From: Zhangjin Wu <falcon@tinylab.org> To: w@1wt.eu Cc: david.laight@aculab.com, arnd@arndb.de, falcon@tinylab.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-riscv@lists.infradead.org, thomas@t-8ch.de, David Laight <David.Laight@ACULAB.COM> Subject: [PATCH v4 06/10] tools/nolibc: __sysret: support syscalls who return a pointer Date: Mon, 19 Jun 2023 23:48:21 +0800 [thread overview] Message-ID: <aae854b2de881f9bc1c82ab9dda53b51d7330c9a.1687187451.git.falcon@tinylab.org> (raw) In-Reply-To: <cover.1687187451.git.falcon@tinylab.org> To support syscalls (e.g. mmap()) who return a pointer and to allow the pointer as big as possible, we should convert the negated errno value to unsigned long (uintptr_t), otherwise, in signed long, a potential big pointer (whose highest bit is 1) will be treated as a failure. tools/include/nolibc/errno.h defines the MAX_ERRNO, let's use it directly. after converting to unsigned long, the negative errno value from -1 to -MAX_ERRNO becomes something like '~1 + 1' (every bit is 1) to '~MAX_ERRNO + 1', '~1 + 1' is the biggest, '~MAX_ERRNO + 1' is the smallest, so, the check becomes: if (ret <= (unsigned long)-1 && ret >= (unsigned long)-MAX_ERRNO) { ... } Since (unsigned long)-1 is the biggest unsigned long value, it is always true if bigger than (unsigned long)-MAX_ERRNO, so, just reserve the following check is enough: if (ret >= (unsigned long)-MAX_ERRNO) { ... } Suggested-by: David Laight <David.Laight@ACULAB.COM> Link: https://lore.kernel.org/linux-riscv/94dd5170929f454fbc0a10a2eb3b108d@AcuMS.aculab.com/ Signed-off-by: Zhangjin Wu <falcon@tinylab.org> --- tools/include/nolibc/sys.h | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/tools/include/nolibc/sys.h b/tools/include/nolibc/sys.h index 4fbefe5adf93..8a6e16472d54 100644 --- a/tools/include/nolibc/sys.h +++ b/tools/include/nolibc/sys.h @@ -28,13 +28,16 @@ #include "errno.h" #include "types.h" -/* Syscall return helper, set errno as -ret when ret < 0 */ + +/* Syscall return helper for library routines + * set errno as -ret when ret in [-MAX_ERRNO, -1] + */ static __inline__ __attribute__((unused, always_inline)) -long __sysret(long ret) +long __sysret(unsigned long ret) { - if (ret < 0) { - SET_ERRNO(-ret); - ret = -1; + if (ret >= (unsigned long)-MAX_ERRNO) { + SET_ERRNO(-(long)ret); + return -1; } return ret; } -- 2.25.1
WARNING: multiple messages have this Message-ID (diff)
From: Zhangjin Wu <falcon@tinylab.org> To: w@1wt.eu Cc: david.laight@aculab.com, arnd@arndb.de, falcon@tinylab.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-riscv@lists.infradead.org, thomas@t-8ch.de, David Laight <David.Laight@ACULAB.COM> Subject: [PATCH v4 06/10] tools/nolibc: __sysret: support syscalls who return a pointer Date: Mon, 19 Jun 2023 23:48:21 +0800 [thread overview] Message-ID: <aae854b2de881f9bc1c82ab9dda53b51d7330c9a.1687187451.git.falcon@tinylab.org> (raw) In-Reply-To: <cover.1687187451.git.falcon@tinylab.org> To support syscalls (e.g. mmap()) who return a pointer and to allow the pointer as big as possible, we should convert the negated errno value to unsigned long (uintptr_t), otherwise, in signed long, a potential big pointer (whose highest bit is 1) will be treated as a failure. tools/include/nolibc/errno.h defines the MAX_ERRNO, let's use it directly. after converting to unsigned long, the negative errno value from -1 to -MAX_ERRNO becomes something