arch: Remove Itanium (IA-64) architecture

The Itanium architecture is obsolete, and an informal survey [0] reveals
that any residual use of Itanium hardware in production is mostly HP-UX
or OpenVMS based. The use of Linux on Itanium appears to be limited to
enthusiasts that occasionally boot a fresh Linux kernel to see whether
things are still working as intended, and perhaps to churn out some
distro packages that are rarely used in practice.

None of the original companies behind Itanium still produce or support
any hardware or software for the architecture, and it is listed as
'Orphaned' in the MAINTAINERS file, as apparently, none of the engineers
that contributed on behalf of those companies (nor anyone else, for that
matter) have been willing to support or maintain the architecture
upstream or even be responsible for applying the odd fix. The Intel
firmware team removed all IA-64 support from the Tianocore/EDK2
reference implementation of EFI in 2018. (Itanium is the original
architecture for which EFI was developed, and the way Linux supports it
deviates significantly from other architectures.) Some distros, such as
Debian and Gentoo, still maintain [unofficial] ia64 ports, but many have
dropped support years ago.

While the argument is being made [1] that there is a 'for the common
good' angle to being able to build and run existing projects such as the
Grid Community Toolkit [2] on Itanium for interoperability testing, the
fact remains that none of those projects are known to be deployed on
Linux/ia64, and very few people actually have access to such a system in
the first place. Even if there were ways imaginable in which Linux/ia64
could be put to good use today, what matters is whether anyone is
actually doing that, and this does not appear to be the case.

There are no emulators widely available, and so boot testing Itanium is
generally infeasible for ordinary contributors. GCC still supports IA-64
but its compile farm [3] no longer has any IA-64 machines. GLIBC would
like to get rid of IA-64 [4] too because it would permit some overdue
code cleanups. In summary, the benefits to the ecosystem of having IA-64
be part of it are mostly theoretical, whereas the maintenance overhead
of keeping it supported is real.

So let's rip off the band aid, and remove the IA-64 arch code entirely.
This follows the timeline proposed by the Debian/ia64 maintainer [5],
which removes support in a controlled manner, leaving IA-64 in a known
good state in the most recent LTS release. Other projects will follow
once the kernel support is removed.

[0] https://lore.kernel.org/all/CAMj1kXFCMh_578jniKpUtx_j8ByHnt=s7S+yQ+vGbKt9ud7+kQ@mail.gmail.com/
[1] https://lore.kernel.org/all/0075883c-7c51-00f5-2c2d-5119c1820410@web.de/
[2] https://gridcf.org/gct-docs/latest/index.html
[3] https://cfarm.tetaneutral.net/machines/list/
[4] https://lore.kernel.org/all/87bkiilpc4.fsf@mid.deneb.enyo.de/
[5] https://lore.kernel.org/all/ff58a3e76e5102c94bb5946d99187b358def688a.camel@physik.fu-berlin.de/

Acked-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

1 files changed, 0 insertions, 532 deletions

diff --git a/arch/ia64/mm/init.c b/arch/ia64/mm/init.c
deleted file mode 100644
index 05b0f2f0c073..000000000000
--- a/arch/ia64/mm/init.c
+++ /dev/null
@@ -1,532 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-/*
- * Initialize MMU support.
