| Message ID | 20170815163036.GJ6090@leverpostej (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, Aug 15, 2017 at 9:30 AM, Mark Rutland <mark.rutland@arm.com> wrote: > On Tue, Aug 15, 2017 at 09:09:36AM -0700, Andy Lutomirski wrote: >> On Tue, Aug 15, 2017 at 5:50 AM, Mark Rutland <mark.rutland@arm.com> wrote: >> > In some cases, an architecture might wish its stacks to be aligned to a >> > boundary larger than THREAD_SIZE. For example, using an alignment of >> > double THREAD_SIZE can allow for stack overflows smaller than >> > THREAD_SIZE to be detected by checking a single bit of the stack >> > pointer. >> > >> > This patch allows architectures to override the alignment of VMAP'd >> > stacks, by defining THREAD_ALIGN. Where not defined, this defaults to >> > THREAD_SIZE, as is the case today. >> >> This looks okay, but it might make sense to move that to a header file >> so THREAD_ALIGN is always available. > > I was a little worried about breaking things, since arches don't define > THREAD_SIZE in a consistent location. > > Looking again, it looks like those are all transitiviely included into > each arch's <asm/thread_info.h>, so I think I can move this into > <linux/thread_info.h>, which'll have to be added to kernel.fork.c's > includes. > > Are you happy with the below fixup? LGTM. > > Thanks, > Mark. > > ---->8---- > diff --git a/include/linux/thread_info.h b/include/linux/thread_info.h > index 250a276..905d769 100644 > --- a/include/linux/thread_info.h > +++ b/include/linux/thread_info.h > @@ -38,6 +38,10 @@ enum { > > #ifdef __KERNEL__ > > +#ifndef THREAD_ALIGN > +#define THREAD_ALIGN THREAD_SIZE > +#endif > + > #ifdef CONFIG_DEBUG_STACK_USAGE > # define THREADINFO_GFP (GFP_KERNEL_ACCOUNT | __GFP_NOTRACK | \ > __GFP_ZERO) > diff --git a/kernel/fork.c b/kernel/fork.c > index 696d692..f12882a 100644 > --- a/kernel/fork.c > +++ b/kernel/fork.c > @@ -88,6 +88,7 @@ > #include <linux/sysctl.h> > #include <linux/kcov.h> > #include <linux/livepatch.h> > +#include <linux/thread_info.h> > > #include <asm/pgtable.h> > #include <asm/pgalloc.h> > @@ -217,9 +218,6 @@ static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, int node) > return s->addr; > } > > -#ifndef THREAD_ALIGN > -#define THREAD_ALIGN THREAD_SIZE > -#endif > stack = __vmalloc_node_range(THREAD_SIZE, THREAD_ALIGN, > VMALLOC_START, VMALLOC_END, > THREADINFO_GFP, >
On Tue, Aug 15, 2017 at 09:33:18AM -0700, Andy Lutomirski wrote: > On Tue, Aug 15, 2017 at 9:30 AM, Mark Rutland <mark.rutland@arm.com> wrote: > > On Tue, Aug 15, 2017 at 09:09:36AM -0700, Andy Lutomirski wrote: > >> This looks okay, but it might make sense to move that to a header file > >> so THREAD_ALIGN is always available. > > > > I was a little worried about breaking things, since arches don't define > > THREAD_SIZE in a consistent location. > > > > Looking again, it looks like those are all transitiviely included into > > each arch's <asm/thread_info.h>, so I think I can move this into > > <linux/thread_info.h>, which'll have to be added to kernel.fork.c's > > includes. > > > > Are you happy with the below fixup? > > LGTM. Cool. I've folded that in and pushed the updated branch. Thanks, Mark.
On Tue, Aug 15, 2017 at 05:39:55PM +0100, Mark Rutland wrote: > On Tue, Aug 15, 2017 at 09:33:18AM -0700, Andy Lutomirski wrote: > > On Tue, Aug 15, 2017 at 9:30 AM, Mark Rutland <mark.rutland@arm.com> wrote: > > > On Tue, Aug 15, 2017 at 09:09:36AM -0700, Andy Lutomirski wrote: > > > >> This looks okay, but it might make sense to move that to a header file > > >> so THREAD_ALIGN is always available. > > > > > > I was a little worried about breaking things, since arches don't define > > > THREAD_SIZE in a consistent location. > > > > > > Looking again, it looks like those are all transitiviely included into > > > each arch's <asm/thread_info.h>, so I think I can move this into > > > <linux/thread_info.h>, which'll have to be added to kernel.fork.c's > > > includes. > > > > > > Are you happy with the below fixup? > > > > LGTM. > > Cool. I've folded that in and pushed the updated branch. I pulled the branch for 4.14. Thanks.
diff --git a/include/linux/thread_info.h b/include/linux/thread_info.h index 250a276..905d769 100644 --- a/include/linux/thread_info.h +++ b/include/linux/thread_info.h @@ -38,6 +38,10 @@ enum { #ifdef __KERNEL__ +#ifndef THREAD_ALIGN +#define THREAD_ALIGN THREAD_SIZE +#endif + #ifdef CONFIG_DEBUG_STACK_USAGE # define THREADINFO_GFP (GFP_KERNEL_ACCOUNT | __GFP_NOTRACK | \ __GFP_ZERO) diff --git a/kernel/fork.c b/kernel/fork.c index 696d692..f12882a 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -88,6 +88,7 @@ #include <linux/sysctl.h> #include <linux/kcov.h> #include <linux/livepatch.h> +#include <linux/thread_info.h> #include <asm/pgtable.h> #include <asm/pgalloc.h> @@ -217,9 +218,6 @@ static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, int node) return s->addr; } -#ifndef THREAD_ALIGN -#define THREAD_ALIGN THREAD_SIZE -#endif stack = __vmalloc_node_range(THREAD_SIZE, THREAD_ALIGN, VMALLOC_START, VMALLOC_END, THREADINFO_GFP,