[RFC PATCH v2 25/31] kvx: Add some library functions
Yann Sionneau
ysionneau at kalray.eu
Fri Jan 20 06:09:56 PST 2023
Add some library functions for kvx, including: delay, memset,
memcpy, strlen, clear_page, copy_page, raw_copy_from/to_user,
asm_clear_user.
Co-developed-by: Clement Leger <clement at clement-leger.fr>
Signed-off-by: Clement Leger <clement at clement-leger.fr>
Co-developed-by: Jules Maselbas <jmaselbas at kalray.eu>
Signed-off-by: Jules Maselbas <jmaselbas at kalray.eu>
Co-developed-by: Julian Vetter <jvetter at kalray.eu>
Signed-off-by: Julian Vetter <jvetter at kalray.eu>
Co-developed-by: Marius Gligor <mgligor at kalray.eu>
Signed-off-by: Marius Gligor <mgligor at kalray.eu>
Co-developed-by: Yann Sionneau <ysionneau at kalray.eu>
Signed-off-by: Yann Sionneau <ysionneau at kalray.eu>
---
Notes:
V1 -> V2: no changes
arch/kvx/include/asm/string.h | 20 ++
arch/kvx/kernel/kvx_ksyms.c | 5 +
arch/kvx/lib/clear_page.S | 40 ++++
arch/kvx/lib/copy_page.S | 90 +++++++++
arch/kvx/lib/delay.c | 39 ++++
arch/kvx/lib/memcpy.c | 70 +++++++
arch/kvx/lib/memset.S | 351 ++++++++++++++++++++++++++++++++++
arch/kvx/lib/strlen.S | 122 ++++++++++++
arch/kvx/lib/usercopy.S | 90 +++++++++
9 files changed, 827 insertions(+)
create mode 100644 arch/kvx/include/asm/string.h
create mode 100644 arch/kvx/lib/clear_page.S
create mode 100644 arch/kvx/lib/copy_page.S
create mode 100644 arch/kvx/lib/delay.c
create mode 100644 arch/kvx/lib/memcpy.c
create mode 100644 arch/kvx/lib/memset.S
create mode 100644 arch/kvx/lib/strlen.S
create mode 100644 arch/kvx/lib/usercopy.S
diff --git a/arch/kvx/include/asm/string.h b/arch/kvx/include/asm/string.h
new file mode 100644
index 000000000000..677c1393a5cd
--- /dev/null
+++ b/arch/kvx/include/asm/string.h
@@ -0,0 +1,20 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2017-2023 Kalray Inc.
+ * Author(s): Clement Leger
+ * Jules Maselbas
+ */
+
+#ifndef _ASM_KVX_STRING_H
+#define _ASM_KVX_STRING_H
+
+#define __HAVE_ARCH_MEMSET
+extern void *memset(void *s, int c, size_t n);
+
+#define __HAVE_ARCH_MEMCPY
+extern void *memcpy(void *dest, const void *src, size_t n);
+
+#define __HAVE_ARCH_STRLEN
+extern size_t strlen(const char *s);
+
+#endif /* _ASM_KVX_STRING_H */
diff --git a/arch/kvx/kernel/kvx_ksyms.c b/arch/kvx/kernel/kvx_ksyms.c
index 18990aaf259f..678f81716dea 100644
--- a/arch/kvx/kernel/kvx_ksyms.c
+++ b/arch/kvx/kernel/kvx_ksyms.c
@@ -22,3 +22,8 @@ DECLARE_EXPORT(__umoddi3);
DECLARE_EXPORT(__divdi3);
DECLARE_EXPORT(__udivdi3);
DECLARE_EXPORT(__multi3);
+
+DECLARE_EXPORT(clear_page);
+DECLARE_EXPORT(copy_page);
+DECLARE_EXPORT(memset);
+DECLARE_EXPORT(asm_clear_user);
diff --git a/arch/kvx/lib/clear_page.S b/arch/kvx/lib/clear_page.S
new file mode 100644
index 000000000000..364fe0663ca2
--- /dev/null
+++ b/arch/kvx/lib/clear_page.S
@@ -0,0 +1,40 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2017-2023 Kalray Inc.
