[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] Why we are doing this (below code) in __init setup_pagetables() method in ARM arch in setup.c.
/* Link in the fixmap pagetable */ pte = mfn_to_xen_entry((((unsigned long) xen_fixmap) + phys_offset) >> PAGE_SHIFT); pte.pt.table = 1; write_pte(xen_second + second_table_offset(FIXMAP_ADDR(0)), pte); /* * No flush required here. Individual flushes are done in * set_fixmap as entries are used. */ /* Break up the Xen mapping into 4k pages and protect them separately. */ for ( i = 0; i < LPAE_ENTRIES; i++ ) { unsigned long mfn = paddr_to_pfn(xen_paddr) + i; unsigned long va = XEN_VIRT_START + (i << PAGE_SHIFT); if ( !is_kernel(va) ) break; pte = mfn_to_xen_entry(mfn); pte.pt.table = 1; /* 4k mappings always have this bit set */ if ( is_kernel_text(va) || is_kernel_inittext(va) ) { pte.pt.xn = 0; pte.pt.ro = 1; } if ( is_kernel_rodata(va) ) pte.pt.ro = 1; write_pte(xen_xenmap + i, pte); /* No flush required here as page table is not hooked in yet. */ } pte = mfn_to_xen_entry((((unsigned long) xen_xenmap) + phys_offset) >> PAGE_SHIFT); pte.pt.table = 1; write_pte(xen_second + second_linear_offset(XEN_VIRT_START), pte); /* Have changed a mapping used for .text. Flush everything for safety. */ flush_xen_text_tlb(); /* From now on, no mapping may be both writable and executable. */ WRITE_CP32(READ_CP32(HSCTLR) | SCTLR_WXN, HSCTLR); _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
|
Lists.xenproject.org is hosted with RackSpace, monitoring our |