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The Itanium architecture is obsolete, and an informal survey [0] reveals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, 265 deletions

diff --git a/arch/ia64/include/asm/uaccess.h b/arch/ia64/include/asm/uaccess.h
deleted file mode 100644
index 60adadeb3e9e..000000000000
--- a/arch/ia64/include/asm/uaccess.h
+++ /dev/null
@@ -1,265 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef _ASM_IA64_UACCESS_H
-#define _ASM_IA64_UACCESS_H
-
-/*
- * This file defines various macros to transfer memory areas across
- * the user/kernel boundary.  This needs to be done carefully because
- * this code is executed in kernel mode and uses user-specified
- * addresses.  Thus, we need to be careful not to let the user to
- * trick us into accessing kernel memory that would normally be
- * inaccessible.  This code is also fairly performance sensitive,
- * so we want to spend as little time doing safety checks as
- * possible.
- *
- * To make matters a bit more interesting, these macros sometimes also
- * called from within the kernel itself, in which case the address
- * validity check must be skipped.  The get_fs() macro tells us what
- * to do: if get_fs()==USER_DS, checking is performed, if
- * get_fs()==KERNEL_DS, checking is bypassed.
- *
- * Note that even if the memory area specified by the user is in a
- * valid address range, it is still possible that we'll get a page
- * fault while accessing it.  This is handled by filling out an
- * exception handler fixup entry for each instruction that has the
- * potential to fault.  When such a fault occurs, the page fault
- * handler checks to see whether the faulting instruction has a fixup
- * associated and, if so, sets r8 to -EFAULT and clears r9 to 0 and
- * then resumes execution at the continuation point.
- *
- * Based on <asm-alpha/uaccess.h>.
- *
- * Copyright (C) 1998, 1999, 2001-2004 Hewlett-Packard Co
- *	David Mosberger-Tang <davidm@hpl.hp.com>
- */
-
-#include <linux/compiler.h>
-#include <linux/page-flags.h>
-
-#include <asm/intrinsics.h>
-#include <linux/pgtable.h>
-#include <asm/io.h>
-#include <asm/extable.h>
-
-/*
- * When accessing user memory, we need to make sure the entire area really is
- * in user-level space.  We also need to make sure that the address doesn't
- * point inside the virtually mapped linear page table.
- */
-static inline int __access_ok(const void __user *p, unsigned long size)
-{
-	unsigned long limit = TASK_SIZE;
-	unsigned long addr = (unsigned long)p;
-
-	return likely((size <= limit) && (addr <= (limit - size)) &&
-		 likely(REGION_OFFSET(addr) < RGN_MAP_LIMIT));
-}
-#define __access_ok __access_ok
-#include <asm-generic/access_ok.h>
-
-/*
- * These are the main single-value transfer routines.  They automatically
- * use the right size if we just have the right pointer type.
- *
- * Careful to not
- * (a) re-use the arguments for side effects (sizeof/typeof is ok)
- * (b) require any knowledge of processes at this stage
- */
-#define put_user(x, ptr)	__put_user_check((__typeof__(*(ptr))) (x), (ptr), sizeof(*(ptr)))
-#define get_user(x, ptr)	__get_user_check((x), (ptr), sizeof(*(ptr)))
-
-/*
- * The "__xxx" versions do not do address space checking, useful when
- * doing multiple accesses to the same area (the programmer has to do the
- * checks by hand with "access_ok()")
- */
-#define __put_user(x, ptr)	__put_user_nocheck((__typeof__(*(ptr))) (x), (ptr), sizeof(*(ptr)))
-#define __get_user(x, ptr)	__get_user_nocheck((x), (ptr), sizeof(*(ptr)))
-
-#ifdef ASM_SUPPORTED
-  struct __large_struct { unsigned long buf[100]; };
-# define __m(x) (*(struct __large_struct __user *)(x))
-
-/* We need to declare the __ex_table section before we can use it in .xdata.  */
-asm (".section \"__ex_table\", \"a\"\n\t.previous");
-
-# define __get_user_size(val, addr, n, err)							\
-do {												\
-	register long __gu_r8 asm ("r8") = 0;							\
-	register long __gu_r9 asm ("r9");							\
-	asm ("\n[1:]\tld"#n" %0=%2%P2\t// %0 and %1 get overwritten by exception handler\n"	\
-	     "\t.xdata4 \"__ex_table\", 1b-., 1f-.+4\n"						\
-	     "[1:]"										\
-	     : "=r"(__gu_r9), "=r"(__gu_r8) : "m"(__m(addr)), "1"(__gu_r8));			\
-	(err) = __gu_r8;									\
-	(val) = __gu_r9;									\
-} while (0)
-
-/*
- * The "__put_user_size()" macro tells gcc it reads from memory instead of writing it.  This
- * is because they do not write to any memory gcc knows about, so there are no aliasing
- * issues.
