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The Itanium architecture is obsolete, and an informal survey [0] reveals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, 412 deletions

diff --git a/arch/ia64/kernel/signal.c b/arch/ia64/kernel/signal.c
deleted file mode 100644
index 51cf6a7ec158ab..00000000000000
--- a/arch/ia64/kernel/signal.c
+++ /dev/null
@@ -1,412 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-/*
- * Architecture-specific signal handling support.
- *
- * Copyright (C) 1999-2004 Hewlett-Packard Co
- *	David Mosberger-Tang <davidm@hpl.hp.com>
- *
- * Derived from i386 and Alpha versions.
- */
-
-#include <linux/errno.h>
-#include <linux/kernel.h>
-#include <linux/mm.h>
-#include <linux/ptrace.h>
-#include <linux/sched.h>
-#include <linux/signal.h>
-#include <linux/smp.h>
-#include <linux/stddef.h>
-#include <linux/tty.h>
-#include <linux/binfmts.h>
-#include <linux/unistd.h>
-#include <linux/wait.h>
-
-#include <asm/intrinsics.h>
-#include <linux/uaccess.h>
-#include <asm/rse.h>
-#include <asm/sigcontext.h>
-
-#include "sigframe.h"
-
-#define DEBUG_SIG	0
-#define STACK_ALIGN	16		/* minimal alignment for stack pointer */
-
-#if _NSIG_WORDS > 1
-# define PUT_SIGSET(k,u)	__copy_to_user((u)->sig, (k)->sig, sizeof(sigset_t))
-# define GET_SIGSET(k,u)	__copy_from_user((k)->sig, (u)->sig, sizeof(sigset_t))
-#else
-# define PUT_SIGSET(k,u)	__put_user((k)->sig[0], &(u)->sig[0])
-# define GET_SIGSET(k,u)	__get_user((k)->sig[0], &(u)->sig[0])
-#endif
-
-static long
-restore_sigcontext (struct sigcontext __user *sc, struct sigscratch *scr)
-{
-	unsigned long ip, flags, nat, um, cfm, rsc;
-	long err;
-
-	/* Always make any pending restarted system calls return -EINTR */
-	current->restart_block.fn = do_no_restart_syscall;
-
-	/* restore scratch that always needs gets updated during signal delivery: */
-	err  = __get_user(flags, &sc->sc_flags);
-	err |= __get_user(nat, &sc->sc_nat);
-	err |= __get_user(ip, &sc->sc_ip);			/* instruction pointer */
-	err |= __get_user(cfm, &sc->sc_cfm);
-	err |= __get_user(um, &sc->sc_um);			/* user mask */
-	err |= __get_user(rsc, &sc->sc_ar_rsc);
-	err |= __get_user(scr->pt.ar_unat, &sc->sc_ar_unat);
-	err |= __get_user(scr->pt.ar_fpsr, &sc->sc_ar_fpsr);
-	err |= __get_user(scr->pt.ar_pfs, &sc->sc_ar_pfs);
-	err |= __get_user(scr->pt.pr, &sc->sc_pr);		/* predicates */
-	err |= __get_user(scr->pt.b0, &sc->sc_br[0]);		/* b0 (rp) */
-	err |= __get_user(scr->pt.b6, &sc->sc_br[6]);		/* b6 */
-	err |= __copy_from_user(&scr->pt.r1, &sc->sc_gr[1], 8);	/* r1 */
-	err |= __copy_from_user(&scr->pt.r8, &sc->sc_gr[8], 4*8);	/* r8-r11 */
-	err |= __copy_from_user(&scr->pt.r12, &sc->sc_gr[12], 2*8);	/* r12-r13 */
-	err |= __copy_from_user(&scr->pt.r15, &sc->sc_gr[15], 8);	/* r15 */
-
-	scr->pt.cr_ifs = cfm | (1UL << 63);
