Re: [PATCH 10/21] target/m68k: Initialize float_status fields in gdb set/get functions

[Philippe Mathieu-Daudé]

On 25/10/24 11:12, Peter Maydell wrote:
> In cf_fpu_gdb_get_reg() and cf_fpu_gdb_set_reg() we use a temporary
> float_status variable to pass to floatx80_to_float64() and
> float64_to_floatx80(), but we don't initialize it, meaning that those
> functions could access uninitialized data.  Zero-init the structs.
>
> (We don't need to set a NaN-propagation rule here because we
> don't use these with a 2-argument fpu operation.)
>
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
> Spotted by code-inspection while I was doing the 2-NaN propagation
> patches.
> ---
>   target/m68k/helper.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/target/m68k/helper.c b/target/m68k/helper.c
> index 9d3db8419de..9bfc6ae97c0 100644
> --- a/target/m68k/helper.c
> +++ b/target/m68k/helper.c
> @@ -36,7 +36,7 @@ static int cf_fpu_gdb_get_reg(CPUState *cs, GByteArray 
> *mem_buf, int n)
>       CPUM68KState *env = &cpu->env;
>   
>       if (n < 8) {
> -        float_status s;
> +        float_status s = {};
>           return gdb_get_reg64(mem_buf, floatx80_to_float64(env->fregs[n].d, 
> &s));

While here, could be renamed as 'discard' like SPARC. Regardless:

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>

>       }
>       switch (n) {
> @@ -56,7 +56,7 @@ static int cf_fpu_gdb_set_reg(CPUState *cs, uint8_t *mem_buf, 
> int n)
>       CPUM68KState *env = &cpu->env;
>   
>       if (n < 8) {
> -        float_status s;
> +        float_status s = {};
>           env->fregs[n].d = float64_to_floatx80(ldq_be_p(mem_buf), &s);
>           return 8;
>       }