Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

12 files changed, 1455 insertions, 0 deletions

diff --git a/arch/riscv/lib/Makefile b/arch/riscv/lib/Makefile
new file mode 100644
index 0000000000..26cb2502ec
--- /dev/null
+++ b/arch/riscv/lib/Makefile
@@ -0,0 +1,13 @@
+# SPDX-License-Identifier: GPL-2.0-only
+lib-y			+= delay.o
+lib-y			+= memcpy.o
+lib-y			+= memset.o
+lib-y			+= memmove.o
+lib-y			+= strcmp.o
+lib-y			+= strlen.o
+lib-y			+= strncmp.o
+lib-$(CONFIG_MMU)	+= uaccess.o
+lib-$(CONFIG_64BIT)	+= tishift.o
+lib-$(CONFIG_RISCV_ISA_ZICBOZ)	+= clear_page.o
+
+obj-$(CONFIG_FUNCTION_ERROR_INJECTION) += error-inject.o
diff --git a/arch/riscv/lib/clear_page.S b/arch/riscv/lib/clear_page.S
new file mode 100644
index 0000000000..d7a256eb53
--- /dev/null
+++ b/arch/riscv/lib/clear_page.S
@@ -0,0 +1,74 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (c) 2023 Ventana Micro Systems Inc.
+ */
+
+#include <linux/linkage.h>
+#include <asm/asm.h>
+#include <asm/alternative-macros.h>
+#include <asm-generic/export.h>
+#include <asm/hwcap.h>
+#include <asm/insn-def.h>
+#include <asm/page.h>
+
+#define CBOZ_ALT(order, old, new)				\
+	ALTERNATIVE(old, new, 0,				\
+		    ((order) << 16) | RISCV_ISA_EXT_ZICBOZ,	\
+		    CONFIG_RISCV_ISA_ZICBOZ)
+
+/* void clear_page(void *page) */
+SYM_FUNC_START(clear_page)
+	li	a2, PAGE_SIZE
+
+	/*
+	 * If Zicboz isn't present, or somehow has a block
+	 * size larger than 4K, then fallback to memset.
+	 */
+	CBOZ_ALT(12, "j .Lno_zicboz", "nop")
+
+	lw	a1, riscv_cboz_block_size
+	add	a2, a0, a2
+.Lzero_loop:
+	CBO_zero(a0)
+	add	a0, a0, a1
+	CBOZ_ALT(11, "bltu a0, a2, .Lzero_loop; ret", "nop; nop")
+	CBO_zero(a0)
+	add	a0, a0, a1
+	CBOZ_ALT(10, "bltu a0, a2, .Lzero_loop; ret", "nop; nop")
+	CBO_zero(a0)
+	add	a0, a0, a1
+	CBO_zero(a0)
+	add	a0, a0, a1
+	CBOZ_ALT(9, "bltu a0, a2, .Lzero_loop; ret", "nop; nop")
+	CBO_zero(a0)
+	add	a0, a0, a1
+	CBO_zero(a0)
+	add	a0, a0, a1
+	CBO_zero(a0)
+	add	a0, a0, a1
+	CBO_zero(a0)
+	add	a0, a0, a1
+	CBOZ_ALT(8, "bltu a0, a2, .Lzero_loop; ret", "nop; nop")
+	CBO_zero(a0)
+	add	a0, a0, a1
+	CBO_zero(a0)
+	add	a0, a0, a1
+	CBO_zero(a0)
+	add	a0, a0, a1
+	CBO_zero(a0)
+	add	a0, a0, a1
+	CBO_zero(a0)
+	add	a0, a0, a1
+	CBO_zero(a0)
+	add	a0, a0, a1
+	CBO_zero(a0)
+	add	a0, a0, a1
+	CBO_zero(a0)
+	add	a0, a0, a1
+	bltu	a0, a2, .Lzero_loop
+	ret
+.Lno_zicboz:
+	li	a1, 0
+	tail	__memset
+SYM_FUNC_END(clear_page)
+EXPORT_SYMBOL(clear_page)
diff --git a/arch/riscv/lib/delay.c b/arch/riscv/lib/delay.c
new file mode 100644
index 0000000000..49d510ba75
--- /dev/null
+++ b/arch/riscv/lib/delay.c
@@ -0,0 +1,111 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2012 Regents of the University of California
+ */
+
+#include <linux/delay.h>
+#include <linux/math.h>
+#include <linux/param.h>
+#include <linux/timex.h>
+#include <linux/types.h>
+#include <linux/export.h>
+
+#include <asm/processor.h>
+
+/*
+ * This is copies from arch/arm/include/asm/delay.h
+ *
+ * Loop (or tick) based delay:
+ *
+ * loops = loops_per_jiffy * jiffies_per_sec * delay_us / us_per_sec
+ *
+ * where:
+ *
+ * jiffies_per_sec = HZ
+ * us_per_sec = 1000000
+ *
+ * Therefore the constant part is HZ / 1000000 which is a small
+ * fractional number. To make this usable with integer math, we
+ * scale up this constant by 2^31, perform the actual multiplication,
+ * and scale the result back down by 2^31 with a simple shift:
+ *
+ * loops = (loops_per_jiffy * delay_us * UDELAY_MULT) >> 31
+ *
+ * where:
+ *
+ * UDELAY_MULT = 2^31 * HZ / 1000000
+ *             = (2^31 / 1000000) * HZ
+ *             = 2147.483648 * HZ
+ *             = 2147 * HZ + 483648 * HZ / 1000000
+ *
+ * 31 is the biggest scale shift value that won't overflow 32 bits for
+ * delay_us * UDELAY_MULT assuming HZ <= 1000 and delay_us <= 2000.
+ */
+#define MAX_UDELAY_US	2000
+#define MAX_UDELAY_HZ	1000
+#define UDELAY_MULT	(2147UL * HZ + 483648UL * HZ / 1000000UL)
+#define UDELAY_SHIFT	31
+
+#if HZ > MAX_UDELAY_HZ
+#error "HZ > MAX_UDELAY_HZ"
+#endif
+
+/*
+ * RISC-V supports both UDELAY and NDELAY.  This is largely the same as above,
+ * but with different constants.  I added 10 bits to the shift to get this, but
+ * the result is that I need a 64-bit multiply, which is slow on 32-bit
+ * platforms.
+ *
+ * NDELAY_MULT = 2^41 * HZ / 1000000000
+ *             = (2^41 / 1000000000) * HZ
+ *             = 2199.02325555 * HZ
+ *             = 2199 * HZ + 23255550 * HZ / 1000000000
+ *
+ * The maximum here is to avoid 64-bit overflow, but it isn't checked as it
+ * won't happen.
