In all of the architectures we have today, we always use PAGE_SIZE.
While in theory one could define different things, none of the
current architectures do, even the ones that have transitioned from
32-bit to 64-bit like i386 and arm. Some ancient mips binaries on
other systems used 8k instead of 4k, but we don't support running
those and likely never will due to their age and obscurity.
Reviewed by: imp (who also contributed the commit message)
Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D19280
For FreeBSD/arm64's cloudabi32 support, I'm going to need a TO_PTR() in
this place. Also use it for all of the other source files, so that the
difference remains as minimal as possible.
MFC after: 2 weeks
Upon successful completion, the execve() system call invokes
exec_setregs() to initialize the registers of the initial thread of the
newly executed process. What is weird is that when execve() returns, it
still goes through the normal system call return path, clobbering the
registers with the system call's return value (td->td_retval).
Though this doesn't seem to be problematic for x86 most of the times (as
the value of eax/rax doesn't matter upon startup), this can be pretty
frustrating for architectures where function argument and return
registers overlap (e.g., ARM). On these systems, exec_setregs() also
needs to initialize td_retval.
Even worse are architectures where cpu_set_syscall_retval() sets
registers to values not derived from td_retval. On these architectures,
there is no way cpu_set_syscall_retval() can set registers to the way it
wants them to be upon the start of execution.
To get rid of this madness, let sys_execve() return EJUSTRETURN. This
will cause cpu_set_syscall_retval() to leave registers intact. This
makes process execution easier to understand. It also eliminates the
difference between execution of the initial process and successive ones.
The initial call to sys_execve() is not performed through a system call
context.
Reviewed by: kib, jhibbits
Differential Revision: https://reviews.freebsd.org/D13180
struct thread.
For all architectures, the syscall trap handlers have to allocate the
structure on the stack. The structure takes 88 bytes on 64bit arches
which is not negligible. Also, it cannot be easily found by other
code, which e.g. caused duplication of some members of the structure
to struct thread already. The change removes td_dbg_sc_code and
td_dbg_sc_nargs which were directly copied from syscall_args.
The structure is put into the copied on fork part of the struct thread
to make the syscall arguments information correct in the child after
fork.
This move will also allow several more uses shortly.
Reviewed by: jhb (previous version)
Sponsored by: The FreeBSD Foundation
MFC after: 3 weeks
X-Differential revision: https://reviews.freebsd.org/D11080
matches static binaries.
Interpretation of the 'static' there is that the binary must not
specify an interpreter. In particular, shared objects are matched by
the brand if BI_CAN_EXEC_DYN is also set.
This improves precision of the brand matching, which should eliminate
surprises due to brand ordering.
Revert r315701.
Discussed with and tested by: ed (previous version)
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
CloudABI executables are statically linked and don't have an
interpreter. Setting the interpreter path to NULL used to work
previously, but r314851 introduced code that checks the string
unconditionally. Running CloudABI executables now causes a null pointer
dereference.
Looking at the rest of imgact_elf.c, it seems various other codepaths
already leaned on the fact that the interpreter path is set. Let's just
go ahead and pick an obviously incorrect interpreter path to appease
imgact_elf.c.
MFC after: 1 week
In order to make CloudABI work on ARMv6, start off by copying over the
sysvec for ARM64 and adjust it to use 32-bit registers. Also add code
for fetching arguments from the stack if needed, as there are fewer
register than on ARM64.
Also import the vDSO that is needed to invoke system calls. This vDSO
uses the intra procedure call register (ip) to store the system call
number. This is a bit simpler than what native FreeBSD does, as FreeBSD
uses r7, while preserving the original r7 into ip.
This sysvec seems to be complete enough to start CloudABI processes.
These processes are capable of linking in the vDSO and are therefore
capable of executing (most?) system calls successfully. Unfortunately,
the biggest show stopper is still that TLS is completely broken:
- The linker used by CloudABI, LLD, still has troubles with some of the
relocations needed for TLS. See LLVM bug 30218 for more details.
- Whereas FreeBSD uses the tpidruro register for TLS, for CloudABI I
want to make use of tpidrurw, so that userspace can modify the base
address directly. This is needed for efficient emulation.
Unfortunately, this register doesn't seem to be preserved across
context switches yet.
Obtained from: https://github.com/NuxiNL/cloudabi (the vDSO)
