> On Mar 5, 2020, at 2:22 PM, Christophe Leroy <christophe.leroy@xxxxxx> wrote: > > > > Le 05/03/2020 à 15:32, Qian Cai a écrit : >> Booting a power9 server with hash MMU could trigger an undefined >> behaviour because pud_offset(p4d, 0) will do, >> 0 >> (PAGE_SHIFT:16 + PTE_INDEX_SIZE:8 + H_PMD_INDEX_SIZE:10) >> Fix it by converting pud_offset() and friends to static inline >> functions. > > I was suggesting to convert pud_index() to static inline, because that's where the shift sits. Is it not possible ? > > Here you seems to fix the problem for now, but if someone reuses pud_index() in another macro one day, the same problem may happen again. > Sounds reasonable. I send out a v3, https://lore.kernel.org/lkml/20200306044852.3236-1-cai@xxxxxx/T/#u > Christophe > >> UBSAN: shift-out-of-bounds in arch/powerpc/mm/ptdump/ptdump.c:282:15 >> shift exponent 34 is too large for 32-bit type 'int' >> CPU: 6 PID: 1 Comm: swapper/0 Not tainted 5.6.0-rc4-next-20200303+ #13 >> Call Trace: >> dump_stack+0xf4/0x164 (unreliable) >> ubsan_epilogue+0x18/0x78 >> __ubsan_handle_shift_out_of_bounds+0x160/0x21c >> walk_pagetables+0x2cc/0x700 >> walk_pud at arch/powerpc/mm/ptdump/ptdump.c:282 >> (inlined by) walk_pagetables at arch/powerpc/mm/ptdump/ptdump.c:311 >> ptdump_check_wx+0x8c/0xf0 >> mark_rodata_ro+0x48/0x80 >> kernel_init+0x74/0x194 >> ret_from_kernel_thread+0x5c/0x74 >> Suggested-by: Christophe Leroy <christophe.leroy@xxxxxx> >> Signed-off-by: Qian Cai <cai@xxxxxx> >> --- >> arch/powerpc/include/asm/book3s/64/pgtable.h | 20 ++++++++++++++------ >> 1 file changed, 14 insertions(+), 6 deletions(-) >> diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h >> index fa60e8594b9f..4967bc9e25e2 100644 >> --- a/arch/powerpc/include/asm/book3s/64/pgtable.h >> +++ b/arch/powerpc/include/asm/book3s/64/pgtable.h >> @@ -1016,12 +1016,20 @@ static inline bool p4d_access_permitted(p4d_t p4d, bool write) >> #define pgd_offset(mm, address) ((mm)->pgd + pgd_index(address)) >> -#define pud_offset(p4dp, addr) \ >> - (((pud_t *) p4d_page_vaddr(*(p4dp))) + pud_index(addr)) >> -#define pmd_offset(pudp,addr) \ >> - (((pmd_t *) pud_page_vaddr(*(pudp))) + pmd_index(addr)) >> -#define pte_offset_kernel(dir,addr) \ >> - (((pte_t *) pmd_page_vaddr(*(dir))) + pte_index(addr)) >> +static inline pud_t *pud_offset(p4d_t *p4d, unsigned long address) >> +{ >> + return (pud_t *)p4d_page_vaddr(*p4d) + pud_index(address); >> +} >> + >> +static inline pmd_t *pmd_offset(pud_t *pud, unsigned long address) >> +{ >> + return (pmd_t *)pud_page_vaddr(*pud) + pmd_index(address); >> +} >> + >> +static inline pte_t *pte_offset_kernel(pmd_t *pmd, unsigned long address) >> +{ >> + return (pte_t *)pmd_page_vaddr(*pmd) + pte_index(address); >> +} >> #define pte_offset_map(dir,addr) pte_offset_kernel((dir), (addr)) >>
