s390/vdso64: add sigreturn,rt_sigreturn and restart_syscall

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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: Sven Schnelle <svens@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

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Sven Schnelle 2021-06-25 14:48:28 +02:00 • committed by Vasily Gorbik

parent d57778feb9

commit 686341f254

2 changed files with 20 additions and 0 deletions

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3

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

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17

arch/s390/kernel/vdso64/vdso_user_wrapper.S

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