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x86/xen: Remove use of VLAs
There's an ongoing effort to remove VLAs[1] from the kernel to eventually turn on -Wvla. It turns out, the few VLAs in use in Xen produce only a single entry array that is always bounded by GDT_SIZE. Clean up the code to get rid of the VLA and the loop. [1] https://lkml.org/lkml/2018/3/7/621 Signed-off-by: Laura Abbott <labbott@redhat.com> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> [boris: Use BUG_ON(size>PAGE_SIZE) instead of GDT_SIZE] Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
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1 changed files with 31 additions and 55 deletions
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@ -421,45 +421,33 @@ static void xen_load_gdt(const struct desc_ptr *dtr)
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{
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{
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unsigned long va = dtr->address;
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unsigned long va = dtr->address;
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unsigned int size = dtr->size + 1;
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unsigned int size = dtr->size + 1;
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unsigned pages = DIV_ROUND_UP(size, PAGE_SIZE);
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unsigned long pfn, mfn;
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unsigned long frames[pages];
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int level;
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int f;
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pte_t *ptep;
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void *virt;
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/*
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/* @size should be at most GDT_SIZE which is smaller than PAGE_SIZE. */
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* A GDT can be up to 64k in size, which corresponds to 8192
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BUG_ON(size > PAGE_SIZE);
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* 8-byte entries, or 16 4k pages..
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*/
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BUG_ON(size > 65536);
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BUG_ON(va & ~PAGE_MASK);
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BUG_ON(va & ~PAGE_MASK);
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for (f = 0; va < dtr->address + size; va += PAGE_SIZE, f++) {
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/*
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int level;
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* The GDT is per-cpu and is in the percpu data area.
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pte_t *ptep;
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* That can be virtually mapped, so we need to do a
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unsigned long pfn, mfn;
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* page-walk to get the underlying MFN for the
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void *virt;
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* hypercall. The page can also be in the kernel's
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* linear range, so we need to RO that mapping too.
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*/
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ptep = lookup_address(va, &level);
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BUG_ON(ptep == NULL);
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/*
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pfn = pte_pfn(*ptep);
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* The GDT is per-cpu and is in the percpu data area.
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mfn = pfn_to_mfn(pfn);
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* That can be virtually mapped, so we need to do a
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virt = __va(PFN_PHYS(pfn));
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* page-walk to get the underlying MFN for the
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* hypercall. The page can also be in the kernel's
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* linear range, so we need to RO that mapping too.
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*/
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ptep = lookup_address(va, &level);
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BUG_ON(ptep == NULL);
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pfn = pte_pfn(*ptep);
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make_lowmem_page_readonly((void *)va);
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mfn = pfn_to_mfn(pfn);
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make_lowmem_page_readonly(virt);
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virt = __va(PFN_PHYS(pfn));
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frames[f] = mfn;
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if (HYPERVISOR_set_gdt(&mfn, size / sizeof(struct desc_struct)))
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make_lowmem_page_readonly((void *)va);
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make_lowmem_page_readonly(virt);
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}
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if (HYPERVISOR_set_gdt(frames, size / sizeof(struct desc_struct)))
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BUG();
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BUG();
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}
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}
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@ -470,34 +458,22 @@ static void __init xen_load_gdt_boot(const struct desc_ptr *dtr)
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{
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{
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unsigned long va = dtr->address;
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unsigned long va = dtr->address;
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unsigned int size = dtr->size + 1;
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unsigned int size = dtr->size + 1;
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unsigned pages = DIV_ROUND_UP(size, PAGE_SIZE);
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unsigned long pfn, mfn;
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unsigned long frames[pages];
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pte_t pte;
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int f;
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/*
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/* @size should be at most GDT_SIZE which is smaller than PAGE_SIZE. */
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* A GDT can be up to 64k in size, which corresponds to 8192
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BUG_ON(size > PAGE_SIZE);
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* 8-byte entries, or 16 4k pages..
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*/
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BUG_ON(size > 65536);
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BUG_ON(va & ~PAGE_MASK);
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BUG_ON(va & ~PAGE_MASK);
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for (f = 0; va < dtr->address + size; va += PAGE_SIZE, f++) {
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pfn = virt_to_pfn(va);
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pte_t pte;
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mfn = pfn_to_mfn(pfn);
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unsigned long pfn, mfn;
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pfn = virt_to_pfn(va);
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pte = pfn_pte(pfn, PAGE_KERNEL_RO);
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mfn = pfn_to_mfn(pfn);
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pte = pfn_pte(pfn, PAGE_KERNEL_RO);
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if (HYPERVISOR_update_va_mapping((unsigned long)va, pte, 0))
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BUG();
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if (HYPERVISOR_update_va_mapping((unsigned long)va, pte, 0))
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if (HYPERVISOR_set_gdt(&mfn, size / sizeof(struct desc_struct)))
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BUG();
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frames[f] = mfn;
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}
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if (HYPERVISOR_set_gdt(frames, size / sizeof(struct desc_struct)))
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BUG();
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BUG();
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}
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}
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