On 02/02/2024 23:31, Brooks Davis wrote:
TL;DR: The implementation of system calls is moving to a seperate
library (libsys). No changes are required to existing software (except
to ensure that libsys is present when building custom disk images).
Code:https://github.com/freebsd/freebsd-src/pull/908
After nearly a decade of intermittent work, I'm about to land a series
of patches which moves system calls, vdso support, and libc's parsing of
the ELF auxiliary argument vector into a separate library (libsys). I
plan to do this early next week (February 5th).
This change serves three primary purposes:
1. It's easier to completely replace system call implementations for
tracing or compartmentalization purposes.
Will that affect code that makes syscalls without currently linking to libc?
2. It simplifies the implementation of restrictions on system calls such
as those implemented by OpenBSD's msyscall(2)
(https://man.openbsd.org/msyscall.2).
That's one to ignore for tools that make syscalls outside of the libc
memory mapping.
3. It allows language runtimes to link with libsys for system call
implementations without requiring libc.
I see that pagesize is on the list of functions that are moving. There
are a couple of other functions that might cause me problems if libc
isn't linked.
Could you do a quick test with an exe linked to libsys but not libc
running under Valgrind memcheck, please?
A+
Paul
