Hi Nathan, On Mon, Oct 14, 2019 at 7:55 AM Nathan Chancellor <natechancellor@xxxxxxxxx> wrote: > > On Sat, Oct 12, 2019 at 05:59:18PM +0530, Shyam Saini wrote: > > This parameters are not changed after early boot. > > By making them __ro_after_init will reduce any attack surface in the > > kernel. > > > > Link: https://lwn.net/Articles/676145/ > > Cc: Christoph Hellwig <hch@xxxxxx> > > Cc: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> > > Cc: Robin Murphy <robin.murphy@xxxxxxx> > > Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx> > > Cc: Christopher Lameter <cl@xxxxxxxxx> > > Cc: Kees Cook <keescook@xxxxxxxxxxxx> > > Signed-off-by: Shyam Saini <mayhs11saini@xxxxxxxxx> > > --- > > kernel/dma/contiguous.c | 8 ++++---- > > 1 file changed, 4 insertions(+), 4 deletions(-) > > > > diff --git a/kernel/dma/contiguous.c b/kernel/dma/contiguous.c > > index 69cfb4345388..1b689b1303cd 100644 > > --- a/kernel/dma/contiguous.c > > +++ b/kernel/dma/contiguous.c > > @@ -42,10 +42,10 @@ struct cma *dma_contiguous_default_area; > > * Users, who want to set the size of global CMA area for their system > > * should use cma= kernel parameter. > > */ > > -static const phys_addr_t size_bytes = (phys_addr_t)CMA_SIZE_MBYTES * SZ_1M; > > -static phys_addr_t size_cmdline = -1; > > -static phys_addr_t base_cmdline; > > -static phys_addr_t limit_cmdline; > > +static const phys_addr_t __ro_after_init size_bytes = (phys_addr_t)CMA_SIZE_MBYTES * SZ_1M; > > The 0day bot reported an issue with this change with clang: > > https://groups.google.com/d/msgid/clang-built-linux/201910140334.nhultlt8%25lkp%40intel.com > > kernel/dma/contiguous.c:46:36: error: 'size_cmdline' causes a section type conflict with 'size_bytes' > static phys_addr_t __ro_after_init size_cmdline = -1; > ^ > kernel/dma/contiguous.c:45:42: note: declared here > static const phys_addr_t __ro_after_init size_bytes = (phys_addr_t)CMA_SIZE_MBYTES * SZ_1M; > ^ > kernel/dma/contiguous.c:47:36: error: 'base_cmdline' causes a section type conflict with 'size_bytes' > static phys_addr_t __ro_after_init base_cmdline; > ^ > kernel/dma/contiguous.c:45:42: note: declared here > static const phys_addr_t __ro_after_init size_bytes = (phys_addr_t)CMA_SIZE_MBYTES * SZ_1M; > ^ > kernel/dma/contiguous.c:48:36: error: 'limit_cmdline' causes a section type conflict with 'size_bytes' > static phys_addr_t __ro_after_init limit_cmdline; > ^ > kernel/dma/contiguous.c:45:42: note: declared here > static const phys_addr_t __ro_after_init size_bytes = (phys_addr_t)CMA_SIZE_MBYTES * SZ_1M; > ^ > 3 errors generated. Thanks for your feedback and reporting this error. > The errors seem kind of cryptic at first but something that is const > should automatically be in the read only section, this part of the > commit seems unnecessary. Removing that part of the change fixes the error. I have overlooked size_bytes variable It shouldn't be const if it is declared as __ro_after_init. I will fix and resend it.