+ * Author(s): Marius Gligor
+ * Clement Leger
+ */
+
+#include <linux/linkage.h>
+#include <linux/export.h>
+#include <linux/const.h>
+
+#include <asm/cache.h>
+#include <asm/page.h>
+
+#define CLEAR_PAGE_LOOP_COUNT (PAGE_SIZE / 32)
+
+/*
+ * Clear page @dest.
+ *
+ * Parameters:
+ * r0 - dest page
+ */
+ENTRY(clear_page)
+ make $r1 = CLEAR_PAGE_LOOP_COUNT
+ ;;
+ make $r4 = 0
+ make $r5 = 0
+ make $r6 = 0
+ make $r7 = 0
+ ;;
+
+ loopdo $r1, clear_page_done
+ ;;
+ so 0[$r0] = $r4r5r6r7
+ addd $r0 = $r0, 32
+ ;;
+ clear_page_done:
+ ret
+ ;;
+ENDPROC(clear_page)
diff --git a/arch/kvx/lib/copy_page.S b/arch/kvx/lib/copy_page.S
new file mode 100644
index 000000000000..4bb82d1c964c
--- /dev/null
+++ b/arch/kvx/lib/copy_page.S
@@ -0,0 +1,90 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2017-2023 Kalray Inc.
+ * Author(s): Clement Leger
+ */
+
+#include <linux/linkage.h>
+#include <linux/const.h>
+
+#include <asm/page.h>
+
+/* We have 8 load/store octuple (32 bytes) per hardware loop */
+#define COPY_SIZE_PER_LOOP (32 * 8)
+#define COPY_PAGE_LOOP_COUNT (PAGE_SIZE / COPY_SIZE_PER_LOOP)
+
+/*
+ * Copy a page from src to dest (both are page aligned)
+ * In order to recover from smem latency, unroll the loop to trigger multiple
+ * onfly loads and avoid waiting too much for them to return.
+ * We use 8 * 32 load even though we could use more (up to 10 loads) to simplify
+ * the handling using a single hardware loop
+ *
+ * Parameters:
+ * r0 - dest
+ * r1 - src
+ */
+ENTRY(copy_page)
+ make $r2 = COPY_PAGE_LOOP_COUNT
+ make $r3 = 0
+ ;;
+ loopdo $r2, copy_page_done
+ ;;
+ /*
+ * Load 8 * 32 bytes using uncached access to avoid hitting
+ * the cache
+ */
+ lo.xs $r32r33r34r35 = $r3[$r1]
+ /* Copy current copy index for store */
+ copyd $r2 = $r3
+ addd $r3 = $r3, 1
+ ;;
+ lo.xs $r36r37r38r39 = $r3[$r1]
+ addd $r3 = $r3, 1
+ ;;
+ lo.xs $r40r41r42r43 = $r3[$r1]
+ addd $r3 = $r3, 1
+ ;;
+ lo.xs $r44r45r46r47 = $r3[$r1]
+ addd $r3 = $r3, 1
+ ;;
+ lo.xs $r48r49r50r51 = $r3[$r1]
+ addd $r3 = $r3, 1
+ ;;
+ lo.xs $r52r53r54r55 = $r3[$r1]
+ addd $r3 = $r3, 1
+ ;;
+ lo.xs $r56r57r58r59 = $r3[$r1]
+ addd $r3 = $r3, 1
+ ;;
+ lo.xs $r60r61r62r63 = $r3[$r1]
+ addd $r3 = $r3, 1
+ ;;
+ /* And then store all of them */
+ so.xs $r2[$r0] = $r32r33r34r35
+ addd $r2 = $r2, 1
+ ;;
+ so.xs $r2[$r0] = $r36r37r38r39
+ addd $r2 = $r2, 1
+ ;;
+ so.xs $r2[$r0] = $r40r41r42r43
+ addd $r2 = $r2, 1
+ ;;
+ so.xs $r2[$r0] = $r44r45r46r47
+ addd $r2 = $r2, 1
+ ;;
+ so.xs $r2[$r0] = $r48r49r50r51
+ addd $r2 = $r2, 1
+ ;;
+ so.xs $r2[$r0] = $r52r53r54r55
+ addd $r2 = $r2, 1
+ ;;
+ so.xs $r2[$r0] = $r56r57r58r59
+ addd $r2 = $r2, 1
+ ;;
+ so.xs $r2[$r0] = $r60r61r62r63
+ ;;
+ copy_page_done:
+ ret
+ ;;
+ENDPROC(copy_page)
diff --git a/arch/kvx/lib/delay.c b/arch/kvx/lib/delay.c
new file mode 100644
index 000000000000..11295eedc3f5
--- /dev/null
+++ b/arch/kvx/lib/delay.c
@@ -0,0 +1,39 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2017-2023 Kalray Inc.
