hexagon: use generic strncpy/strnlen from_user

Remove the hexagon implementation of strncpy/strnlen and instead use
the generic version. The hexagon version reads the data twice for
strncpy() by doing an extra strnlen(), and it apparently lacks a check
for user_addr_max().

Reviewed-by: Christoph Hellwig <[e-mail]>
Signed-off-by: Arnd Bergmann <[e-mail]>

arch/hexagon/Kconfig

···
 	# GENERIC_ALLOCATOR is used by dma_alloc_coherent()
 	select GENERIC_ALLOCATOR
 	select GENERIC_IRQ_SHOW
+	select GENERIC_STRNCPY_FROM_USER
+	select GENERIC_STRNLEN_USER
 	select HAVE_ARCH_KGDB
 	select HAVE_ARCH_TRACEHOOK
 	select NEED_SG_DMA_LENGTH

arch/hexagon/include/asm/uaccess.h

···
 __kernel_size_t __clear_user_hexagon(void __user *dest, unsigned long count);
 #define __clear_user(a, s) __clear_user_hexagon((a), (s))
 
-extern long __strnlen_user(const char __user *src, long n);
-
-static inline strnlen_user(const char __user *src, long n)
-{
-        if (!access_ok(src, 1))
-		return 0;
-
-	return __strnlen_user(src, n);
-}
-/*  get around the ifndef in asm-generic/uaccess.h  */
+extern long strnlen_user(const char __user *src, long n);
 #define strnlen_user strnlen_user
 
-static inline long strncpy_from_user(char *dst, const char __user *src, long n);
+extern long strncpy_from_user(char *dst, const char __user *src, long n)
 #define strncpy_from_user strncpy_from_user
 
 #include <asm-generic/uaccess.h>
 
-/*  Todo:  an actual accelerated version of this.  */
-static inline long strncpy_from_user(char *dst, const char __user *src, long n)
-{
-	long res = strnlen_user(src, n);
-
-	if (unlikely(!res))
-		return -EFAULT;
-
-	if (res > n) {
-		long left = raw_copy_from_user(dst, src, n);
-		if (unlikely(left))
-			memset(dst + (n - left), 0, left);
-		return n;
-	} else {
-		long left = raw_copy_from_user(dst, src, res);
-		if (unlikely(left))
-			memset(dst + (res - left), 0, left);
-		return res-1;
-	}
-}
 
 #endif

arch/hexagon/kernel/hexagon_ksyms.c

···
 EXPORT_SYMBOL(raw_copy_from_user);
 EXPORT_SYMBOL(raw_copy_to_user);
 EXPORT_SYMBOL(iounmap);
-EXPORT_SYMBOL(__strnlen_user);
 EXPORT_SYMBOL(__vmgetie);
 EXPORT_SYMBOL(__vmsetie);
 EXPORT_SYMBOL(__vmyield);

arch/hexagon/mm/Makefile

···
 #
 
 obj-y := init.o ioremap.o uaccess.o vm_fault.o cache.o
-obj-y += copy_to_user.o copy_from_user.o strnlen_user.o vm_tlb.o
+obj-y += copy_to_user.o copy_from_user.o vm_tlb.o

arch/hexagon/mm/strnlen_user.S

···
-/* SPDX-License-Identifier: GPL-2.0-only */
-/*
- * User string length functions for kernel
- *
- * Copyright (c) 2010-2011, The Linux Foundation. All rights reserved.
- */
-
-#define isrc	r0
-#define max	r1	/*  Do not change!  */
-
-#define end	r2
-#define tmp1	r3
-
-#define obo	r6	/*  off-by-one  */
-#define start	r7
-#define mod8	r8
-#define dbuf    r15:14
-#define dcmp	r13:12
-
-/*
- * The vector mask version of this turned out *really* badly.
- * The hardware loop version also turned out *really* badly.
- * Seems straight pointer arithmetic basically wins here.
- */
-
-#define fname __strnlen_user
-
-	.text
-	.global fname
-	.type fname, @function
-	.p2align 5  /*  why?  */
-fname:
-	{
-		mod8 = and(isrc,#7);
-		end = add(isrc,max);
-		start = isrc;
-	}
-	{
-		P0 = cmp.eq(mod8,#0);
-		mod8 = and(end,#7);
-		dcmp = #0;
-		if (P0.new) jump:t dw_loop;	/*  fire up the oven  */
-	}
-
-alignment_loop:
-fail_1:	{
-		tmp1 = memb(start++#1);
-	}
-	{
-		P0 = cmp.eq(tmp1,#0);
-		if (P0.new) jump:nt exit_found;
-		P1 = cmp.gtu(end,start);
-		mod8 = and(start,#7);
-	}
-	{
-		if (!P1) jump exit_error;  /*  hit the end  */
-		P0 = cmp.eq(mod8,#0);
-	}
-	{
-		if (!P0) jump alignment_loop;
-	}
-
-
-
-dw_loop:
-fail_2:	{
-		dbuf = memd(start);
-		obo = add(start,#1);
-	}
-	{
-		P0 = vcmpb.eq(dbuf,dcmp);
-	}
-	{
-		tmp1 = P0;
-		P0 = cmp.gtu(end,start);
-	}
-	{
-		tmp1 = ct0(tmp1);
-		mod8 = and(end,#7);
-		if (!P0) jump end_check;
-	}
-	{
-		P0 = cmp.eq(tmp1,#32);
-		if (!P0.new) jump:nt exit_found;
-		if (!P0.new) start = add(obo,tmp1);
-	}
-	{
-		start = add(start,#8);
-		jump dw_loop;
-	}	/*  might be nice to combine these jumps...   */
-
-
-end_check:
-	{
-		P0 = cmp.gt(tmp1,mod8);
-		if (P0.new) jump:nt exit_error;	/*  neverfound!  */
-		start = add(obo,tmp1);
-	}
-
-exit_found:
-	{
-		R0 = sub(start,isrc);
-		jumpr R31;
-	}
-
-exit_error:
-	{
-		R0 = add(max,#1);
-		jumpr R31;
-	}
-
-	/*  Uh, what does the "fixup" return here?  */
-	.falign
-fix_1:
-	{
-		R0 = #0;
-		jumpr R31;
-	}
-
-	.size fname,.-fname
-
-
-.section __ex_table,"a"
-.long fail_1,fix_1
-.long fail_2,fix_1
-.previous