+ */
+#define MAX_NDELAY_NS   (1ULL << 42)
+#define MAX_NDELAY_HZ	MAX_UDELAY_HZ
+#define NDELAY_MULT	((unsigned long long)(2199ULL * HZ + 23255550ULL * HZ / 1000000000ULL))
+#define NDELAY_SHIFT	41
+
+#if HZ > MAX_NDELAY_HZ
+#error "HZ > MAX_NDELAY_HZ"
+#endif
+
+void __delay(unsigned long cycles)
+{
+	u64 t0 = get_cycles();
+
+	while ((unsigned long)(get_cycles() - t0) < cycles)
+		cpu_relax();
+}
+EXPORT_SYMBOL(__delay);
+
+void udelay(unsigned long usecs)
+{
+	u64 ucycles = (u64)usecs * lpj_fine * UDELAY_MULT;
+	u64 n;
+
+	if (unlikely(usecs > MAX_UDELAY_US)) {
+		n = (u64)usecs * riscv_timebase;
+		do_div(n, 1000000);
+
+		__delay(n);
+		return;
+	}
+
+	__delay(ucycles >> UDELAY_SHIFT);
+}
+EXPORT_SYMBOL(udelay);
+
+void ndelay(unsigned long nsecs)
+{
+	/*
+	 * This doesn't bother checking for overflow, as it won't happen (it's
+	 * an hour) of delay.
+	 */
+	unsigned long long ncycles = nsecs * lpj_fine * NDELAY_MULT;
+	__delay(ncycles >> NDELAY_SHIFT);
+}
+EXPORT_SYMBOL(ndelay);
diff --git a/arch/riscv/lib/error-inject.c b/arch/riscv/lib/error-inject.c
new file mode 100644
index 0000000000..d667ade2bc
--- /dev/null
+++ b/arch/riscv/lib/error-inject.c
@@ -0,0 +1,10 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/error-injection.h>
+#include <linux/kprobes.h>
+
+void override_function_with_return(struct pt_regs *regs)
+{
+	instruction_pointer_set(regs, regs->ra);
+}
+NOKPROBE_SYMBOL(override_function_with_return);
diff --git a/arch/riscv/lib/memcpy.S b/arch/riscv/lib/memcpy.S
new file mode 100644
index 0000000000..1a40d01a95
--- /dev/null
+++ b/arch/riscv/lib/memcpy.S
@@ -0,0 +1,110 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2013 Regents of the University of California
+ */
+
+#include <linux/linkage.h>
+#include <asm/asm.h>
+
+/* void *memcpy(void *, const void *, size_t) */
+ENTRY(__memcpy)
+WEAK(memcpy)
+	move t6, a0  /* Preserve return value */
+
+	/* Defer to byte-oriented copy for small sizes */
+	sltiu a3, a2, 128
+	bnez a3, 4f
+	/* Use word-oriented copy only if low-order bits match */
+	andi a3, t6, SZREG-1
+	andi a4, a1, SZREG-1
+	bne a3, a4, 4f
+
+	beqz a3, 2f  /* Skip if already aligned */
+	/*
+	 * Round to nearest double word-aligned address
+	 * greater than or equal to start address
+	 */
+	andi a3, a1, ~(SZREG-1)
+	addi a3, a3, SZREG
+	/* Handle initial misalignment */
+	sub a4, a3, a1
+1:
+	lb a5, 0(a1)
+	addi a1, a1, 1
+	sb a5, 0(t6)
+	addi t6, t6, 1
+	bltu a1, a3, 1b
+	sub a2, a2, a4  /* Update count */
+
+2:
+	andi a4, a2, ~((16*SZREG)-1)
+	beqz a4, 4f
+	add a3, a1, a4
+3:
+	REG_L a4,       0(a1)
+	REG_L a5,   SZREG(a1)
+	REG_L a6, 2*SZREG(a1)
+	REG_L a7, 3*SZREG(a1)
+	REG_L t0, 4*SZREG(a1)
+	REG_L t1, 5*SZREG(a1)
+	REG_L t2, 6*SZREG(a1)
+	REG_L t3, 7*SZREG(a1)
+	REG_L t4, 8*SZREG(a1)
+	REG_L t5, 9*SZREG(a1)
+	REG_S a4,       0(t6)
+	REG_S a5,   SZREG(t6)
+	REG_S a6, 2*SZREG(t6)
+	REG_S a7, 3*SZREG(t6)
+	REG_S t0, 4*SZREG(t6)
+	REG_S t1, 5*SZREG(t6)
+	REG_S t2, 6*SZREG(t6)
+	REG_S t3, 7*SZREG(t6)
+	REG_S t4, 8*SZREG(t6)
+	REG_S t5, 9*SZREG(t6)
+	REG_L a4, 10*SZREG(a1)
+	REG_L a5, 11*SZREG(a1)
+	REG_L a6, 12*SZREG(a1)
+	REG_L a7, 13*SZREG(a1)
+	REG_L t0, 14*SZREG(a1)
+	REG_L t1, 15*SZREG(a1)
+	addi a1, a1, 16*SZREG
+	REG_S a4, 10*SZREG(t6)
+	REG_S a5, 11*SZREG(t6)
+	REG_S a6, 12*SZREG(t6)
+	REG_S a7, 13*SZREG(t6)
+	REG_S t0, 14*SZREG(t6)
+	REG_S t1, 15*SZREG(t6)
+	addi t6, t6, 16*SZREG
+	bltu a1, a3, 3b
+	andi a2, a2, (16*SZREG)-1  /* Update count */
+
+4:
+	/* Handle trailing misalignment */
+	beqz a2, 6f
+	add a3, a1, a2
+
+	/* Use word-oriented copy if co-aligned to word boundary */
+	or a5, a1, t6
+	or a5, a5, a3
+	andi a5, a5, 3
+	bnez a5, 5f
+7:
+	lw a4, 0(a1)
+	addi a1, a1, 4
+	sw a4, 0(t6)
+	addi t6, t6, 4
+	bltu a1, a3, 7b
+
+	ret
+
+5:
+	lb a4, 0(a1)
+	addi a1, a1, 1
+	sb a4, 0(t6)
+	addi t6, t6, 1
+	bltu a1, a3, 5b
+6:
+	ret
+END(__memcpy)
+SYM_FUNC_ALIAS(__pi_memcpy, __memcpy)
+SYM_FUNC_ALIAS(__pi___memcpy, __memcpy)
diff --git a/arch/riscv/lib/memmove.S b/arch/riscv/lib/memmove.S
new file mode 100644
index 0000000000..838ff2022f
--- /dev/null
+++ b/arch/riscv/lib/memmove.S
@@ -0,0 +1,318 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2022 Michael T. Kloos <michael@michaelkloos.com>
+ */
+
+#include <linux/linkage.h>
+#include <asm/asm.h>
+
+SYM_FUNC_START(__memmove)
+SYM_FUNC_START_WEAK(memmove)
+	/*
+	 * Returns
+	 *   a0 - dest
+	 *
+	 * Parameters
+	 *   a0 - Inclusive first byte of dest
+	 *   a1 - Inclusive first byte of src
+	 *   a2 - Length of copy n
+	 *
+	 * Because the return matches the parameter register a0,
+	 * we will not clobber or modify that register.