-	scr->pt.ar_rsc = rsc | (3 << 2); /* force PL3 */
-
-	/* establish new instruction pointer: */
-	scr->pt.cr_iip = ip & ~0x3UL;
-	ia64_psr(&scr->pt)->ri = ip & 0x3;
-	scr->pt.cr_ipsr = (scr->pt.cr_ipsr & ~IA64_PSR_UM) | (um & IA64_PSR_UM);
-
-	scr->scratch_unat = ia64_put_scratch_nat_bits(&scr->pt, nat);
-
-	if (!(flags & IA64_SC_FLAG_IN_SYSCALL)) {
-		/* Restore most scratch-state only when not in syscall. */
-		err |= __get_user(scr->pt.ar_ccv, &sc->sc_ar_ccv);		/* ar.ccv */
-		err |= __get_user(scr->pt.b7, &sc->sc_br[7]);			/* b7 */
-		err |= __get_user(scr->pt.r14, &sc->sc_gr[14]);			/* r14 */
-		err |= __copy_from_user(&scr->pt.ar_csd, &sc->sc_ar25, 2*8); /* ar.csd & ar.ssd */
-		err |= __copy_from_user(&scr->pt.r2, &sc->sc_gr[2], 2*8);	/* r2-r3 */
-		err |= __copy_from_user(&scr->pt.r16, &sc->sc_gr[16], 16*8);	/* r16-r31 */
-	}
-
-	if ((flags & IA64_SC_FLAG_FPH_VALID) != 0) {
-		struct ia64_psr *psr = ia64_psr(&scr->pt);
-
-		err |= __copy_from_user(current->thread.fph, &sc->sc_fr[32], 96*16);
-		psr->mfh = 0;	/* drop signal handler's fph contents... */
-		preempt_disable();
-		if (psr->dfh)
-			ia64_drop_fpu(current);
-		else {
-			/* We already own the local fph, otherwise psr->dfh wouldn't be 0.  */
-			__ia64_load_fpu(current->thread.fph);
-			ia64_set_local_fpu_owner(current);
-		}
-		preempt_enable();
-	}
-	return err;
-}
-
-long
-ia64_rt_sigreturn (struct sigscratch *scr)
-{
-	extern char ia64_strace_leave_kernel, ia64_leave_kernel;
-	struct sigcontext __user *sc;
-	sigset_t set;
-	long retval;
-
-	sc = &((struct sigframe __user *) (scr->pt.r12 + 16))->sc;
-
-	/*
-	 * When we return to the previously executing context, r8 and r10 have already
-	 * been setup the way we want them.  Indeed, if the signal wasn't delivered while
-	 * in a system call, we must not touch r8 or r10 as otherwise user-level state
-	 * could be corrupted.
-	 */
-	retval = (long) &ia64_leave_kernel;
-	if (test_thread_flag(TIF_SYSCALL_TRACE)
-	    || test_thread_flag(TIF_SYSCALL_AUDIT))
-		/*
-		 * strace expects to be notified after sigreturn returns even though the
-		 * context to which we return may not be in the middle of a syscall.
-		 * Thus, the return-value that strace displays for sigreturn is
-		 * meaningless.
-		 */
-		retval = (long) &ia64_strace_leave_kernel;
-
-	if (!access_ok(sc, sizeof(*sc)))
-		goto give_sigsegv;
-
-	if (GET_SIGSET(&set, &sc->sc_mask))
-		goto give_sigsegv;
-
-	set_current_blocked(&set);
-
-	if (restore_sigcontext(sc, scr))
-		goto give_sigsegv;
-
-#if DEBUG_SIG
-	printk("SIG return (%s:%d): sp=%lx ip=%lx\n",
-	       current->comm, current->pid, scr->pt.r12, scr->pt.cr_iip);
-#endif
-	if (restore_altstack(&sc->sc_stack))
-		goto give_sigsegv;
-	return retval;
-
-  give_sigsegv:
-	force_sig(SIGSEGV);
-	return retval;
-}
-
-/*
- * This does just the minimum required setup of sigcontext.
