Messages in this thread | | | Date | Mon, 20 Mar 2023 11:54:14 +0100 | Subject | Re: [PATCH v8 2/4] mm: Introduce memblock_isolate_memory | From | Alexandre Ghiti <> |
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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."
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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