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s390/rseq: use trap4 for RSEQ_SIG 

Use trap4 as the guard instruction for the restartable sequence abort
handler.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Martin Schwidefsky 2019-04-10 12:28:41 +02:00
parent e91012ee85
commit e24e4712ef
1 changed files with 8 additions and 1 deletions
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9
tools/testing/selftests/rseq/rseq-s390.h
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@ -1,6 +1,13 @@
/* SPDX-License-Identifier: LGPL-2.1 OR MIT */
#define RSEQ_SIG 0x53053053
/*
* RSEQ_SIG uses the trap4 instruction. As Linux does not make use of the
* access-register mode nor the linkage stack this instruction will always
* cause a special-operation exception (the trap-enabled bit in the DUCT
* is and will stay 0). The instruction pattern is
* b2 ff 0f ff trap4 4095(%r0)
*/
#define RSEQ_SIG 0xB2FF0FFF
#define rseq_smp_mb() __asm__ __volatile__ ("bcr 15,0" ::: "memory")
#define rseq_smp_rmb() rseq_smp_mb()