[v2] target/hppa qemu v8.2 regression fixes

[PATCH v2 8/9] target/hppa: Avoid accessing %gr0 when raising exception

Posted by deller@kernel.org 10 months, 3 weeks ago

From: Helge Deller <deller@gmx.de>

The value of unwind_breg may reference register %r0, but we need to avoid
accessing gr0 directly and use the value 0 instead.

At runtime I've seen unwind_breg being zero with the Linux kernel when
rfi is used to jump to smp_callin().

Signed-off-by: Helge Deller <deller@gmx.de>
---
 target/hppa/mem_helper.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/target/hppa/mem_helper.c b/target/hppa/mem_helper.c
index 011b192406..42bd0063c0 100644
--- a/target/hppa/mem_helper.c
+++ b/target/hppa/mem_helper.c
@@ -335,7 +335,7 @@ raise_exception_with_ior(CPUHPPAState *env, int excp, uintptr_t retaddr,
 
                 cpu_restore_state(cs, retaddr);
 
-                b = env->gr[env->unwind_breg];
+                b = env->unwind_breg ? env->gr[env->unwind_breg] : 0;
                 b >>= (env->psw & PSW_W ? 62 : 30);
                 env->cr[CR_IOR] |= b << 62;
 
-- 
2.43.0

Re: [PATCH v2 8/9] target/hppa: Avoid accessing %gr0 when raising exception

Posted by Richard Henderson 10 months, 3 weeks ago

On 1/8/24 00:22, deller@kernel.org wrote:
> From: Helge Deller <deller@gmx.de>
> 
> The value of unwind_breg may reference register %r0, but we need to avoid
> accessing gr0 directly and use the value 0 instead.
> 
> At runtime I've seen unwind_breg being zero with the Linux kernel when
> rfi is used to jump to smp_callin().
> 
> Signed-off-by: Helge Deller <deller@gmx.de>
> ---
>   target/hppa/mem_helper.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/target/hppa/mem_helper.c b/target/hppa/mem_helper.c
> index 011b192406..42bd0063c0 100644
> --- a/target/hppa/mem_helper.c
> +++ b/target/hppa/mem_helper.c
> @@ -335,7 +335,7 @@ raise_exception_with_ior(CPUHPPAState *env, int excp, uintptr_t retaddr,
>   
>                   cpu_restore_state(cs, retaddr);
>   
> -                b = env->gr[env->unwind_breg];
> +                b = env->unwind_breg ? env->gr[env->unwind_breg] : 0;
>                   b >>= (env->psw & PSW_W ? 62 : 30);
>                   env->cr[CR_IOR] |= b << 62;
>   

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>


r~