linux-dev/arch/arm/kernel/vmlinux.lds.S, branch linus/master

ARM: implement support for vmap'ed stacks

2021-12-03T14:11:33Z

Wire up the generic support for managing task stack allocations via vmalloc, and implement the entry code that detects whether we faulted because of a stack overrun (or future stack overrun caused by pushing the pt_regs array) While this adds a fair amount of tricky entry asm code, it should be noted that it only adds a TST + branch to the svc_entry path. The code implementing the non-trivial handling of the overflow stack is emitted out-of-line into the .text section. Since on ARM, we rely on do_translation_fault() to keep PMD level page table entries that cover the vmalloc region up to date, we need to ensure that we don't hit such a stale PMD entry when accessing the stack. So we do a dummy read from the new stack while still running from the old one on the context switch path, and bump the vmalloc_seq counter when PMD level entries in the vmalloc range are modified, so that the MM switch fetches the latest version of the entries. Note that we need to increase the per-mode stack by 1 word, to gain some space to stash a GPR until we know it is safe to touch the stack. However, due to the cacheline alignment of the struct, this does not actually increase the memory footprint of the struct stack array at all. Signed-off-by: Ard Biesheuvel Tested-by: Keith Packard Tested-by: Marc Zyngier Tested-by: Vladimir Murzin # ARMv7M

ARM: 9140/1: allow compile-testing without machine record

2021-10-25T12:12:34Z

A lot of randconfig builds end up not selecting any machine type at all. This is generally fine for the purpose of compile testing, but of course it means that the kernel is not usable on actual hardware, and it causes a warning about this fact. As most of the build bots now force-enable CONFIG_COMPILE_TEST for randconfig builds, use that as a guard to control whether we warn on this type of broken configuration. We could do the same for the missing-cpu-type warning, but those configurations fail to build much earlier. Signed-off-by: Arnd Bergmann Signed-off-by: Russell King (Oracle)

ARM: 9088/1: Split KERNEL_OFFSET from PAGE_OFFSET

2021-06-13T17:16:40Z

We want to be able to compile the kernel into an address different from PAGE_OFFSET (start of lowmem) + TEXT_OFFSET, so start to pry apart the address of where the kernel is located from the address where the lowmem is located by defining and using KERNEL_OFFSET in a few key places. Signed-off-by: Linus Walleij Signed-off-by: Russell King

arm/build: Always handle .ARM.exidx and .ARM.extab sections

2020-10-27T18:32:21Z

After turning on warnings for orphan section placement, enabling CONFIG_UNWINDER_FRAME_POINTER instead of CONFIG_UNWINDER_ARM causes thousands of warnings when clang + ld.lld are used: $ scripts/config --file arch/arm/configs/multi_v7_defconfig \ -d CONFIG_UNWINDER_ARM \ -e CONFIG_UNWINDER_FRAME_POINTER $ make -skj"$(nproc)" ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- LLVM=1 defconfig zImage ld.lld: warning: init/built-in.a(main.o):(.ARM.extab) is being placed in '.ARM.extab' ld.lld: warning: init/built-in.a(main.o):(.ARM.extab.init.text) is being placed in '.ARM.extab.init.text' ld.lld: warning: init/built-in.a(main.o):(.ARM.extab.ref.text) is being placed in '.ARM.extab.ref.text' ld.lld: warning: init/built-in.a(do_mounts.o):(.ARM.extab.init.text) is being placed in '.ARM.extab.init.text' ld.lld: warning: init/built-in.a(do_mounts.o):(.ARM.extab) is being placed in '.ARM.extab' ld.lld: warning: init/built-in.a(do_mounts_rd.o):(.ARM.extab.init.text) is being placed in '.ARM.extab.init.text' ld.lld: warning: init/built-in.a(do_mounts_rd.o):(.ARM.extab) is being placed in '.ARM.extab' ld.lld: warning: init/built-in.a(do_mounts_initrd.o):(.ARM.extab.init.text) is being placed in '.ARM.extab.init.text' ld.lld: warning: init/built-in.a(initramfs.o):(.ARM.extab.init.text) is being placed in '.ARM.extab.init.text' ld.lld: warning: init/built-in.a(initramfs.o):(.ARM.extab) is being placed in '.ARM.extab' ld.lld: warning: init/built-in.a(calibrate.o):(.ARM.extab.init.text) is being placed in '.ARM.extab.init.text' ld.lld: warning: init/built-in.a(calibrate.o):(.ARM.extab) is being placed in '.ARM.extab' These sections are handled by the ARM_UNWIND_SECTIONS define, which is only added to the list of sections when CONFIG_ARM_UNWIND is set. CONFIG_ARM_UNWIND is a hidden symbol that is only selected when CONFIG_UNWINDER_ARM is set so CONFIG_UNWINDER_FRAME_POINTER never handles these sections. According to the help text of CONFIG_UNWINDER_ARM, these sections should be discarded so that the kernel image size is not affected. Fixes: 5a17850e251a ("arm/build: Warn on orphan section placement") Link: https://github.com/ClangBuiltLinux/linux/issues/1152 Reported-by: kernel test robot Signed-off-by: Nathan Chancellor Review-by: Nick Desaulniers Tested-by: Nick Desaulniers [kees: Made the discard slightly more specific] Signed-off-by: Kees Cook Link: https://lore.kernel.org/r/20200928224854.3224862-1-natechancellor@gmail.com

