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Re: [Qemu-devel] [PATCH v2 3/3] target-arm: get_phys_addr_lpae: more xn
From: |
Peter Maydell |
Subject: |
Re: [Qemu-devel] [PATCH v2 3/3] target-arm: get_phys_addr_lpae: more xn control |
Date: |
Wed, 11 Mar 2015 17:49:39 +0000 |
On 11 March 2015 at 17:42, Andrew Jones <address@hidden> wrote:
> On Wed, Mar 11, 2015 at 05:02:00PM +0000, Peter Maydell wrote:
>> > + if (is_aa64) {
>> > + switch (regime_el(env, mmu_idx)) {
>> > + case 1:
>> > + if (is_user && !user_rw) {
>> > + wxn = 0;
>>
>> I don't understand this. We ignore the WXN bit if this is
>> a user access and the page is not readable ?
>
> Yup. If the page is not readable or writeable, AP[1]=0. I almost
> submitted an errata to the ARM ARM when I saw this on the 2nd line
> of table D4-32. I thought it must be a typo. However I tested it
> on hardware, and it works this way. So at least the weirdness has
> been implemented consistently...
Still confused. If the page isn't readable or writable
then WXN isn't going to kick in anyway because WXN only
affects writable pages. I don't see what the case is
where this bit of code will make a difference.
-- PMM
- [Qemu-devel] [PATCH v2 0/3] tcg-arm: LPAE: fix and extend xn control, Andrew Jones, 2015/03/10
- [Qemu-devel] [PATCH v2 1/3] target-arm: convert check_ap to ap_to_rw_prot, Andrew Jones, 2015/03/10
- [Qemu-devel] [PATCH v2 2/3] target-arm: fix get_phys_addr_v6/SCTLR_AFE access check, Andrew Jones, 2015/03/10
- [Qemu-devel] [PATCH v2 3/3] target-arm: get_phys_addr_lpae: more xn control, Andrew Jones, 2015/03/10
- Re: [Qemu-devel] [PATCH v2 3/3] target-arm: get_phys_addr_lpae: more xn control, Peter Maydell, 2015/03/11
- Re: [Qemu-devel] [PATCH v2 3/3] target-arm: get_phys_addr_lpae: more xn control, Andrew Jones, 2015/03/11
- Re: [Qemu-devel] [PATCH v2 3/3] target-arm: get_phys_addr_lpae: more xn control,
Peter Maydell <=
- Re: [Qemu-devel] [PATCH v2 3/3] target-arm: get_phys_addr_lpae: more xn control, Andrew Jones, 2015/03/11
- Re: [Qemu-devel] [PATCH v2 3/3] target-arm: get_phys_addr_lpae: more xn control, Peter Maydell, 2015/03/11
- Re: [Qemu-devel] [PATCH v2 3/3] target-arm: get_phys_addr_lpae: more xn control, Andrew Jones, 2015/03/11
- Re: [Qemu-devel] [PATCH v2 3/3] target-arm: get_phys_addr_lpae: more xn control, Peter Maydell, 2015/03/11