- *
- * Copyright (C) 1998-2003 Hewlett-Packard Co
- *	David Mosberger-Tang <davidm@hpl.hp.com>
- */
-#include <linux/kernel.h>
-#include <linux/init.h>
-
-#include <linux/dma-map-ops.h>
-#include <linux/dmar.h>
-#include <linux/efi.h>
-#include <linux/elf.h>
-#include <linux/memblock.h>
-#include <linux/mm.h>
-#include <linux/sched/signal.h>
-#include <linux/mmzone.h>
-#include <linux/module.h>
-#include <linux/personality.h>
-#include <linux/reboot.h>
-#include <linux/slab.h>
-#include <linux/swap.h>
-#include <linux/proc_fs.h>
-#include <linux/bitops.h>
-#include <linux/kexec.h>
-#include <linux/swiotlb.h>
-
-#include <asm/dma.h>
-#include <asm/efi.h>
-#include <asm/io.h>
-#include <asm/numa.h>
-#include <asm/patch.h>
-#include <asm/pgalloc.h>
-#include <asm/sal.h>
-#include <asm/sections.h>
-#include <asm/tlb.h>
-#include <linux/uaccess.h>
-#include <asm/unistd.h>
-#include <asm/mca.h>
-
-extern void ia64_tlb_init (void);
-
-unsigned long MAX_DMA_ADDRESS = PAGE_OFFSET + 0x100000000UL;
-
-struct page *zero_page_memmap_ptr;	/* map entry for zero page */
-EXPORT_SYMBOL(zero_page_memmap_ptr);
-
-void
-__ia64_sync_icache_dcache (pte_t pte)
-{
-	unsigned long addr;
-	struct folio *folio;
-
-	folio = page_folio(pte_page(pte));
-	addr = (unsigned long)folio_address(folio);
-
-	if (test_bit(PG_arch_1, &folio->flags))
-		return;				/* i-cache is already coherent with d-cache */
-
-	flush_icache_range(addr, addr + folio_size(folio));
-	set_bit(PG_arch_1, &folio->flags);	/* mark page as clean */
-}
-
-/*
- * Since DMA is i-cache coherent, any (complete) folios that were written via
- * DMA can be marked as "clean" so that lazy_mmu_prot_update() doesn't have to
- * flush them when they get mapped into an executable vm-area.
- */
-void arch_dma_mark_clean(phys_addr_t paddr, size_t size)
-{
-	unsigned long pfn = PHYS_PFN(paddr);
-	struct folio *folio = page_folio(pfn_to_page(pfn));
-	ssize_t left = size;
-	size_t offset = offset_in_folio(folio, paddr);
-
-	if (offset) {
-		left -= folio_size(folio) - offset;
-		if (left <= 0)
-			return;
-		folio = folio_next(folio);
-	}
-
-	while (left >= (ssize_t)folio_size(folio)) {
-		left -= folio_size(folio);
-		set_bit(PG_arch_1, &pfn_to_page(pfn)->flags);
-		if (!left)
-			break;
-		folio = folio_next(folio);
-	}
-}
-
-inline void
-ia64_set_rbs_bot (void)
-{
-	unsigned long stack_size = rlimit_max(RLIMIT_STACK) & -16;
-
-	if (stack_size > MAX_USER_STACK_SIZE)
-		stack_size = MAX_USER_STACK_SIZE;
-	current->thread.rbs_bot = PAGE_ALIGN(current->mm->start_stack - stack_size);
-}
-
-/*
- * This performs some platform-dependent address space initialization.
- * On IA-64, we want to setup the VM area for the register backing
- * store (which grows upwards) and install the gateway page which is
- * used for signal trampolines, etc.
- */
-void
-ia64_init_addr_space (void)
-{
-	struct vm_area_struct *vma;
-
-	ia64_set_rbs_bot();
-
-	/*
-	 * If we're out of memory and kmem_cache_alloc() returns NULL, we simply ignore
-	 * the problem.  When the process attempts to write to the register backing store
-	 * for the first time, it will get a SEGFAULT in this case.
