On Wed, Nov 15, 2023 at 9:35 PM Ilya Leoshkevich <iii@xxxxxxxxxxxxx> wrote: > > The pages for the KMSAN metadata associated with most kernel mappings > are taken from memblock by the common code. However, vmalloc and module > metadata needs to be defined by the architectures. > > Be a little bit more careful than x86: allocate exactly MODULES_LEN > for the module shadow and origins, and then take 2/3 of vmalloc for > the vmalloc shadow and origins. This ensures that users passing small > vmalloc= values on the command line do not cause module metadata > collisions. > > Signed-off-by: Ilya Leoshkevich <iii@xxxxxxxxxxxxx> > --- > arch/s390/boot/startup.c | 8 ++++++++ > arch/s390/include/asm/pgtable.h | 10 ++++++++++ > 2 files changed, 18 insertions(+) > > diff --git a/arch/s390/boot/startup.c b/arch/s390/boot/startup.c > index 8104e0e3d188..297c1062372a 100644 > --- a/arch/s390/boot/startup.c > +++ b/arch/s390/boot/startup.c > @@ -253,9 +253,17 @@ static unsigned long setup_kernel_memory_layout(void) > MODULES_END = round_down(__abs_lowcore, _SEGMENT_SIZE); > MODULES_VADDR = MODULES_END - MODULES_LEN; > VMALLOC_END = MODULES_VADDR; > +#ifdef CONFIG_KMSAN > + VMALLOC_END -= MODULES_LEN * 2; > +#endif > > /* allow vmalloc area to occupy up to about 1/2 of the rest virtual space left */ > vmalloc_size = min(vmalloc_size, round_down(VMALLOC_END / 2, _REGION3_SIZE)); > +#ifdef CONFIG_KMSAN > + /* take 2/3 of vmalloc area for KMSAN shadow and origins */ > + vmalloc_size = round_down(vmalloc_size / 3, PAGE_SIZE); Is it okay that vmalloc_size is only aligned on PAGE_SIZE? E.g. above the alignment is _REGION3_SIZE.
