From adab66b71abfe206a020f11e561f4df41f0b2aba Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (VMware)" Date: Mon, 14 Dec 2020 12:33:51 -0500 Subject: Revert: "ring-buffer: Remove HAVE_64BIT_ALIGNED_ACCESS" It was believed that metag was the only architecture that required the ring buffer to keep 8 byte words aligned on 8 byte architectures, and with its removal, it was assumed that the ring buffer code did not need to handle this case. It appears that sparc64 also requires this. The following was reported on a sparc64 boot up: kernel: futex hash table entries: 65536 (order: 9, 4194304 bytes, linear) kernel: Running postponed tracer tests: kernel: Testing tracer function: kernel: Kernel unaligned access at TPC[552a20] trace_function+0x40/0x140 kernel: Kernel unaligned access at TPC[552a24] trace_function+0x44/0x140 kernel: Kernel unaligned access at TPC[552a20] trace_function+0x40/0x140 kernel: Kernel unaligned access at TPC[552a24] trace_function+0x44/0x140 kernel: Kernel unaligned access at TPC[552a20] trace_function+0x40/0x140 kernel: PASSED Need to put back the 64BIT aligned code for the ring buffer. Link: https://lore.kernel.org/r/CADxRZqzXQRYgKc=y-KV=S_yHL+Y8Ay2mh5ezeZUnpRvg+syWKw@mail.gmail.com Cc: stable@vger.kernel.org Fixes: 86b3de60a0b6 ("ring-buffer: Remove HAVE_64BIT_ALIGNED_ACCESS") Reported-by: Anatoly Pugachev Signed-off-by: Steven Rostedt (VMware) --- arch/Kconfig | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) (limited to 'arch/Kconfig') diff --git a/arch/Kconfig b/arch/Kconfig index 56b6ccc0e32d..fa716994f77e 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -143,6 +143,22 @@ config UPROBES managed by the kernel and kept transparent to the probed application. ) +config HAVE_64BIT_ALIGNED_ACCESS + def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS + help + Some architectures require 64 bit accesses to be 64 bit + aligned, which also requires structs containing 64 bit values + to be 64 bit aligned too. This includes some 32 bit + architectures which can do 64 bit accesses, as well as 64 bit + architectures without unaligned access. + + This symbol should be selected by an architecture if 64 bit + accesses are required to be 64 bit aligned in this way even + though it is not a 64 bit architecture. + + See Documentation/unaligned-memory-access.txt for more + information on the topic of unaligned memory accesses. + config HAVE_EFFICIENT_UNALIGNED_ACCESS bool help -- cgit v1.2.3-58-ga151