+ * Author(s): Clement Leger
+ */
+
+#include <linux/export.h>
+#include <linux/delay.h>
+
+#include <asm/param.h>
+#include <asm/timex.h>
+
+void __delay(unsigned long loops)
+{
+ cycles_t target_cycle = get_cycles() + loops;
+
+ while (get_cycles() < target_cycle);
+}
+EXPORT_SYMBOL(__delay);
+
+inline void __const_udelay(unsigned long xloops)
+{
+ u64 loops = (u64)xloops * (u64)loops_per_jiffy * HZ;
+
+ __delay(loops >> 32);
+}
+EXPORT_SYMBOL(__const_udelay);
+
+void __udelay(unsigned long usecs)
+{
+ __const_udelay(usecs * 0x10C7UL); /* 2**32 / 1000000 (rounded up) */
+}
+EXPORT_SYMBOL(__udelay);
+
+void __ndelay(unsigned long nsecs)
+{
+ __const_udelay(nsecs * 0x5UL); /* 2**32 / 1000000000 (rounded up) */
+}
+EXPORT_SYMBOL(__ndelay);
diff --git a/arch/kvx/lib/memcpy.c b/arch/kvx/lib/memcpy.c
new file mode 100644
index 000000000000..b81f746a80ee
--- /dev/null
+++ b/arch/kvx/lib/memcpy.c
@@ -0,0 +1,70 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2017-2023 Kalray Inc.
+ * Author(s): Clement Leger
+ * Yann Sionneau
+ */
+
+#include <linux/export.h>
+#include <linux/types.h>
+
+void *memcpy(void *dest, const void *src, size_t n)
+{
+ __uint128_t *tmp128_d = dest;
+ const __uint128_t *tmp128_s = src;
+ uint64_t *tmp64_d;
+ const uint64_t *tmp64_s;
+ uint32_t *tmp32_d;
+ const uint32_t *tmp32_s;
+ uint16_t *tmp16_d;
+ const uint16_t *tmp16_s;
+ uint8_t *tmp8_d;
+ const uint8_t *tmp8_s;
+
+ while (n >= 16) {
+ *tmp128_d = *tmp128_s;
+ tmp128_d++;
+ tmp128_s++;
+ n -= 16;
+ }
+
+ tmp64_d = (uint64_t *) tmp128_d;
+ tmp64_s = (uint64_t *) tmp128_s;
+ while (n >= 8) {
+ *tmp64_d = *tmp64_s;
+ tmp64_d++;
+ tmp64_s++;
+ n -= 8;
+ }
+
+ tmp32_d = (uint32_t *) tmp64_d;
+ tmp32_s = (uint32_t *) tmp64_s;
+ while (n >= 4) {
+ *tmp32_d = *tmp32_s;
+ tmp32_d++;
+ tmp32_s++;
+ n -= 4;
+ }
+
+ tmp16_d = (uint16_t *) tmp32_d;
+ tmp16_s = (uint16_t *) tmp32_s;
+ while (n >= 2) {
+ *tmp16_d = *tmp16_s;
+ tmp16_d++;
+ tmp16_s++;
+ n -= 2;
+ }
+
+ tmp8_d = (uint8_t *) tmp16_d;
+ tmp8_s = (uint8_t *) tmp16_s;
+ while (n >= 1) {
+ *tmp8_d = *tmp8_s;
+ tmp8_d++;
+ tmp8_s++;
+ n--;
+ }
+
+ return dest;
+}
+EXPORT_SYMBOL(memcpy);
+
diff --git a/arch/kvx/lib/memset.S b/arch/kvx/lib/memset.S
new file mode 100644
index 000000000000..9eebc28da2be
--- /dev/null
+++ b/arch/kvx/lib/memset.S
@@ -0,0 +1,351 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2017-2023 Kalray Inc.
