Messages in this thread | ![/](/images/icornerl.gif) | | Date | Thu, 21 Dec 2023 13:14:17 +0100 | From | Alexander Gordeev <> | Subject | Re: [PATCH v3 28/34] s390/mm: Define KMSAN metadata for vmalloc and modules |
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On Thu, Dec 14, 2023 at 12:24:48AM +0100, Ilya Leoshkevich 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. > > Reviewed-by: Alexander Potapenko <glider@google.com> > Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com> > --- > 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..e37e7ffda430 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));
Since commit 2a65c6e1ad06 ("s390/boot: always align vmalloc area on segment boundary") vmalloc_size is aligned on _SEGMENT_SIZE boundary.
> +#ifdef CONFIG_KMSAN > + /* take 2/3 of vmalloc area for KMSAN shadow and origins */ > + vmalloc_size = round_down(vmalloc_size / 3, _REGION3_SIZE);
And thus, the alignment here should be _SEGMENT_SIZE as well.
> + VMALLOC_END -= vmalloc_size * 2; > +#endif > VMALLOC_START = VMALLOC_END - vmalloc_size; > > /* split remaining virtual space between 1:1 mapping & vmemmap array */
...
With the above fixup: Acked-by: Alexander Gordeev <agordeev@linux.ibm.com>
Thanks!
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