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Re: [PATCH] target/s390x/tcg: SPX: check validity of new prefix
From: |
David Hildenbrand |
Subject: |
Re: [PATCH] target/s390x/tcg: SPX: check validity of new prefix |
Date: |
Mon, 27 Jun 2022 18:27:11 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.9.0 |
On 27.06.22 15:12, Janis Schoetterl-Glausch wrote:
> According to the architecture, SET PREFIX must try to access the new
> prefix area and recognize an addressing exception if the area is not
> accessible.
> For qemu this check prevents a crash in cpu_map_lowcore after an
> inaccessible prefix area has been set.
I don't think that's possible. Our memory increments are 1 MiB and one
would have to cross a 1~MiB range with the second page to trigger that.
IIRC that's impossible with SPX address alignment requirements?
>
> Signed-off-by: Janis Schoetterl-Glausch <scgl@linux.ibm.com>
> ---
>
>
> Is there a stricter check to see if the memory is accessible?
>
>
> target/s390x/tcg/misc_helper.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/target/s390x/tcg/misc_helper.c b/target/s390x/tcg/misc_helper.c
> index aab9c47747..c8447b36fc 100644
> --- a/target/s390x/tcg/misc_helper.c
> +++ b/target/s390x/tcg/misc_helper.c
> @@ -158,6 +158,10 @@ void HELPER(spx)(CPUS390XState *env, uint64_t a1)
> if (prefix == old_prefix) {
> return;
> }
> + if (!mmu_absolute_addr_valid(prefix, true) ||
> + !mmu_absolute_addr_valid(prefix + TARGET_PAGE_SIZE, true)) {
> + tcg_s390_program_interrupt(env, PGM_ADDRESSING, GETPC());
> + }
>
> env->psa = prefix;
> HELPER_LOG("prefix: %#x\n", prefix);
>
> base-commit: 3a821c52e1a30ecd9a436f2c67cc66b5628c829f
--
Thanks,
David / dhildenb