+ * Author(s): Clement Leger
+ * Marius Gligor
+ */
+
+#include <linux/linkage.h>
+
+#include <asm/cache.h>
+
+#define REPLICATE_BYTE_MASK 0x0101010101010101
+#define MIN_SIZE_FOR_ALIGN 128
+
+/*
+ * Optimized memset for kvx architecture
+ *
+ * In order to optimize memset on kvx, we can use various things:
+ * - conditionnal store which avoid branch penalty
+ * - store half/word/double/quad/octuple to store up to 16 bytes at a time
+ * - dzerol to zero a cacheline when the pattern is '0' (often the case)
+ * - hardware loop for steady cases.
+ *
+ * First, we assume that memset is mainly used for zeroing areas. In order
+ * to optimize this case, we consider it to be the fast path of the algorithm.
+ * In both cases (0 and non 0 pattern), we start by checking if the size is
+ * below a minimum size. If so, we skip the alignment part. Indeed, the kvx
+ * supports misalignment and the penalty for letting it do unaligned accesses is
+ * lower than trying to realigning us. So for small sizes, we don't even bother
+ * to realign. Minor difference is that in the memset with 0, we skip after the
+ * dzerol loop since dzerol must be cache-line aligned (no misalignment of
+ * course).
+ * Regarding the non 0 pattern memset, we use sbmm to replicate the pattern on
+ * all bits on a register in one call.
+ * Once alignment has been reached, we can do the hardware loop for both cases(
+ * store octuple/dzerol) in order to optimize throughput. Care must be taken to
+ * align hardware loops on at least 8 bytes for performances.
+ * Once the main loop has been done, we finish the copy by checking length to do
+ * the necessary calls to store remaining bytes.
+ *
+ * Pseudo code (applies for non 0 pattern):
+ *
+ * int memset(void *dest, char pattern, long length)
+ * {
+ * long dest_align = -((long) dest);
+ * long copy;
+ * long orig_dest = dest;
+ *
+ * uint64_t pattern = sbmm8(pattern, 0x0101010101010101);
+ * uint128_t pattern128 = pattern << 64 | pattern;
+ * uint256_t pattern128 = pattern128 << 128 | pattern128;
+ *
+ * // Keep only low bits
+ * dest_align &= 0x1F;
+ * length -= dest_align;
+ *
+ * // Byte align
+ * copy = align & (1 << 0);
+ * if (copy)
+ * *((u8 *) dest) = pattern;
+ * dest += copy;
+ * // Half align
+ * copy = align & (1 << 1);
+ * if (copy)
+ * *((u16 *) dest) = pattern;
+ * dest += copy;
+ * // Word align
+ * copy = align & (1 << 2);
+ * if (copy)
+ * *((u32 *) dest) = pattern;
+ * dest += copy;
+ * // Double align
+ * copy = align & (1 << 3);
+ * if (copy)
+ * *((u64 *) dest) = pattern;
+ * dest += copy;
+ * // Quad align
+ * copy = align & (1 << 4);
+ * if (copy)
+ * *((u128 *) dest) = pattern128;
+ * dest += copy;
+ *
+ * // We are now aligned on 256 bits
+ * loop_octuple_count = size >> 5;
+ * for (i = 0; i < loop_octuple_count; i++) {
+ * *((u256 *) dest) = pattern256;
+ * dest += 32;
+ * }
+ *
+ * if (length == 0)
+ * return orig_dest;
+ *
+ * // Copy remaining part
+ * remain = length & (1 << 4);
+ * if (copy)
+ * *((u128 *) dest) = pattern128;
+ * dest += remain;
+ * remain = length & (1 << 3);
+ * if (copy)
+ * *((u64 *) dest) = pattern;
+ * dest += remain;
+ * remain = length & (1 << 2);
+ * if (copy)
+ * *((u32 *) dest) = pattern;
+ * dest += remain;
+ * remain = length & (1 << 1);
+ * if (copy)
+ * *((u16 *) dest) = pattern;
+ * dest += remain;
