On Thu, Feb 03, 2022 at 07:05:13AM +0000, Christophe Leroy wrote:
>
>
> Le 03/02/2022 à 01:01, Luis Chamberlain a écrit :
> > On Sat, Jan 29, 2022 at 05:02:09PM +0000, Christophe Leroy wrote:
> >> diff --git a/kernel/module.c b/kernel/module.c
> >> index 11f51e17fb9f..f3758115ebaa 100644
> >> --- a/kernel/module.c
> >> +++ b/kernel/module.c
> >> @@ -81,7 +81,9 @@
> >> /* If this is set, the section belongs in the init part of the module */
> >> #define INIT_OFFSET_MASK (1UL << (BITS_PER_LONG-1))
> >>
> >> +#ifndef CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
> >> #define data_layout core_layout
> >> +#endif
> >>
> >> /*
> >> * Mutex protects:
> >> @@ -111,6 +113,12 @@ static struct mod_tree_root {
> >> #define module_addr_min mod_tree.addr_min
> >> #define module_addr_max mod_tree.addr_max
> >>
> >> +#ifdef CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
> >> +static struct mod_tree_root mod_data_tree __cacheline_aligned = {
> >> + .addr_min = -1UL,
> >> +};
> >> +#endif
> >> +
> >> #ifdef CONFIG_MODULES_TREE_LOOKUP
> >>
> >> /*
> >> @@ -186,6 +194,11 @@ static void mod_tree_insert(struct module *mod)
> >> __mod_tree_insert(&mod->core_layout.mtn, &mod_tree);
> >> if (mod->init_layout.size)
> >> __mod_tree_insert(&mod->init_layout.mtn, &mod_tree);
> >> +
> >> +#ifdef CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
> >> + mod->data_layout.mtn.mod = mod;
> >> + __mod_tree_insert(&mod->data_layout.mtn, &mod_data_tree);
> >> +#endif
> >
> >
> > kernel/ directory has quite a few files, module.c is the second to
> > largest file, and it has tons of stuff. Aaron is doing work to
> > split things out to make code easier to read and so that its easier
> > to review changes. See:
> >
> > https://lkml.kernel.org/r/20220130213214.1042497-1-atomlin@xxxxxxxxxx
> >
> > I think this is a good patch example which could benefit from that work.
> > So I'd much prefer to see that work go in first than this, so to see if
> > we can make the below changes more compartamentalized.
> >
> > Curious, how much testing has been put into this series?
>
>
> I tested the change up to (including) patch 4 to verify it doesn't
> introduce regression when not using
> CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC,
> Then I tested with patch 5. I first tried with the 'hello world' test
> module. After that I loaded several important modules and checked I
> didn't get any regression, both with and without STRICT_MODULES_RWX and
> I checked the consistency in /proc/vmallocinfo
> /proc/modules /sys/class/modules/*
I wonder if we have a test for STRICT_MODULES_RWX.
> I also tested with a hacked module_alloc() to force branch trampolines.
So to verify that reducing these trampolines actually helps on an
architecture? I wonder if we can generalize this somehow to let archs
verify such strategies can help.
I was hoping for a bit more wider testing, like actually users, etc.
It does not seem like so. So we can get to that by merging this soon
into modules-next and having this bleed out issues with linux-next.
We are in good time to do this now.
The kmod tree has tons of tests:
https://git.kernel.org/pub/scm/utils/kernel/kmod/kmod.git/
Can you use that to verify there are no regressions?
Aaron, Michal, if you can do the same that'd be appreciated.
Luis
