Messages in this thread | | | Date | Thu, 25 Feb 2021 22:11:51 -0500 | From | Steven Rostedt <> | Subject | Re: [PATCH] static_call: Fix the module key fixup |
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On Thu, 25 Feb 2021 23:03:51 +0100 Peter Zijlstra <peterz@infradead.org> wrote:
> Subject: static_call: Fix the module key fixup > > Provided the target address of a R_X86_64_PC32 relocation is aligned, > the low two bits should be invariant between the relative and absolute > value. > > Turns out the address is not aligned and things go sideways, ensure we > transfer the bits in the absolute form when fixing up the key address. >
Link: https://lore.kernel.org/lkml/20210225131221.11dab26e@gandalf.local.home/
> Reported-by: Steven Rostedt <rostedt@goodmis.org>
Tested-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
-- Steve
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> > --- > kernel/static_call.c | 7 ++++--- > 1 file changed, 4 insertions(+), 3 deletions(-) > > diff --git a/kernel/static_call.c b/kernel/static_call.c > index 6906c6ec4c97..ae825295cf68 100644 > --- a/kernel/static_call.c > +++ b/kernel/static_call.c > @@ -349,7 +349,8 @@ static int static_call_add_module(struct module *mod) > struct static_call_site *site; > > for (site = start; site != stop; site++) { > - unsigned long addr = (unsigned long)static_call_key(site); > + unsigned long s_key = (long)site->key + (long)&site->key; > + unsigned long addr = s_key & ~STATIC_CALL_SITE_FLAGS; > unsigned long key; > > /* > @@ -373,8 +374,8 @@ static int static_call_add_module(struct module *mod) > return -EINVAL; > } > > - site->key = (key - (long)&site->key) | > - (site->key & STATIC_CALL_SITE_FLAGS); > + key |= s_key & STATIC_CALL_SITE_FLAGS; > + site->key = key - (long)&site->key; > } > > return __static_call_init(mod, start, stop);
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