parisc: Add cacheflush() syscall

Signed-off-by: Helge Deller <deller@gmx.de>

arch/parisc/include/uapi/asm/cachectl.h

+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+#ifndef _ASM_CACHECTL
+#define _ASM_CACHECTL
+
+/*
+ * Options for cacheflush system call
+ */
+#define ICACHE	(1<<0)		/* flush instruction cache	  */
+#define DCACHE	(1<<1)		/* writeback and flush data cache */
+#define BCACHE	(ICACHE|DCACHE) /* flush both caches		  */
+
+#endif	/* _ASM_CACHECTL */

arch/parisc/kernel/cache.c

@@ -19,6 +19,7 @@
 #include <linux/pagemap.h>
 #include <linux/sched.h>
 #include <linux/sched/mm.h>
+#include <linux/syscalls.h>
 #include <asm/pdc.h>
 #include <asm/cache.h>
 #include <asm/cacheflush.h>
@@ -28,6 +29,7 @@
 #include <asm/sections.h>
 #include <asm/shmparam.h>
 #include <asm/mmu_context.h>
+#include <asm/cachectl.h>
 
 int split_tlb __ro_after_init;
 int dcache_stride __ro_after_init;
@@ -790,3 +792,50 @@ void invalidate_kernel_vmap_range(void *vaddr, int size)
 	flush_tlb_kernel_range(start, end);
 }
 EXPORT_SYMBOL(invalidate_kernel_vmap_range);
+
+
+SYSCALL_DEFINE3(cacheflush, unsigned long, addr, unsigned long, bytes,
+	unsigned int, cache)
+{
+	unsigned long start, end;
+	ASM_EXCEPTIONTABLE_VAR(error);
+
+	if (bytes == 0)
+		return 0;
+	if (!access_ok((void __user *) addr, bytes))
+		return -EFAULT;
+
+	end = addr + bytes;
+
+	if (cache & DCACHE) {
+		start = addr;
+		__asm__ __volatile__ (
+#ifdef CONFIG_64BIT
+			"1: cmpb,*<<,n	%0,%2,1b\n"
+#else
+			"1: cmpb,<<,n	%0,%2,1b\n"
+#endif
+			"   fic,m	%3(%4,%0)\n"
+			"2: sync\n"
+			ASM_EXCEPTIONTABLE_ENTRY_EFAULT(1b, 2b)
+			: "+r" (start), "+r" (error)
+			: "r" (end), "r" (dcache_stride), "i" (SR_USER));
+	}
+
+	if (cache & ICACHE && error == 0) {
+		start = addr;
+		__asm__ __volatile__ (
+#ifdef CONFIG_64BIT
+			"1: cmpb,*<<,n	%0,%2,1b\n"
+#else
+			"1: cmpb,<<,n	%0,%2,1b\n"
+#endif
+			"   fdc,m	%3(%4,%0)\n"
+			"2: sync\n"
+			ASM_EXCEPTIONTABLE_ENTRY_EFAULT(1b, 2b)
+			: "+r" (start), "+r" (error)
+			: "r" (end), "r" (icache_stride), "i" (SR_USER));
+	}
+
+	return error;
+}

arch/parisc/kernel/syscalls/syscall.tbl

@@ -400,6 +400,7 @@
 353	common	pkey_free		sys_pkey_free
 354	common	rseq			sys_rseq
 355	common	kexec_file_load		sys_kexec_file_load		sys_kexec_file_load
+356	common	cacheflush		sys_cacheflush
 # up to 402 is unassigned and reserved for arch specific syscalls
 403	32	clock_gettime64			sys_clock_gettime		sys_clock_gettime
 404	32	clock_settime64			sys_clock_settime		sys_clock_settime