+	 *
+	 * Note: This currently only works on little-endian.
+	 * To port to big-endian, reverse the direction of shifts
+	 * in the 2 misaligned fixup copy loops.
+	 */
+
+	/* Return if nothing to do */
+	beq a0, a1, return_from_memmove
+	beqz a2, return_from_memmove
+
+	/*
+	 * Register Uses
+	 *      Forward Copy: a1 - Index counter of src
+	 *      Reverse Copy: a4 - Index counter of src
+	 *      Forward Copy: t3 - Index counter of dest
+	 *      Reverse Copy: t4 - Index counter of dest
+	 *   Both Copy Modes: t5 - Inclusive first multibyte/aligned of dest
+	 *   Both Copy Modes: t6 - Non-Inclusive last multibyte/aligned of dest
+	 *   Both Copy Modes: t0 - Link / Temporary for load-store
+	 *   Both Copy Modes: t1 - Temporary for load-store
+	 *   Both Copy Modes: t2 - Temporary for load-store
+	 *   Both Copy Modes: a5 - dest to src alignment offset
+	 *   Both Copy Modes: a6 - Shift ammount
+	 *   Both Copy Modes: a7 - Inverse Shift ammount
+	 *   Both Copy Modes: a2 - Alternate breakpoint for unrolled loops
+	 */
+
+	/*
+	 * Solve for some register values now.
+	 * Byte copy does not need t5 or t6.
+	 */
+	mv   t3, a0
+	add  t4, a0, a2
+	add  a4, a1, a2
+
+	/*
+	 * Byte copy if copying less than (2 * SZREG) bytes. This can
+	 * cause problems with the bulk copy implementation and is
+	 * small enough not to bother.
+	 */
+	andi t0, a2, -(2 * SZREG)
+	beqz t0, byte_copy
+
+	/*
+	 * Now solve for t5 and t6.
+	 */
+	andi t5, t3, -SZREG
+	andi t6, t4, -SZREG
+	/*
+	 * If dest(Register t3) rounded down to the nearest naturally
+	 * aligned SZREG address, does not equal dest, then add SZREG
+	 * to find the low-bound of SZREG alignment in the dest memory
+	 * region.  Note that this could overshoot the dest memory
+	 * region if n is less than SZREG.  This is one reason why
+	 * we always byte copy if n is less than SZREG.
+	 * Otherwise, dest is already naturally aligned to SZREG.
+	 */
+	beq  t5, t3, 1f
+		addi t5, t5, SZREG
+	1:
+
+	/*
+	 * If the dest and src are co-aligned to SZREG, then there is
+	 * no need for the full rigmarole of a full misaligned fixup copy.
+	 * Instead, do a simpler co-aligned copy.
+	 */
+	xor  t0, a0, a1
+	andi t1, t0, (SZREG - 1)
+	beqz t1, coaligned_copy
+	/* Fall through to misaligned fixup copy */
+
+misaligned_fixup_copy:
+	bltu a1, a0, misaligned_fixup_copy_reverse
+
+misaligned_fixup_copy_forward:
+	jal  t0, byte_copy_until_aligned_forward
+
+	andi a5, a1, (SZREG - 1) /* Find the alignment offset of src (a1) */
+	slli a6, a5, 3 /* Multiply by 8 to convert that to bits to shift */
+	sub  a5, a1, t3 /* Find the difference between src and dest */
+	andi a1, a1, -SZREG /* Align the src pointer */
+	addi a2, t6, SZREG /* The other breakpoint for the unrolled loop*/
+
+	/*
+	 * Compute The Inverse Shift
+	 * a7 = XLEN - a6 = XLEN + -a6
+	 * 2s complement negation to find the negative: -a6 = ~a6 + 1
+	 * Add that to XLEN.  XLEN = SZREG * 8.
+	 */
+	not  a7, a6
+	addi a7, a7, (SZREG * 8 + 1)
+
+	/*
+	 * Fix Misalignment Copy Loop - Forward
+	 * load_val0 = load_ptr[0];
+	 * do {
+	 * 	load_val1 = load_ptr[1];
+	 * 	store_ptr += 2;
+	 * 	store_ptr[0 - 2] = (load_val0 >> {a6}) | (load_val1 << {a7});
+	 *
+	 * 	if (store_ptr == {a2})
+	 * 		break;
+	 *
+	 * 	load_val0 = load_ptr[2];
+	 * 	load_ptr += 2;
+	 * 	store_ptr[1 - 2] = (load_val1 >> {a6}) | (load_val0 << {a7});
+	 *
+	 * } while (store_ptr != store_ptr_end);
+	 * store_ptr = store_ptr_end;
+	 */
+
+	REG_L t0, (0 * SZREG)(a1)
+	1:
+	REG_L t1, (1 * SZREG)(a1)
+	addi  t3, t3, (2 * SZREG)
+	srl   t0, t0, a6
+	sll   t2, t1, a7
+	or    t2, t0, t2
+	REG_S t2, ((0 * SZREG) - (2 * SZREG))(t3)
+
+	beq   t3, a2, 2f
+
+	REG_L t0, (2 * SZREG)(a1)
+	addi  a1, a1, (2 * SZREG)
+	srl   t1, t1, a6
+	sll   t2, t0, a7
+	or    t2, t1, t2
+	REG_S t2, ((1 * SZREG) - (2 * SZREG))(t3)
+
+	bne   t3, t6, 1b
+	2:
+	mv    t3, t6 /* Fix the dest pointer in case the loop was broken */
+
+	add  a1, t3, a5 /* Restore the src pointer */
+	j byte_copy_forward /* Copy any remaining bytes */
+
+misaligned_fixup_copy_reverse:
+	jal  t0, byte_copy_until_aligned_reverse
+
+	andi a5, a4, (SZREG - 1) /* Find the alignment offset of src (a4) */
+	slli a6, a5, 3 /* Multiply by 8 to convert that to bits to shift */
+	sub  a5, a4, t4 /* Find the difference between src and dest */
+	andi a4, a4, -SZREG /* Align the src pointer */
+	addi a2, t5, -SZREG /* The other breakpoint for the unrolled loop*/
+
+	/*
+	 * Compute The Inverse Shift
+	 * a7 = XLEN - a6 = XLEN + -a6
+	 * 2s complement negation to find the negative: -a6 = ~a6 + 1
+	 * Add that to XLEN.  XLEN = SZREG * 8.