- * Specifically, it only installs data that is either not knowable at
- * the user-level or that gets modified before execution in the
- * trampoline starts.  Everything else is done at the user-level.
- */
-static long
-setup_sigcontext (struct sigcontext __user *sc, sigset_t *mask, struct sigscratch *scr)
-{
-	unsigned long flags = 0, ifs, cfm, nat;
-	long err = 0;
-
-	ifs = scr->pt.cr_ifs;
-
-	if (on_sig_stack((unsigned long) sc))
-		flags |= IA64_SC_FLAG_ONSTACK;
-	if ((ifs & (1UL << 63)) == 0)
-		/* if cr_ifs doesn't have the valid bit set, we got here through a syscall */
-		flags |= IA64_SC_FLAG_IN_SYSCALL;
-	cfm = ifs & ((1UL << 38) - 1);
-	ia64_flush_fph(current);
-	if ((current->thread.flags & IA64_THREAD_FPH_VALID)) {
-		flags |= IA64_SC_FLAG_FPH_VALID;
-		err = __copy_to_user(&sc->sc_fr[32], current->thread.fph, 96*16);
-	}
-
-	nat = ia64_get_scratch_nat_bits(&scr->pt, scr->scratch_unat);
-
-	err |= __put_user(flags, &sc->sc_flags);
-	err |= __put_user(nat, &sc->sc_nat);
-	err |= PUT_SIGSET(mask, &sc->sc_mask);
-	err |= __put_user(cfm, &sc->sc_cfm);
-	err |= __put_user(scr->pt.cr_ipsr & IA64_PSR_UM, &sc->sc_um);
-	err |= __put_user(scr->pt.ar_rsc, &sc->sc_ar_rsc);
-	err |= __put_user(scr->pt.ar_unat, &sc->sc_ar_unat);		/* ar.unat */
-	err |= __put_user(scr->pt.ar_fpsr, &sc->sc_ar_fpsr);		/* ar.fpsr */
-	err |= __put_user(scr->pt.ar_pfs, &sc->sc_ar_pfs);
-	err |= __put_user(scr->pt.pr, &sc->sc_pr);			/* predicates */
-	err |= __put_user(scr->pt.b0, &sc->sc_br[0]);			/* b0 (rp) */
-	err |= __put_user(scr->pt.b6, &sc->sc_br[6]);			/* b6 */
-	err |= __copy_to_user(&sc->sc_gr[1], &scr->pt.r1, 8);		/* r1 */
-	err |= __copy_to_user(&sc->sc_gr[8], &scr->pt.r8, 4*8);		/* r8-r11 */
-	err |= __copy_to_user(&sc->sc_gr[12], &scr->pt.r12, 2*8);	/* r12-r13 */
-	err |= __copy_to_user(&sc->sc_gr[15], &scr->pt.r15, 8);		/* r15 */
-	err |= __put_user(scr->pt.cr_iip + ia64_psr(&scr->pt)->ri, &sc->sc_ip);
-
-	if (!(flags & IA64_SC_FLAG_IN_SYSCALL)) {
-		/* Copy scratch regs to sigcontext if the signal didn't interrupt a syscall. */
-		err |= __put_user(scr->pt.ar_ccv, &sc->sc_ar_ccv);		/* ar.ccv */
-		err |= __put_user(scr->pt.b7, &sc->sc_br[7]);			/* b7 */
-		err |= __put_user(scr->pt.r14, &sc->sc_gr[14]);			/* r14 */
-		err |= __copy_to_user(&sc->sc_ar25, &scr->pt.ar_csd, 2*8); /* ar.csd & ar.ssd */
-		err |= __copy_to_user(&sc->sc_gr[2], &scr->pt.r2, 2*8);		/* r2-r3 */
-		err |= __copy_to_user(&sc->sc_gr[16], &scr->pt.r16, 16*8);	/* r16-r31 */
-	}
-	return err;
-}
-
-/*
- * Check whether the register-backing store is already on the signal stack.
