While the GCC and Clang compilers already define __ASSEMBLER__
automatically when compiling assembly code, __ASSEMBLY__ is a
macro that only gets defined by the Makefiles in the kernel.
This can be very confusing when switching between userspace
and kernelspace coding, or when dealing with UAPI headers that
rather should use __ASSEMBLER__ instead. So let's standardize on
the __ASSEMBLER__ macro that is provided by the compilers now.
This is mostly a mechanical patch (done with a simple "sed -i"
statement), with some manual tweaks in <asm/frame.h>, <asm/hw_irq.h>
and <asm/setup.h> that mentioned this macro in comments with some
missing underscores.
Signed-off-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20250314071013.1575167-38-thuth@redhat.com
Saves a CALL to an out-of-line thunk for the common case of 1
argument.
Suggested-by: Scott Constable <scott.d.constable@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Kees Cook <kees@kernel.org>
Link: https://lore.kernel.org/r/20250224124200.927885784@infradead.org
Notably, don't attempt to decode an immediate when MOD == 3.
Additionally have it return the instruction length, such that WARN
like bugs can more reliably skip to the correct instruction.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Link: https://lore.kernel.org/r/20250207122546.721120726@infradead.org
Pretty much every caller of is_endbr() actually wants to test something at an
address and ends up doing get_kernel_nofault(). Fold the lot into a more
convenient helper.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Link: https://lore.kernel.org/r/20250207122546.181367417@infradead.org
The current name doesn't reflect what it does very well.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Link: https://lkml.kernel.org/r/20230622144321.427441595%40infradead.org
UEFI v2.10 extends the EFI memory attributes table with a flag that
indicates whether or not all RuntimeServicesCode regions were
constructed with ENDBR landing pads, permitting the OS to map these
regions with IBT restrictions enabled.
So let's take this into account on x86 as well.
Suggested-by: Peter Zijlstra <peterz@infradead.org> # ibt_save() changes
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Add a macro which prevents a function from getting sealed if there are
no compile-time references to it.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Message-Id: <20220818213927.e44fmxkoq4yj6ybn@treble>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Objtool's --ibt option generates .ibt_endbr_seal which lists
superfluous ENDBR instructions. That is those instructions for which
the function is never indirectly called.
Overwrite these ENDBR instructions with a NOP4 such that these
function can never be indirect called, reducing the number of viable
ENDBR targets in the kernel.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20220308154319.822545231@infradead.org
Add Kconfig, Makefile and basic instruction support for x86 IBT.
(Ab)use __DISABLE_EXPORTS to disable IBT since it's already employed
to mark compressed and purgatory. Additionally mark realmode with it
as well to avoid inserting ENDBR instructions there. While ENDBR is
technically a NOP, inserting them was causing some grief due to code
growth. There's also a problem with using __noendbr in code compiled
without -fcf-protection=branch.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20220308154317.519875203@infradead.org