+	 */
+	not  a7, a6
+	addi a7, a7, (SZREG * 8 + 1)
+
+	/*
+	 * Fix Misalignment Copy Loop - Reverse
+	 * load_val1 = load_ptr[0];
+	 * do {
+	 * 	load_val0 = load_ptr[-1];
+	 * 	store_ptr -= 2;
+	 * 	store_ptr[1] = (load_val0 >> {a6}) | (load_val1 << {a7});
+	 *
+	 * 	if (store_ptr == {a2})
+	 * 		break;
+	 *
+	 * 	load_val1 = load_ptr[-2];
+	 * 	load_ptr -= 2;
+	 * 	store_ptr[0] = (load_val1 >> {a6}) | (load_val0 << {a7});
+	 *
+	 * } while (store_ptr != store_ptr_end);
+	 * store_ptr = store_ptr_end;
+	 */
+
+	REG_L t1, ( 0 * SZREG)(a4)
+	1:
+	REG_L t0, (-1 * SZREG)(a4)
+	addi  t4, t4, (-2 * SZREG)
+	sll   t1, t1, a7
+	srl   t2, t0, a6
+	or    t2, t1, t2
+	REG_S t2, ( 1 * SZREG)(t4)
+
+	beq   t4, a2, 2f
+
+	REG_L t1, (-2 * SZREG)(a4)
+	addi  a4, a4, (-2 * SZREG)
+	sll   t0, t0, a7
+	srl   t2, t1, a6
+	or    t2, t0, t2
+	REG_S t2, ( 0 * SZREG)(t4)
+
+	bne   t4, t5, 1b
+	2:
+	mv    t4, t5 /* Fix the dest pointer in case the loop was broken */
+
+	add  a4, t4, a5 /* Restore the src pointer */
+	j byte_copy_reverse /* Copy any remaining bytes */
+
+/*
+ * Simple copy loops for SZREG co-aligned memory locations.
+ * These also make calls to do byte copies for any unaligned
+ * data at their terminations.
+ */
+coaligned_copy:
+	bltu a1, a0, coaligned_copy_reverse
+
+coaligned_copy_forward:
+	jal t0, byte_copy_until_aligned_forward
+
+	1:
+	REG_L t1, ( 0 * SZREG)(a1)
+	addi  a1, a1, SZREG
+	addi  t3, t3, SZREG
+	REG_S t1, (-1 * SZREG)(t3)
+	bne   t3, t6, 1b
+
+	j byte_copy_forward /* Copy any remaining bytes */
+
+coaligned_copy_reverse:
+	jal t0, byte_copy_until_aligned_reverse
+
+	1:
+	REG_L t1, (-1 * SZREG)(a4)
+	addi  a4, a4, -SZREG
+	addi  t4, t4, -SZREG
+	REG_S t1, ( 0 * SZREG)(t4)
+	bne   t4, t5, 1b
+
+	j byte_copy_reverse /* Copy any remaining bytes */
+
+/*
+ * These are basically sub-functions within the function.  They
+ * are used to byte copy until the dest pointer is in alignment.
+ * At which point, a bulk copy method can be used by the
+ * calling code.  These work on the same registers as the bulk
+ * copy loops.  Therefore, the register values can be picked
+ * up from where they were left and we avoid code duplication
+ * without any overhead except the call in and return jumps.
+ */
+byte_copy_until_aligned_forward:
+	beq  t3, t5, 2f
+	1:
+	lb   t1,  0(a1)
+	addi a1, a1, 1
+	addi t3, t3, 1
+	sb   t1, -1(t3)
+	bne  t3, t5, 1b
+	2:
+	jalr zero, 0x0(t0) /* Return to multibyte copy loop */
+
+byte_copy_until_aligned_reverse:
+	beq  t4, t6, 2f
+	1:
+	lb   t1, -1(a4)
+	addi a4, a4, -1
+	addi t4, t4, -1
+	sb   t1,  0(t4)
+	bne  t4, t6, 1b
+	2:
+	jalr zero, 0x0(t0) /* Return to multibyte copy loop */
+
+/*
+ * Simple byte copy loops.
+ * These will byte copy until they reach the end of data to copy.
+ * At that point, they will call to return from memmove.
