kernel/linux.git/scripts/Makefile.lib, branch v6.6.131

objtool: Silence more KCOV warnings, part 2

2025-05-02T05:51:04+00:00

commit 55c78035a1a8dfb05f1472018ce2a651701adb7d upstream. Similar to GCOV, KCOV can leave behind dead code and undefined behavior. Warnings related to those should be ignored. The previous commit: 6b023c784204 ("objtool: Silence more KCOV warnings") ... only did so for CONFIG_CGOV_KERNEL. Also do it for CONFIG_KCOV, but for real this time. Fixes the following warning: vmlinux.o: warning: objtool: synaptics_report_mt_data: unexpected end of section .text.synaptics_report_mt_data Fixes: 6b023c784204 ("objtool: Silence more KCOV warnings") Reported-by: kernel test robot Signed-off-by: Josh Poimboeuf Signed-off-by: Ingo Molnar Cc: Linus Torvalds Link: https://lore.kernel.org/r/a44ba16e194bcbc52c1cef3d3cd9051a62622723.1743481539.git.jpoimboe@kernel.org Closes: https://lore.kernel.org/oe-kbuild-all/202503282236.UhfRsF3B-lkp@intel.com/ Signed-off-by: Greg Kroah-Hartman

kbuild: switch from lz4c to lz4 for compression

2025-02-08T08:52:35+00:00

commit e397a603e49cc7c7c113fad9f55a09637f290c34 upstream. Replace lz4c with lz4 for kernel image compression. Although lz4 and lz4c are functionally similar, lz4c has been deprecated upstream since 2018. Since as early as Ubuntu 16.04 and Fedora 25, lz4 and lz4c have been packaged together, making it safe to update the requirement from lz4c to lz4. Consequently, some distributions and build systems, such as OpenEmbedded, have fully transitioned to using lz4. OpenEmbedded core adopted this change in commit fe167e082cbd ("bitbake.conf: require lz4 instead of lz4c"), causing compatibility issues when building the mainline kernel in the latest OpenEmbedded environment, as seen in the errors below. This change also updates the LZ4 compression commands to make it backward compatible by replacing stdin and stdout with the '-' option, due to some unclear reason, the stdout keyword does not work for lz4 and '-' works for both. In addition, this modifies the legacy '-c1' with '-9' which is also compatible with both. This fixes the mainline kernel build failures with the latest master OpenEmbedded builds associated with the mentioned compatibility issues. LZ4 arch/arm/boot/compressed/piggy_data /bin/sh: 1: lz4c: not found ... ... ERROR: oe_runmake failed Link: https://github.com/lz4/lz4/pull/553 Suggested-by: Francesco Dolcini Signed-off-by: Parth Pancholi Signed-off-by: Masahiro Yamada Cc: Salvatore Bonaccorso Signed-off-by: Greg Kroah-Hartman

kbuild: avoid build error when single DTB is turned into composite DTB

2024-08-03T06:54:36+00:00

[ Upstream commit 712aba5543b88996bc4682086471076fbf048927 ] As commit afa974b77128 ("kbuild: add real-prereqs shorthand for $(filter-out FORCE,$^)") explained, $(real-prereqs) is not just a list of objects when linking a multi-object module. If a single-object module is turned into a multi-object module, $^ (and therefore $(real-prereqs) as well) contains header files recorded in the *.cmd file. Such headers must be filtered out. Now that a DTB can be built either from a single source or multiple source files, the same issue can occur. Consider the following scenario: First, foo.dtb is implemented as a single-blob device tree. The code looks something like this: [Sample Code 1] Makefile: dtb-y += foo.dtb foo.dts: #include /dts-v1/; / { }; When it is compiled, .foo.dtb.cmd records that foo.dtb depends on scripts/dtc/include-prefixes/dt-bindings/gpio/gpio.h. Later, foo.dtb is split into a base and an overlay. The code looks something like this: [Sample Code 2] Makefile: dtb-y += foo.dtb foo-dtbs := foo-base.dtb foo-addon.dtbo foo-base.dts: #include /dts-v1/; / { }; foo-addon.dtso: /dts-v1/; /plugin/; / { }; If you rebuild foo.dtb without 'make clean', you will get this error: Overlay 'scripts/dtc/include-prefixes/dt-bindings/gpio/gpio.h' is incomplete $(real-prereqs) contains not only foo-base.dtb and foo-addon.dtbo but also scripts/dtc/include-prefixes/dt-bindings/gpio/gpio.h, which is passed to scripts/dtc/fdtoverlay. Fixes: 15d16d6dadf6 ("kbuild: Add generic rule to apply fdtoverlay") Signed-off-by: Masahiro Yamada Signed-off-by: Sasha Levin

kbuild: Disallow DTB overlays to built from .dts named source files

2023-05-22T01:34:37+00:00

As a follow up to the series allowing DTB overlays to built from .dtso files. Now that all overlays have been renamed, remove the ability to build from overlays from .dts files to prevent any files with the old name from accidental being added. Signed-off-by: Andrew Davis Reviewed-by: Geert Uytterhoeven Acked-by: Andy Shevchenko Signed-off-by: Masahiro Yamada

kbuild: unify cmd_dt_S_dtb and cmd_dt_S_dtbo

2023-01-22T14:43:33+00:00

cmd_dt_S_dtb and cmd_dt_S_dtbo are almost the same; the only difference is the prefix of the begin/end symbols. (__dtb vs __dtbo) Signed-off-by: Masahiro Yamada Reviewed-by: Nicolas Schier

