From ea24213d8088f9da73e1b6aadf7abd2435b70397 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Mon, 25 Feb 2019 12:50:09 +0100 Subject: objtool: Add UACCESS validation It is important that UACCESS regions are as small as possible; furthermore the UACCESS state is not scheduled, so doing anything that might directly call into the scheduler will cause random code to be ran with UACCESS enabled. Teach objtool too track UACCESS state and warn about any CALL made while UACCESS is enabled. This very much includes the __fentry__() and __preempt_schedule() calls. Note that exceptions _do_ save/restore the UACCESS state, and therefore they can drive preemption. This also means that all exception handlers must have an otherwise redundant UACCESS disable instruction; therefore ignore this warning for !STT_FUNC code (exception handlers are not normal functions). Signed-off-by: Peter Zijlstra (Intel) Acked-by: Josh Poimboeuf Cc: Borislav Petkov Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Signed-off-by: Ingo Molnar --- scripts/Makefile.build | 3 +++ 1 file changed, 3 insertions(+) (limited to 'scripts') diff --git a/scripts/Makefile.build b/scripts/Makefile.build index 76ca30cc4791..0c5969fa795f 100644 --- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -222,6 +222,9 @@ endif ifdef CONFIG_RETPOLINE objtool_args += --retpoline endif +ifdef CONFIG_X86_SMAP + objtool_args += --uaccess +endif # 'OBJECT_FILES_NON_STANDARD := y': skip objtool checking for a directory # 'OBJECT_FILES_NON_STANDARD_foo.o := 'y': skip objtool checking for a file -- cgit v1.2.3