Linux powerpc new system call instruction and ABI

Dmitry V. Levin ldv at
Thu May 20 12:59:48 AEST 2021

On Thu, May 20, 2021 at 12:45:57PM +1000, Nicholas Piggin wrote:
> Excerpts from Dmitry V. Levin's message of May 20, 2021 11:06 am:
> > On Wed, May 19, 2021 at 07:48:47PM -0400, Rich Felker wrote:
> >> On Wed, May 19, 2021 at 06:09:25PM +0000, Joakim Tjernlund wrote:
> > [...]
> >> > W.r.t breaking ABI, isn't that what PowerPC is trying to do with the new syscall I/F? 
> >> 
> >> No, it's a new independent interface.
> > 
> > Unfortunately, being a new independent interface doesn't mean it isn't
> > an ABI break.  In fact, it was a severe ABI break, and this thread is
> > an attempt to find a hotfix.
> It is an ABI break, that was known. The ptrace info stuff I fixed with 
> the patch earlier was obviously a bug in my initial implementation and 
> not intended (sorry my ptrace testing was not sufficient, and thanks for
> reporting it, by the way).

Could you check whether tools/testing/selftests/ptrace/get_syscall_info.c
passes again with your fix, please?
If yes, then PTRACE_GET_SYSCALL_INFO is fixed.

By the way, kernel tracing and audit subsystems also use those functions
from asm/syscall.h and asm/ptrace.h, so your ptrace fix is likely to fix
these subsystems as well.


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