+ */
+byte_copy:
+	bltu a1, a0, byte_copy_reverse
+
+byte_copy_forward:
+	beq  t3, t4, 2f
+	1:
+	lb   t1,  0(a1)
+	addi a1, a1, 1
+	addi t3, t3, 1
+	sb   t1, -1(t3)
+	bne  t3, t4, 1b
+	2:
+	ret
+
+byte_copy_reverse:
+	beq  t4, t3, 2f
+	1:
+	lb   t1, -1(a4)
+	addi a4, a4, -1
+	addi t4, t4, -1
+	sb   t1,  0(t4)
+	bne  t4, t3, 1b
+	2:
+
+return_from_memmove:
+	ret
+
+SYM_FUNC_END(memmove)
+SYM_FUNC_END(__memmove)
+SYM_FUNC_ALIAS(__pi_memmove, __memmove)
+SYM_FUNC_ALIAS(__pi___memmove, __memmove)
diff --git a/arch/riscv/lib/memset.S b/arch/riscv/lib/memset.S
new file mode 100644
index 0000000000..34c5360c67
--- /dev/null
+++ b/arch/riscv/lib/memset.S
@@ -0,0 +1,113 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2013 Regents of the University of California
+ */
+
+
+#include <linux/linkage.h>
+#include <asm/asm.h>
+
+/* void *memset(void *, int, size_t) */
+ENTRY(__memset)
+WEAK(memset)
+	move t0, a0  /* Preserve return value */
+
+	/* Defer to byte-oriented fill for small sizes */
+	sltiu a3, a2, 16
+	bnez a3, 4f
+
+	/*
+	 * Round to nearest XLEN-aligned address
+	 * greater than or equal to start address
+	 */
+	addi a3, t0, SZREG-1
+	andi a3, a3, ~(SZREG-1)
+	beq a3, t0, 2f  /* Skip if already aligned */
+	/* Handle initial misalignment */
+	sub a4, a3, t0
+1:
+	sb a1, 0(t0)
+	addi t0, t0, 1
+	bltu t0, a3, 1b
+	sub a2, a2, a4  /* Update count */
+
+2: /* Duff's device with 32 XLEN stores per iteration */
+	/* Broadcast value into all bytes */
+	andi a1, a1, 0xff
+	slli a3, a1, 8
+	or a1, a3, a1
+	slli a3, a1, 16
+	or a1, a3, a1
+#ifdef CONFIG_64BIT
+	slli a3, a1, 32
+	or a1, a3, a1
+#endif
+
+	/* Calculate end address */
+	andi a4, a2, ~(SZREG-1)
+	add a3, t0, a4
+
+	andi a4, a4, 31*SZREG  /* Calculate remainder */
+	beqz a4, 3f            /* Shortcut if no remainder */
+	neg a4, a4
+	addi a4, a4, 32*SZREG  /* Calculate initial offset */
+
+	/* Adjust start address with offset */
+	sub t0, t0, a4
+
+	/* Jump into loop body */
+	/* Assumes 32-bit instruction lengths */
+	la a5, 3f
+#ifdef CONFIG_64BIT
+	srli a4, a4, 1
+#endif
+	add a5, a5, a4
+	jr a5
+3:
+	REG_S a1,        0(t0)
+	REG_S a1,    SZREG(t0)
+	REG_S a1,  2*SZREG(t0)
+	REG_S a1,  3*SZREG(t0)
+	REG_S a1,  4*SZREG(t0)
+	REG_S a1,  5*SZREG(t0)
+	REG_S a1,  6*SZREG(t0)
+	REG_S a1,  7*SZREG(t0)
+	REG_S a1,  8*SZREG(t0)
+	REG_S a1,  9*SZREG(t0)
+	REG_S a1, 10*SZREG(t0)
+	REG_S a1, 11*SZREG(t0)
+	REG_S a1, 12*SZREG(t0)
+	REG_S a1, 13*SZREG(t0)
+	REG_S a1, 14*SZREG(t0)
+	REG_S a1, 15*SZREG(t0)
+	REG_S a1, 16*SZREG(t0)
+	REG_S a1, 17*SZREG(t0)
+	REG_S a1, 18*SZREG(t0)
+	REG_S a1, 19*SZREG(t0)
+	REG_S a1, 20*SZREG(t0)
+	REG_S a1, 21*SZREG(t0)
+	REG_S a1, 22*SZREG(t0)
+	REG_S a1, 23*SZREG(t0)
+	REG_S a1, 24*SZREG(t0)
+	REG_S a1, 25*SZREG(t0)
+	REG_S a1, 26*SZREG(t0)
+	REG_S a1, 27*SZREG(t0)
+	REG_S a1, 28*SZREG(t0)
+	REG_S a1, 29*SZREG(t0)
+	REG_S a1, 30*SZREG(t0)
+	REG_S a1, 31*SZREG(t0)
+	addi t0, t0, 32*SZREG
+	bltu t0, a3, 3b
+	andi a2, a2, SZREG-1  /* Update count */
+
+4:
+	/* Handle trailing misalignment */
+	beqz a2, 6f
+	add a3, t0, a2
+5:
+	sb a1, 0(t0)
+	addi t0, t0, 1
+	bltu t0, a3, 5b
+6:
+	ret
+END(__memset)
diff --git a/arch/riscv/lib/strcmp.S b/arch/riscv/lib/strcmp.S
new file mode 100644
index 0000000000..687b2bea5c
--- /dev/null
+++ b/arch/riscv/lib/strcmp.S
@@ -0,0 +1,122 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include <linux/linkage.h>
+#include <asm/asm.h>
+#include <asm/alternative-macros.h>
+#include <asm/hwcap.h>
+
+/* int strcmp(const char *cs, const char *ct) */
+SYM_FUNC_START(strcmp)
+
+	ALTERNATIVE("nop", "j strcmp_zbb", 0, RISCV_ISA_EXT_ZBB, CONFIG_RISCV_ISA_ZBB)
+
+	/*
+	 * Returns
+	 *   a0 - comparison result, value like strcmp
+	 *
+	 * Parameters
+	 *   a0 - string1
+	 *   a1 - string2
+	 *
+	 * Clobbers
+	 *   t0, t1
+	 */
+1:
+	lbu	t0, 0(a0)
+	lbu	t1, 0(a1)
+	addi	a0, a0, 1
+	addi	a1, a1, 1
+	bne	t0, t1, 2f
+	bnez	t0, 1b
+	li	a0, 0
+	ret
+2:
+	/*
+	 * strcmp only needs to return (< 0, 0, > 0) values
+	 * not necessarily -1, 0, +1
+	 */
+	sub	a0, t0, t1
+	ret
+
+/*
+ * Variant of strcmp using the ZBB extension if available.
+ * The code was published as part of the bitmanip manual
+ * in Appendix A.
+ */
+#ifdef CONFIG_RISCV_ISA_ZBB
+strcmp_zbb:
+
+.option push
+.option arch,+zbb
+
+	/*
+	 * Returns
+	 *   a0 - comparison result, value like strcmp
+	 *
+	 * Parameters
+	 *   a0 - string1
+	 *   a1 - string2
+	 *
+	 * Clobbers
+	 *   t0, t1, t2, t3, t4
+	 */
+
+	or	t2, a0, a1
+	li	t4, -1
+	and	t2, t2, SZREG-1
+	bnez	t2, 3f
+
+	/* Main loop for aligned string.  */
+	.p2align 3
+1:
+	REG_L	t0, 0(a0)
+	REG_L	t1, 0(a1)
+	orc.b	t3, t0
+	bne	t3, t4, 2f
+	addi	a0, a0, SZREG
+	addi	a1, a1, SZREG
+	beq	t0, t1, 1b
+
+	/*
+	 * Words don't match, and no null byte in the first
+	 * word. Get bytes in big-endian order and compare.
+	 */
+#ifndef CONFIG_CPU_BIG_ENDIAN
+	rev8	t0, t0
+	rev8	t1, t1
+#endif
+
+	/* Synthesize (t0 >= t1) ? 1 : -1 in a branchless sequence. */
+	sltu	a0, t0, t1
+	neg	a0, a0
+	ori	a0, a0, 1
+	ret
+
+2:
+	/*
+	 * Found a null byte.
