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The Itanium architecture is obsolete, and an informal survey [0] reveals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

5 files changed, 2 insertions, 96 deletions

diff --git a/drivers/misc/sgi-gru/gru.h b/drivers/misc/sgi-gru/gru.h
index 3ad76cd18b4b..6ae045037219 100644
--- a/drivers/misc/sgi-gru/gru.h
+++ b/drivers/misc/sgi-gru/gru.h
@@ -30,9 +30,7 @@
 /*
  * Size used to map GRU GSeg
  */
-#if defined(CONFIG_IA64)
-#define GRU_GSEG_PAGESIZE	(256 * 1024UL)
-#elif defined(CONFIG_X86_64)
+#if defined(CONFIG_X86_64)
 #define GRU_GSEG_PAGESIZE	(256 * 1024UL)		/* ZZZ 2MB ??? */
 #else
 #error "Unsupported architecture"
diff --git a/drivers/misc/sgi-gru/gru_instructions.h b/drivers/misc/sgi-gru/gru_instructions.h
index 04d5170ac149..da5eb9edf9ec 100644
--- a/drivers/misc/sgi-gru/gru_instructions.h
+++ b/drivers/misc/sgi-gru/gru_instructions.h
@@ -29,17 +29,7 @@ extern void gru_wait_abort_proc(void *cb);
  * Architecture dependent functions
  */
 
-#if defined(CONFIG_IA64)
-#include <linux/compiler.h>
-#include <asm/intrinsics.h>
-#define __flush_cache(p)		ia64_fc((unsigned long)p)
-/* Use volatile on IA64 to ensure ordering via st4.rel */
-#define gru_ordered_store_ulong(p, v)					\
-		do {							\
-			barrier();					\
-			*((volatile unsigned long *)(p)) = v; /* force st.rel */	\
-		} while (0)
-#elif defined(CONFIG_X86_64)
+#if defined(CONFIG_X86_64)
 #include <asm/cacheflush.h>
 #define __flush_cache(p)		clflush(p)
 #define gru_ordered_store_ulong(p, v)					\
diff --git a/drivers/misc/sgi-gru/grufile.c b/drivers/misc/sgi-gru/grufile.c
index a3d659c11cc4..e755690c9805 100644
--- a/drivers/misc/sgi-gru/grufile.c
+++ b/drivers/misc/sgi-gru/grufile.c
@@ -337,72 +337,6 @@ static unsigned long gru_chiplet_cpu_to_mmr(int chiplet, int cpu, int *corep)
 	return mmr;
 }
 
-#ifdef CONFIG_IA64
-
-static int gru_irq_count[GRU_CHIPLETS_PER_BLADE];
-
-static void gru_noop(struct irq_data *d)
-{
-}
-
-static struct irq_chip gru_chip[GRU_CHIPLETS_PER_BLADE] = {
-	[0 ... GRU_CHIPLETS_PER_BLADE - 1] {
-		.irq_mask	= gru_noop,
-		.irq_unmask	= gru_noop,
-		.irq_ack	= gru_noop
-	}
-};
-
-static int gru_chiplet_setup_tlb_irq(int chiplet, char *irq_name,
-			irq_handler_t irq_handler, int cpu, int blade)
-{
-	unsigned long mmr;
-	int irq = IRQ_GRU + chiplet;
-	int ret, core;
-
-	mmr = gru_chiplet_cpu_to_mmr(chiplet, cpu, &core);
-	if (mmr == 0)
-		return 0;
-
-	if (gru_irq_count[chiplet] == 0) {
-		gru_chip[chiplet].name = irq_name;
-		ret = irq_set_chip(irq, &gru_chip[chiplet]);
-		if (ret) {
-			printk(KERN_ERR "%s: set_irq_chip failed, errno=%d\n",
-			       GRU_DRIVER_ID_STR, -ret);
-			return ret;
-		}
-
-		ret = request_irq(irq, irq_handler, 0, irq_name, NULL);
-		if (ret) {
-			printk(KERN_ERR "%s: request_irq failed, errno=%d\n",
-			       GRU_DRIVER_ID_STR, -ret);
-			return ret;
-		}
-	}
-	gru_irq_count[chiplet]++;
-
-	return 0;
-}
-
-static void gru_chiplet_teardown_tlb_irq(int chiplet, int cpu, int blade)
-{
-	unsigned long mmr;
-	int core, irq = IRQ_GRU + chiplet;
-
-	if (gru_irq_count[chiplet] == 0)
-		return;
-
-	mmr = gru_chiplet_cpu_to_mmr(chiplet, cpu, &core);
-	if (mmr == 0)
-		return;
-
-	if (--gru_irq_count[chiplet] == 0)
-		free_irq(irq, NULL);
-}
-
-#elif defined CONFIG_X86_64
-
 static int gru_chiplet_setup_tlb_irq(int chiplet, char *irq_name,
 			irq_handler_t irq_handler, int cpu, int blade)
 {
@@ -447,8 +381,6 @@ static void gru_chiplet_teardown_tlb_irq(int chiplet, int cpu, int blade)
 	}
 }
 
