kernel/linux.git/tools/include/nolibc/string.h, branch v6.12.80

tools/nolibc: include arch.h from string.h

2024-07-29T05:52:56+00:00

string.h tests for the macros NOLIBC_ARCH_HAS_$FUNC to use the architecture-optimized function variants. However if string.h is included before arch.h header then that check does not work, leading to duplicate function definitions. Fixes: 553845eebd60 ("tools/nolibc: x86-64: Use `rep movsb` for `memcpy()` and `memmove()`") Fixes: 12108aa8c1a1 ("tools/nolibc: x86-64: Use `rep stosb` for `memset()`") Cc: stable@vger.kernel.org Acked-by: Willy Tarreau Link: https://lore.kernel.org/r/20240725-arch-has-func-v1-1-5521ed354acd@weissschuh.net Signed-off-by: Thomas Weißschuh

tools/nolibc/string: remove open-coded strnlen()

2024-04-10T21:27:06+00:00

The same header already defines an implementation of strnlen(), so use it. Signed-off-by: Thomas Weißschuh

tools/nolibc: Fix strlcpy() return code and size usage

2024-04-10T21:19:02+00:00

The return code should always be strlen(src), and we should copy at most size-1 bytes. While we are there, make sure to null-terminate the dst buffer if we copied something. Signed-off-by: Rodrigo Campos Signed-off-by: Thomas Weißschuh

tools/nolibc: Fix strlcat() return code and size usage

2024-04-10T21:19:01+00:00

The return code should always be strlen(src) + strnlen(dst, size). Let's make sure to copy at most size-1 bytes from src and null-terminate the dst buffer if we did copied something. While we can use strnlen() and strncpy() to implement strlcat(), this is simple enough and results in shorter code when compiled. Signed-off-by: Rodrigo Campos Signed-off-by: Thomas Weißschuh

tools/nolibc/string: export strlen()

2024-04-10T21:19:01+00:00

As with commit 8d304a374023, "tools/nolibc/string: export memset() and memmove()", gcc -Os without -ffreestanding may fail to compile with: cc -fno-asynchronous-unwind-tables -fno-ident -s -Os -nostdlib -lgcc -static -o test test.c /usr/bin/ld: /tmp/cccIasKL.o: in function `main': test.c:(.text.startup+0x1e): undefined reference to `strlen' collect2: error: ld returned 1 exit status As on the aforementioned commit, this patch adds a section to export this function so compilation works on those cases too. Signed-off-by: Rodrigo Campos Signed-off-by: Thomas Weißschuh

tools/nolibc: string: Remove the `_nolibc_memcpy_up()` function

2023-10-12T19:14:03+00:00

This function is only called by memcpy(), there is no real reason to have this wrapper. Delete this function and move the code to memcpy() directly. Signed-off-by: Ammar Faizi Reviewed-by: Alviro Iskandar Setiawan Signed-off-by: Willy Tarreau Signed-off-by: Thomas Weißschuh

tools/nolibc: string: Remove the `_nolibc_memcpy_down()` function

2023-10-12T19:14:02+00:00

This nolibc internal function is not used. Delete it. It was probably supposed to handle memmove(), but today the memmove() has its own implementation. Signed-off-by: Ammar Faizi Reviewed-by: Alviro Iskandar Setiawan Signed-off-by: Willy Tarreau Signed-off-by: Thomas Weißschuh

tools/nolibc: x86-64: Use `rep stosb` for `memset()`

2023-10-12T19:14:00+00:00

Simplify memset() on the x86-64 arch. The x86-64 arch has a 'rep stosb' instruction, which can perform memset() using only a single instruction, given: %al = value (just like the second argument of memset()) %rdi = destination %rcx = length Before this patch: ``` 00000000000010c9 : 10c9: 48 89 f8 mov %rdi,%rax 10cc: 48 85 d2 test %rdx,%rdx 10cf: 74 0e je 10df 10d1: 31 c9 xor %ecx,%ecx 10d3: 40 88 34 08 mov %sil,(%rax,%rcx,1) 10d7: 48 ff c1 inc %rcx 10da: 48 39 ca cmp %rcx,%rdx 10dd: 75 f4 jne 10d3 10df: c3 ret ``` After this patch: ``` 0000000000001511 : 1511: 96 xchg %eax,%esi 1512: 48 89 d1 mov %rdx,%rcx 1515: 57 push %rdi 1516: f3 aa rep stos %al,%es:(%rdi) 1518: 58 pop %rax 1519: c3 ret ``` v2: - Use pushq %rdi / popq %rax (Alviro). - Use xchg %eax, %esi (Willy). Link: https://lore.kernel.org/lkml/ZO9e6h2jjVIMpBJP@1wt.eu Suggested-by: Alviro Iskandar Setiawan Suggested-by: Willy Tarreau Signed-off-by: Ammar Faizi Reviewed-by: Alviro Iskandar Setiawan Signed-off-by: Willy Tarreau Signed-off-by: Thomas Weißschuh

