From: Laurent Vivier <laurent@vivier.eu>
To: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>, qemu-devel@nongnu.org
Subject: Re: [PATCH v2 3/3] target/m68k: add M68K_FEATURE_UNALIGNED_DATA feature
Date: Tue, 9 Mar 2021 20:47:50 +0100 [thread overview]
Message-ID: <691abea3-7bd7-e0f6-5abe-d2742fd41a5f@vivier.eu> (raw)
In-Reply-To: <20210308121155.2476-4-mark.cave-ayland@ilande.co.uk>
Le 08/03/2021 à 13:11, Mark Cave-Ayland a écrit :
> According to the M68040UM Appendix D the requirement for data accesses to be
> word aligned is only for the 68000, 68008 and 68010 CPUs. Later CPUs from the
> 68020 onwards will allow unaligned data accesses but at the cost of being less
> efficient.
>
> Add a new M68K_FEATURE_UNALIGNED_DATA feature to specify that data accesses are
> not required to be word aligned, and don't perform the alignment on the stack
> pointer when taking an exception if this feature is not selected.
>
> This is required because the MacOS DAFB driver attempts to call an A-trap
> with a byte-aligned stack pointer during initialisation and without this the
> stack pointer is off by one when the A-trap returns.
>
> Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
> Reviewed-by: Laurent Vivier <laurent@vivier.eu>
> ---
> target/m68k/cpu.c | 1 +
> target/m68k/cpu.h | 2 ++
> target/m68k/op_helper.c | 5 ++++-
> 3 files changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/target/m68k/cpu.c b/target/m68k/cpu.c
> index 37d2ed9dc7..a14874b4da 100644
> --- a/target/m68k/cpu.c
> +++ b/target/m68k/cpu.c
> @@ -161,6 +161,7 @@ static void m68020_cpu_initfn(Object *obj)
> m68k_set_feature(env, M68K_FEATURE_CAS);
> m68k_set_feature(env, M68K_FEATURE_CHK2);
> m68k_set_feature(env, M68K_FEATURE_MSP);
> + m68k_set_feature(env, M68K_FEATURE_UNALIGNED_DATA);
> }
>
> /*
> diff --git a/target/m68k/cpu.h b/target/m68k/cpu.h
> index ce558e9b03..402c86c876 100644
> --- a/target/m68k/cpu.h
> +++ b/target/m68k/cpu.h
> @@ -527,6 +527,8 @@ enum m68k_features {
> M68K_FEATURE_MOVEP,
> /* MOVEC insn. (from 68010) */
> M68K_FEATURE_MOVEC,
> + /* Unaligned data accesses (680[2346]0) */
> + M68K_FEATURE_UNALIGNED_DATA,
> };
>
> static inline int m68k_feature(CPUM68KState *env, int feature)
> diff --git a/target/m68k/op_helper.c b/target/m68k/op_helper.c
> index 59a6448296..3fa7b7e19e 100644
> --- a/target/m68k/op_helper.c
> +++ b/target/m68k/op_helper.c
> @@ -348,7 +348,10 @@ static void m68k_interrupt_all(CPUM68KState *env, int is_hw)
> cpu_m68k_set_sr(env, sr);
> sp = env->aregs[7];
>
> - sp &= ~1;
> + if (!m68k_feature(env, M68K_FEATURE_UNALIGNED_DATA)) {
> + sp &= ~1;
> + }
> +
> if (cs->exception_index == EXCP_ACCESS) {
> if (env->mmu.fault) {
> cpu_abort(cs, "DOUBLE MMU FAULT\n");
>
Applied to my m68k-for-6.0 branch
Thanks,
Laurent
prev parent reply other threads:[~2021-03-09 20:26 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-08 12:11 [PATCH v2 0/3] target/m68k: MacOS related fixes Mark Cave-Ayland
2021-03-08 12:11 ` [PATCH v2 1/3] target/m68k: don't set SSW ATC bit for physical bus errors Mark Cave-Ayland
2021-03-09 19:46 ` Laurent Vivier
2021-03-08 12:11 ` [PATCH v2 2/3] target/m68k: reformat m68k_features enum Mark Cave-Ayland
2021-03-08 17:33 ` Laurent Vivier
2021-03-09 14:21 ` Richard Henderson
2021-03-09 19:46 ` Laurent Vivier
2021-03-08 12:11 ` [PATCH v2 3/3] target/m68k: add M68K_FEATURE_UNALIGNED_DATA feature Mark Cave-Ayland
2021-03-09 14:21 ` Richard Henderson
2021-03-09 19:47 ` Laurent Vivier [this message]
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