+ * remain = length & (1 << 0);
+ * if (copy)
+ * *((u8 *) dest) = pattern;
+ * dest += remain;
+ *
+ * return orig_dest;
+ * }
+ */
+
+.text
+.align 16
+ENTRY(memset):
+ make $r32 = 0
+ make $r33 = 0
+ /* Check if length < KVX_DCACHE_LINE_SIZE */
+ compd.ltu $r7 = $r2, KVX_DCACHE_LINE_SIZE
+ /* Jump to generic memset if pattern is != 0 */
+ cb.dnez $r1? memset_non_0_pattern
+ ;;
+ /* Preserve return value */
+ copyd $r3 = $r0
+ /* Invert address to compute size to copy to be aligned on 32 bytes */
+ negd $r5 = $r0
+ /* Remaining bytes for 16 bytes store (for alignment on 64 bytes) */
+ andd $r8 = $r2, (1 << 5)
+ copyq $r34r35 = $r32, $r33
+ /* Skip loopdo with dzerol if length < KVX_DCACHE_LINE_SIZE */
+ cb.dnez $r7? .Ldzerol_done
+ ;;
+ /* Compute the size that will be copied to align on 64 bytes boundary */
+ andw $r6 = $r5, 0x3F
+ /* Check if address is aligned on 64 bytes */
+ andw $r9 = $r0, 0x3F
+ /* Alignment */
+ nop
+ ;;
+ /* If address already aligned on 64 bytes, jump to dzerol loop */
+ cb.deqz $r9? .Laligned_64
+ /* Remove unaligned part from length */
+ sbfd $r2 = $r6, $r2
+ /* Check if we need to copy 1 byte */
+ andw $r4 = $r5, (1 << 0)
+ ;;
+ /* If we are not aligned, store byte */
+ sb.dnez $r4? [$r0] = $r32
+ /* Check if we need to copy 2 bytes */
+ andw $r4 = $r5, (1 << 1)
+ /* Add potentially copied part for next store offset */
+ addd $r0 = $r0, $r4
+ ;;
+ sh.dnez $r4? [$r0] = $r32
+ /* Check if we need to copy 4 bytes */
+ andw $r4 = $r5, (1 << 2)
+ addd $r0 = $r0, $r4
+ ;;
+ sw.dnez $r4? [$r0] = $r32
+ /* Check if we need to copy 8 bytes */
+ andw $r4 = $r5, (1 << 3)
+ addd $r0 = $r0, $r4
+ ;;
+ sd.dnez $r4? [$r0] = $r32
+ /* Check if we need to copy 16 bytes */
+ andw $r4 = $r5, (1 << 4)
+ addd $r0 = $r0, $r4
+ ;;
+ sq.dnez $r4? [$r0] = $r32r33
+ /* Check if we need to copy 32 bytes */
+ andw $r4 = $r5, (1 << 5)
+ addd $r0 = $r0, $r4
+ ;;
+ so.dnez $r4? [$r0] = $r32r33r34r35
+ addd $r0 = $r0, $r4
+ ;;
+.Laligned_64:
+ /* Prepare amount of data for dzerol */
+ srld $r10 = $r2, 6
+ /* Size to be handled in loopdo */
+ andd $r4 = $r2, ~0x3F
+ make $r11 = 64
+ cb.deqz $r2? .Lmemset_done
+ ;;
+ /* Remaining bytes for 16 bytes store */
+ andw $r8 = $r2, (1 << 5)
+ /* Skip dzerol if there are not enough data for 64 bytes store */
+ cb.deqz $r10? .Ldzerol_done
+ /* Update length to copy */
+ sbfd $r2 = $r4, $r2
+ ;;
+ loopdo $r10, .Ldzerol_done
+ ;;
+ so 0[$r0], $r32r33r34r35
+ ;;
+ so 32[$r0], $r32r33r34r35
+ addd $r0 = $r0, $r11
+ ;;
+ .Ldzerol_done:
+ /*
+ * Now that we have handled every aligned bytes using 'dzerol', we can
+ * handled the remainder of length using store by decrementing size
+ * We also exploit the fact we are aligned to simply check remaining
+ * size */
+ so.dnez $r8? [$r0] = $r32r33r34r35
+ addd $r0 = $r0, $r8
+ /* Remaining bytes for 16 bytes store */
+ andw $r8 = $r2, (1 << 4)
+ cb.deqz $r2? .Lmemset_done
+ ;;
+ sq.dnez $r8? [$r0] = $r32r33
+ addd $r0 = $r0, $r8
+ /* Remaining bytes for 8 bytes store */
+ andw $r8 = $r2, (1 << 3)
+ ;;
+ sd.dnez $r8? [$r0] = $r32
+ addd $r0 = $r0, $r8
+ /* Remaining bytes for 4 bytes store */
+ andw $r8 = $r2, (1 << 2)
+ ;;
+ sw.dnez $r8? [$r0] = $r32
+ addd $r0 = $r0, $r8
+ /* Remaining bytes for 2 bytes store */
+ andw $r8 = $r2, (1 << 1)
+ ;;
+ sh.dnez $r8? [$r0] = $r32
+ addd $r0 = $r0, $r8
+ ;;
