From 53e2489b201d84ed5d9fc8bcdd65551bb6b43b9a Mon Sep 17 00:00:00 2001 From: Ian Moffett Date: Sat, 15 Nov 2025 18:52:55 -0500 Subject: kern/amd64: cpu: Add kernel fence for trap entry A kernel fence ensures that the GS base will contain kernel data on entry. Signed-off-by: Ian Moffett --- sys/inc/arch/amd64/kfence.h | 51 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 51 insertions(+) create mode 100644 sys/inc/arch/amd64/kfence.h (limited to 'sys/inc/arch') diff --git a/sys/inc/arch/amd64/kfence.h b/sys/inc/arch/amd64/kfence.h new file mode 100644 index 0000000..110c9a8 --- /dev/null +++ b/sys/inc/arch/amd64/kfence.h @@ -0,0 +1,51 @@ +/* + * Copyright (c) 2025 Ian Marco Moffett and the Osmora Team. + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are met: + * + * 1. Redistributions of source code must retain the above copyright notice, + * this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. Neither the name of Hyra nor the names of its + * contributors may be used to endorse or promote products derived from + * this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" + * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE + * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR + * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF + * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS + * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN + * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE + * POSSIBILITY OF SUCH DAMAGE. + */ + +#ifndef _MACHINE_KENTRY_H_ +#define _MACHINE_KENTRY_H_ + +/* + * Kernel entry/exit handling for traps with error codes + * on the stack + */ +#define KFENCE_EC \ + testq $0x3, 16(%rsp) ; \ + jz 1f ; \ + lfence ; \ + swapgs ; \ + 1: + +#define KFENCE ; \ + testq $0x3, 8(%rsp) ; \ + jz 1f ; \ + lfence ; \ + swapgs ; \ + 1: + +#endif /* !_MACHINE_KENTRY_H_ */ -- cgit v1.2.3