kernel.git/arch/arm64/Makefile, branch linux-4.9.y

arm64: makefile fix build of .i file in external module case

2019-11-28T17:28:53Z

[ Upstream commit 98356eb0ae499c63e78073ccedd9a5fc5c563288 ] After 'a66649dab350 arm64: fix vdso-offsets.h dependency' if one will try to build .i file in case of external kernel module, build fails complaining that prepare0 target is missing. This issue came up with SystemTap when it tries to build variety of .i files for its own generated kernel modules trying to figure given kernel features/capabilities. The issue is that prepare0 is defined in top level Makefile only if KBUILD_EXTMOD is not defined. .i file rule depends on prepare and in case KBUILD_EXTMOD defined top level Makefile contains empty rule for prepare. But after mentioned commit arch/arm64/Makefile would introduce dependency on prepare0 through its own prepare target. Fix it to put proper ifdef KBUILD_EXTMOD around code introduced by mentioned commit. It matches what top level Makefile does. Acked-by: Kevin Brodsky Signed-off-by: Victor Kamensky Signed-off-by: Catalin Marinas Signed-off-by: Sasha Levin

arm64: remove no-op -p linker flag

2018-12-01T08:44:21Z

(commit 1a381d4a0a9a0f999a13faaba22bf6b3fc80dcb9 upstream) Linking the ARM64 defconfig kernel with LLVM lld fails with the error: ld.lld: error: unknown argument: -p Makefile:1015: recipe for target 'vmlinux' failed Without this flag, the ARM64 defconfig kernel successfully links with lld and boots on Dragonboard 410c. After digging through binutils source and changelogs, it turns out that -p is only relevant to ancient binutils installations targeting 32-bit ARM. binutils accepts -p for AArch64 too, but it's always been undocumented and silently ignored. A comment in ld/emultempl/aarch64elf.em explains that it's "Only here for backwards compatibility". Since this flag is a no-op on ARM64, we can safely drop it. Acked-by: Will Deacon Reviewed-by: Nick Desaulniers Signed-off-by: Greg Hackmann Signed-off-by: Catalin Marinas Signed-off-by: Nick Desaulniers Signed-off-by: Sasha Levin

arm64: prevent regressions in compressed kernel image size when upgrading to binutils 2.27

2017-12-20T09:07:31Z

[ Upstream commit fd9dde6abcb9bfe6c6bee48834e157999f113971 ] Upon upgrading to binutils 2.27, we found that our lz4 and gzip compressed kernel images were significantly larger, resulting is 10ms boot time regressions. As noted by Rahul: "aarch64 binaries uses RELA relocations, where each relocation entry includes an addend value. This is similar to x86_64. On x86_64, the addend values are also stored at the relocation offset for relative relocations. This is an optimization: in the case where code does not need to be relocated, the loader can simply skip processing relative relocations. In binutils-2.25, both bfd and gold linkers did this for x86_64, but only the gold linker did this for aarch64. The kernel build here is using the bfd linker, which stored zeroes at the relocation offsets for relative relocations. Since a set of zeroes compresses better than a set of non-zero addend values, this behavior was resulting in much better lz4 compression. The bfd linker in binutils-2.27 is now storing the actual addend values at the relocation offsets. The behavior is now consistent with what it does for x86_64 and what gold linker does for both architectures. The change happened in this upstream commit: https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=1f56df9d0d5ad89806c24e71f296576d82344613 Since a bunch of zeroes got replaced by non-zero addend values, we see the side effect of lz4 compressed image being a bit bigger. To get the old behavior from the bfd linker, "--no-apply-dynamic-relocs" flag can be used: $ LDFLAGS="--no-apply-dynamic-relocs" make With this flag, the compressed image size is back to what it was with binutils-2.25. If the kernel is using ASLR, there aren't additional runtime costs to --no-apply-dynamic-relocs, as the relocations will need to be applied again anyway after the kernel is relocated to a random address. If the kernel is not using ASLR, then presumably the current default behavior of the linker is better. Since the static linker performed the dynamic relocs, and the kernel is not moved to a different address at load time, it can skip applying the relocations all over again." Some measurements: $ ld -v GNU ld (binutils-2.25-f3d35cf6) 2.25.51.20141117 ^ $ ls -l vmlinux -rwxr-x--- 1 ndesaulniers eng 300652760 Oct 26 11:57 vmlinux $ ls -l Image.lz4-dtb -rw-r----- 1 ndesaulniers eng 16932627 Oct 26 11:57 Image.lz4-dtb $ ld -v GNU ld (binutils-2.27-53dd00a1) 2.27.0.20170315 ^ pre patch: $ ls -l vmlinux -rwxr-x--- 1 ndesaulniers eng 300376208 Oct 26 11:43 vmlinux $ ls -l Image.lz4-dtb -rw-r----- 1 ndesaulniers eng 18159474 Oct 26 11:43 Image.lz4-dtb post patch: $ ls -l vmlinux -rwxr-x--- 1 ndesaulniers eng 300376208 Oct 26 12:06 vmlinux $ ls -l Image.lz4-dtb -rw-r----- 1 ndesaulniers eng 16932466 Oct 26 12:06 Image.lz4-dtb By Siqi's measurement w/ gzip: binutils 2.27 with this patch (with --no-apply-dynamic-relocs): Image 41535488 Image.gz 13404067 binutils 2.27 without this patch (without --no-apply-dynamic-relocs): Image 41535488 Image.gz 14125516 Any compression scheme should be able to get better results from the longer runs of zeros, not just GZIP and LZ4. 10ms boot time savings isn't anything to get excited about, but users of arm64+compression+bfd-2.27 should not have to pay a penalty for no runtime improvement. Reported-by: Gopinath Elanchezhian Reported-by: Sindhuri Pentyala Reported-by: Wei Wang Suggested-by: Ard Biesheuvel Suggested-by: Rahul Chaudhry Suggested-by: Siqi Lin Suggested-by: Stephen Hines Signed-off-by: Nick Desaulniers Reviewed-by: Ard Biesheuvel [will: added comment to Makefile] Signed-off-by: Will Deacon Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

