Re: [PATCH for 5.2 07/12] rseq/selftests: s390: use trap4 for RSEQ_SIG
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From: shuah <shuah@kernel.org>
Date: 2019-05-16 20:39:33
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Hi Mathieu, On 4/29/19 9:27 AM, Mathieu Desnoyers wrote:
quoted hunk ↗ jump to hunk
From: Martin Schwidefsky <redacted> Use trap4 as the guard instruction for the restartable sequence abort handler. Signed-off-by: Martin Schwidefsky <redacted> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> --- tools/testing/selftests/rseq/rseq-s390.h | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)diff --git a/tools/testing/selftests/rseq/rseq-s390.h b/tools/testing/selftests/rseq/rseq-s390.h index 7c4f3a70b6c7..1d05c5187ae6 100644 --- a/tools/testing/selftests/rseq/rseq-s390.h +++ b/tools/testing/selftests/rseq/rseq-s390.h@@ -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()
I generated my pull request for Linus and did a sanity check and ran into merge conflict on this patch. Looks like this is already in Linus's tree. Can you confirm! I have to drop this patch and regenerate my pull request. Can you confirm! thanks, -- Shuah