- */
-static inline int
-rbs_on_sig_stack (unsigned long bsp)
-{
-	return (bsp - current->sas_ss_sp < current->sas_ss_size);
-}
-
-static long
-setup_frame(struct ksignal *ksig, sigset_t *set, struct sigscratch *scr)
-{
-	extern char __kernel_sigtramp[];
-	unsigned long tramp_addr, new_rbs = 0, new_sp;
-	struct sigframe __user *frame;
-	long err;
-
-	new_sp = scr->pt.r12;
-	tramp_addr = (unsigned long) __kernel_sigtramp;
-	if (ksig->ka.sa.sa_flags & SA_ONSTACK) {
-		int onstack = sas_ss_flags(new_sp);
-
-		if (onstack == 0) {
-			new_sp = current->sas_ss_sp + current->sas_ss_size;
-			/*
-			 * We need to check for the register stack being on the
-			 * signal stack separately, because it's switched
-			 * separately (memory stack is switched in the kernel,
-			 * register stack is switched in the signal trampoline).
-			 */
-			if (!rbs_on_sig_stack(scr->pt.ar_bspstore))
-				new_rbs = ALIGN(current->sas_ss_sp,
-						sizeof(long));
-		} else if (onstack == SS_ONSTACK) {
-			unsigned long check_sp;
-
-			/*
-			 * If we are on the alternate signal stack and would
-			 * overflow it, don't. Return an always-bogus address
-			 * instead so we will die with SIGSEGV.
-			 */
-			check_sp = (new_sp - sizeof(*frame)) & -STACK_ALIGN;
-			if (!likely(on_sig_stack(check_sp))) {
-				force_sigsegv(ksig->sig);
-				return 1;
-			}
-		}
-	}
-	frame = (void __user *) ((new_sp - sizeof(*frame)) & -STACK_ALIGN);
-
-	if (!access_ok(frame, sizeof(*frame))) {
-		force_sigsegv(ksig->sig);
-		return 1;
-	}
-
-	err  = __put_user(ksig->sig, &frame->arg0);
-	err |= __put_user(&frame->info, &frame->arg1);
-	err |= __put_user(&frame->sc, &frame->arg2);
-	err |= __put_user(new_rbs, &frame->sc.sc_rbs_base);
-	err |= __put_user(0, &frame->sc.sc_loadrs);	/* initialize to zero */
-	err |= __put_user(ksig->ka.sa.sa_handler, &frame->handler);
-
-	err |= copy_siginfo_to_user(&frame->info, &ksig->info);
-
-	err |= __save_altstack(&frame->sc.sc_stack, scr->pt.r12);
-	err |= setup_sigcontext(&frame->sc, set, scr);
-
-	if (unlikely(err)) {
-		force_sigsegv(ksig->sig);
-		return 1;
-	}
-
-	scr->pt.r12 = (unsigned long) frame - 16;	/* new stack pointer */
-	scr->pt.ar_fpsr = FPSR_DEFAULT;			/* reset fpsr for signal handler */
-	scr->pt.cr_iip = tramp_addr;
-	ia64_psr(&scr->pt)->ri = 0;			/* start executing in first slot */
-	ia64_psr(&scr->pt)->be = 0;			/* force little-endian byte-order */
-	/*
-	 * Force the interruption function mask to zero.  This has no effect when a
-	 * system-call got interrupted by a signal (since, in that case, scr->pt_cr_ifs is
-	 * ignored), but it has the desirable effect of making it possible to deliver a
-	 * signal with an incomplete register frame (which happens when a mandatory RSE
-	 * load faults).  Furthermore, it has no negative effect on the getting the user's
-	 * dirty partition preserved, because that's governed by scr->pt.loadrs.
