diff options
Diffstat (limited to 'io-Do-not-implement-fstat-with-fstatat.patch')
| -rw-r--r-- | io-Do-not-implement-fstat-with-fstatat.patch | 165 |
1 files changed, 165 insertions, 0 deletions
diff --git a/io-Do-not-implement-fstat-with-fstatat.patch b/io-Do-not-implement-fstat-with-fstatat.patch new file mode 100644 index 0000000..98aab20 --- /dev/null +++ b/io-Do-not-implement-fstat-with-fstatat.patch @@ -0,0 +1,165 @@ +From 551101e8240b7514fc646d1722f8b79c90362b8f Mon Sep 17 00:00:00 2001 +From: Adhemerval Zanella <adhemerval.zanella@linaro.org> +Date: Mon, 11 Sep 2023 10:25:48 -0300 +Subject: [PATCH] io: Do not implement fstat with fstatat + +AT_EMPTY_PATH is a requirement to implement fstat over fstatat, +however it does not prevent the kernel to read the path argument. +It is not an issue, but on x86-64 with SMAP-capable CPUs the kernel is +forced to perform expensive user memory access. After that regular +lookup is performed which adds even more overhead. + +Instead, issue the fstat syscall directly on LFS fstat implementation +(32 bit architectures will still continue to use statx, which is +required to have 64 bit time_t support). it should be even a +small performance gain on non x86_64, since there is no need +to handle the path argument. + +Checked on x86_64-linux-gnu. +--- + sysdeps/unix/sysv/linux/fstat64.c | 37 +++++++++++++++++++++++-- + sysdeps/unix/sysv/linux/fstatat64.c | 12 ++------ + sysdeps/unix/sysv/linux/internal-stat.h | 31 +++++++++++++++++++++ + 3 files changed, 68 insertions(+), 12 deletions(-) + create mode 100644 sysdeps/unix/sysv/linux/internal-stat.h + +diff --git a/sysdeps/unix/sysv/linux/fstat64.c b/sysdeps/unix/sysv/linux/fstat64.c +index 124384e57f..a291f0825b 100644 +--- a/sysdeps/unix/sysv/linux/fstat64.c ++++ b/sysdeps/unix/sysv/linux/fstat64.c +@@ -19,20 +19,53 @@ + #define __fstat __redirect___fstat + #define fstat __redirect_fstat + #include <sys/stat.h> ++#undef __fstat ++#undef fstat + #include <fcntl.h> +-#include <kernel_stat.h> +-#include <stat_t64_cp.h> ++#include <internal-stat.h> + #include <errno.h> + + int + __fstat64_time64 (int fd, struct __stat64_t64 *buf) + { ++#if !FSTATAT_USE_STATX ++# if XSTAT_IS_XSTAT64 ++# ifdef __NR_fstat ++ /* 64-bit kABI, e.g. aarch64, ia64, powerpc64*, s390x, riscv64, and ++ x86_64. */ ++ return INLINE_SYSCALL_CALL (fstat, fd, buf); ++# elif defined __NR_fstat64 ++# if STAT64_IS_KERNEL_STAT64 ++ /* 64-bit kABI outlier, e.g. alpha */ ++ return INLINE_SYSCALL_CALL (fstat64, fd, buf); ++# else ++ /* 64-bit kABI outlier, e.g. sparc64. */ ++ struct kernel_stat64 kst64; ++ int r = INLINE_SYSCALL_CALL (fstat64, fd, &kst64); ++ if (r == 0) ++ __cp_stat64_kstat64 (buf, &kst64); ++ return r; ++# endif /* STAT64_IS_KERNEL_STAT64 */ ++# endif ++# else /* XSTAT_IS_XSTAT64 */ ++ /* 64-bit kabi outlier, e.g. mips64 and mips64-n32. */ ++ struct kernel_stat kst; ++ int r = INLINE_SYSCALL_CALL (fstat, fd, &kst); ++ if (r == 0) ++ __cp_kstat_stat64_t64 (&kst, buf); ++ return r; ++# endif ++#else /* !FSTATAT_USE_STATX */ ++ /* All kABIs with non-LFS support and with old 32-bit time_t support ++ e.g. arm, csky, i386, hppa, m68k, microblaze, nios2, sh, powerpc32, ++ and sparc32. */ + if (fd < 0) + { + __set_errno (EBADF); + return -1; + } + return __fstatat64_time64 (fd, "", buf, AT_EMPTY_PATH); ++#endif + } + #if __TIMESIZE != 64 + hidden_def (__fstat64_time64) +diff --git a/sysdeps/unix/sysv/linux/fstatat64.c b/sysdeps/unix/sysv/linux/fstatat64.c +index 3509d3ca6d..127c6ff601 100644 +--- a/sysdeps/unix/sysv/linux/fstatat64.c ++++ b/sysdeps/unix/sysv/linux/fstatat64.c +@@ -21,12 +21,10 @@ + #include <sys/stat.h> + #include <fcntl.h> + #include <string.h> +-#include <kernel_stat.h> + #include <sysdep.h> + #include <time.h> +-#include <kstat_cp.h> +-#include <stat_t64_cp.h> + #include <sys/sysmacros.h> ++#include <internal-stat.h> + + #if __TIMESIZE == 64 \ + && (__WORDSIZE == 32 \ +@@ -40,11 +38,7 @@ _Static_assert (sizeof (__blkcnt_t) == sizeof (__blkcnt64_t), + "__blkcnt_t and __blkcnt64_t must match"); + #endif + +-#if (__WORDSIZE == 32 \ +- && (!defined __SYSCALL_WORDSIZE || __SYSCALL_WORDSIZE == 32)) \ +- || defined STAT_HAS_TIME32 \ +- || (!defined __NR_newfstatat && !defined __NR_fstatat64) +-# define FSTATAT_USE_STATX 1 ++#if FSTATAT_USE_STATX + + static inline int + fstatat64_time64_statx (int fd, const char *file, struct __stat64_t64 *buf, +@@ -79,8 +73,6 @@ fstatat64_time64_statx (int fd, const char *file, struct __stat64_t64 *buf, + + return r; + } +-#else +-# define FSTATAT_USE_STATX 0 + #endif + + /* Only statx supports 64-bit timestamps for 32-bit architectures with +diff --git a/sysdeps/unix/sysv/linux/internal-stat.h b/sysdeps/unix/sysv/linux/internal-stat.h +new file mode 100644 +index 0000000000..e3b0569853 +--- /dev/null ++++ b/sysdeps/unix/sysv/linux/internal-stat.h +@@ -0,0 +1,31 @@ ++/* Internal stat definitions. ++ Copyright (C) 2023 Free Software Foundation, Inc. ++ This file is part of the GNU C Library. ++ ++ The GNU C Library is free software; you can redistribute it and/or ++ modify it under the terms of the GNU Lesser General Public ++ License as published by the Free Software Foundation; either ++ version 2.1 of the License, or (at your option) any later version. ++ ++ The GNU C Library is distributed in the hope that it will be useful, ++ but WITHOUT ANY WARRANTY; without even the implied warranty of ++ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU ++ Lesser General Public License for more details. ++ ++ You should have received a copy of the GNU Lesser General Public ++ License along with the GNU C Library; if not, see ++ <https://www.gnu.org/licenses/>. */ ++ ++#include <sysdep.h> ++#include <stat_t64_cp.h> ++#include <kernel_stat.h> ++#include <kstat_cp.h> ++ ++#if (__WORDSIZE == 32 \ ++ && (!defined __SYSCALL_WORDSIZE || __SYSCALL_WORDSIZE == 32)) \ ++ || defined STAT_HAS_TIME32 \ ++ || (!defined __NR_newfstatat && !defined __NR_fstatat64) ++# define FSTATAT_USE_STATX 1 ++#else ++# define FSTATAT_USE_STATX 0 ++#endif +-- +2.33.0 + |