pm24.git/arch/arm64/kernel/pi/Makefile, branch master

Makefile: remove redundant tool coverage variables

2024-05-14T14:35:48Z

Now Kbuild provides reasonable defaults for objtool, sanitizers, and profilers. Remove redundant variables. Note: This commit changes the coverage for some objects: - include arch/mips/vdso/vdso-image.o into UBSAN, GCOV, KCOV - include arch/sparc/vdso/vdso-image-*.o into UBSAN - include arch/sparc/vdso/vma.o into UBSAN - include arch/x86/entry/vdso/extable.o into KASAN, KCSAN, UBSAN, GCOV, KCOV - include arch/x86/entry/vdso/vdso-image-*.o into KASAN, KCSAN, UBSAN, GCOV, KCOV - include arch/x86/entry/vdso/vdso32-setup.o into KASAN, KCSAN, UBSAN, GCOV, KCOV - include arch/x86/entry/vdso/vma.o into GCOV, KCOV - include arch/x86/um/vdso/vma.o into KASAN, GCOV, KCOV I believe these are positive effects because all of them are kernel space objects. Signed-off-by: Masahiro Yamada Reviewed-by: Kees Cook Tested-by: Roberto Sassu

arm64: kernel: Create initial ID map from C code

2024-02-16T12:42:34Z

The asm code that creates the initial ID map is rather intricate and hard to follow. This is problematic because it makes adding support for things like LPA2 or WXN more difficult than necessary. Also, it is parameterized like the rest of the MM code to run with a configurable number of levels, which is rather pointless, given that all AArch64 CPUs implement support for 48-bit virtual addressing, and that many systems exist with DRAM located outside of the 39-bit addressable range, which is the only smaller VA size that is widely used, and we need additional tricks to make things work in that combination. So let's bite the bullet, and rip out all the asm macros, and fiddly code, and replace it with a C implementation based on the newly added routines for creating the early kernel VA mappings. And while at it, create the initial ID map based on 48-bit virtual addressing as well, regardless of the number of configured levels for the kernel proper. Note that this code may execute with the MMU and caches disabled, and is therefore not permitted to make unaligned accesses. This shouldn't generally happen in any case for the algorithm as implemented, but to be sure, let's pass -mstrict-align to the compiler just in case. Signed-off-by: Ard Biesheuvel Link: https://lore.kernel.org/r/20240214122845.2033971-66-ardb+git@google.com Signed-off-by: Catalin Marinas

arm64: head: Move early kernel mapping routines into C code

2024-02-16T12:42:33Z

The asm version of the kernel mapping code works fine for creating a coarse grained identity map, but for mapping the kernel down to its exact boundaries with the right attributes, it is not suitable. This is why we create a preliminary RWX kernel mapping first, and then rebuild it from scratch later on. So let's reimplement this in C, in a way that will make it unnecessary to create the kernel page tables yet another time in paging_init(). Signed-off-by: Ard Biesheuvel Link: https://lore.kernel.org/r/20240214122845.2033971-63-ardb+git@google.com Signed-off-by: Catalin Marinas

arm64: head: move dynamic shadow call stack patching into early C runtime

2024-02-16T12:42:30Z

Once we update the early kernel mapping code to only map the kernel once with the right permissions, we can no longer perform code patching via this mapping. So move this code to an earlier stage of the boot, right after applying the relocations. Signed-off-by: Ard Biesheuvel Link: https://lore.kernel.org/r/20240214122845.2033971-54-ardb+git@google.com Signed-off-by: Catalin Marinas

arm64: idreg-override: Move to early mini C runtime

2024-02-16T12:42:28Z

We will want to parse the ID register overrides even earlier, so that we can take them into account before creating the kernel mapping. So migrate the code and make it work in the context of the early C runtime. We will move the invocation to an earlier stage in a subsequent patch. Signed-off-by: Ard Biesheuvel Link: https://lore.kernel.org/r/20240214122845.2033971-49-ardb+git@google.com Signed-off-by: Catalin Marinas

arm64: head: move relocation handling to C code

2024-02-16T12:42:28Z

Now that we have a mini C runtime before the kernel mapping is up, we can move the non-trivial relocation processing code out of head.S and reimplement it in C. Signed-off-by: Ard Biesheuvel Link: https://lore.kernel.org/r/20240214122845.2033971-48-ardb+git@google.com Signed-off-by: Catalin Marinas

arm64: kernel: Don't rely on objcopy to make code under pi/ __init

2024-02-16T12:42:28Z

We will add some code under pi/ that contains global variables that should not end up in __initdata, as they will not be writable via the initial ID map. So only rely on objcopy for making the libfdt code __init, and use explicit annotations for the rest. Signed-off-by: Ard Biesheuvel Link: https://lore.kernel.org/r/20240214122845.2033971-47-ardb+git@google.com Signed-off-by: Catalin Marinas

arm64: kernel: Manage absolute relocations in code built under pi/

2024-02-16T12:42:28Z

The mini C runtime runs before relocations are processed, and so it cannot rely on statically initialized pointer variables. Add a check to ensure that such code does not get introduced by accident, by going over the relocations in each object, identifying the ones that operate on data sections that are part of the executable image, and raising an error if any relocations of type R_AARCH64_ABS64 exist. Note that such relocations are permitted in other places (e.g., debug sections) and will never occur in compiler generated code sections when using the small code model, so only check sections that have SHF_ALLOC set and SHF_EXECINSTR cleared. To accommodate cases where statically initialized symbol references are unavoidable, introduce a special case for ELF input data sections that have ".rodata.prel64" in their names, and in these cases, instead of rejecting any encountered ABS64 relocations, convert them into PREL64 relocations, which don't require any runtime fixups. Note that the code in question must still be modified to deal with this, as it needs to convert the 64-bit signed offsets into absolute addresses before use. Signed-off-by: Ard Biesheuvel Link: https://lore.kernel.org/r/20240214122845.2033971-46-ardb+git@google.com Signed-off-by: Catalin Marinas

arm64: kernel: Disable latent_entropy GCC plugin in early C runtime

2023-12-12T11:06:27Z

In subsequent patches, mark portions of the early C code will be marked as __init. Unfortunarely, __init implies __latent_entropy, and this would result in the early C code being instrumented in an unsafe manner. Disable the latent entropy plugin for the early C code. Acked-by: Mark Rutland Signed-off-by: Ard Biesheuvel Link: https://lore.kernel.org/r/20231129111555.3594833-44-ardb@google.com Signed-off-by: Will Deacon

arm64: unwind: add asynchronous unwind tables to kernel and modules

2022-11-09T18:06:35Z

Enable asynchronous unwind table generation for both the core kernel as well as modules, and emit the resulting .eh_frame sections as init code so we can use the unwind directives for code patching at boot or module load time. This will be used by dynamic shadow call stack support, which will rely on code patching rather than compiler codegen to emit the shadow call stack push and pop instructions. Signed-off-by: Ard Biesheuvel Reviewed-by: Nick Desaulniers Reviewed-by: Sami Tolvanen Tested-by: Sami Tolvanen Link: https://lore.kernel.org/r/20221027155908.1940624-2-ardb@kernel.org Signed-off-by: Will Deacon