-	 */
-	vma = vm_area_alloc(current->mm);
-	if (vma) {
-		vma_set_anonymous(vma);
-		vma->vm_start = current->thread.rbs_bot & PAGE_MASK;
-		vma->vm_end = vma->vm_start + PAGE_SIZE;
-		vm_flags_init(vma, VM_DATA_DEFAULT_FLAGS|VM_GROWSUP|VM_ACCOUNT);
-		vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
-		mmap_write_lock(current->mm);
-		if (insert_vm_struct(current->mm, vma)) {
-			mmap_write_unlock(current->mm);
-			vm_area_free(vma);
-			return;
-		}
-		mmap_write_unlock(current->mm);
-	}
-
-	/* map NaT-page at address zero to speed up speculative dereferencing of NULL: */
-	if (!(current->personality & MMAP_PAGE_ZERO)) {
-		vma = vm_area_alloc(current->mm);
-		if (vma) {
-			vma_set_anonymous(vma);
-			vma->vm_end = PAGE_SIZE;
-			vma->vm_page_prot = __pgprot(pgprot_val(PAGE_READONLY) | _PAGE_MA_NAT);
-			vm_flags_init(vma, VM_READ | VM_MAYREAD | VM_IO |
-				      VM_DONTEXPAND | VM_DONTDUMP);
-			mmap_write_lock(current->mm);
-			if (insert_vm_struct(current->mm, vma)) {
-				mmap_write_unlock(current->mm);
-				vm_area_free(vma);
-				return;
-			}
-			mmap_write_unlock(current->mm);
-		}
-	}
-}
-
-void
-free_initmem (void)
-{
-	free_reserved_area(ia64_imva(__init_begin), ia64_imva(__init_end),
-			   -1, "unused kernel");
-}
-
-void __init
-free_initrd_mem (unsigned long start, unsigned long end)
-{
-	/*
-	 * EFI uses 4KB pages while the kernel can use 4KB or bigger.
-	 * Thus EFI and the kernel may have different page sizes. It is
-	 * therefore possible to have the initrd share the same page as
-	 * the end of the kernel (given current setup).
-	 *
-	 * To avoid freeing/using the wrong page (kernel sized) we:
-	 *	- align up the beginning of initrd
-	 *	- align down the end of initrd
-	 *
-	 *  |             |
-	 *  |=============| a000
-	 *  |             |
-	 *  |             |
-	 *  |             | 9000
-	 *  |/////////////|
-	 *  |/////////////|
-	 *  |=============| 8000
-	 *  |///INITRD////|
-	 *  |/////////////|
-	 *  |/////////////| 7000
-	 *  |             |
-	 *  |KKKKKKKKKKKKK|
-	 *  |=============| 6000
-	 *  |KKKKKKKKKKKKK|
-	 *  |KKKKKKKKKKKKK|
-	 *  K=kernel using 8KB pages
-	 *
-	 * In this example, we must free page 8000 ONLY. So we must align up
-	 * initrd_start and keep initrd_end as is.
-	 */
-	start = PAGE_ALIGN(start);
-	end = end & PAGE_MASK;
-
-	if (start < end)
-		printk(KERN_INFO "Freeing initrd memory: %ldkB freed\n", (end - start) >> 10);
-
-	for (; start < end; start += PAGE_SIZE) {
-		if (!virt_addr_valid(start))
-			continue;
-		free_reserved_page(virt_to_page(start));
-	}
-}
-
-/*
- * This installs a clean page in the kernel's page table.
- */
-static struct page * __init
-put_kernel_page (struct page *page, unsigned long address, pgprot_t pgprot)
-{
-	pgd_t *pgd;
-	p4d_t *p4d;
-	pud_t *pud;
-	pmd_t *pmd;
-	pte_t *pte;
-
-	pgd = pgd_offset_k(address);		/* note: this is NOT pgd_offset()! */
-
-	{
-		p4d = p4d_alloc(&init_mm, pgd, address);
-		if (!p4d)
-			goto out;
-		pud = pud_alloc(&init_mm, p4d, address);
-		if (!pud)
-			goto out;
-		pmd = pmd_alloc(&init_mm, pud, address);
-		if (!pmd)
-			goto out;
-		pte = pte_alloc_kernel(pmd, address);
-		if (!pte)
-			goto out;
-		if (!pte_none(*pte))
-			goto out;
-		set_pte(pte, mk_pte(page, pgprot));
-	}
-  out:
-	/* no need for flush_tlb */
-	return page;
-}
-
-static void __init
-setup_gate (void)
-{
-	struct page *page;
-
-	/*
-	 * Map the gate page twice: once read-only to export the ELF
-	 * headers etc. and once execute-only page to enable
