Commit 686341f2 authored by Sven Schnelle's avatar Sven Schnelle Committed by Vasily Gorbik
Browse files

s390/vdso64: add sigreturn,rt_sigreturn and restart_syscall 



Add minimalistic trampolines to vdso64 so we can return from signal
without using the stack which requires pgm check handler hacks when
NX is enabled.

restart_syscall will be called from vdso to work around the architectural
limitation that the syscall number might be encoded in the svc instruction,
and therefore can not be changed.

Signed-off-by: default avatarSven Schnelle <svens@linux.ibm.com>
Reviewed-by: default avatarHeiko Carstens <hca@linux.ibm.com>
Signed-off-by: default avatarVasily Gorbik <gor@linux.ibm.com>
parent d57778fe

arch/s390/kernel/vdso64/vdso64.lds.S

+3 −0
Original line number Diff line number Diff line
@@ -137,6 +137,9 @@ VERSION 
		__kernel_clock_gettime;

		__kernel_clock_getres;

		__kernel_getcpu;

		__kernel_restart_syscall;

		__kernel_rt_sigreturn;

		__kernel_sigreturn;

	local: *;

	};

}

arch/s390/kernel/vdso64/vdso_user_wrapper.S

+17 −0
Original line number Diff line number Diff line
@@ -37,3 +37,20 @@ vdso_func gettimeofday 
vdso_func clock_getres

vdso_func clock_gettime

vdso_func getcpu



.macro vdso_syscall func,syscall

	.globl __kernel_\func

	.type  __kernel_\func,@function

	.align 8

__kernel_\func:

	CFI_STARTPROC

	svc	\syscall

	/* Make sure we notice when a syscall returns, which shouldn't happen */

	.word	0

	CFI_ENDPROC

	.size	__kernel_\func,.-__kernel_\func

.endm



vdso_syscall restart_syscall,__NR_restart_syscall

vdso_syscall sigreturn,__NR_sigreturn

vdso_syscall rt_sigreturn,__NR_rt_sigreturn