- */
-# define __put_user_size(val, addr, n, err)							\
-do {												\
-	register long __pu_r8 asm ("r8") = 0;							\
-	asm volatile ("\n[1:]\tst"#n" %1=%r2%P1\t// %0 gets overwritten by exception handler\n"	\
-		      "\t.xdata4 \"__ex_table\", 1b-., 1f-.\n"					\
-		      "[1:]"									\
-		      : "=r"(__pu_r8) : "m"(__m(addr)), "rO"(val), "0"(__pu_r8));		\
-	(err) = __pu_r8;									\
-} while (0)
-
-#else /* !ASM_SUPPORTED */
-# define RELOC_TYPE	2	/* ip-rel */
-# define __get_user_size(val, addr, n, err)				\
-do {									\
-	__ld_user("__ex_table", (unsigned long) addr, n, RELOC_TYPE);	\
-	(err) = ia64_getreg(_IA64_REG_R8);				\
-	(val) = ia64_getreg(_IA64_REG_R9);				\
-} while (0)
-# define __put_user_size(val, addr, n, err)				\
-do {									\
-	__st_user("__ex_table", (unsigned long) addr, n, RELOC_TYPE,	\
-		  (__force unsigned long) (val));			\
-	(err) = ia64_getreg(_IA64_REG_R8);				\
-} while (0)
-#endif /* !ASM_SUPPORTED */
-
-extern void __get_user_unknown (void);
-
-/*
- * Evaluating arguments X, PTR, SIZE, and SEGMENT may involve subroutine-calls, which
- * could clobber r8 and r9 (among others).  Thus, be careful not to evaluate it while
- * using r8/r9.
- */
-#define __do_get_user(check, x, ptr, size)						\
-({											\
-	const __typeof__(*(ptr)) __user *__gu_ptr = (ptr);				\
-	__typeof__ (size) __gu_size = (size);						\
-	long __gu_err = -EFAULT;							\
-	unsigned long __gu_val = 0;							\
-	if (!check || __access_ok(__gu_ptr, size))					\
-		switch (__gu_size) {							\
-		      case 1: __get_user_size(__gu_val, __gu_ptr, 1, __gu_err); break;	\
-		      case 2: __get_user_size(__gu_val, __gu_ptr, 2, __gu_err); break;	\
-		      case 4: __get_user_size(__gu_val, __gu_ptr, 4, __gu_err); break;	\
-		      case 8: __get_user_size(__gu_val, __gu_ptr, 8, __gu_err); break;	\
-		      default: __get_user_unknown(); break;				\
-		}									\
-	(x) = (__force __typeof__(*(__gu_ptr))) __gu_val;				\
-	__gu_err;									\
-})
-
-#define __get_user_nocheck(x, ptr, size)	__do_get_user(0, x, ptr, size)
-#define __get_user_check(x, ptr, size)	__do_get_user(1, x, ptr, size)
-
-extern void __put_user_unknown (void);
-
-/*
- * Evaluating arguments X, PTR, SIZE, and SEGMENT may involve subroutine-calls, which
- * could clobber r8 (among others).  Thus, be careful not to evaluate them while using r8.
