Messages in this thread | | | Subject | Re: [PATCH v1 1/4] kasan: introduce set_pmd_early_shadow() | From | Jürgen Groß <> | Date | Wed, 15 Jan 2020 12:09:50 +0100 |
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On 15.01.20 11:54, Sergey Dyasli wrote: > Hi Juergen, > > On 08/01/2020 15:20, Sergey Dyasli wrote: >> It is incorrect to call pmd_populate_kernel() multiple times for the >> same page table. Xen notices it during kasan_populate_early_shadow(): >> >> (XEN) mm.c:3222:d155v0 mfn 3704b already pinned >> >> This happens for kasan_early_shadow_pte when USE_SPLIT_PTE_PTLOCKS is >> enabled. Fix this by introducing set_pmd_early_shadow() which calls >> pmd_populate_kernel() only once and uses set_pmd() afterwards. >> >> Signed-off-by: Sergey Dyasli <sergey.dyasli@citrix.com> > > Looks like the plan to use set_pmd() directly has failed: it's an > arch-specific function and can't be used in arch-independent code > (as kbuild test robot has proven). > > Do you see any way out of this other than disabling SPLIT_PTE_PTLOCKS > for PV KASAN?
Change set_pmd_early_shadow() like the following:
#ifdef CONFIG_XEN_PV static inline void set_pmd_early_shadow(pmd_t *pmd, pte_t *early_shadow) { static bool pmd_populated = false;
if (likely(pmd_populated)) { set_pmd(pmd, __pmd(__pa(early_shadow) | _PAGE_TABLE)); } else { pmd_populate_kernel(&init_mm, pmd, early_shadow); pmd_populated = true; } } #else static inline void set_pmd_early_shadow(pmd_t *pmd, pte_t *early_shadow) { pmd_populate_kernel(&init_mm, pmd, early_shadow); } #endif
... and move it to include/xen/xen-ops.h and call it with lm_alias(kasan_early_shadow_pte) as the second parameter.
Juergen
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