+	 * If words don't match, fall back to simple loop.
+	 */
+	bne	t0, t1, 3f
+
+	/* Otherwise, strings are equal. */
+	li	a0, 0
+	ret
+
+	/* Simple loop for misaligned strings. */
+	.p2align 3
+3:
+	lbu	t0, 0(a0)
+	lbu	t1, 0(a1)
+	addi	a0, a0, 1
+	addi	a1, a1, 1
+	bne	t0, t1, 4f
+	bnez	t0, 3b
+
+4:
+	sub	a0, t0, t1
+	ret
+
+.option pop
+#endif
+SYM_FUNC_END(strcmp)
diff --git a/arch/riscv/lib/strlen.S b/arch/riscv/lib/strlen.S
new file mode 100644
index 0000000000..8ae3064e45
--- /dev/null
+++ b/arch/riscv/lib/strlen.S
@@ -0,0 +1,133 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include <linux/linkage.h>
+#include <asm/asm.h>
+#include <asm/alternative-macros.h>
+#include <asm/hwcap.h>
+
+/* int strlen(const char *s) */
+SYM_FUNC_START(strlen)
+
+	ALTERNATIVE("nop", "j strlen_zbb", 0, RISCV_ISA_EXT_ZBB, CONFIG_RISCV_ISA_ZBB)
+
+	/*
+	 * Returns
+	 *   a0 - string length
+	 *
+	 * Parameters
+	 *   a0 - String to measure
+	 *
+	 * Clobbers:
+	 *   t0, t1
+	 */
+	mv	t1, a0
+1:
+	lbu	t0, 0(t1)
+	beqz	t0, 2f
+	addi	t1, t1, 1
+	j	1b
+2:
+	sub	a0, t1, a0
+	ret
+
+/*
+ * Variant of strlen using the ZBB extension if available
+ */
+#ifdef CONFIG_RISCV_ISA_ZBB
+strlen_zbb:
+
+#ifdef CONFIG_CPU_BIG_ENDIAN
+# define CZ	clz
+# define SHIFT	sll
+#else
+# define CZ	ctz
+# define SHIFT	srl
+#endif
+
+.option push
+.option arch,+zbb
+
+	/*
+	 * Returns
+	 *   a0 - string length
+	 *
+	 * Parameters
+	 *   a0 - String to measure
+	 *
+	 * Clobbers
+	 *   t0, t1, t2, t3
+	 */
+
+	/* Number of irrelevant bytes in the first word. */
+	andi	t2, a0, SZREG-1
+
+	/* Align pointer. */
+	andi	t0, a0, -SZREG
+
+	li	t3, SZREG
+	sub	t3, t3, t2
+	slli	t2, t2, 3
+
+	/* Get the first word.  */
+	REG_L	t1, 0(t0)
+
+	/*
+	 * Shift away the partial data we loaded to remove the irrelevant bytes
+	 * preceding the string with the effect of adding NUL bytes at the
+	 * end of the string's first word.
+	 */
+	SHIFT	t1, t1, t2
+
+	/* Convert non-NUL into 0xff and NUL into 0x00. */
+	orc.b	t1, t1
+
+	/* Convert non-NUL into 0x00 and NUL into 0xff. */
+	not	t1, t1
+
+	/*
+	 * Search for the first set bit (corresponding to a NUL byte in the
+	 * original chunk).
+	 */
+	CZ	t1, t1
+
+	/*
+	 * The first chunk is special: compare against the number
+	 * of valid bytes in this chunk.
+	 */
+	srli	a0, t1, 3
+	bgtu	t3, a0, 2f
+
+	/* Prepare for the word comparison loop. */
+	addi	t2, t0, SZREG
+	li	t3, -1
+
+	/*
+	 * Our critical loop is 4 instructions and processes data in
+	 * 4 byte or 8 byte chunks.
+	 */
+	.p2align 3
+1:
+	REG_L	t1, SZREG(t0)
+	addi	t0, t0, SZREG
+	orc.b	t1, t1
+	beq	t1, t3, 1b
+
+	not	t1, t1
+	CZ	t1, t1
+	srli	t1, t1, 3
+
+	/* Get number of processed bytes. */
+	sub	t2, t0, t2
+
+	/* Add number of characters in the first word.  */
+	add	a0, a0, t2
+
+	/* Add number of characters in the last word.  */
+	add	a0, a0, t1
+2:
+	ret
+
+.option pop
+#endif
+SYM_FUNC_END(strlen)
+SYM_FUNC_ALIAS(__pi_strlen, strlen)
diff --git a/arch/riscv/lib/strncmp.S b/arch/riscv/lib/strncmp.S
new file mode 100644
index 0000000000..aba5b31486
--- /dev/null
+++ b/arch/riscv/lib/strncmp.S
@@ -0,0 +1,138 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include <linux/linkage.h>
+#include <asm/asm.h>
+#include <asm/alternative-macros.h>
+#include <asm/hwcap.h>
+
+/* int strncmp(const char *cs, const char *ct, size_t count) */
+SYM_FUNC_START(strncmp)
+
+	ALTERNATIVE("nop", "j strncmp_zbb", 0, RISCV_ISA_EXT_ZBB, CONFIG_RISCV_ISA_ZBB)
+
+	/*
+	 * Returns
+	 *   a0 - comparison result, value like strncmp
+	 *
+	 * Parameters
+	 *   a0 - string1
+	 *   a1 - string2
+	 *   a2 - number of characters to compare
+	 *
+	 * Clobbers
+	 *   t0, t1, t2
+	 */
+	li	t2, 0
+1:
+	beq	a2, t2, 2f
+	lbu	t0, 0(a0)
+	lbu	t1, 0(a1)
+	addi	a0, a0, 1
+	addi	a1, a1, 1
+	bne	t0, t1, 3f
+	addi	t2, t2, 1
+	bnez	t0, 1b
+2:
+	li	a0, 0
+	ret
+3:
+	/*
+	 * strncmp only needs to return (< 0, 0, > 0) values
+	 * not necessarily -1, 0, +1
+	 */
+	sub	a0, t0, t1
+	ret
+
+/*
+ * Variant of strncmp using the ZBB extension if available
+ */
+#ifdef CONFIG_RISCV_ISA_ZBB
+strncmp_zbb:
+
+.option push
+.option arch,+zbb
+
+	/*
+	 * Returns
+	 *   a0 - comparison result, like strncmp
+	 *
+	 * Parameters
+	 *   a0 - string1
+	 *   a1 - string2
+	 *   a2 - number of characters to compare
+	 *
+	 * Clobbers
+	 *   t0, t1, t2, t3, t4, t5, t6
+	 */
+
+	or	t2, a0, a1
+	li	t5, -1
+	and	t2, t2, SZREG-1
+	add	t4, a0, a2
+	bnez	t2, 3f
+
+	/* Adjust limit for fast-path.  */
+	andi	t6, t4, -SZREG
+
+	/* Main loop for aligned string.  */
+	.p2align 3
+1:
+	bge	a0, t6, 3f
+	REG_L	t0, 0(a0)
+	REG_L	t1, 0(a1)
+	orc.b	t3, t0
+	bne	t3, t5, 2f
+	orc.b	t3, t1
+	bne	t3, t5, 2f
+	addi	a0, a0, SZREG
+	addi	a1, a1, SZREG
+	beq	t0, t1, 1b
+
+	/*
+	 * Words don't match, and no null byte in the first
+	 * word. Get bytes in big-endian order and compare.
