| Message ID | 20210109044622.8312-1-hailongliiu@yeah.net (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | arm/kasan:fix the arry size of kasan_early_shadow_pte | expand |
(+ Linus) On Sat, 9 Jan 2021 at 05:50, Hailong liu <hailongliiu@yeah.net> wrote: > > From: Hailong Liu <liu.hailong6@zte.com.cn> > > The size of kasan_early_shadow_pte[] now is PTRS_PER_PTE which defined to > 512 for arm architecture. This means that it only covers the prev Linux pte > entries, but not the HWTABLE pte entries for arm. > > The reason it works well current is that the symbol kasan_early_shadow_page > immediately following kasan_early_shadow_pte in memory is page aligned, > which makes kasan_early_shadow_pte look like a 4KB size array. But we can't > ensure the order always right with different compiler/linker, nor more bss > symbols be introduced. > > We had a test with QEMU + vexpress：put a 512KB-size symbol with attribute > __section(".bss..page_aligned") after kasan_early_shadow_pte, and poison it > after kasan_early_init(). Then enabled CONFIG_KASAN, it failed to boot up. > > Signed-off-by: Hailong Liu <liu.hailong6@zte.com.cn> > Signed-off-by: Ziliang Guo <guo.ziliang@zte.com.cn> > --- > include/linux/kasan.h | 6 +++++- > mm/kasan/init.c | 3 ++- > 2 files changed, 7 insertions(+), 2 deletions(-) > > diff --git a/include/linux/kasan.h b/include/linux/kasan.h > index 5e0655fb2a6f..fe1ae73ff8b5 100644 > --- a/include/linux/kasan.h > +++ b/include/linux/kasan.h > @@ -35,8 +35,12 @@ struct kunit_kasan_expectation { > #define KASAN_SHADOW_INIT 0 > #endif > > +#ifndef PTE_HWTABLE_PTRS > +#define PTE_HWTABLE_PTRS 0 > +#endif > + > extern unsigned char kasan_early_shadow_page[PAGE_SIZE]; > -extern pte_t kasan_early_shadow_pte[PTRS_PER_PTE]; > +extern pte_t kasan_early_shadow_pte[PTRS_PER_PTE + PTE_HWTABLE_PTRS]; > extern pmd_t kasan_early_shadow_pmd[PTRS_PER_PMD]; > extern pud_t kasan_early_shadow_pud[PTRS_PER_PUD]; > extern p4d_t kasan_early_shadow_p4d[MAX_PTRS_PER_P4D]; > diff --git a/mm/kasan/init.c b/mm/kasan/init.c > index bc0ad208b3a7..7ca0b92d5886 100644 > --- a/mm/kasan/init.c > +++ b/mm/kasan/init.c > @@ -64,7 +64,8 @@ static inline bool kasan_pmd_table(pud_t pud) > return false; > } > #endif > -pte_t kasan_early_shadow_pte[PTRS_PER_PTE] __page_aligned_bss; > +pte_t kasan_early_shadow_pte[PTRS_PER_PTE + PTE_HWTABLE_PTRS] > + __page_aligned_bss; > > static inline bool kasan_pte_table(pmd_t pmd) > { > -- > 2.17.1 > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
On Sat, Jan 9, 2021 at 5:51 AM Hailong liu <hailongliiu@yeah.net> wrote: > From: Hailong Liu <liu.hailong6@zte.com.cn> > > The size of kasan_early_shadow_pte[] now is PTRS_PER_PTE which defined to > 512 for arm architecture. This means that it only covers the prev Linux pte > entries, but not the HWTABLE pte entries for arm. > > The reason it works well current is that the symbol kasan_early_shadow_page > immediately following kasan_early_shadow_pte in memory is page aligned, > which makes kasan_early_shadow_pte look like a 4KB size array. But we can't > ensure the order always right with different compiler/linker, nor more bss > symbols be introduced. > > We had a test with QEMU + vexpress：put a 512KB-size symbol with attribute > __section(".bss..page_aligned") after kasan_early_shadow_pte, and poison it > after kasan_early_init(). Then enabled CONFIG_KASAN, it failed to boot up. > > Signed-off-by: Hailong Liu <liu.hailong6@zte.com.cn> > Signed-off-by: Ziliang Guo <guo.ziliang@zte.com.cn> OK I see the problem, I think. > +#ifndef PTE_HWTABLE_PTRS > +#define PTE_HWTABLE_PTRS 0 > +#endif Can this even happen? We have either pgtable-2level.h or pgtable-3level.h, both of which define PTE_HWTABLE_PTRS. > extern unsigned char kasan_early_shadow_page[PAGE_SIZE]; > -extern pte_t kasan_early_shadow_pte[PTRS_PER_PTE]; > +extern pte_t kasan_early_shadow_pte[PTRS_PER_PTE + PTE_HWTABLE_PTRS]; Yeah this looks exactly like bm_pte so it makes sense. If you drop the first ifndef, Reviewed-by: Linus Walleij <linus.walleij@linaro.org> Yours, Linus Walleij
At 2021-01-10 05:26:08, "Linus Walleij" <linus.walleij@linaro.org> wrote: >On Sat, Jan 9, 2021 at 5:51 AM Hailong liu <hailongliiu@yeah.net> wrote: > >> From: Hailong Liu <liu.hailong6@zte.com.cn> >> >> The size of kasan_early_shadow_pte[] now is PTRS_PER_PTE which defined to >> 512 for arm architecture. This means that it only covers the prev Linux pte >> entries, but not the HWTABLE pte entries for arm. >> >> The reason it works well current is that the symbol kasan_early_shadow_page >> immediately following kasan_early_shadow_pte in memory is page aligned, >> which makes kasan_early_shadow_pte look like a 4KB size array. But we can't >> ensure the order always right with different compiler/linker, nor more bss >> symbols be introduced. >> >> We had a test with QEMU + vexpress：put a 512KB-size symbol with attribute >> __section(".bss..page_aligned") after kasan_early_shadow_pte, and poison it >> after kasan_early_init(). Then enabled CONFIG_KASAN, it failed to boot up. >> >> Signed-off-by: Hailong Liu <liu.hailong6@zte.com.cn> >> Signed-off-by: Ziliang Guo <guo.ziliang@zte.com.cn> > >OK I see the problem, I think. > >> +#ifndef PTE_HWTABLE_PTRS >> +#define PTE_HWTABLE_PTRS 0 >> +#endif > >Can this even happen? We have either pgtable-2level.h or >pgtable-3level.h, both of which define PTE_HWTABLE_PTRS. > I guess not for arm. But I'm not sure for other ARCHs. >> extern unsigned char kasan_early_shadow_page[PAGE_SIZE]; >> -extern pte_t kasan_early_shadow_pte[PTRS_PER_PTE]; >> +extern pte_t kasan_early_shadow_pte[PTRS_PER_PTE + PTE_HWTABLE_PTRS]; > >Yeah this looks exactly like bm_pte so it makes sense. > Yes, it comes from prototype of pm_pte. And it does solve the problems our project encountered and seems to work well for now. >If you drop the first ifndef, >Reviewed-by: Linus Walleij <linus.walleij@linaro.org> > >Yours, >Linus Walleij Thanks.
