lkml.org 
[lkml]   [2019]   [Jan]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [RFC PATCH v7 07/16] arm64/mm, xpfo: temporarily map dcache regions
    On Thu, Jan 10, 2019 at 02:09:39PM -0700, Khalid Aziz wrote:
    > From: Juerg Haefliger <juerg.haefliger@canonical.com>
    >
    > If the page is unmapped by XPFO, a data cache flush results in a fatal
    > page fault, so let's temporarily map the region, flush the cache, and then
    > unmap it.
    >
    > v6: actually flush in the face of xpfo, and temporarily map the underlying
    > memory so it can be flushed correctly
    >
    > CC: linux-arm-kernel@lists.infradead.org
    > Signed-off-by: Juerg Haefliger <juerg.haefliger@canonical.com>
    > Signed-off-by: Tycho Andersen <tycho@docker.com>
    > Signed-off-by: Khalid Aziz <khalid.aziz@oracle.com>
    > ---
    > arch/arm64/mm/flush.c | 7 +++++++
    > 1 file changed, 7 insertions(+)
    >
    > diff --git a/arch/arm64/mm/flush.c b/arch/arm64/mm/flush.c
    > index 30695a868107..f12f26b60319 100644
    > --- a/arch/arm64/mm/flush.c
    > +++ b/arch/arm64/mm/flush.c
    > @@ -20,6 +20,7 @@
    > #include <linux/export.h>
    > #include <linux/mm.h>
    > #include <linux/pagemap.h>
    > +#include <linux/xpfo.h>
    >
    > #include <asm/cacheflush.h>
    > #include <asm/cache.h>
    > @@ -28,9 +29,15 @@
    > void sync_icache_aliases(void *kaddr, unsigned long len)
    > {
    > unsigned long addr = (unsigned long)kaddr;
    > + unsigned long num_pages = XPFO_NUM_PAGES(addr, len);

    Is it possible that the 'len' is more than 32 pages? Or say 1000's
    of pages? Which would blow away your stack.

    > + void *mapping[num_pages];
    >
    > if (icache_is_aliasing()) {
    > + xpfo_temp_map(kaddr, len, mapping,
    > + sizeof(mapping[0]) * num_pages);
    > __clean_dcache_area_pou(kaddr, len);
    > + xpfo_temp_unmap(kaddr, len, mapping,
    > + sizeof(mapping[0]) * num_pages);
    > __flush_icache_all();
    > } else {
    > flush_icache_range(addr, addr + len);
    > --
    > 2.17.1
    >

    \
     
     \ /
      Last update: 2019-01-23 15:58    [W:3.558 / U:1.192 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site