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authorPeter Zijlstra <peterz@infradead.org>2019-02-25 14:50:09 +0300
committerIngo Molnar <mingo@kernel.org>2019-04-03 12:02:24 +0300
commitea24213d8088f9da73e1b6aadf7abd2435b70397 (patch)
treefba1e181531f8f20ff04ed6a57e10b8bd2805343 /scripts/Makefile.build
parent54262aa2830151f89699fa8a6c5aa05f0992e672 (diff)
downloadlinux-ea24213d8088f9da73e1b6aadf7abd2435b70397.tar.xz
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) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'scripts/Makefile.build')
-rw-r--r--scripts/Makefile.build3
1 files changed, 3 insertions, 0 deletions
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