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https://sourceware.org/git/glibc.git
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b65d3e5f0f
Beginning with the upcoming 4.1 release, Linux on a subset of 32-bit ARM hardware will provide fast user-space implementations of the following system calls: - gettimeofday - clock_gettime The kernel implementation depends on the ARMv7 Generic Timers Extension to accelerate these system calls. So CPUs such as Cortex-A15 and -A7 benefit, while Cortex-A9, -A8, and pre-v7 CPUs do not. On systems where the VDSO does not provide any speedup, the kernel prevents the relevant symbol lookups from succeeding. On OMAP5 (Cortex-A15) gettimeofday latency decreases from ~350ns to ~120ns. On BeagleBone Black (Cortex-A8) it goes from ~650ns to ~660ns, which to my mind is an acceptable cost. Verified that no new test failures are introduced on kernels with and without the VDSO. * sysdeps/unix/sysv/linux/arm/Makefile: (sysdep_routines): Include dl-vdso. * sysdeps/unix/sysv/linux/arm/init-first.c: New file: Use VDSO routines for gettimeofday, clock_gettime if available. * sysdeps/unix/sysv/linux/arm/libc-vdso.h: New file: Declare VDSO symbols. * sysdeps/unix/sysv/linux/arm/sysdep.h: [HAVE_GETTIMEOFDAY_VSYSCALL]: Define. [HAVE_CLOCK_GETTIME_VSYSCALL]: Define. * sysdeps/unix/sysv/linux/arm/Versions: Add __vdso_clock_gettime.
74 lines
1.6 KiB
Makefile
74 lines
1.6 KiB
Makefile
ifeq ($(subdir),elf)
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sysdep_routines += dl-vdso
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sysdep-rtld-routines += aeabi_read_tp libc-do-syscall
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endif
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ifeq ($(subdir),misc)
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sysdep_routines += ioperm
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sysdep_headers += sys/elf.h sys/io.h
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endif
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ifeq ($(subdir),signal)
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sysdep_routines += sigrestorer
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endif
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ifeq ($(subdir),resource)
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sysdep_routines += oldgetrlimit64
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endif
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ifeq ($(subdir),stdlib)
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gen-as-const-headers += ucontext_i.sym
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endif
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# Add a syscall function to each library that needs one.
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ifeq ($(subdir),crypt)
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libcrypt-sysdep_routines += libc-do-syscall
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endif
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ifeq ($(subdir),rt)
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librt-sysdep_routines += libc-do-syscall
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librt-shared-only-routines += libc-do-syscall
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endif
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ifeq ($(subdir),nptl)
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libpthread-sysdep_routines += libc-do-syscall
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libpthread-shared-only-routines += libc-do-syscall
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endif
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ifeq ($(subdir),resolv)
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libanl-sysdep_routines += libc-do-syscall
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libanl-shared-only-routines += libc-do-syscall
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endif
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ifeq ($(subdir),csu)
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sysdep_routines += libc-do-syscall
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endif
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ifeq ($(subdir),nscd)
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nscd-modules += libc-do-syscall
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endif
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ifeq ($(subdir),nss)
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libnss_db-sysdep_routines += libc-do-syscall
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libnss_db-shared-only-routines += libc-do-syscall
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endif
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ifeq ($(subdir),posix)
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LDFLAGS-tst-rfc3484 += $(common-objpfx)csu/libc-do-syscall.o
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LDFLAGS-tst-rfc3484-2 += $(common-objpfx)csu/libc-do-syscall.o
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LDFLAGS-tst-rfc3484-3 += $(common-objpfx)csu/libc-do-syscall.o
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endif
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abi-variants := soft hard
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ifeq (,$(filter $(default-abi),$(abi-variants)))
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Unknown ABI, must be one of $(abi-variants)
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endif
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abi-includes :=
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abi-soft-options := -U__ARM_PCS_VFP
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abi-soft-condition := !defined __ARM_PCS_VFP
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abi-hard-options := -D__ARM_PCS_VFP
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abi-hard-condition := defined __ARM_PCS_VFP
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