-	 * privilege-promotion via "epc":
-	 */
-	page = virt_to_page(ia64_imva(__start_gate_section));
-	put_kernel_page(page, GATE_ADDR, PAGE_READONLY);
-#ifdef HAVE_BUGGY_SEGREL
-	page = virt_to_page(ia64_imva(__start_gate_section + PAGE_SIZE));
-	put_kernel_page(page, GATE_ADDR + PAGE_SIZE, PAGE_GATE);
-#else
-	put_kernel_page(page, GATE_ADDR + PERCPU_PAGE_SIZE, PAGE_GATE);
-	/* Fill in the holes (if any) with read-only zero pages: */
-	{
-		unsigned long addr;
-
-		for (addr = GATE_ADDR + PAGE_SIZE;
-		     addr < GATE_ADDR + PERCPU_PAGE_SIZE;
-		     addr += PAGE_SIZE)
-		{
-			put_kernel_page(ZERO_PAGE(0), addr,
-					PAGE_READONLY);
-			put_kernel_page(ZERO_PAGE(0), addr + PERCPU_PAGE_SIZE,
-					PAGE_READONLY);
-		}
-	}
-#endif
-	ia64_patch_gate();
-}
-
-static struct vm_area_struct gate_vma;
-
-static int __init gate_vma_init(void)
-{
-	vma_init(&gate_vma, NULL);
-	gate_vma.vm_start = FIXADDR_USER_START;
-	gate_vma.vm_end = FIXADDR_USER_END;
-	vm_flags_init(&gate_vma, VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC);
-	gate_vma.vm_page_prot = __pgprot(__ACCESS_BITS | _PAGE_PL_3 | _PAGE_AR_RX);
-
-	return 0;
-}
-__initcall(gate_vma_init);
-
-struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
-{
-	return &gate_vma;
-}
-
-int in_gate_area_no_mm(unsigned long addr)
-{
-	if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
-		return 1;
-	return 0;
-}
-
-int in_gate_area(struct mm_struct *mm, unsigned long addr)
-{
-	return in_gate_area_no_mm(addr);
-}
-
-void ia64_mmu_init(void *my_cpu_data)
-{
-	unsigned long pta, impl_va_bits;
-	extern void tlb_init(void);
-
-#ifdef CONFIG_DISABLE_VHPT
-#	define VHPT_ENABLE_BIT	0
-#else
-#	define VHPT_ENABLE_BIT	1
-#endif
-
-	/*
-	 * Check if the virtually mapped linear page table (VMLPT) overlaps with a mapped
-	 * address space.  The IA-64 architecture guarantees that at least 50 bits of
-	 * virtual address space are implemented but if we pick a large enough page size
-	 * (e.g., 64KB), the mapped address space is big enough that it will overlap with
-	 * VMLPT.  I assume that once we run on machines big enough to warrant 64KB pages,
-	 * IMPL_VA_MSB will be significantly bigger, so this is unlikely to become a
-	 * problem in practice.  Alternatively, we could truncate the top of the mapped
-	 * address space to not permit mappings that would overlap with the VMLPT.
-	 * --davidm 00/12/06
-	 */
-#	define pte_bits			3
-#	define mapped_space_bits	(3*(PAGE_SHIFT - pte_bits) + PAGE_SHIFT)
-	/*
-	 * The virtual page table has to cover the entire implemented address space within
-	 * a region even though not all of this space may be mappable.  The reason for
-	 * this is that the Access bit and Dirty bit fault handlers perform
-	 * non-speculative accesses to the virtual page table, so the address range of the
-	 * virtual page table itself needs to be covered by virtual page table.
-	 */
-#	define vmlpt_bits		(impl_va_bits - PAGE_SHIFT + pte_bits)
-#	define POW2(n)			(1ULL << (n))
-
-	impl_va_bits = ffz(~(local_cpu_data->unimpl_va_mask | (7UL << 61)));
-
-	if (impl_va_bits < 51 || impl_va_bits > 61)
-		panic("CPU has bogus IMPL_VA_MSB value of %lu!\n", impl_va_bits - 1);
-	/*
-	 * mapped_space_bits - PAGE_SHIFT is the total number of ptes we need,
-	 * which must fit into "vmlpt_bits - pte_bits" slots. Second half of
-	 * the test makes sure that our mapped space doesn't overlap the
-	 * unimplemented hole in the middle of the region.