like '~1 + 1' (every bit is 1) to '~MAX_ERRNO + 1', '~1 + 1' is the biggest, '~MAX_ERRNO + 1' is the smallest, so, the check becomes: if (ret <= (unsigned long)-1 && ret >= (unsigned long)-MAX_ERRNO) { ... } Since (unsigned long)-1 is the biggest unsigned long value, it is always true if bigger than (unsigned long)-MAX_ERRNO, so, just reserve the following check is enough: if (ret >= (unsigned long)-MAX_ERRNO) { ... } Suggested-by: David Laight <David.Laight@ACULAB.COM> Link: https://lore.kernel.org/linux-riscv/94dd5170929f454fbc0a10a2eb3b108d@AcuMS.aculab.com/ Signed-off-by: Zhangjin Wu <falcon@tinylab.org> --- tools/include/nolibc/sys.h | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/tools/include/nolibc/sys.h b/tools/include/nolibc/sys.h index 4fbefe5adf93..8a6e16472d54 100644 --- a/tools/include/nolibc/sys.h +++ b/tools/include/nolibc/sys.h @@ -28,13 +28,16 @@ #include "errno.h" #include "types.h" -/* Syscall return helper, set errno as -ret when ret < 0 */ + +/* Syscall return helper for library routines + * set errno as -ret when ret in [-MAX_ERRNO, -1] + */ static __inline__ __attribute__((unused, always_inline)) -long __sysret(long ret) +long __sysret(unsigned long ret) { - if (ret < 0) { - SET_ERRNO(-ret); - ret = -1; + if (ret >= (unsigned long)-MAX_ERRNO) { + SET_ERRNO(-(long)ret); + return -1; } return ret; } -- 2.25.1 _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv
next prev parent reply other threads:[~2023-06-19 15:50 UTC|newest] Thread overview: 108+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-06-19 15:40 [PATCH v4 00/10] tools/nolibc: add a new syscall helper Zhangjin Wu 2023-06-19 15:40 ` Zhangjin Wu 2023-06-19 15:41 ` [PATCH v4 01/10] tools/nolibc: sys.h: add a syscall return helper Zhangjin Wu 2023-06-19 15:41 ` Zhangjin Wu 2023-06-19 15:42 ` [PATCH v4 02/10] tools/nolibc: unistd.h: apply __sysret() helper Zhangjin Wu 2023-06-19 15:42 ` Zhangjin Wu 2023-06-19 15:44 ` [PATCH v4 03/10] tools/nolibc: sys.h: " Zhangjin Wu 2023-06-19 15:44 ` Zhangjin Wu 2023-06-19 15:45 ` [PATCH v4 04/10] tools/nolibc: unistd.h: reorder the syscall macros Zhangjin Wu 2023-06-19 15:45 ` Zhangjin Wu 2023-06-19 15:47 ` [PATCH v4 05/10] tools/nolibc: add missing my_syscall6() for mips Zhangjin Wu 2023-06-19 15:47 ` Zhangjin Wu 2023-06-19 15:48 ` Zhangjin Wu [this message] 2023-06-19 15:48 ` [PATCH v4 06/10] tools/nolibc: __sysret: support syscalls who return a pointer Zhangjin Wu 2023-06-19 15:51 ` [PATCH v4 07/10] tools/nolibc: clean up mmap() support Zhangjin Wu 2023-06-19 15:51 ` Zhangjin Wu 2023-06-21 18:48 ` Thomas Weißschuh 2023-06-21 18:48 ` Thomas Weißschuh 2023-06-22 19:08 ` Zhangjin Wu 2023-06-22 19:08 ` Zhangjin Wu 2023-06-19 15:52 ` [PATCH v4 08/10] selftests/nolibc: add EXPECT_PTREQ, EXPECT_PTRNE and EXPECT_PTRER Zhangjin Wu 2023-06-19 15:52 ` Zhangjin Wu 2023-06-19 15:54 ` [PATCH v4 09/10] selftests/nolibc: add sbrk_0 to test current brk getting Zhangjin Wu 2023-06-19 15:54 ` Zhangjin Wu 2023-06-19 15:55 ` [PATCH v4 10/10] selftests/nolibc: add mmap and munmap test cases Zhangjin Wu 2023-06-19 15:55 ` Zhangjin Wu 2023-06-19 16:14 ` Zhangjin Wu 2023-06-19 16:14 ` Zhangjin Wu 2023-06-21 18:58 ` Thomas Weißschuh 2023-06-21 18:58 ` Thomas Weißschuh 2023-06-22 19:32 ` Zhangjin Wu 2023-06-22 19:32 ` Zhangjin Wu 2023-06-22 19:56 ` Thomas Weißschuh 2023-06-22 19:56 ` Thomas Weißschuh 2023-06-24 7:47 ` Zhangjin Wu 