arm/build: Assert for unwanted sections

2020-09-01T08:03:18Z

In preparation for warning on orphan sections, enforce expected-to-be-zero-sized sections (since discarding them might hide problems with them suddenly gaining unexpected entries). Signed-off-by: Kees Cook Signed-off-by: Ingo Molnar Cc: Russell King Link: https://lore.kernel.org/r/20200821194310.3089815-19-keescook@chromium.org

arm/build: Add missing sections

2020-09-01T08:03:18Z

Add missing text stub sections .vfp11_veneer and .v4_bx, as well as missing DWARF sections, when present in the build. Signed-off-by: Kees Cook Signed-off-by: Ingo Molnar Reviewed-by: Nick Desaulniers Cc: Russell King Link: https://lore.kernel.org/r/20200821194310.3089815-18-keescook@chromium.org

arm/build: Explicitly keep .ARM.attributes sections

2020-09-01T08:03:18Z

In preparation for adding --orphan-handling=warn, explicitly keep the .ARM.attributes section (at address 0[1]) by expanding the existing ELF_DETAILS macro into ARM_DETAILS. [1] https://reviews.llvm.org/D85867 Suggested-by: Nick Desaulniers Signed-off-by: Kees Cook Signed-off-by: Ingo Molnar Reviewed-by: Fangrui Song Cc: Russell King Link: https://lore.kernel.org/lkml/CAKwvOdk-racgq5pxsoGS6Vtifbtrk5fmkmnoLxrQMaOvV0nPWw@mail.gmail.com/ Link: https://lore.kernel.org/r/20200821194310.3089815-17-keescook@chromium.org

arm/build: Refactor linker script headers

2020-09-01T08:03:17Z

In preparation for adding --orphan-handling=warn, refactor the linker script header includes, and extract common macros. Signed-off-by: Kees Cook Signed-off-by: Ingo Molnar Cc: Russell King Link: https://lore.kernel.org/r/20200821194310.3089815-16-keescook@chromium.org

vmlinux.lds.h: Split ELF_DETAILS from STABS_DEBUG

2020-09-01T07:50:35Z

The .comment section doesn't belong in STABS_DEBUG. Split it out into a new macro named ELF_DETAILS. This will gain other non-debug sections that need to be accounted for when linking with --orphan-handling=warn. Signed-off-by: Kees Cook Signed-off-by: Ingo Molnar Cc: linux-arch@vger.kernel.org Link: https://lore.kernel.org/r/20200821194310.3089815-5-keescook@chromium.org

mm: reorder includes after introduction of linux/pgtable.h

2020-06-09T16:39:13Z

The replacement of with made the include of the latter in the middle of asm includes. Fix this up with the aid of the below script and manual adjustments here and there. import sys import re if len(sys.argv) is not 3: print "USAGE: %s

" % (sys.argv[0]) sys.exit(1) hdr_to_move="#include " % sys.argv[2] moved = False in_hdrs = False with open(sys.argv[1], "r") as f: lines = f.readlines() for _line in lines: line = _line.rstrip(' ') if line == hdr_to_move: continue if line.startswith("#include Signed-off-by: Andrew Morton Cc: Arnd Bergmann Cc: Borislav Petkov Cc: Brian Cain Cc: Catalin Marinas Cc: Chris Zankel Cc: "David S. Miller" Cc: Geert Uytterhoeven Cc: Greentime Hu Cc: Greg Ungerer Cc: Guan Xuetao Cc: Guo Ren Cc: Heiko Carstens Cc: Helge Deller Cc: Ingo Molnar Cc: Ley Foon Tan Cc: Mark Salter Cc: Matthew Wilcox Cc: Matt Turner Cc: Max Filippov Cc: Michael Ellerman Cc: Michal Simek Cc: Nick Hu Cc: Paul Walmsley Cc: Richard Weinberger Cc: Rich Felker Cc: Russell King Cc: Stafford Horne Cc: Thomas Bogendoerfer Cc: Thomas Gleixner Cc: Tony Luck Cc: Vincent Chen Cc: Vineet Gupta Cc: Will Deacon Cc: Yoshinori Sato Link: http://lkml.kernel.org/r/20200514170327.31389-4-rppt@kernel.org Signed-off-by: Linus Torvalds