-	 */
-	if ((mapped_space_bits - PAGE_SHIFT > vmlpt_bits - pte_bits) ||
-	    (mapped_space_bits > impl_va_bits - 1))
-		panic("Cannot build a big enough virtual-linear page table"
-		      " to cover mapped address space.\n"
-		      " Try using a smaller page size.\n");
-
-
-	/* place the VMLPT at the end of each page-table mapped region: */
-	pta = POW2(61) - POW2(vmlpt_bits);
-
-	/*
-	 * Set the (virtually mapped linear) page table address.  Bit
-	 * 8 selects between the short and long format, bits 2-7 the
-	 * size of the table, and bit 0 whether the VHPT walker is
-	 * enabled.
-	 */
-	ia64_set_pta(pta | (0 << 8) | (vmlpt_bits << 2) | VHPT_ENABLE_BIT);
-
-	ia64_tlb_init();
-
-#ifdef	CONFIG_HUGETLB_PAGE
-	ia64_set_rr(HPAGE_REGION_BASE, HPAGE_SHIFT << 2);
-	ia64_srlz_d();
-#endif
-}
-
-int __init register_active_ranges(u64 start, u64 len, int nid)
-{
-	u64 end = start + len;
-
-#ifdef CONFIG_KEXEC
-	if (start > crashk_res.start && start < crashk_res.end)
-		start = crashk_res.end;
-	if (end > crashk_res.start && end < crashk_res.end)
-		end = crashk_res.start;
-#endif
-
-	if (start < end)
-		memblock_add_node(__pa(start), end - start, nid, MEMBLOCK_NONE);
-	return 0;
-}
-
-int
-find_max_min_low_pfn (u64 start, u64 end, void *arg)
-{
-	unsigned long pfn_start, pfn_end;
-#ifdef CONFIG_FLATMEM
-	pfn_start = (PAGE_ALIGN(__pa(start))) >> PAGE_SHIFT;
-	pfn_end = (PAGE_ALIGN(__pa(end - 1))) >> PAGE_SHIFT;
-#else
-	pfn_start = GRANULEROUNDDOWN(__pa(start)) >> PAGE_SHIFT;
-	pfn_end = GRANULEROUNDUP(__pa(end - 1)) >> PAGE_SHIFT;
-#endif
-	min_low_pfn = min(min_low_pfn, pfn_start);
-	max_low_pfn = max(max_low_pfn, pfn_end);
-	return 0;
-}
-
-/*
- * Boot command-line option "nolwsys" can be used to disable the use of any light-weight
- * system call handler.  When this option is in effect, all fsyscalls will end up bubbling
- * down into the kernel and calling the normal (heavy-weight) syscall handler.  This is
- * useful for performance testing, but conceivably could also come in handy for debugging
- * purposes.
- */
-
-static int nolwsys __initdata;
-
-static int __init
-nolwsys_setup (char *s)
-{
-	nolwsys = 1;
-	return 1;
-}
-
-__setup("nolwsys", nolwsys_setup);
-
-void __init
-mem_init (void)
-{
-	int i;
-
-	BUG_ON(PTRS_PER_PGD * sizeof(pgd_t) != PAGE_SIZE);
-	BUG_ON(PTRS_PER_PMD * sizeof(pmd_t) != PAGE_SIZE);
-	BUG_ON(PTRS_PER_PTE * sizeof(pte_t) != PAGE_SIZE);
-
-	/*
-	 * This needs to be called _after_ the command line has been parsed but
-	 * _before_ any drivers that may need the PCI DMA interface are
-	 * initialized or bootmem has been freed.