On Sun, Jan 10, 2021 at 11:21 AM hailong <hailongliiu@yeah.net> wrote: > >> +#ifndef PTE_HWTABLE_PTRS > >> +#define PTE_HWTABLE_PTRS 0 > >> +#endif > > > >Can this even happen? We have either pgtable-2level.h or > >pgtable-3level.h, both of which define PTE_HWTABLE_PTRS. > > > > I guess not for arm. But I'm not sure for other ARCHs. Oh it's a generic include. Sorry for the confusion. All good then! Yours, Linus Walleij
On Sun, 10 Jan 2021 13:03:49 +0100 Linus Walleij <linus.walleij@linaro.org> wrote: > On Sun, Jan 10, 2021 at 11:21 AM hailong <hailongliiu@yeah.net> wrote: > > > >> +#ifndef PTE_HWTABLE_PTRS > > >> +#define PTE_HWTABLE_PTRS 0 > > >> +#endif > > > > > >Can this even happen? We have either pgtable-2level.h or > > >pgtable-3level.h, both of which define PTE_HWTABLE_PTRS. > > > > > > > I guess not for arm. But I'm not sure for other ARCHs. > > Oh it's a generic include. Sorry for the confusion. > > All good then! > This code is 2+ years old. Do we think it warrants a cc:stable?
On Tue, 12 Jan 2021 at 07:19, Andrew Morton <akpm@linux-foundation.org> wrote: > > On Sun, 10 Jan 2021 13:03:49 +0100 Linus Walleij <linus.walleij@linaro.org> wrote: > > > On Sun, Jan 10, 2021 at 11:21 AM hailong <hailongliiu@yeah.net> wrote: > > > > > >> +#ifndef PTE_HWTABLE_PTRS > > > >> +#define PTE_HWTABLE_PTRS 0 > > > >> +#endif > > > > > > > >Can this even happen? We have either pgtable-2level.h or > > > >pgtable-3level.h, both of which define PTE_HWTABLE_PTRS. > > > > > > > > > > I guess not for arm. But I'm not sure for other ARCHs. > > > > Oh it's a generic include. Sorry for the confusion. > > > > All good then! > > > > This code is 2+ years old. Do we think it warrants a cc:stable? > Not needed - ARM only gained Kasan support this cycle, and this patch does not affect any other architectures
diff --git a/include/linux/kasan.h b/include/linux/kasan.h index 5e0655fb2a6f..fe1ae73ff8b5 100644 --- a/include/linux/kasan.h +++ b/include/linux/kasan.h @@ -35,8 +35,12 @@ struct kunit_kasan_expectation { #define KASAN_SHADOW_INIT 0 #endif +#ifndef PTE_HWTABLE_PTRS +#define PTE_HWTABLE_PTRS 0 +#endif + extern unsigned char kasan_early_shadow_page[PAGE_SIZE]; -extern pte_t kasan_early_shadow_pte[PTRS_PER_PTE]; +extern pte_t kasan_early_shadow_pte[PTRS_PER_PTE + PTE_HWTABLE_PTRS]; extern pmd_t kasan_early_shadow_pmd[PTRS_PER_PMD]; extern pud_t kasan_early_shadow_pud[PTRS_PER_PUD]; extern p4d_t kasan_early_shadow_p4d[MAX_PTRS_PER_P4D]; diff --git a/mm/kasan/init.c b/mm/kasan/init.c index bc0ad208b3a7..7ca0b92d5886 100644 --- a/mm/kasan/init.c +++ b/mm/kasan/init.c @@ -64,7 +64,8 @@ static inline bool kasan_pmd_table(pud_t pud) return false; } #endif -pte_t kasan_early_shadow_pte[PTRS_PER_PTE] __page_aligned_bss; +pte_t kasan_early_shadow_pte[PTRS_PER_PTE + PTE_HWTABLE_PTRS] + __page_aligned_bss; static inline bool kasan_pte_table(pmd_t pmd) {