
> ... then you could get rid of the if-statement here and remove one level of 
> indentation in the code below.

Yes that's the  way to do it. I feel embarrassed for not thinking
of it :)

Thanks,
Nick

>
> > +		if (func && handlers[trap].func) {
> > +			printf("exception handler installed twice %#x\n", trap);
> > +			abort();
> > +		}
> >   		handlers[trap].func = func;
> >   		handlers[trap].data = data;
> > +	} else {
> > +		printf("invalid exception handler %#x\n", trap);
> > +		abort();
> >   	}
> >   }
> >   
>
>   Thomas
diff mbox series

Patch

diff --git a/lib/powerpc/processor.c b/lib/powerpc/processor.c
index ec85b9d..70391aa 100644
--- a/lib/powerpc/processor.c
+++ b/lib/powerpc/processor.c
@@ -19,11 +19,23 @@  static struct {
 void handle_exception(int trap, void (*func)(struct pt_regs *, void *),
 		      void * data)
 {
+	if (trap & 0xff) {
+		printf("invalid exception handler %#x\n", trap);
+		abort();
+	}
+
 	trap >>= 8;
 
 	if (trap < 16) {
+		if (func && handlers[trap].func) {
+			printf("exception handler installed twice %#x\n", trap);
+			abort();
+		}
 		handlers[trap].func = func;
 		handlers[trap].data = data;
+	} else {
+		printf("invalid exception handler %#x\n", trap);
+		abort();
 	}
 }