[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v1 1/4] kasan: introduce set_pmd_early_shadow()
On 15.01.20 17:32, Sergey Dyasli wrote: On 15/01/2020 11:09, Jürgen Groß wrote: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@xxxxxxxxxx>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.Your suggestion to use ifdef is really good, especially now when I figured out that CONFIG_XEN_PV implies X86. But I don't like the idea of kasan code calling a non-empty function from xen-ops.h when CONFIG_XEN_PV is not defined. I'd prefer to keep set_pmd_early_shadow() in mm/kasan/init.c with the suggested ifdef. Fine with me. Juergen _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxxx https://lists.xenproject.org/mailman/listinfo/xen-devel
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