2023-06-24 7:47 ` Zhangjin Wu 2023-06-28 13:07 ` [PATCH v5 00/14] tools/nolibc: add a new syscall helper Zhangjin Wu 2023-06-28 13:07 ` Zhangjin Wu 2023-06-28 13:08 ` [PATCH v5 01/14] tools/nolibc: sys.h: add a syscall return helper Zhangjin Wu 2023-06-28 13:08 ` Zhangjin Wu 2023-06-28 13:11 ` [PATCH v5 02/14] tools/nolibc: unistd.h: apply __sysret() helper Zhangjin Wu 2023-06-28 13:11 ` Zhangjin Wu 2023-06-28 13:13 ` [PATCH v5 03/14] tools/nolibc: sys.h: " Zhangjin Wu 2023-06-28 13:13 ` Zhangjin Wu 2023-06-28 13:14 ` [PATCH v5 04/14] tools/nolibc: unistd.h: reorder the syscall macros Zhangjin Wu 2023-06-28 13:14 ` Zhangjin Wu 2023-06-28 13:17 ` [PATCH v5 05/14] tools/nolibc: string.h: clean up multiple whitespaces with tab Zhangjin Wu 2023-06-28 13:17 ` Zhangjin Wu 2023-06-28 13:19 ` [PATCH v5 06/14] tools/nolibc: arch-*.h: clean up multiple whitespaces Zhangjin Wu 2023-06-28 13:19 ` Zhangjin Wu 2023-07-02 18:44 ` Willy Tarreau 2023-07-02 18:44 ` Willy Tarreau 2023-07-03 14:02 ` Zhangjin Wu 2023-07-03 14:02 ` Zhangjin Wu 2023-06-28 13:22 ` [PATCH v5 07/14] tools/nolibc: arch-loongarch.h: shrink with SYSCALL_CLOBBERLIST Zhangjin Wu 2023-06-28 13:22 ` Zhangjin Wu 2023-07-02 18:50 ` Willy Tarreau 2023-07-02 18:50 ` Willy Tarreau 2023-07-03 11:28 ` Zhangjin Wu 2023-07-03 11:28 ` Zhangjin Wu 2023-06-28 13:31 ` [PATCH v5 08/14] tools/nolibc: arch-mips.h: " Zhangjin Wu 2023-06-28 13:31 ` Zhangjin Wu 2023-06-28 13:37 ` [PATCH v5 09/14] tools/nolibc: add missing my_syscall6() for mips Zhangjin Wu 2023-06-28 13:37 ` Zhangjin Wu 2023-07-02 18:55 ` Willy Tarreau 2023-07-02 18:55 ` Willy Tarreau 2023-07-03 10:13 ` Zhangjin Wu 2023-07-03 10:13 ` Zhangjin Wu 2023-06-28 13:39 ` [PATCH v5 10/14] tools/nolibc: __sysret: support syscalls who return a pointer Zhangjin Wu 2023-06-28 13:39 ` Zhangjin Wu 2023-07-02 19:17 ` Willy Tarreau 2023-07-02 19:17 ` Willy Tarreau 2023-07-03 8:36 ` Zhangjin Wu 2023-07-03 8:36 ` Zhangjin Wu 2023-07-03 10:03 ` Willy Tarreau 2023-07-03 10:03 ` Willy Tarreau 2023-07-03 11:15 ` Zhangjin Wu 2023-07-03 11:15 ` Zhangjin Wu 2023-06-28 13:41 ` [PATCH v5 11/14] tools/nolibc: clean up mmap() support Zhangjin Wu 2023-06-28 13:41 ` Zhangjin Wu 2023-07-02 19:23 ` Willy Tarreau 2023-07-02 19:23 ` Willy Tarreau 2023-07-03 6:51 ` Zhangjin Wu 2023-07-03 6:51 ` Zhangjin Wu 2023-06-28 13:44 ` [PATCH v5 12/14] selftests/nolibc: add EXPECT_PTREQ, EXPECT_PTRNE and EXPECT_PTRER Zhangjin Wu 2023-06-28 13:44 ` Zhangjin Wu 2023-06-28 13:46 ` [PATCH v5 13/14] selftests/nolibc: add sbrk_0 to test current brk getting Zhangjin Wu 2023-06-28 13:46 ` Zhangjin Wu 2023-06-28 13:51 ` [PATCH v5 14/14] selftests/nolibc: add mmap and munmap test cases Zhangjin Wu 2023-06-28 13:51 ` Zhangjin Wu 2023-07-02 19:33 ` Willy Tarreau 2023-07-02 19:33 ` Willy Tarreau 2023-07-03 6:03 ` Zhangjin Wu 2023-07-03 6:03 ` Zhangjin Wu 2023-07-03 7:25 ` Willy Tarreau 2023-07-03 7:25 ` Willy Tarreau 2023-07-03 8:06 ` Zhangjin Wu 2023-07-03 8:06 ` Zhangjin Wu 2023-07-03 8:20 ` Thomas Weißschuh 2023-07-03 8:20 ` Thomas Weißschuh 2023-07-03 9:15 ` Zhangjin Wu 2023-07-03 9:15 ` Zhangjin Wu 2023-07-03 9:56 ` Willy Tarreau 2023-07-03 9:56 ` Willy Tarreau 2023-07-03 11:24 ` Zhangjin Wu 2023-07-03 11:24 ` Zhangjin Wu 2023-07-02 19:34 ` [PATCH v5 00/14] tools/nolibc: add a new syscall helper Willy Tarreau 2023-07-02 19:34 ` Willy Tarreau
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