[libc-dev] Linux powerpc new system call instruction and ABI
Dmitry V. Levin via libc-dev
libc-dev at lists.llvm.org
Tue May 18 16:13:34 PDT 2021
On Thu, Jun 11, 2020 at 06:12:01PM +1000, Nicholas Piggin wrote:
> - Error handling: The consensus among kernel, glibc, and musl is to move to
> using negative return values in r3 rather than CR0[SO]=1 to indicate error,
> which matches most other architectures, and is closer to a function call.
Apparently, the patchset merged by commit v5.9-rc1~100^2~164 was
incomplete: all functions defined in arch/powerpc/include/asm/ptrace.h and
arch/powerpc/include/asm/syscall.h that use ccr are broken when scv is used.
This includes syscall_get_error() and all its users including
PTRACE_GET_SYSCALL_INFO API, which in turn makes strace unusable
when scv is used.
See also https://bugzilla.redhat.com/1929836
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