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* x86/alternative: Rename apply_ibt_endbr()Peter Zijlstra2023-07-101-1/+1
| | | | | | | | | 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
* efi: x86: Wire up IBT annotation in memory attributes tableArd Biesheuvel2023-02-091-2/+2
| | | | | | | | | | | | | | 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>
* x86/ibt, objtool: Add IBT_NOSEAL()Josh Poimboeuf2022-08-191-0/+11
| | | | | | | | | 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>
* x86/alternative: Use .ibt_endbr_seal to seal indirect callsPeter Zijlstra2022-03-151-0/+12
| | | | | | | | | | | | | | 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
* x86/ibt: Disable IBT around firmwarePeter Zijlstra2022-03-151-0/+6
| | | | | | | | | Assume firmware isn't IBT clean and disable it across calls. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Kees Cook <keescook@chromium.org> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Link: https://lore.kernel.org/r/20220308154318.759989383@infradead.org
* x86/ibt: Base IBT bitsPeter Zijlstra2022-03-151-0/+87
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