+	 */
+#ifndef CONFIG_CPU_BIG_ENDIAN
+	rev8	t0, t0
+	rev8	t1, t1
+#endif
+
+	/* Synthesize (t0 >= t1) ? 1 : -1 in a branchless sequence.  */
+	sltu	a0, t0, t1
+	neg	a0, a0
+	ori	a0, a0, 1
+	ret
+
+2:
+	/*
+	 * Found a null byte.
+	 * If words don't match, fall back to simple loop.
+	 */
+	bne	t0, t1, 3f
+
+	/* Otherwise, strings are equal.  */
+	li	a0, 0
+	ret
+
+	/* Simple loop for misaligned strings.  */
+	.p2align 3
+3:
+	bge	a0, t4, 5f
+	lbu	t0, 0(a0)
+	lbu	t1, 0(a1)
+	addi	a0, a0, 1
+	addi	a1, a1, 1
+	bne	t0, t1, 4f
+	bnez	t0, 3b
+
+4:
+	sub	a0, t0, t1
+	ret
+
+5:
+	li	a0, 0
+	ret
+
+.option pop
+#endif
+SYM_FUNC_END(strncmp)
diff --git a/arch/riscv/lib/tishift.S b/arch/riscv/lib/tishift.S
new file mode 100644
index 0000000000..ef90075c4b
--- /dev/null
+++ b/arch/riscv/lib/tishift.S
@@ -0,0 +1,76 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2018 Free Software Foundation, Inc.
+ */
+
+#include <linux/linkage.h>
+#include <asm-generic/export.h>
+
+SYM_FUNC_START(__lshrti3)
+	beqz	a2, .L1
+	li	a5,64
+	sub	a5,a5,a2
+	sext.w	a4,a5
+	blez	a5, .L2
+	sext.w	a2,a2
+	srl	a0,a0,a2
+	sll	a4,a1,a4
+	srl	a2,a1,a2
+	or	a0,a0,a4
+	mv	a1,a2
+.L1:
+	ret
+.L2:
+	negw	a0,a4
+	li	a2,0
+	srl	a0,a1,a0
+	mv	a1,a2
+	ret
+SYM_FUNC_END(__lshrti3)
+EXPORT_SYMBOL(__lshrti3)
+
+SYM_FUNC_START(__ashrti3)
+	beqz	a2, .L3
+	li	a5,64
+	sub	a5,a5,a2
+	sext.w	a4,a5
+	blez	a5, .L4
+	sext.w	a2,a2
+	srl	a0,a0,a2
+	sll	a4,a1,a4
+	sra	a2,a1,a2
+	or	a0,a0,a4
+	mv	a1,a2
+.L3:
+	ret
+.L4:
+	negw	a0,a4
+	srai	a2,a1,0x3f
+	sra	a0,a1,a0
+	mv	a1,a2
+	ret
+SYM_FUNC_END(__ashrti3)
+EXPORT_SYMBOL(__ashrti3)
+
+SYM_FUNC_START(__ashlti3)
+	beqz	a2, .L5
+	li	a5,64
+	sub	a5,a5,a2
+	sext.w	a4,a5
+	blez	a5, .L6
+	sext.w	a2,a2
+	sll	a1,a1,a2
+	srl	a4,a0,a4
+	sll	a2,a0,a2
+	or	a1,a1,a4
+	mv	a0,a2
+.L5:
+	ret
+.L6:
+	negw	a1,a4
+	li	a2,0
+	sll	a1,a0,a1
+	mv	a0,a2
+	ret
+SYM_FUNC_END(__ashlti3)
+EXPORT_SYMBOL(__ashlti3)
diff --git a/arch/riscv/lib/uaccess.S b/arch/riscv/lib/uaccess.S
new file mode 100644
index 0000000000..09b47ebacf
--- /dev/null
+++ b/arch/riscv/lib/uaccess.S
@@ -0,0 +1,237 @@
+#include <linux/linkage.h>
+#include <asm-generic/export.h>
+#include <asm/asm.h>
+#include <asm/asm-extable.h>
+#include <asm/csr.h>
+
+	.macro fixup op reg addr lbl
+100:
+	\op \reg, \addr
+	_asm_extable	100b, \lbl
+	.endm
+
+ENTRY(__asm_copy_to_user)
+ENTRY(__asm_copy_from_user)
+
+	/* Enable access to user memory */
+	li t6, SR_SUM
+	csrs CSR_STATUS, t6
+
+	/*
+	 * Save the terminal address which will be used to compute the number
+	 * of bytes copied in case of a fixup exception.
+	 */
+	add	t5, a0, a2
+
+	/*
+	 * Register allocation for code below:
+	 * a0 - start of uncopied dst
+	 * a1 - start of uncopied src
+	 * a2 - size
+	 * t0 - end of uncopied dst
+	 */
+	add	t0, a0, a2
+
+	/*
+	 * Use byte copy only if too small.
+	 * SZREG holds 4 for RV32 and 8 for RV64
+	 */
+	li	a3, 9*SZREG /* size must be larger than size in word_copy */
+	bltu	a2, a3, .Lbyte_copy_tail
+
+	/*
+	 * Copy first bytes until dst is aligned to word boundary.
+	 * a0 - start of dst
+	 * t1 - start of aligned dst
+	 */
+	addi	t1, a0, SZREG-1
+	andi	t1, t1, ~(SZREG-1)
+	/* dst is already aligned, skip */
+	beq	a0, t1, .Lskip_align_dst
+1:
+	/* a5 - one byte for copying data */
+	fixup lb      a5, 0(a1), 10f
+	addi	a1, a1, 1	/* src */
+	fixup sb      a5, 0(a0), 10f
+	addi	a0, a0, 1	/* dst */
+	bltu	a0, t1, 1b	/* t1 - start of aligned dst */
+
+.Lskip_align_dst:
+	/*
+	 * Now dst is aligned.
