To avoid clobbering of any registers by the trampoline code use Linux
way to call signal handlers. I.e., we are out from the kernel right into
the signal handler, put return address from the signal handler into the
link register.
The mysterious NOP is required for some unwinders (e.g. libc++) that
unconditionally subtract one from the result of _Unwind_GetIP() in order
to identify the calling function.
MFC after: 1 week
To allow unwinders to go througth a previous to sigreturn frame we should
properly emulate the trampoline frame record which should points to the
previous frame and set the trampoline frame pointer to the emulated frame
before calling signal handler.
MFC after: 1 week
An Aarch64 sigreturn trampoline frame can't currently be described in
a DWARF .eh_frame section, because Aarch64 does not define a register
number for PC and provide no direct way to encode PC of the previous
frame. Instead, unwinders (libgcc, gdb, libunwind) detect the sigreturn
frame by looking for the sigreturn instruction. If a sigreturn frame is
detected, unwinders restores all the gprs, SP and PC by assuming that
sp points to an rt_sigframe Linux kernel struct
When entering the kernel, the link register (lr) contains the return
address of the previous frame, the exception link register (elr) contains
the address of the next instruction after the one which generated the
exception, i.e., PC.
MFC after: 1 week
The SPDX folks have obsoleted the BSD-2-Clause-FreeBSD identifier. Catch
up to that fact and revert to their recommended match of BSD-2-Clause.
Discussed with: pfg
MFC After: 3 days
Sponsored by: Netflix
As of version 2.6.0 of the Linux kernel, dev_t is a 32-bit unsigned integer
on all platforms. Prior the 2.6 kernel dev_t type was an unsigned short.
However, since the firs commit of the Linuxulator, mknod syscall get int dev
argument.
Also, there is some confusion here, while the kernel declares a dev_t type
as a 32-bit sized, the user-space dev_t type can be size of 64 bits, e.g.,
in the Glibc library.
To avoid confusion and to help porting of the Linuxulator to other platforms
use explicit l_dev_t for dev argument of mknod syscalls.
Export default MINSIGSTKSZ value for the x86 until we do not preserve AVX
registers in the signal context.
Differential Revision: https://reviews.freebsd.org/D39644
MFC after: 1 month
Have more accruate comments. While #if, #else, etc are copied to the
header files, lines that don't start with # are not. And #include files
are only output to sysinc (which winds up at the front of init_sysent.c
which seems a bit odd). This is all radically undocumented, and likely
has drifted somewhat from 4.4BSD and what other systems do (they've
drifted too, fwiw).
Sponsored by: Netflix
To avoid confusing people, rename linux_timer.h to linux_time.h,
as linux_timer.c is the implementation of timer syscalls only,
while linux_time.c contains implementation of all stuff declared
in linux_time.h.
MFC after: 2 weeks
Include vm headers directly where they needed. The linux_util.h included
in a most source files of the Linuxulator, avoid collecting a rarely used
includes here.
MFC after: 2 weeks
This allows the syscallname() function to give a usable result for Linux
ABIs.
Reported by: jrtc27
Reviewed by: jrtc27, markj, jhb
MFC after: 1 week
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D37199
Store the shared page address in struct vmspace.
Also instead of storing absolute addresses of various shared page
segments save their offsets with respect to the shared page address.
This will be more useful when the shared page address is randomized.
Approved by: mw(mentor)
Sponsored by: Stormshield
Obtained from: Semihalf
Reviewed by: kib
Differential Revision: https://reviews.freebsd.org/D35393
The implemenation differs from others Linuxulators.
For unwinders Linux ucontext_t is stored, however native machine context
is used to store/restore process state to avoid code duplication.
As DWARF Aarch64 does not define a register number for PC and provides no
direct way to encode the PC of the previous frame, CFI cannot describe a
signal trampoline frame. So, modified the vdso linker script to discard
unused sections.
Extensions are not implemented.
MFC after: 2 weeks
Rework the defintion of struct siginfo so that the array padding
struct siginfo to SI_MAX_SIZE can be placed in a union along side of the
rest of the struct siginfo members. The result is that we no longer need
the __ARCH_SI_PREAMBLE_SIZE or SI_PAD_SIZE definitions.
Move struct siginfo definition under /compat/linux to reduce MD part.
To avoid headers polution include linux_siginfo.h in the MD linux.h
MFC after: 2 weeks
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
On i386 are two semtimedop. The old one is called via multiplexor and
uses 32-bit timespec, and new semtimedop_tim64, which is uses 64-bit
timespec.
MFC after: 2 weeks
