Replace sigframe sf_extramask by native sigset_t and use it to
store/restore the thread signal mask without conversion to/from
Linux signal mask.
Pointy hat to: dchagin
MFC after: 2 weeks
(cherry picked from commit 4a6c2d075d)
To reduce sendsig code difference and to avoid confusing me,
rename sf_sc to sf_uc to match the content.
MFC after: 2 weeks
(cherry picked from commit 6e826d27c3)
The signal trampoine-related definitions are used only in the MD part
of code, wherefore moved from everywhere used linux.h to separate MD
headers.
MFC after: 2 weeks
(cherry picked from commit 21f2461741)
The vDSO (virtual dynamic shared object) is a small shared library that the
kernel maps R/O into the address space of all Linux processes on image
activation. The vDSO is a fully formed ELF image, shared by all processes
with the same ABI, has no process private data.
The primary purpose of the vDSO:
- non-executable stack, signal trampolines not copied to the stack;
- signal trampolines unwind, mandatory for the NPTL;
- to avoid contex-switch overhead frequently used system calls can be
implemented in the vDSO: for now gettimeofday, clock_gettime.
The first two have been implemented, so add the implementation of system
calls.
System calls implemenation based on a native timekeeping code with some
limitations:
- ifunc can't be used, as vDSO r/o mapped to the process VA and rtld
can't relocate symbols;
- reading HPET memory is not implemented for now (TODO).
In case on any error vDSO system calls fallback to the kernel system
calls. For unimplemented vDSO system calls added prototypes which call
corresponding kernel system call.
Relnotes: yes
Tested by: trasz (arm64)
Differential revision: https://reviews.freebsd.org/D30900
MFC after: 2 weeks
(cherry picked from commit 9931033bbf)
