Re: [patch 00/18] entry: Consolidate and rework syscall entry handling
From: "H. Peter Anvin" <hpa@zytor.com>
Date: 2026-08-31 20:01:32
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linux-alpha, linux-arch, linux-m68k, linux-mips, linux-riscv, linux-s390, linux-sh, linux-um, linuxppc-dev, lkml, loongarch, sparclinux
On 2026-08-31 01:50, Heiko Carstens wrote:
On Thu, Aug 27, 2026 at 03:22:35PM -0700, H. Peter Anvin wrote:quoted
This isn't a hard thing to solve in any way: replacing the pointer argument with a two-element structure return would do the trick. As far as I know, *all* architectures that support Linux support returning structures with two register-sized values in registers.That is unfortunately not true. The s390 ABI defines that structures, regardless of size, are returned in a return value buffer allocated by the caller.
*Groan* You guys should use an improved ABI for the kernel like i386 does (different from the standard ABI used in user space)... That being said, perhaps s390(x) isn't affected by the underlying problem, and passing a pointer to a structure isn't any more expensive than passing a pointer to a variable... -hpa