| Message ID | 1470760554-129111-2-git-send-email-thgarnie@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, Aug 09, 2016 at 09:35:54AM -0700, Thomas Garnier wrote: > Default implementation expects 6 pages maximum are needed for low page > allocations. If KASLR memory randomization is enabled, the worse case > of e820 layout would require 12 pages (no large pages). It is due to the > PUD level randomization and the variable e820 memory layout. > > This bug was found while doing extensive testing of KASLR memory > randomization on different type of hardware. > > Fixes: 021182e52fe0 ("Enable KASLR for physical mapping memory regions") > Signed-off-by: Thomas Garnier <thgarnie@google.com> > --- > Based on next-20160805 > --- > arch/x86/mm/init.c | 14 ++++++++++++-- > 1 file changed, 12 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c > index 6209289..796e7af 100644 > --- a/arch/x86/mm/init.c > +++ b/arch/x86/mm/init.c > @@ -122,8 +122,18 @@ __ref void *alloc_low_pages(unsigned int num) > return __va(pfn << PAGE_SHIFT); > } > > -/* need 3 4k for initial PMD_SIZE, 3 4k for 0-ISA_END_ADDRESS */ > -#define INIT_PGT_BUF_SIZE (6 * PAGE_SIZE) > +/* > + * By default need 3 4k for initial PMD_SIZE, 3 4k for 0-ISA_END_ADDRESS. > + * With KASLR memory randomization, depending on the machine e860 memory layout > + * and the PUD alignement. We may need twice more pages when KASLR memoy > + * randomization is enabled. Can you please integrate all review feedback before you send your next versions? There's no "e860" thing and s/memoy/memory/ and s/alignement/alignment/ IOW, just integrate a spellchecker into your workflow. Thanks.
On Tue, Aug 9, 2016 at 9:54 AM, Borislav Petkov <bp@suse.de> wrote: > On Tue, Aug 09, 2016 at 09:35:54AM -0700, Thomas Garnier wrote: >> Default implementation expects 6 pages maximum are needed for low page >> allocations. If KASLR memory randomization is enabled, the worse case >> of e820 layout would require 12 pages (no large pages). It is due to the >> PUD level randomization and the variable e820 memory layout. >> >> This bug was found while doing extensive testing of KASLR memory >> randomization on different type of hardware. >> >> Fixes: 021182e52fe0 ("Enable KASLR for physical mapping memory regions") >> Signed-off-by: Thomas Garnier <thgarnie@google.com> >> --- >> Based on next-20160805 >> --- >> arch/x86/mm/init.c | 14 ++++++++++++-- >> 1 file changed, 12 insertions(+), 2 deletions(-) >> >> diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c >> index 6209289..796e7af 100644 >> --- a/arch/x86/mm/init.c >> +++ b/arch/x86/mm/init.c >> @@ -122,8 +122,18 @@ __ref void *alloc_low_pages(unsigned int num) >> return __va(pfn << PAGE_SHIFT); >> } >> >> -/* need 3 4k for initial PMD_SIZE, 3 4k for 0-ISA_END_ADDRESS */ >> -#define INIT_PGT_BUF_SIZE (6 * PAGE_SIZE) >> +/* >> + * By default need 3 4k for initial PMD_SIZE, 3 4k for 0-ISA_END_ADDRESS. >> + * With KASLR memory randomization, depending on the machine e860 memory layout >> + * and the PUD alignement. We may need twice more pages when KASLR memoy >> + * randomization is enabled. > > Can you please integrate all review feedback before you send your next > versions? > > There's no "e860" thing and > s/memoy/memory/ and > s/alignement/alignment/ > > IOW, just integrate a spellchecker into your workflow. Will do, thanks. > > Thanks. > > -- > Regards/Gruss, > Boris. > > ECO tip #101: Trim your mails when you reply. > > SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg) > --
diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c index 6209289..796e7af 100644 --- a/arch/x86/mm/init.c +++ b/arch/x86/mm/init.c @@ -122,8 +122,18 @@ __ref void *alloc_low_pages(unsigned int num) return __va(pfn << PAGE_SHIFT); } -/* need 3 4k for initial PMD_SIZE, 3 4k for 0-ISA_END_ADDRESS */ -#define INIT_PGT_BUF_SIZE (6 * PAGE_SIZE) +/* + * By default need 3 4k for initial PMD_SIZE, 3 4k for 0-ISA_END_ADDRESS. + * With KASLR memory randomization, depending on the machine e860 memory layout + * and the PUD alignement. We may need twice more pages when KASLR memoy + * randomization is enabled. + */ +#ifndef CONFIG_RANDOMIZE_MEMORY +#define INIT_PGD_PAGE_COUNT 6 +#else +#define INIT_PGD_PAGE_COUNT 12 +#endif +#define INIT_PGT_BUF_SIZE (INIT_PGD_PAGE_COUNT * PAGE_SIZE) RESERVE_BRK(early_pgt_alloc, INIT_PGT_BUF_SIZE); void __init early_alloc_pgt_buf(void) {
Default implementation expects 6 pages maximum are needed for low page allocations. If KASLR memory randomization is enabled, the worse case of e820 layout would require 12 pages (no large pages). It is due to the PUD level randomization and the variable e820 memory layout. This bug was found while doing extensive testing of KASLR memory randomization on different type of hardware. Fixes: 021182e52fe0 ("Enable KASLR for physical mapping memory regions") Signed-off-by: Thomas Garnier <thgarnie@google.com> --- Based on next-20160805 --- arch/x86/mm/init.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-)