+ sb.odd $r2? [$r0] = $r32
+ /* Restore original value */
+ copyd $r0 = $r3
+ ret
+ ;;
+
+.align 16
+memset_non_0_pattern:
+ /* Preserve return value */
+ copyd $r3 = $r0
+ /* Replicate the first pattern byte on all bytes */
+ sbmm8 $r32 = $r1, REPLICATE_BYTE_MASK
+ /* Check if length < MIN_SIZE_FOR_ALIGN */
+ compd.geu $r7 = $r2, MIN_SIZE_FOR_ALIGN
+ /* Invert address to compute size to copy to be aligned on 32 bytes */
+ negd $r5 = $r0
+ ;;
+ /* Check if we are aligned on 32 bytes */
+ andw $r9 = $r0, 0x1F
+ /* Compute the size that will be copied to align on 32 bytes boundary */
+ andw $r6 = $r5, 0x1F
+ /*
+ * If size < MIN_SIZE_FOR_ALIGN bits, directly go to so, it will be done
+ * unaligned but that is still better that what we can do with sb
+ */
+ cb.deqz $r7? .Laligned_32
+ ;;
+ /* Remove unaligned part from length */
+ sbfd $r2 = $r6, $r2
+ /* If we are already aligned on 32 bytes, jump to main "so" loop */
+ cb.deqz $r9? .Laligned_32
+ /* Check if we need to copy 1 byte */
+ andw $r4 = $r5, (1 << 0)
+ ;;
+ /* If we are not aligned, store byte */
+ sb.dnez $r4? [$r0] = $r32
+ /* Check if we need to copy 2 bytes */
+ andw $r4 = $r5, (1 << 1)
+ /* Add potentially copied part for next store offset */
+ addd $r0 = $r0, $r4
+ ;;
+ sh.dnez $r4? [$r0] = $r32
+ /* Check if we need to copy 4 bytes */
+ andw $r4 = $r5, (1 << 2)
+ addd $r0 = $r0, $r4
+ ;;
+ sw.dnez $r4? [$r0] = $r32
+ /* Check if we need to copy 8 bytes */
+ andw $r4 = $r5, (1 << 3)
+ addd $r0 = $r0, $r4
+ /* Copy second part of pattern for sq */
+ copyd $r33 = $r32
+ ;;
+ sd.dnez $r4? [$r0] = $r32
+ /* Check if we need to copy 16 bytes */
+ andw $r4 = $r5, (1 << 4)
+ addd $r0 = $r0, $r4
+ ;;
+ sq.dnez $r4? [$r0] = $r32r33
+ addd $r0 = $r0, $r4
+ ;;
+.Laligned_32:
+ /* Copy second part of pattern for sq */
+ copyd $r33 = $r32
+ /* Prepare amount of data for 32 bytes store */
+ srld $r10 = $r2, 5
+ nop
+ nop
+ ;;
+ copyq $r34r35 = $r32, $r33
+ /* Remaining bytes for 16 bytes store */
+ andw $r8 = $r2, (1 << 4)
+ make $r11 = 32
+ /* Check if there are enough data for 32 bytes store */
+ cb.deqz $r10? .Laligned_32_done
+ ;;
+ loopdo $r10, .Laligned_32_done
+ ;;
+ so 0[$r0] = $r32r33r34r35
+ addd $r0 = $r0, $r11
+ ;;
+ .Laligned_32_done:
+ /*
+ * Now that we have handled every aligned bytes using 'so', we can
+ * handled the remainder of length using store by decrementing size
+ * We also exploit the fact we are aligned to simply check remaining
+ * size */
+ sq.dnez $r8? [$r0] = $r32r33
+ addd $r0 = $r0, $r8
+ /* Remaining bytes for 8 bytes store */
+ andw $r8 = $r2, (1 << 3)
+ cb.deqz $r2? .Lmemset_done
+ ;;
+ sd.dnez $r8? [$r0] = $r32
+ addd $r0 = $r0, $r8
+ /* Remaining bytes for 4 bytes store */
+ andw $r8 = $r2, (1 << 2)
+ ;;
+ sw.dnez $r8? [$r0] = $r32
+ addd $r0 = $r0, $r8
+ /* Remaining bytes for 2 bytes store */
+ andw $r8 = $r2, (1 << 1)
+ ;;
+ sh.dnez $r8? [$r0] = $r32
+ addd $r0 = $r0, $r8
+ ;;
+ sb.odd $r2? [$r0] = $r32
+ /* Restore original value */
+ copyd $r0 = $r3
+ ret
+ ;;
+.Lmemset_done:
+ /* Restore original value */
+ copyd $r0 = $r3
+ ret
+ ;;
+ENDPROC(memset)
diff --git a/arch/kvx/lib/strlen.S b/arch/kvx/lib/strlen.S
new file mode 100644
index 000000000000..8298402a7898
--- /dev/null
+++ b/arch/kvx/lib/strlen.S
@@ -0,0 +1,122 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2017-2023 Kalray Inc.
