On Thu, Sep 23, 2021 at 12:01 PM Richard Palethorpe rpalethorpe@suse.de wrote:
Arnd Bergmann arnd@arndb.de writes:
On Wed, Sep 22, 2021 at 10:46 AM Richard Palethorpe rpalethorpe@suse.de wrote:
Richard Palethorpe rpalethorpe@suse.de writes:
I also noticed that only x86 and s390 even have separate entry points for normal syscalls when called in compat mode, while the others all just zero the upper halves of the registers in the low-level entry code and then call the native entry point.
It looks to me like aarch64 also has something similar? At any rate, I can try to fix it for x86 and investigate what else might be effected.
arm64 also has a custom asm/syscall_wrapper.h, but it only does this for accessing pt_regs (as x86 does), not for doing any argument conversion. x86 does the 32-to-64 widening in the wrapper, arm64 relies on the pt_regs already having the upper halves zeroed.
Arnd