linux: Consolidate fxstatat{64}

System Internals / glibc - Adhemerval Zanella [linaro.org] - 11 September 2020 17:35 UTC

The LFS support is implemented on fxstat64.c, instead of fxstat.c for 64-bit architectures. The fxstatat.c implements the non-LFS and it is a no-op for !XSTAT_IS_XSTAT64.

The generic non-LFS implementation handles two cases:

1. New kABIs which uses generic pre 64-bit time Linux ABI (csky and nios): it issues __NR_fstatat64 plus handle the overflow on st_ino, st_size, or st_blocks. It only handles _STAT_VER_KERNEL.

2. Old kABIs with old non-LFS support (arm, i386, hppa, m68k, mips32, microblaze, s390, sh, powerpc, and sparc32). it issues __NR_fstatat64 and convert to non-LFS stat struct based on the
version.

Also non-LFS mips64 is an outlier and it has its own implementation since _STAT_VER_LINUX requires a different conversion function (it uses the kernel_stat as the sysissues argument since its exported ABI is different than the kernel one for both non-LFS and LFS implementation).

The generic LFS implementation handles multiple cases:

1. XSTAT_IS_XSTAT64 being 1:

1.1. 64-bit kABI (aarch64, ia64, powerpc64*, s390x, riscv64, and x86_64): it issues __NR_newfstatat for _STAT_VER_KERNEL or _STAT_VER_LINUX.

1.2. 64-bit kABI outlier (sparc64): it issuess fstatat64 with a temporary stat64 and convert to output stat64 based on the input version (and using a sparc64 specific __xstat32_conv).

1.3. New 32-bit kABIs with only 64-bit time_t support (arc and riscv32): it issues __NR_statx and covert to struct stat64.

2. Old ABIs with XSTAT_IS_XSTAT64 being 0 (arm, csky, i386, hppa, m68k, microblaze, mips32, nios2, sh, powerpc32, and sparc32): it issues __NR_fstat64.

Also, two special cases requires specific implementations:

1. alpha: it uses the __NR_fstatat64 syscall instead.

2. mips64: as for non-LFS implementation its ABIs differ from glibc exported one, which requires an specific conversion function to handle the kernel_stat.

Checked with a build for all affected ABIs. I also checked on x86_64, i686, powerpc, powerpc64le, sparcv9, sparc64, s390, and s390x.

5f85cc2f47 linux: Consolidate fxstatat{64}
sysdeps/unix/sysv/linux/Makefile | 3 +-
sysdeps/unix/sysv/linux/alpha/dl-fxstatat64.c | 1 -
sysdeps/unix/sysv/linux/alpha/fxstatat.c | 52 -----------------
.../{generic/wordsize-32 => alpha}/fxstatat64.c | 35 ++++++------
sysdeps/unix/sysv/linux/arm/fxstatat.c | 1 -
sysdeps/unix/sysv/linux/fxstatat.c | 53 +++++++-----------
sysdeps/unix/sysv/linux/fxstatat64.c | 65 +++++++++++++---------
.../unix/sysv/linux/generic/wordsize-32/fxstatat.c | 56 -------------------
sysdeps/unix/sysv/linux/hppa/fxstatat.c | 1 -
sysdeps/unix/sysv/linux/i386/fxstatat.c | 54 ------------------
sysdeps/unix/sysv/linux/m68k/fxstatat.c | 1 -
sysdeps/unix/sysv/linux/microblaze/fxstatat.c | 1 -
sysdeps/unix/sysv/linux/mips/mips32/fxstatat.c | 1 -
.../linux/{wordsize-64 => mips/mips64}/fxstatat.c | 33 +++--------
sysdeps/unix/sysv/linux/mips/mips64/fxstatat64.c | 28 ++--------
.../unix/sysv/linux/powerpc/powerpc32/fxstatat.c | 1 -
sysdeps/unix/sysv/linux/s390/s390-32/fxstatat.c | 1 -
sysdeps/unix/sysv/linux/sh/fxstatat.c | 1 -
sysdeps/unix/sysv/linux/sparc/sparc32/fxstatat.c | 1 -
.../unix/sysv/linux/sparc/sparc64/dl-fxstatat64.c | 1 -
sysdeps/unix/sysv/linux/sparc/sparc64/fxstatat.c | 1 -
.../unix/sysv/linux/wordsize-64/dl-fxstatat64.c | 1 -
sysdeps/unix/sysv/linux/wordsize-64/fxstatat64.c | 1 -
23 files changed, 92 insertions(+), 301 deletions(-)

Upstream: sourceware.org


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