-	 */
-	do {
-#ifdef CONFIG_INTEL_IOMMU
-		detect_intel_iommu();
-		if (iommu_detected)
-			break;
-#endif
-		swiotlb_init(true, SWIOTLB_VERBOSE);
-	} while (0);
-
-#ifdef CONFIG_FLATMEM
-	BUG_ON(!mem_map);
-#endif
-
-	set_max_mapnr(max_low_pfn);
-	high_memory = __va(max_low_pfn * PAGE_SIZE);
-	memblock_free_all();
-
-	/*
-	 * For fsyscall entrypoints with no light-weight handler, use the ordinary
-	 * (heavy-weight) handler, but mark it by setting bit 0, so the fsyscall entry
-	 * code can tell them apart.
-	 */
-	for (i = 0; i < NR_syscalls; ++i) {
-		extern unsigned long fsyscall_table[NR_syscalls];
-		extern unsigned long sys_call_table[NR_syscalls];
-
-		if (!fsyscall_table[i] || nolwsys)
-			fsyscall_table[i] = sys_call_table[i] | 1;
-	}
-	setup_gate();
-}
-
-#ifdef CONFIG_MEMORY_HOTPLUG
-int arch_add_memory(int nid, u64 start, u64 size,
-		    struct mhp_params *params)
-{
-	unsigned long start_pfn = start >> PAGE_SHIFT;
-	unsigned long nr_pages = size >> PAGE_SHIFT;
-	int ret;
-
-	if (WARN_ON_ONCE(params->pgprot.pgprot != PAGE_KERNEL.pgprot))
-		return -EINVAL;
-
-	ret = __add_pages(nid, start_pfn, nr_pages, params);
-	if (ret)
-		printk("%s: Problem encountered in __add_pages() as ret=%d\n",
-		       __func__,  ret);
-
-	return ret;
-}
-
-void arch_remove_memory(u64 start, u64 size, struct vmem_altmap *altmap)
-{
-	unsigned long start_pfn = start >> PAGE_SHIFT;
-	unsigned long nr_pages = size >> PAGE_SHIFT;
-
-	__remove_pages(start_pfn, nr_pages, altmap);
-}
-#endif
-
-static const pgprot_t protection_map[16] = {
-	[VM_NONE]					= PAGE_NONE,
-	[VM_READ]					= PAGE_READONLY,
-	[VM_WRITE]					= PAGE_READONLY,
-	[VM_WRITE | VM_READ]				= PAGE_READONLY,
-	[VM_EXEC]					= __pgprot(__ACCESS_BITS | _PAGE_PL_3 |
-								   _PAGE_AR_X_RX),
-	[VM_EXEC | VM_READ]				= __pgprot(__ACCESS_BITS | _PAGE_PL_3 |
-								   _PAGE_AR_RX),
-	[VM_EXEC | VM_WRITE]				= PAGE_COPY_EXEC,
-	[VM_EXEC | VM_WRITE | VM_READ]			= PAGE_COPY_EXEC,
-	[VM_SHARED]					= PAGE_NONE,
-	[VM_SHARED | VM_READ]				= PAGE_READONLY,
-	[VM_SHARED | VM_WRITE]				= PAGE_SHARED,
-	[VM_SHARED | VM_WRITE | VM_READ]		= PAGE_SHARED,
-	[VM_SHARED | VM_EXEC]				= __pgprot(__ACCESS_BITS | _PAGE_PL_3 |
-								   _PAGE_AR_X_RX),
-	[VM_SHARED | VM_EXEC | VM_READ]			= __pgprot(__ACCESS_BITS | _PAGE_PL_3 |
-								   _PAGE_AR_RX),
-	[VM_SHARED | VM_EXEC | VM_WRITE]		= __pgprot(__ACCESS_BITS | _PAGE_PL_3 |
-								   _PAGE_AR_RWX),
-	[VM_SHARED | VM_EXEC | VM_WRITE | VM_READ]	= __pgprot(__ACCESS_BITS | _PAGE_PL_3 |
-								   _PAGE_AR_RWX)
-};
-DECLARE_VM_GET_PAGE_PROT