+	 * Use shift-copy if src is misaligned.
+	 * Use word-copy if both src and dst are aligned because
+	 * can not use shift-copy which do not require shifting
+	 */
+	/* a1 - start of src */
+	andi	a3, a1, SZREG-1
+	bnez	a3, .Lshift_copy
+
+.Lword_copy:
+        /*
+	 * Both src and dst are aligned, unrolled word copy
+	 *
+	 * a0 - start of aligned dst
+	 * a1 - start of aligned src
+	 * t0 - end of aligned dst
+	 */
+	addi	t0, t0, -(8*SZREG) /* not to over run */
+2:
+	fixup REG_L   a4,        0(a1), 10f
+	fixup REG_L   a5,    SZREG(a1), 10f
+	fixup REG_L   a6,  2*SZREG(a1), 10f
+	fixup REG_L   a7,  3*SZREG(a1), 10f
+	fixup REG_L   t1,  4*SZREG(a1), 10f
+	fixup REG_L   t2,  5*SZREG(a1), 10f
+	fixup REG_L   t3,  6*SZREG(a1), 10f
+	fixup REG_L   t4,  7*SZREG(a1), 10f
+	fixup REG_S   a4,        0(a0), 10f
+	fixup REG_S   a5,    SZREG(a0), 10f
+	fixup REG_S   a6,  2*SZREG(a0), 10f
+	fixup REG_S   a7,  3*SZREG(a0), 10f
+	fixup REG_S   t1,  4*SZREG(a0), 10f
+	fixup REG_S   t2,  5*SZREG(a0), 10f
+	fixup REG_S   t3,  6*SZREG(a0), 10f
+	fixup REG_S   t4,  7*SZREG(a0), 10f
+	addi	a0, a0, 8*SZREG
+	addi	a1, a1, 8*SZREG
+	bltu	a0, t0, 2b
+
+	addi	t0, t0, 8*SZREG /* revert to original value */
+	j	.Lbyte_copy_tail
+
+.Lshift_copy:
+
+	/*
+	 * Word copy with shifting.
+	 * For misaligned copy we still perform aligned word copy, but
+	 * we need to use the value fetched from the previous iteration and
+	 * do some shifts.
+	 * This is safe because reading is less than a word size.
+	 *
+	 * a0 - start of aligned dst
+	 * a1 - start of src
+	 * a3 - a1 & mask:(SZREG-1)
+	 * t0 - end of uncopied dst
+	 * t1 - end of aligned dst
+	 */
+	/* calculating aligned word boundary for dst */
+	andi	t1, t0, ~(SZREG-1)
+	/* Converting unaligned src to aligned src */
+	andi	a1, a1, ~(SZREG-1)
+
+	/*
+	 * Calculate shifts
+	 * t3 - prev shift
+	 * t4 - current shift
+	 */
+	slli	t3, a3, 3 /* converting bytes in a3 to bits */
+	li	a5, SZREG*8
+	sub	t4, a5, t3
+
+	/* Load the first word to combine with second word */
+	fixup REG_L   a5, 0(a1), 10f
+
+3:
+	/* Main shifting copy
+	 *
+	 * a0 - start of aligned dst
+	 * a1 - start of aligned src
+	 * t1 - end of aligned dst
+	 */
+
+	/* At least one iteration will be executed */
+	srl	a4, a5, t3
+	fixup REG_L   a5, SZREG(a1), 10f
+	addi	a1, a1, SZREG
+	sll	a2, a5, t4
+	or	a2, a2, a4
+	fixup REG_S   a2, 0(a0), 10f
+	addi	a0, a0, SZREG
+	bltu	a0, t1, 3b
+
+	/* Revert src to original unaligned value  */
+	add	a1, a1, a3
+
+.Lbyte_copy_tail:
+	/*
+	 * Byte copy anything left.
+	 *
+	 * a0 - start of remaining dst
+	 * a1 - start of remaining src
+	 * t0 - end of remaining dst
+	 */
+	bgeu	a0, t0, .Lout_copy_user  /* check if end of copy */
+4:
+	fixup lb      a5, 0(a1), 10f
+	addi	a1, a1, 1	/* src */
+	fixup sb      a5, 0(a0), 10f
+	addi	a0, a0, 1	/* dst */
+	bltu	a0, t0, 4b	/* t0 - end of dst */
+
+.Lout_copy_user:
+	/* Disable access to user memory */
+	csrc CSR_STATUS, t6
+	li	a0, 0
+	ret
+
+	/* Exception fixup code */
+10:
+	/* Disable access to user memory */
+	csrc CSR_STATUS, t6
+	sub a0, t5, a0
+	ret
+ENDPROC(__asm_copy_to_user)
+ENDPROC(__asm_copy_from_user)
+EXPORT_SYMBOL(__asm_copy_to_user)
+EXPORT_SYMBOL(__asm_copy_from_user)
+
+
+ENTRY(__clear_user)
+
+	/* Enable access to user memory */
+	li t6, SR_SUM
+	csrs CSR_STATUS, t6
+
+	add a3, a0, a1
+	addi t0, a0, SZREG-1
+	andi t1, a3, ~(SZREG-1)
+	andi t0, t0, ~(SZREG-1)
+	/*
+	 * a3: terminal address of target region
+	 * t0: lowest doubleword-aligned address in target region
+	 * t1: highest doubleword-aligned address in target region
+	 */
+	bgeu t0, t1, 2f
+	bltu a0, t0, 4f
+1:
+	fixup REG_S, zero, (a0), 11f
+	addi a0, a0, SZREG
+	bltu a0, t1, 1b
+2:
+	bltu a0, a3, 5f
+
+3:
+	/* Disable access to user memory */
+	csrc CSR_STATUS, t6
+	li a0, 0
+	ret
+4: /* Edge case: unalignment */
+	fixup sb, zero, (a0), 11f
+	addi a0, a0, 1
+	bltu a0, t0, 4b
+	j 1b
+5: /* Edge case: remainder */
+	fixup sb, zero, (a0), 11f
+	addi a0, a0, 1
+	bltu a0, a3, 5b
+	j 3b
+
+	/* Exception fixup code */
+11:
+	/* Disable access to user memory */
+	csrc CSR_STATUS, t6
+	sub a0, a3, a0
+	ret
+ENDPROC(__clear_user)
+EXPORT_SYMBOL(__clear_user)