Messages in this thread | | | Date | Mon, 24 Sep 2018 15:03:38 +0100 | From | Mark Rutland <> | Subject | Re: [PATCH v5 1/6] arm64/mm: Introduce the init_pg_dir. |
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On Mon, Sep 24, 2018 at 02:01:37PM +0100, Mark Rutland wrote: > On Mon, Sep 17, 2018 at 12:43:28PM +0800, Jun Yao wrote: > > To make the swapper_pg_dir read only, we will move it to the rodata > > section. And force the kernel to set up the initial page table in > > the init_pg_dir. After generating all levels page table, we copy > > only the top level into the swapper_pg_dir during paging_init().
> > +#define INIT_PG_TABLES \ > > + . = ALIGN(PAGE_SIZE); \ > > + init_pg_dir = .; \ > > + . += SWAPPER_DIR_SIZE; \ > > + init_pg_end = .; > > This will allocate a full set of PGD + PUD + PMD (+ PTE) levels, but the > commit message says we only copy the top level table. > > The memory for otjher levels of table can be re-allocated once the > kernel init phase is over, so that seems a bit worrying. > > Do we switch over to new copies of those levels, or do we continue using > the entries from INIT_PG_TABLES?
I now see that we already allocate copies of those levels of table (and free the originals in paging_init), so this is not a problem.
Sorry for the noise!
Mark.
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