Messages in this thread | | | Date | Thu, 23 Mar 2023 12:52:36 +0100 | Subject | Re: [PATCH v8 2/4] mm: Introduce memblock_isolate_memory | From | Alexandre Ghiti <> |
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On 3/20/23 18:44, Mike Rapoport wrote: > On Mon, Mar 20, 2023 at 11:54:14AM +0100, Alexandre Ghiti wrote: >> Hi Mike, >> >> On 3/16/23 21:12, Mike Rapoport wrote: >>> Hi Alexandre, >>> >>> On Thu, Mar 16, 2023 at 02:17:09PM +0100, Alexandre Ghiti wrote: >>>> This function allows to split a region in memblock.memory and will be >>>> useful when setting up the linear mapping with STRICT_KERNEL_RWX: it >>>> allows to isolate the kernel text/rodata and then avoid to map those >>>> regions with a PUD/P4D/PGD. >>> Sorry I've missed it last time. The changelog is fine in the context of >> >> No worries :) >> >> >>> this series, but if you look at it as a part of memblock changelog it >>> doesn't provide enough background on why memblock_isolate_memory() is >>> useful. >>> >>> Can you please add more context so it would be self explanatory? >> >> What about: "memblock.memory contains the list of memory regions and a >> memory region can cover memory that will be mapped with different >> permissions. So to ease the mapping process, allow to isolate those regions >> by introducing a new function called memblock_isolate_memory. This will be >> used in arch specific code to isolate the kernel text/rodata regions when >> STRICT_KERNEL_RWX is enabled so that we avoid mapping them with PUD/P4D/PGD >> mappings." > With this change > > ... STRICT_KERNEL_RWX is enabled so that they can be mapped with base pages.
Actually they will get mapped with PMD mappings :) I'll just append: "or PMD mapping" to your sentence above if that's ok with you.
> > Acked-by: Mike Rapoport (IBM) <rppt@kernel.org>
Thanks for your review,
Alex
> >> Thanks, >> >> Alex >> >> >>>> Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com> >>>> Reviewed-by: Anup Patel <anup@brainfault.org> >>>> Tested-by: Anup Patel <anup@brainfault.org> >>>> --- >>>> include/linux/memblock.h | 1 + >>>> mm/memblock.c | 20 ++++++++++++++++++++ >>>> 2 files changed, 21 insertions(+) >>>> >>>> diff --git a/include/linux/memblock.h b/include/linux/memblock.h >>>> index 50ad19662a32..2f7ef97c0da7 100644 >>>> --- a/include/linux/memblock.h >>>> +++ b/include/linux/memblock.h >>>> @@ -125,6 +125,7 @@ int memblock_clear_hotplug(phys_addr_t base, phys_addr_t size); >>>> int memblock_mark_mirror(phys_addr_t base, phys_addr_t size); >>>> int memblock_mark_nomap(phys_addr_t base, phys_addr_t size); >>>> int memblock_clear_nomap(phys_addr_t base, phys_addr_t size); >>>> +int memblock_isolate_memory(phys_addr_t base, phys_addr_t size); >>>> void memblock_free_all(void); >>>> void memblock_free(void *ptr, size_t size); >>>> diff --git a/mm/memblock.c b/mm/memblock.c >>>> index 25fd0626a9e7..e8c651a37012 100644 >>>> --- a/mm/memblock.c >>>> +++ b/mm/memblock.c >>>> @@ -805,6 +805,26 @@ static int __init_memblock memblock_isolate_range(struct memblock_type *type, >>>> return 0; >>>> } >>>> +/** >>>> + * memblock_isolate_memory - isolate given range in memblock.memory >>>> + * @base: base of range to isolate >>>> + * @size: size of range to isolate >>>> + * >>>> + * Isolates the given range in memblock.memory so that it does not share any >>>> + * region with other ranges. >>>> + * >>>> + * Return: >>>> + * 0 on success, -errno on failure. >>>> + */ >>>> + >>>> +int __init_memblock memblock_isolate_memory(phys_addr_t base, phys_addr_t size) >>>> +{ >>>> + int start_rgn, end_rgn; >>>> + >>>> + return memblock_isolate_range(&memblock.memory, base, size, >>>> + &start_rgn, &end_rgn); >>>> +} >>>> + >>>> static int __init_memblock memblock_remove_range(struct memblock_type *type, >>>> phys_addr_t base, phys_addr_t size) >>>> { >>>> -- >>>> 2.37.2 >>>>
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