target/m68k: fix two writes to %sr

[PATCH 2/2] target/m68k: Perform writback before modifying SR

Posted by Richard Henderson 3 years, 4 months ago

Writes to SR may change security state, which may involve
a swap of %ssp with %usp as reflected in %a7.  Finish the
writeback of %sp@+ before swapping stack pointers.

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1206
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 target/m68k/translate.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/target/m68k/translate.c b/target/m68k/translate.c
index 87044382c3..8506da0a0b 100644
--- a/target/m68k/translate.c
+++ b/target/m68k/translate.c
@@ -2285,9 +2285,9 @@ static void gen_set_sr_im(DisasContext *s, uint16_t val, int ccr_only)
         tcg_gen_movi_i32(QREG_CC_N, val & CCF_N ? -1 : 0);
         tcg_gen_movi_i32(QREG_CC_X, val & CCF_X ? 1 : 0);
     } else {
-        TCGv sr = tcg_const_i32(val);
-        gen_helper_set_sr(cpu_env, sr);
-        tcg_temp_free(sr);
+        /* Must writeback before changing security state. */
+        do_writebacks(s);
+        gen_helper_set_sr(cpu_env, tcg_constant_i32(val));
     }
     set_cc_op(s, CC_OP_FLAGS);
 }
@@ -2297,6 +2297,8 @@ static void gen_set_sr(DisasContext *s, TCGv val, int ccr_only)
     if (ccr_only) {
         gen_helper_set_ccr(cpu_env, val);
     } else {
+        /* Must writeback before changing security state. */
+        do_writebacks(s);
         gen_helper_set_sr(cpu_env, val);
     }
     set_cc_op(s, CC_OP_FLAGS);
-- 
2.34.1

Re: [PATCH 2/2] target/m68k: Perform writback before modifying SR

Posted by Laurent Vivier 3 years, 4 months ago

Le 13/09/2022 à 16:28, Richard Henderson a écrit :
> Writes to SR may change security state, which may involve
> a swap of %ssp with %usp as reflected in %a7.  Finish the
> writeback of %sp@+ before swapping stack pointers.
> 
> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1206
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>   target/m68k/translate.c | 8 +++++---
>   1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/target/m68k/translate.c b/target/m68k/translate.c
> index 87044382c3..8506da0a0b 100644
> --- a/target/m68k/translate.c
> +++ b/target/m68k/translate.c
> @@ -2285,9 +2285,9 @@ static void gen_set_sr_im(DisasContext *s, uint16_t val, int ccr_only)
>           tcg_gen_movi_i32(QREG_CC_N, val & CCF_N ? -1 : 0);
>           tcg_gen_movi_i32(QREG_CC_X, val & CCF_X ? 1 : 0);
>       } else {
> -        TCGv sr = tcg_const_i32(val);
> -        gen_helper_set_sr(cpu_env, sr);
> -        tcg_temp_free(sr);
> +        /* Must writeback before changing security state. */
> +        do_writebacks(s);
> +        gen_helper_set_sr(cpu_env, tcg_constant_i32(val));
>       }
>       set_cc_op(s, CC_OP_FLAGS);
>   }
> @@ -2297,6 +2297,8 @@ static void gen_set_sr(DisasContext *s, TCGv val, int ccr_only)
>       if (ccr_only) {
>           gen_helper_set_ccr(cpu_env, val);
>       } else {
> +        /* Must writeback before changing security state. */
> +        do_writebacks(s);
>           gen_helper_set_sr(cpu_env, val);
>       }
>       set_cc_op(s, CC_OP_FLAGS);

Applied to my m68k-for-7.2 branch

Thanks,
Laurent

Re: [PATCH 2/2] target/m68k: Perform writback before modifying SR

Posted by Mark Cave-Ayland 3 years, 4 months ago

On 13/09/2022 15:28, Richard Henderson wrote:

> Writes to SR may change security state, which may involve
> a swap of %ssp with %usp as reflected in %a7.  Finish the
> writeback of %sp@+ before swapping stack pointers.
> 
> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1206
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>   target/m68k/translate.c | 8 +++++---
>   1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/target/m68k/translate.c b/target/m68k/translate.c
> index 87044382c3..8506da0a0b 100644
> --- a/target/m68k/translate.c
> +++ b/target/m68k/translate.c
> @@ -2285,9 +2285,9 @@ static void gen_set_sr_im(DisasContext *s, uint16_t val, int ccr_only)
>           tcg_gen_movi_i32(QREG_CC_N, val & CCF_N ? -1 : 0);
>           tcg_gen_movi_i32(QREG_CC_X, val & CCF_X ? 1 : 0);
>       } else {
> -        TCGv sr = tcg_const_i32(val);
> -        gen_helper_set_sr(cpu_env, sr);
> -        tcg_temp_free(sr);
> +        /* Must writeback before changing security state. */
> +        do_writebacks(s);
> +        gen_helper_set_sr(cpu_env, tcg_constant_i32(val));
>       }
>       set_cc_op(s, CC_OP_FLAGS);
>   }
> @@ -2297,6 +2297,8 @@ static void gen_set_sr(DisasContext *s, TCGv val, int ccr_only)
>       if (ccr_only) {
>           gen_helper_set_ccr(cpu_env, val);
>       } else {
> +        /* Must writeback before changing security state. */
> +        do_writebacks(s);
>           gen_helper_set_sr(cpu_env, val);
>       }
>       set_cc_op(s, CC_OP_FLAGS);

Thanks Richard! Subject needs s/writback/writeback/ but anyhow:

Reviewed-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>


ATB,

Mark.

Re: [PATCH 2/2] target/m68k: Perform writback before modifying SR

Posted by Laurent Vivier 3 years, 4 months ago

Le 13/09/2022 à 16:28, Richard Henderson a écrit :
> Writes to SR may change security state, which may involve
> a swap of %ssp with %usp as reflected in %a7.  Finish the
> writeback of %sp@+ before swapping stack pointers.
> 
> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1206
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>   target/m68k/translate.c | 8 +++++---
>   1 file changed, 5 insertions(+), 3 deletions(-)
> 

Reviewed-by: Laurent Vivier <laurent@vivier.eu>