arm64: kernel: force ET_DYN ELF type for CONFIG_RELOCATABLE=y

2016-10-20T10:37:25Z

GNU ld used to set the ELF file type to ET_DYN for PIE executables, which is the same file type used for shared libraries. However, this was changed recently, and now PIE executables are emitted as ET_EXEC instead. The distinction is only relevant for ELF loaders, and so there is little reason to care about the difference when building the kernel, which is why the change has gone unnoticed until now. However, debuggers do use the ELF binary, and expect ET_EXEC type files to appear in memory at the exact offset described in the ELF metadata. This means source level debugging is no longer possible when KASLR is in effect or when executing the stub. So add the -shared LD option when building with CONFIG_RELOCATABLE=y. This forces the ELF file type to be set to ET_DYN (which is what you get when building with binutils 2.24 and earlier anyway), and has no other ill effects. Signed-off-by: Ard Biesheuvel Signed-off-by: Will Deacon

arm64: Set UTS_MACHINE in the Makefile

2016-08-31T11:31:38Z

The make rpm target depends on proper UTS_MACHINE definition. Also, use the variable in arch/arm64/kernel/setup.c, so that it's not accidentally removed in the future. Reported-and-tested-by: Fabian Vogt Signed-off-by: Michal Marek Signed-off-by: Will Deacon

arm64: errata: Pass --fix-cortex-a53-843419 to ld if workaround enabled

2016-08-26T10:33:22Z

Cortex-A53 erratum 843419 is worked around by the linker, although it is a configure-time option to GCC as to whether ld is actually asked to apply the workaround or not. This patch ensures that we pass --fix-cortex-a53-843419 to the linker when both CONFIG_ARM64_ERRATUM_843419=y and the linker supports the option. Acked-by: Ard Biesheuvel Signed-off-by: Will Deacon

Merge tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux

2016-08-06T12:58:59Z

Pull arm64 fixes from Will Deacon: - fix HugeTLB leak due to CoW and PTE_RDONLY mismatch - avoid accessing unmapped FDT fields when checking validity - correctly account for vDSO AUX entry in ARCH_DLINFO - fix kallsyms with absolute expressions in linker script - kill unnecessary symbol-based relocs in vmlinux * tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: arm64: Fix copy-on-write referencing in HugeTLB arm64: mm: avoid fdt_check_header() before the FDT is fully mapped arm64: Define AT_VECTOR_SIZE_ARCH for ARCH_DLINFO arm64: relocatable: suppress R_AARCH64_ABS64 relocations in vmlinux arm64: vmlinux.lds: make __rela_offset and __dynsym_offset ABSOLUTE

