src/lib/libc/arm/sys, branch releng/12.2

Reimplement brk() and sbrk() to avoid the use of _end.

2018-06-04T19:35:15Z

Previously, libc.so would initialize its notion of the break address using _end, a special symbol emitted by the static linker following the bss section. Compatibility issues between lld and ld.bfd could cause the wrong definition of _end (libc.so's definition rather than that of the executable) to be used, breaking the brk()/sbrk() interface. Avoid this problem and future interoperability issues by simply not relying on _end. Instead, modify the break() system call to return the kernel's view of the current break address, and have libc initialize its state using an extra syscall upon the first use of the interface. As a side effect, this appears to fix brk()/sbrk() usage in executables run with rtld direct exec, since the kernel and libc.so no longer maintain separate views of the process' break address. PR: 228574 Reviewed by: kib (previous version) MFC after: 2 months Differential Revision: https://reviews.freebsd.org/D15663

Remove architecture specific shmat.S files.

2018-04-05T18:17:46Z

These files are identical to the generated system calls. In the case of MIPS, the file was already disconnected from the build. Submitted by: Ali Mashtizadeh Reviewed by: kib Differential Revision: https://reviews.freebsd.org/D14976

Remove architecture specific sigreturn.S files.

2018-04-04T22:45:08Z

All of these files are identical (modulo license blocks and VCS IDs) to the files generated by lib/libc/sys/Makefile.inc and serve no purpose. Reported by: Ali Mashtizadeh Reviewed by: kib Sponsored by: DARPA, AFRL Differential Revision: https://reviews.freebsd.org/D14953

libc: further adoption of SPDX licensing ID tags.

2017-11-25T17:12:48Z

Mainly focus on files that use BSD 2-Clause license, however the tool I was using mis-identified many licenses so this was mostly a manual - error prone - task. The Software Package Data Exchange (SPDX) group provides a specification to make it easier for automated tools to detect and summarize well known opensource licenses. We are gradually adopting the specification, noting that the tags are considered only advisory and do not, in any way, superceed or replace the license texts.

Reduce duplicate NOASM and PSEUDO definitions

2016-09-08T22:38:20Z

The initial value of NOASM is nearly the same in all cases and the initial value of PSEUDO is the same in all cases so reduce duplication (and hopefully, future merge conflicts) by machine independent defaults. Also document the PSEUDO variable. Reviewed by: jhb, kib Obtained from: CheriBSD Sponsored by: DARPA, AFRL Differential Revision: https://reviews.freebsd.org/D7820

Rewrite ptrace(2) wrappers in C.

2016-08-29T18:47:51Z

Besides removing hand-translation to assembler, this also adds missing wrappers for arm64 and risc-v. Reviewed by: emaste, jhb Sponsored by: The FreeBSD Foundation MFC after: 1 week Differential revision: https://reviews.freebsd.org/D7694

Remove unusedd and obsolete openbsd_poll system call. (Phase 1)

2016-08-18T10:50:40Z

Reported by: brooks Reviewed by: brooks,jhb Differential Revision: https://reviews.freebsd.org/D7548

Implement userspace gettimeofday(2) with HPET timecounter.

2016-08-17T09:52:09Z

Right now, userspace (fast) gettimeofday(2) on x86 only works for RDTSC. For older machines, like Core2, where RDTSC is not C2/C3 invariant, and which fall to HPET hardware, this means that the call has both the penalty of the syscall and of the uncached hw behind the QPI or PCIe connection to the sought bridge. Nothing can me done against the access latency, but the syscall overhead can be removed. System already provides mappable /dev/hpetX devices, which gives straight access to the HPET registers page. Add yet another algorithm to the x86 'vdso' timehands. Libc is updated to handle both RDTSC and HPET. For HPET, the index of the hpet device to mmap is passed from kernel to userspace, index might be changed and libc invalidates its mapping as needed. Remove cpu_fill_vdso_timehands() KPI, instead require that timecounters which can be used from userspace, to provide tc_fill_vdso_timehands{,32}() methods. Merge i386 and amd64 libc//sys/__vdso_gettc.c into one source file in the new libc/x86/sys location. __vdso_gettc() internal interface is changed to move timecounter algorithm detection into the MD code. Measurements show that RDTSC even with the syscall overhead is faster than userspace HPET access. But still, userspace HPET is three-four times faster than syscall HPET on several Core2 and SandyBridge machines. Tested by: Howard Su Sponsored by: The FreeBSD Foundation MFC after: 1 month Differential revision: https://reviews.freebsd.org/D7473

Replace use of the pipe(2) system call with pipe2(2) with a zero flags

2016-06-22T21:11:27Z

value. This eliminates the need for machine dependant assembly wrappers for pipe(2). It also make passing an invalid address to pipe(2) return EFAULT rather than triggering a segfault. Document this behavior (which was already true for pipe2(2), but undocumented). Reviewed by: andrew Approved by: re (gjb) Sponsored by: DARPA, AFRL Differential Revision: https://reviews.freebsd.org/D6815

Do not compile ARMv6 instructions on ARMv4/v5. Although clang is fine

2015-12-24T22:13:52Z

with mrrc, gcc is not. The disabled code is not executed on ARMv4 anyway. Reported and reviewed by: ian Sponsored by: The FreeBSD Foundation