glibc/sysdeps/unix/sysv/linux/s390/s390-64/setcontext.S
Stefan Liebler e57d8fc97b S390: Always use svc 0
On s390x syscalls are triggered by svc instruction. One can
pass the syscall number encoded in the instruction "svc 123"
or by storing it in r1:
lghi r1,123
svc 0

If the syscall number is encoded in the instruction, this can
cause broken syscall restarts.  Therefore this patch is now just
passing the syscall number in r1.

See also kernel-commit:
"s390/signal: switch to using vdso for sigreturn and syscall restart"
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/arch/s390/[%e2%80%a6]call.c?h=v6.0-rc1&id=df29a7440c4b5c65765c8f60396b3b13063e24e9

As information, the "svc 0" feature was introduced in kernel 2.5.62:
commit b5aad611393ef2e132e3648fa4c6e56a9cfa8708
2022-08-30 10:54:46 +02:00

73 lines
2.1 KiB
ArmAsm

/* Copyright (C) 2001-2022 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <sysdep.h>
#include <features.h>
#include "ucontext_i.h"
/* __setcontext (const ucontext_t *ucp)
Restores the machine context in UCP and thereby resumes execution
in that context.
This implementation is intended to be used for *synchronous* context
switches only. Therefore, it does not have to restore anything
other than the PRESERVED state. */
ENTRY(__setcontext)
lgr %r0,%r2
/* sigprocmask (SIG_SETMASK, &sc->sc_mask, NULL). */
la %r3,SC_MASK(%r2)
la %r2,SIG_SETMASK
slgr %r4,%r4
lghi %r5,_NSIG8
lghi %r1,SYS_ify(rt_sigprocmask)
svc 0
/* Load fpu context. */
lgr %r1,%r0
lfpc SC_FPC(%r1)
ld %f0,SC_FPRS(%r1)
ld %f1,SC_FPRS+8(%r1)
ld %f2,SC_FPRS+16(%r1)
ld %f3,SC_FPRS+24(%r1)
ld %f4,SC_FPRS+32(%r1)
ld %f5,SC_FPRS+40(%r1)
ld %f6,SC_FPRS+48(%r1)
ld %f7,SC_FPRS+56(%r1)
ld %f8,SC_FPRS+64(%r1)
ld %f9,SC_FPRS+72(%r1)
ld %f10,SC_FPRS+80(%r1)
ld %f11,SC_FPRS+88(%r1)
ld %f12,SC_FPRS+96(%r1)
ld %f13,SC_FPRS+104(%r1)
ld %f14,SC_FPRS+112(%r1)
ld %f15,SC_FPRS+120(%r1)
/* Don't touch %a0 and %a1, used for thread purposes. */
lam %a2,%a15,SC_ACRS+8(%r1)
/* Load general purpose registers. */
lmg %r0,%r15,SC_GPRS(%r1)
/* Return. */
br %r14
END(__setcontext)
weak_alias (__setcontext, setcontext)