-	 */
-	scr->pt.cr_ifs = (1UL << 63);
-
-	/*
-	 * Note: this affects only the NaT bits of the scratch regs (the ones saved in
-	 * pt_regs), which is exactly what we want.
-	 */
-	scr->scratch_unat = 0; /* ensure NaT bits of r12 is clear */
-
-#if DEBUG_SIG
-	printk("SIG deliver (%s:%d): sig=%d sp=%lx ip=%lx handler=%p\n",
-	       current->comm, current->pid, ksig->sig, scr->pt.r12, frame->sc.sc_ip, frame->handler);
-#endif
-	return 0;
-}
-
-static long
-handle_signal (struct ksignal *ksig, struct sigscratch *scr)
-{
-	int ret = setup_frame(ksig, sigmask_to_save(), scr);
-
-	if (!ret)
-		signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP));
-
-	return ret;
-}
-
-/*
- * Note that `init' is a special process: it doesn't get signals it doesn't want to
- * handle.  Thus you cannot kill init even with a SIGKILL even by mistake.
- */
-void
-ia64_do_signal (struct sigscratch *scr, long in_syscall)
-{
-	long restart = in_syscall;
-	long errno = scr->pt.r8;
-	struct ksignal ksig;
-
-	/*
-	 * This only loops in the rare cases of handle_signal() failing, in which case we
-	 * need to push through a forced SIGSEGV.
-	 */
-	while (1) {
-		if (!get_signal(&ksig))
-			break;
-
-		/*
-		 * get_signal() may have run a debugger (via notify_parent())
-		 * and the debugger may have modified the state (e.g., to arrange for an
-		 * inferior call), thus it's important to check for restarting _after_
-		 * get_signal().
-		 */
-		if ((long) scr->pt.r10 != -1)
-			/*
-			 * A system calls has to be restarted only if one of the error codes
-			 * ERESTARTNOHAND, ERESTARTSYS, or ERESTARTNOINTR is returned.  If r10
-			 * isn't -1 then r8 doesn't hold an error code and we don't need to
-			 * restart the syscall, so we can clear the "restart" flag here.
-			 */
-			restart = 0;
-
-		if (ksig.sig <= 0)
-			break;
-
-		if (unlikely(restart)) {
-			switch (errno) {
-			case ERESTART_RESTARTBLOCK:
-			case ERESTARTNOHAND:
-				scr->pt.r8 = EINTR;
-				/* note: scr->pt.r10 is already -1 */
-				break;
-			case ERESTARTSYS:
-				if ((ksig.ka.sa.sa_flags & SA_RESTART) == 0) {
-					scr->pt.r8 = EINTR;
-					/* note: scr->pt.r10 is already -1 */
-					break;
-				}
-				fallthrough;
-			case ERESTARTNOINTR:
-				ia64_decrement_ip(&scr->pt);
-				restart = 0; /* don't restart twice if handle_signal() fails... */
-			}
-		}
-
-		/*
-		 * Whee!  Actually deliver the signal.  If the delivery failed, we need to
-		 * continue to iterate in this loop so we can deliver the SIGSEGV...
-		 */
-		if (handle_signal(&ksig, scr))
-			return;
-	}
-
-	/* Did we come from a system call? */
-	if (restart) {
-		/* Restart the system call - no handlers present */
-		if (errno == ERESTARTNOHAND || errno == ERESTARTSYS || errno == ERESTARTNOINTR
-		    || errno == ERESTART_RESTARTBLOCK)
-		{
-			/*
-			 * Note: the syscall number is in r15 which is saved in
-			 * pt_regs so all we need to do here is adjust ip so that
-			 * the "break" instruction gets re-executed.
-			 */
-			ia64_decrement_ip(&scr->pt);
-			if (errno == ERESTART_RESTARTBLOCK)
-				scr->pt.r15 = __NR_restart_syscall;
-		}
-	}
-
-	/* if there's no signal to deliver, we just put the saved sigmask
-	 * back */
-	restore_saved_sigmask();
-}