+ * Author(s): Jules Maselbas
+ */
+#include <linux/linkage.h>
+#include <asm/export.h>
+
+/*
+ * kvx optimized strlen
+ *
+ * This implementation of strlen only does aligned memory accesses.
+ * Since we don't know the total length the idea is to do double word
+ * load and stop on the first null byte found. As it's always safe to
+ * read more up to a lower 8-bytes boundary.
+ *
+ * This implementation of strlen uses a trick to detect if a double
+ * word contains a null byte [1]:
+ *
+ * > #define haszero(v) (((v) - 0x01010101UL) & ~(v) & 0x80808080UL)
+ * > The sub-expression (v - 0x01010101UL), evaluates to a high bit set
+ * > in any byte whenever the corresponding byte in v is zero or greater
+ * > than 0x80. The sub-expression ~v & 0x80808080UL evaluates to high
+ * > bits set in bytes where the byte of v doesn't have its high bit set
+ * > (so the byte was less than 0x80). Finally, by ANDing these two sub-
+ * > expressions the result is the high bits set where the bytes in v
+ * > were zero, since the high bits set due to a value greater than 0x80
+ * > in the first sub-expression are masked off by the second.
+ *
+ * [1] http://graphics.stanford.edu/~seander/bithacks.html#ZeroInWord
+ *
+ * A second trick is used to get the exact number of characters before
+ * the first null byte in a double word:
+ *
+ * clz(sbmmt(zero, 0x0102040810204080))
+ *
+ * This trick uses the haszero result which maps null byte to 0x80 and
+ * others value to 0x00. The idea is to count the number of consecutive
+ * null byte in the double word (counting from less significant byte
+ * to most significant byte). To do so, using the bit matrix transpose
+ * will "pack" all high bit (0x80) to the most significant byte (MSB).
+ * It is not possible to count the trailing zeros in this MSB, however
+ * if a byte swap is done before the bit matrix transpose we still have
+ * all the information in the MSB but now we can count the leading zeros.
+ * The instruction sbmmt with the matrix 0x0102040810204080 does exactly
+ * what we need a byte swap followed by a bit transpose.
+ *
+ * A last trick is used to handle the first double word misalignment.
+ * This is done by masking off the N lower bytes (excess read) with N
+ * between 0 and 7. The mask is applied on haszero results and will
+ * force the N lower bytes to be considered not null.