arm64: relocatable: suppress R_AARCH64_ABS64 relocations in vmlinux

2016-07-29T09:45:01Z

The linker routines that we rely on to produce a relocatable PIE binary treat it as a shared ELF object in some ways, i.e., it emits symbol based R_AARCH64_ABS64 relocations into the final binary since doing so would be appropriate when linking a shared library that is subject to symbol preemption. (This means that an executable can override certain symbols that are exported by a shared library it is linked with, and that the shared library *must* update all its internal references as well, and point them to the version provided by the executable.) Symbol preemption does not occur for OS hosted PIE executables, let alone for vmlinux, and so we would prefer to get rid of these symbol based relocations. This would allow us to simplify the relocation routines, and to strip the .dynsym, .dynstr and .hash sections from the binary. (Note that these are tiny, and are placed in the .init segment, but they clutter up the vmlinux binary.) Note that these R_AARCH64_ABS64 relocations are only emitted for absolute references to symbols defined in the linker script, all other relocatable quantities are covered by anonymous R_AARCH64_RELATIVE relocations that simply list the offsets to all 64-bit values in the binary that need to be fixed up based on the offset between the link time and run time addresses. Fortunately, GNU ld has a -Bsymbolic option, which is intended for shared libraries to allow them to ignore symbol preemption, and unconditionally bind all internal symbol references to its own definitions. So set it for our PIE binary as well, and get rid of the asoociated sections and the relocation code that processes them. Signed-off-by: Ard Biesheuvel [will: fixed conflict with __dynsym_offset linker script entry] Signed-off-by: Will Deacon

Merge tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux

2016-07-27T18:16:05Z

Pull arm64 updates from Catalin Marinas: - Kexec support for arm64 - Kprobes support - Expose MIDR_EL1 and REVIDR_EL1 CPU identification registers to sysfs - Trapping of user space cache maintenance operations and emulation in the kernel (CPU errata workaround) - Clean-up of the early page tables creation (kernel linear mapping, EFI run-time maps) to avoid splitting larger blocks (e.g. pmds) into smaller ones (e.g. ptes) - VDSO support for CLOCK_MONOTONIC_RAW in clock_gettime() - ARCH_HAS_KCOV enabled for arm64 - Optimise IP checksum helpers - SWIOTLB optimisation to only allocate/initialise the buffer if the available RAM is beyond the 32-bit mask - Properly handle the "nosmp" command line argument - Fix for the initialisation of the CPU debug state during early boot - vdso-offsets.h build dependency workaround - Build fix when RANDOMIZE_BASE is enabled with MODULES off * tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (64 commits) arm64: arm: Fix-up the removal of the arm64 regs_query_register_name() prototype arm64: Only select ARM64_MODULE_PLTS if MODULES=y arm64: mm: run pgtable_page_ctor() on non-swapper translation table pages arm64: mm: make create_mapping_late() non-allocating arm64: Honor nosmp kernel command line option arm64: Fix incorrect per-cpu usage for boot CPU arm64: kprobes: Add KASAN instrumentation around stack accesses arm64: kprobes: Cleanup jprobe_return arm64: kprobes: Fix overflow when saving stack arm64: kprobes: WARN if attempting to step with PSTATE.D=1 arm64: debug: remove unused local_dbg_{enable, disable} macros arm64: debug: remove redundant spsr manipulation arm64: debug: unmask PSTATE.D earlier arm64: localise Image objcopy flags arm64: ptrace: remove extra define for CPSR's E bit kprobes: Add arm64 case in kprobe example module arm64: Add kernel return probes support (kretprobes) arm64: Add trampoline code for kretprobes arm64: kprobes instruction simulation support arm64: Treat all entry code as non-kprobe-able ...

arm64: localise Image objcopy flags

2016-07-19T14:30:23Z

We currently define OBJCOPYFLAGS in the top-level arm64 Makefile, and thus these flags will be passed to all uses of objcopy, kernel-wide, for which they are not explicitly overridden. The flags we set are intended for converting vmlinux (and ELF) into Image (a raw binary), and thus the flags chosen are problematic for some other uses which do not expect a raw binary result, e.g. the upcoming lkdtm rodata test: http://www.openwall.com/lists/kernel-hardening/2016/06/08/2 This patch localises the objcopy flags such that they are only used for the vmlinux -> Image conversion. Signed-off-by: Mark Rutland Cc: Will Deacon Acked-by: Kees Cook Tested-by: Laura Abbott Signed-off-by: Catalin Marinas