- */
-#define __do_put_user(check, x, ptr, size)						\
-({											\
-	__typeof__ (x) __pu_x = (x);							\
-	__typeof__ (*(ptr)) __user *__pu_ptr = (ptr);					\
-	__typeof__ (size) __pu_size = (size);						\
-	long __pu_err = -EFAULT;							\
-											\
-	if (!check || __access_ok(__pu_ptr, __pu_size))					\
-		switch (__pu_size) {							\
-		      case 1: __put_user_size(__pu_x, __pu_ptr, 1, __pu_err); break;	\
-		      case 2: __put_user_size(__pu_x, __pu_ptr, 2, __pu_err); break;	\
-		      case 4: __put_user_size(__pu_x, __pu_ptr, 4, __pu_err); break;	\
-		      case 8: __put_user_size(__pu_x, __pu_ptr, 8, __pu_err); break;	\
-		      default: __put_user_unknown(); break;				\
-		}									\
-	__pu_err;									\
-})
-
-#define __put_user_nocheck(x, ptr, size)	__do_put_user(0, x, ptr, size)
-#define __put_user_check(x, ptr, size)	__do_put_user(1, x, ptr, size)
-
-/*
- * Complex access routines
- */
-extern unsigned long __must_check __copy_user (void __user *to, const void __user *from,
-					       unsigned long count);
-
-static inline unsigned long
-raw_copy_to_user(void __user *to, const void *from, unsigned long count)
-{
-	return __copy_user(to, (__force void __user *) from, count);
-}
-
-static inline unsigned long
-raw_copy_from_user(void *to, const void __user *from, unsigned long count)
-{
-	return __copy_user((__force void __user *) to, from, count);
-}
-
-#define INLINE_COPY_FROM_USER
-#define INLINE_COPY_TO_USER
-
-extern unsigned long __do_clear_user (void __user *, unsigned long);
-
-#define __clear_user(to, n)		__do_clear_user(to, n)
-
-#define clear_user(to, n)					\
-({								\
-	unsigned long __cu_len = (n);				\
-	if (__access_ok(to, __cu_len))				\
-		__cu_len = __do_clear_user(to, __cu_len);	\
-	__cu_len;						\
-})
-
-
-/*
- * Returns: -EFAULT if exception before terminator, N if the entire buffer filled, else
- * strlen.
- */
-extern long __must_check __strncpy_from_user (char *to, const char __user *from, long to_len);
-
-#define strncpy_from_user(to, from, n)					\
-({									\
-	const char __user * __sfu_from = (from);			\
-	long __sfu_ret = -EFAULT;					\
-	if (__access_ok(__sfu_from, 0))					\
-		__sfu_ret = __strncpy_from_user((to), __sfu_from, (n));	\
-	__sfu_ret;							\
-})
-
-/*
- * Returns: 0 if exception before NUL or reaching the supplied limit
- * (N), a value greater than N if the limit would be exceeded, else
- * strlen.
- */
-extern unsigned long __strnlen_user (const char __user *, long);
-
-#define strnlen_user(str, len)					\
-({								\
-	const char __user *__su_str = (str);			\
-	unsigned long __su_ret = 0;				\
-	if (__access_ok(__su_str, 0))				\
-		__su_ret = __strnlen_user(__su_str, len);	\
-	__su_ret;						\
-})
-
-#define ARCH_HAS_TRANSLATE_MEM_PTR	1
-static __inline__ void *
-xlate_dev_mem_ptr(phys_addr_t p)
-{
-	struct page *page;
-	void *ptr;
-
-	page = pfn_to_page(p >> PAGE_SHIFT);
-	if (PageUncached(page))
-		ptr = (void *)p + __IA64_UNCACHED_OFFSET;
-	else
-		ptr = __va(p);
-
-	return ptr;
-}
-
-#endif /* _ASM_IA64_UACCESS_H */