+ *
+ * This is a C implementation of the algorithm described above:
+ *
+ * size_t strlen(char *s) {
+ * uint64_t *p = (uint64_t *)((uintptr_t)s) & ~0x7;
+ * uint64_t rem = ((uintptr_t)s) % 8;
+ * uint64_t low = -0x0101010101010101;
+ * uint64_t high = 0x8080808080808080;
+ * uint64_t dword, zero;
+ * uint64_t msk, len;
+ *
+ * dword = *p++;
+ * zero = (dword + low) & ~dword & high;
+ * msk = 0xffffffffffffffff << (rem * 8);
+ * zero &= msk;
+ *
+ * while (!zero) {
+ * dword = *p++;
+ * zero = (dword + low) & ~dword & high;
+ * }
+ *
+ * zero = __builtin_kvx_sbmmt8(zero, 0x0102040810204080);
+ * len = ((void *)p - (void *)s) - 8;
+ * len += __builtin_kvx_clzd(zero);
+ *
+ * return len;
+ * }
+ */
+
+.text
+.align 16
+ENTRY(strlen)
+ andd $r1 = $r0, ~0x7
+ andd $r2 = $r0, 0x7
+ make $r10 = -0x0101010101010101
+ make $r11 = 0x8080808080808080
+ ;;
+ ld $r4 = 0[$r1]
+ sllw $r2 = $r2, 3
+ make $r3 = 0xffffffffffffffff
+ ;;
+ slld $r2 = $r3, $r2
+ addd $r5 = $r4, $r10
+ andnd $r6 = $r4, $r11
+ ;;
+ andd $r6 = $r6, $r2
+ make $r3 = 0
+ ;;
+.loop:
+ andd $r4 = $r5, $r6
+ addd $r1 = $r1, 0x8
+ ;;
+ cb.dnez $r4? .end
+ ld.deqz $r4? $r4 = [$r1]
+ ;;
+ addd $r5 = $r4, $r10
+ andnd $r6 = $r4, $r11
+ goto .loop
+ ;;
+.end:
+ addd $r1 = $r1, -0x8
+ sbmmt8 $r4 = $r4, 0x0102040810204080
+ ;;
+ clzd $r4 = $r4
+ sbfd $r1 = $r0, $r1
+ ;;
+ addd $r0 = $r4, $r1
+ ret
+ ;;
+ENDPROC(strlen)
+EXPORT_SYMBOL(strlen)
diff --git a/arch/kvx/lib/usercopy.S b/arch/kvx/lib/usercopy.S
new file mode 100644
index 000000000000..bc7e1a45e1c7
--- /dev/null
+++ b/arch/kvx/lib/usercopy.S
@@ -0,0 +1,90 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2017-2023 Kalray Inc.
+ * Author(s): Clement Leger
+ */
+#include <linux/linkage.h>
+
+/**
+ * Copy from/to a user buffer
+ * r0 = to buffer
+ * r1 = from buffer
+ * r2 = size to copy
+ * This function can trapped when hitting a non-mapped page.
+ * It will trigger a trap NOMAPPING and the trap handler will interpret
+ * it and check if instruction pointer is inside __ex_table.
+ * The next step are described later !
+ */
+.text
+ENTRY(raw_copy_from_user)
+ENTRY(raw_copy_to_user)
+ /**
+ * naive implementation byte per byte
+ */
+ make $r33 = 0x0;
+ /* If size == 0, exit directly */
+ cb.deqz $r2? copy_exit
+ ;;
+ loopdo $r2, copy_exit
+ ;;
+0: lbz $r34 = $r33[$r1]
+ ;;
+1: sb $r33[$r0] = $r34
+ addd $r33 = $r33, 1 /* Ptr increment */
+ addd $r2 = $r2, -1 /* Remaining bytes to copy */
+ ;;
+ copy_exit:
+ copyd $r0 = $r2
+ ret
+ ;;
+ENDPROC(raw_copy_to_user)
+ENDPROC(raw_copy_from_user)
+
+/**
+ * Exception table
+ * each entry correspond to the following:
+ * .dword trapping_addr, restore_addr
+ *
+ * On trap, the handler will try to locate if $spc is matching a
+ * trapping address in the exception table. If so, the restore addr
+ * will be put in the return address of the trap handler, allowing
+ * to properly finish the copy and return only the bytes copied/cleared
+ */
+.pushsection __ex_table,"a"
+.balign 8
+.dword 0b, copy_exit
+.dword 1b, copy_exit
+.popsection
+
+/**
+ * Clear a user buffer
+ * r0 = buffer to clear
+ * r1 = size to clear
+ */
+.text
+ENTRY(asm_clear_user)
+ /**
+ * naive implementation byte per byte
+ */
+ make $r33 = 0x0;
+ make $r34 = 0x0;
+ /* If size == 0, exit directly */
+ cb.deqz $r1? clear_exit
+ ;;
+ loopdo $r1, clear_exit
+ ;;
+40: sb $r33[$r0] = $r34
+ addd $r33 = $r33, 1 /* Ptr increment */
+ addd $r1 = $r1, -1 /* Remaining bytes to copy */
+ ;;
+ clear_exit:
+ copyd $r0 = $r1
+ ret
+ ;;
+ENDPROC(asm_clear_user)
+
+.pushsection __ex_table,"a"
+.balign 8
+.dword 40b, clear_exit
+.popsection
+
--
2.37.2
More information about the linux-riscv
mailing list