On Tue, 7 Feb 2023 at 07:15, Zhenhua Huang <quic_zhenhuah@xxxxxxxxxxx> wrote: > > Export the variable to ease the judgement of whether kfence enabled > at runtime. It should be more precise than through kernel config > "CONFIG_KFENCE". > > For example We can disable kfence at runtime using bootargs > "kfence.sample_interval=0" but CONFIG_KFENCE enabled. > It was false positive. > > Signed-off-by: Zhenhua Huang <quic_zhenhuah@xxxxxxxxxxx> > --- > arch/arm64/mm/pageattr.c | 3 ++- > include/linux/kfence.h | 2 ++ > mm/kfence/core.c | 2 +- > 3 files changed, 5 insertions(+), 2 deletions(-) > > diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c > index 79dd201..208d780 100644 > --- a/arch/arm64/mm/pageattr.c > +++ b/arch/arm64/mm/pageattr.c > @@ -7,6 +7,7 @@ > #include <linux/module.h> > #include <linux/sched.h> > #include <linux/vmalloc.h> > +#include <linux/kfence.h> > > #include <asm/cacheflush.h> > #include <asm/set_memory.h> > @@ -27,7 +28,7 @@ bool can_set_direct_map(void) > * protect/unprotect single pages. > */ > return (rodata_enabled && rodata_full) || debug_pagealloc_enabled() || > - IS_ENABLED(CONFIG_KFENCE); > + kfence_enabled; Unfortunately this won't work, because it's possible to enable KFENCE after the kernel has booted with e.g.: echo 100 > /sys/module/kfence/parameters/sample_interval What is the problem you have encountered? Is the page-granular direct map causing issues?