-#endif
-
 static void gru_teardown_tlb_irqs(void)
 {
 	int blade;
@@ -514,12 +446,8 @@ static int __init gru_init(void)
 	if (!gru_supported())
 		return 0;
 
-#if defined CONFIG_IA64
-	gru_start_paddr = 0xd000000000UL; /* ZZZZZZZZZZZZZZZZZZZ fixme */
-#else
 	gru_start_paddr = uv_read_local_mmr(UVH_RH_GAM_GRU_OVERLAY_CONFIG) &
 				0x7fffffffffffUL;
-#endif
 	gru_start_vaddr = __va(gru_start_paddr);
 	gru_end_paddr = gru_start_paddr + GRU_MAX_BLADES * GRU_SIZE;
 	printk(KERN_INFO "GRU space: 0x%lx - 0x%lx\n",
diff --git a/drivers/misc/sgi-gru/gruhandles.c b/drivers/misc/sgi-gru/gruhandles.c
index 1d75d5e540bc..695316a83b01 100644
--- a/drivers/misc/sgi-gru/gruhandles.c
+++ b/drivers/misc/sgi-gru/gruhandles.c
@@ -11,16 +11,10 @@
 #include "grutables.h"
 
 /* 10 sec */
-#ifdef CONFIG_IA64
-#include <asm/processor.h>
-#define GRU_OPERATION_TIMEOUT	(((cycles_t) local_cpu_data->itc_freq)*10)
-#define CLKS2NSEC(c)		((c) *1000000000 / local_cpu_data->itc_freq)
-#else
 #include <linux/sync_core.h>
 #include <asm/tsc.h>
 #define GRU_OPERATION_TIMEOUT	((cycles_t) tsc_khz*10*1000)
 #define CLKS2NSEC(c)		((c) * 1000000 / tsc_khz)
-#endif
 
 /* Extract the status field from a kernel handle */
 #define GET_MSEG_HANDLE_STATUS(h)	(((*(unsigned long *)(h)) >> 16) & 3)
diff --git a/drivers/misc/sgi-gru/grumain.c b/drivers/misc/sgi-gru/grumain.c
index 4eb4b9455139..0f5b09e290c8 100644
--- a/drivers/misc/sgi-gru/grumain.c
+++ b/drivers/misc/sgi-gru/grumain.c
@@ -41,16 +41,12 @@ struct device *grudev = &gru_device;
  */
 int gru_cpu_fault_map_id(void)
 {
-#ifdef CONFIG_IA64
-	return uv_blade_processor_id() % GRU_NUM_TFM;
-#else
 	int cpu = smp_processor_id();
 	int id, core;
 
 	core = uv_cpu_core_number(cpu);
 	id = core + UV_MAX_INT_CORES * uv_cpu_socket_number(cpu);
 	return id;
-#endif
 }
 
 /*--------- ASID Management -------------------------------------------