On Fri, 1 Jul 2022 at 16:23, Alexander Potapenko <glider@xxxxxxxxxx> wrote: > > KMSAN is going to use 3/4 of existing vmalloc space to hold the > metadata, therefore we lower VMALLOC_END to make sure vmalloc() doesn't > allocate past the first 1/4. > > Signed-off-by: Alexander Potapenko <glider@xxxxxxxxxx> > --- > v2: > -- added x86: to the title > > Link: https://linux-review.googlesource.com/id/I9d8b7f0a88a639f1263bc693cbd5c136626f7efd > --- > arch/x86/include/asm/pgtable_64_types.h | 41 ++++++++++++++++++++++++- > arch/x86/mm/init_64.c | 2 +- > 2 files changed, 41 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/include/asm/pgtable_64_types.h b/arch/x86/include/asm/pgtable_64_types.h > index 70e360a2e5fb7..ad6ded5b1dedf 100644 > --- a/arch/x86/include/asm/pgtable_64_types.h > +++ b/arch/x86/include/asm/pgtable_64_types.h > @@ -139,7 +139,46 @@ extern unsigned int ptrs_per_p4d; > # define VMEMMAP_START __VMEMMAP_BASE_L4 > #endif /* CONFIG_DYNAMIC_MEMORY_LAYOUT */ > > -#define VMALLOC_END (VMALLOC_START + (VMALLOC_SIZE_TB << 40) - 1) > +#define VMEMORY_END (VMALLOC_START + (VMALLOC_SIZE_TB << 40) - 1) Comment what VMEMORY_END is? (Seems obvious, but less guessing is better here.) > +#ifndef CONFIG_KMSAN > +#define VMALLOC_END VMEMORY_END > +#else > +/* > + * In KMSAN builds vmalloc area is four times smaller, and the remaining 3/4 > + * are used to keep the metadata for virtual pages. The memory formerly > + * belonging to vmalloc area is now laid out as follows: > + * > + * 1st quarter: VMALLOC_START to VMALLOC_END - new vmalloc area > + * 2nd quarter: KMSAN_VMALLOC_SHADOW_START to > + * VMALLOC_END+KMSAN_VMALLOC_SHADOW_OFFSET - vmalloc area shadow > + * 3rd quarter: KMSAN_VMALLOC_ORIGIN_START to > + * VMALLOC_END+KMSAN_VMALLOC_ORIGIN_OFFSET - vmalloc area origins > + * 4th quarter: KMSAN_MODULES_SHADOW_START to KMSAN_MODULES_ORIGIN_START > + * - shadow for modules, > + * KMSAN_MODULES_ORIGIN_START to > + * KMSAN_MODULES_ORIGIN_START + MODULES_LEN - origins for modules. > + */ > +#define VMALLOC_QUARTER_SIZE ((VMALLOC_SIZE_TB << 40) >> 2) > +#define VMALLOC_END (VMALLOC_START + VMALLOC_QUARTER_SIZE - 1) > + > +/* > + * vmalloc metadata addresses are calculated by adding shadow/origin offsets > + * to vmalloc address. > + */ > +#define KMSAN_VMALLOC_SHADOW_OFFSET VMALLOC_QUARTER_SIZE > +#define KMSAN_VMALLOC_ORIGIN_OFFSET (VMALLOC_QUARTER_SIZE << 1) > + > +#define KMSAN_VMALLOC_SHADOW_START (VMALLOC_START + KMSAN_VMALLOC_SHADOW_OFFSET) > +#define KMSAN_VMALLOC_ORIGIN_START (VMALLOC_START + KMSAN_VMALLOC_ORIGIN_OFFSET) > + > +/* > + * The shadow/origin for modules are placed one by one in the last 1/4 of > + * vmalloc space. > + */ > +#define KMSAN_MODULES_SHADOW_START (VMALLOC_END + KMSAN_VMALLOC_ORIGIN_OFFSET + 1) > +#define KMSAN_MODULES_ORIGIN_START (KMSAN_MODULES_SHADOW_START + MODULES_LEN) > +#endif /* CONFIG_KMSAN */ > > #define MODULES_VADDR (__START_KERNEL_map + KERNEL_IMAGE_SIZE) > /* The module sections ends with the start of the fixmap */ > diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c > index 39c5246964a91..5806331172361 100644 > --- a/arch/x86/mm/init_64.c > +++ b/arch/x86/mm/init_64.c > @@ -1287,7 +1287,7 @@ static void __init preallocate_vmalloc_pages(void) > unsigned long addr; > const char *lvl; > > - for (addr = VMALLOC_START; addr <= VMALLOC_END; addr = ALIGN(addr + 1, PGDIR_SIZE)) { > + for (addr = VMALLOC_START; addr <= VMEMORY_END; addr = ALIGN(addr + 1, PGDIR_SIZE)) { > pgd_t *pgd = pgd_offset_k(addr); > p4d_t *p4d; > pud_t *pud; > -- > 2.37.0.rc0.161.g10f37bed90-goog >
