Adding upstream version 6.1.76.upstream/6.1.76upstream

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

1 files changed, 316 insertions, 0 deletions

diff --git a/arch/riscv/lib/memmove.S b/arch/riscv/lib/memmove.S
new file mode 100644
index 000000000..e0609e1f0
--- /dev/null
+++ b/arch/riscv/lib/memmove.S
@@ -0,0 +1,316 @@
+/* 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)