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
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
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
Note that this still uses FreeBSD-style sigframe;
this will be addressed later.
Reviewed By: dchagin
Sponsored By: EPSRC
Differential Revision: https://reviews.freebsd.org/D31258
In preparation for vDSO code revision get rid of incomplete vDSO methods
from locore, but leave .note.Linux section commented out.
.note.Linux section is used by glibc rtld to get the kernel version, that
saves one system call call. I'll try to implement it later, if figure out
how to use it with jails.
MFC after: 2 weeks
Previously it would return "arm64", which was breaking build
for Linux kernel. While here, reshuffle entries in the auxv
vector to match real Linux.
Reviewed By: emaste
Sponsored By: EPSRC
Differential Revision: https://reviews.freebsd.org/D30500
Follow-up to r353959 and r368070: do the same for other architectures.
arm32 already seems to use its own .fnstart/.fnend directives, which
appear to be ARM-specific variants of the same thing. Likewise, MIPS
uses .frame directives.
Reviewed by: arichardson
Differential Revision: https://reviews.freebsd.org/D27387
It is assembled using "${CC} -x assembler-with-cpp", which by convention
(bsd.suffixes.mk) uses the .asm extension.
This is a portion of the review referenced below (D18344). That review
also renamed linux_support.s to .S, but that is a functional change
(using the compiler's integrated assembler instead of as) and will be
revisited separately.
MFC after: 1 week
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D18344
2019-07-30 17:18:31 +00:00
Renamed from sys/arm64/linux/linux_locore.s (Browse further)