tools/nolibc: x86-64: Use `rep movsb` for `memcpy()` and `memmove()`

2023-10-12T19:13:56+00:00

Simplify memcpy() and memmove() on the x86-64 arch. The x86-64 arch has a 'rep movsb' instruction, which can perform memcpy() using only a single instruction, given: %rdi = destination %rsi = source %rcx = length Additionally, it can also handle the overlapping case by setting DF=1 (backward copy), which can be used as the memmove() implementation. Before this patch: ``` 00000000000010ab : 10ab: 48 89 f8 mov %rdi,%rax 10ae: 31 c9 xor %ecx,%ecx 10b0: 48 39 f7 cmp %rsi,%rdi 10b3: 48 83 d1 ff adc $0xffffffffffffffff,%rcx 10b7: 48 85 d2 test %rdx,%rdx 10ba: 74 25 je 10e1 10bc: 48 83 c9 01 or $0x1,%rcx 10c0: 48 39 f0 cmp %rsi,%rax 10c3: 48 c7 c7 ff ff ff ff mov $0xffffffffffffffff,%rdi 10ca: 48 0f 43 fa cmovae %rdx,%rdi 10ce: 48 01 cf add %rcx,%rdi 10d1: 44 8a 04 3e mov (%rsi,%rdi,1),%r8b 10d5: 44 88 04 38 mov %r8b,(%rax,%rdi,1) 10d9: 48 01 cf add %rcx,%rdi 10dc: 48 ff ca dec %rdx 10df: 75 f0 jne 10d1 10e1: c3 ret 00000000000010e2 : 10e2: 48 89 f8 mov %rdi,%rax 10e5: 48 85 d2 test %rdx,%rdx 10e8: 74 12 je 10fc 10ea: 31 c9 xor %ecx,%ecx 10ec: 40 8a 3c 0e mov (%rsi,%rcx,1),%dil 10f0: 40 88 3c 08 mov %dil,(%rax,%rcx,1) 10f4: 48 ff c1 inc %rcx 10f7: 48 39 ca cmp %rcx,%rdx 10fa: 75 f0 jne 10ec 10fc: c3 ret ``` After this patch: ``` // memmove is an alias for memcpy 000000000040133b : 40133b: 48 89 d1 mov %rdx,%rcx 40133e: 48 89 f8 mov %rdi,%rax 401341: 48 89 fa mov %rdi,%rdx 401344: 48 29 f2 sub %rsi,%rdx 401347: 48 39 ca cmp %rcx,%rdx 40134a: 72 03 jb 40134f 40134c: f3 a4 rep movsb %ds:(%rsi),%es:(%rdi) 40134e: c3 ret 40134f: 48 8d 7c 0f ff lea -0x1(%rdi,%rcx,1),%rdi 401354: 48 8d 74 0e ff lea -0x1(%rsi,%rcx,1),%rsi 401359: fd std 40135a: f3 a4 rep movsb %ds:(%rsi),%es:(%rdi) 40135c: fc cld 40135d: c3 ret ``` v3: - Make memmove as an alias for memcpy (Willy). - Make the forward copy the likely case (Alviro). v2: - Fix the broken memmove implementation (David). Link: https://lore.kernel.org/lkml/20230902062237.GA23141@1wt.eu Link: https://lore.kernel.org/lkml/5a821292d96a4dbc84c96ccdc6b5b666@AcuMS.aculab.com Suggested-by: David Laight Signed-off-by: Ammar Faizi Signed-off-by: Willy Tarreau Signed-off-by: Thomas Weißschuh

tools/nolibc: use standard asm statements

2023-06-09T18:46:07+00:00

Most of the code was migrated to C99-conformant __asm__ statements before. It seems string.h was missed. Signed-off-by: Thomas Weißschuh Signed-off-by: Willy Tarreau Signed-off-by: Paul E. McKenney