Merge tag 'powerpc-6.2-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux

2022-12-19T13:13:33+00:00

Pull powerpc updates from Michael Ellerman: - Add powerpc qspinlock implementation optimised for large system scalability and paravirt. See the merge message for more details - Enable objtool to be built on powerpc to generate mcount locations - Use a temporary mm for code patching with the Radix MMU, so the writable mapping is restricted to the patching CPU - Add an option to build the 64-bit big-endian kernel with the ELFv2 ABI - Sanitise user registers on interrupt entry on 64-bit Book3S - Many other small features and fixes Thanks to Aboorva Devarajan, Angel Iglesias, Benjamin Gray, Bjorn Helgaas, Bo Liu, Chen Lifu, Christoph Hellwig, Christophe JAILLET, Christophe Leroy, Christopher M. Riedl, Colin Ian King, Deming Wang, Disha Goel, Dmitry Torokhov, Finn Thain, Geert Uytterhoeven, Gustavo A. R. Silva, Haowen Bai, Joel Stanley, Jordan Niethe, Julia Lawall, Kajol Jain, Laurent Dufour, Li zeming, Miaoqian Lin, Michael Jeanson, Nathan Lynch, Naveen N. Rao, Nayna Jain, Nicholas Miehlbradt, Nicholas Piggin, Pali Rohár, Randy Dunlap, Rohan McLure, Russell Currey, Sathvika Vasireddy, Shaomin Deng, Stephen Kitt, Stephen Rothwell, Thomas Weißschuh, Tiezhu Yang, Uwe Kleine-König, Xie Shaowen, Xiu Jianfeng, XueBing Chen, Yang Yingliang, Zhang Jiaming, ruanjinjie, Jessica Yu, and Wolfram Sang. * tag 'powerpc-6.2-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (181 commits) powerpc/code-patching: Fix oops with DEBUG_VM enabled powerpc/qspinlock: Fix 32-bit build powerpc/prom: Fix 32-bit build powerpc/rtas: mandate RTAS syscall filtering powerpc/rtas: define pr_fmt and convert printk call sites powerpc/rtas: clean up includes powerpc/rtas: clean up rtas_error_log_max initialization powerpc/pseries/eeh: use correct API for error log size powerpc/rtas: avoid scheduling in rtas_os_term() powerpc/rtas: avoid device tree lookups in rtas_os_term() powerpc/rtasd: use correct OF API for event scan rate powerpc/rtas: document rtas_call() powerpc/pseries: unregister VPA when hot unplugging a CPU powerpc/pseries: reset the RCU watchdogs after a LPM powerpc: Take in account addition CPU node when building kexec FDT powerpc: export the CPU node count powerpc/cpuidle: Set CPUIDLE_FLAG_POLLING for snooze state powerpc/dts/fsl: Fix pca954x i2c-mux node names cxl: Remove unnecessary cxl_pci_window_alignment() selftests/powerpc: Fix resource leaks ...

Merge tag 'x86_core_for_v6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2022-12-14T23:03:00+00:00

Pull x86 core updates from Borislav Petkov: - Add the call depth tracking mitigation for Retbleed which has been long in the making. It is a lighterweight software-only fix for Skylake-based cores where enabling IBRS is a big hammer and causes a significant performance impact. What it basically does is, it aligns all kernel functions to 16 bytes boundary and adds a 16-byte padding before the function, objtool collects all functions' locations and when the mitigation gets applied, it patches a call accounting thunk which is used to track the call depth of the stack at any time. When that call depth reaches a magical, microarchitecture-specific value for the Return Stack Buffer, the code stuffs that RSB and avoids its underflow which could otherwise lead to the Intel variant of Retbleed. This software-only solution brings a lot of the lost performance back, as benchmarks suggest: https://lore.kernel.org/all/20220915111039.092790446@infradead.org/ That page above also contains a lot more detailed explanation of the whole mechanism - Implement a new control flow integrity scheme called FineIBT which is based on the software kCFI implementation and uses hardware IBT support where present to annotate and track indirect branches using a hash to validate them - Other misc fixes and cleanups * tag 'x86_core_for_v6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (80 commits) x86/paravirt: Use common macro for creating simple asm paravirt functions x86/paravirt: Remove clobber bitmask from .parainstructions x86/debug: Include percpu.h in debugreg.h to get DECLARE_PER_CPU() et al x86/cpufeatures: Move X86_FEATURE_CALL_DEPTH from bit 18 to bit 19 of word 11, to leave space for WIP X86_FEATURE_SGX_EDECCSSA bit x86/Kconfig: Enable kernel IBT by default x86,pm: Force out-of-line memcpy() objtool: Fix weak hole vs prefix symbol objtool: Optimize elf_dirty_reloc_sym() x86/cfi: Add boot time hash randomization x86/cfi: Boot time selection of CFI scheme x86/ibt: Implement FineIBT objtool: Add --cfi to generate the .cfi_sites section x86: Add prefix symbols for function padding objtool: Add option to generate prefix symbols objtool: Avoid O(bloody terrible) behaviour -- an ode to libelf objtool: Slice up elf_create_section_symbol() kallsyms: Revert "Take callthunks into account" x86: Unconfuse CONFIG_ and X86_FEATURE_ namespaces x86/retpoline: Fix crash printing warning x86/paravirt: Fix a !PARAVIRT build warning ...

objtool: Add --mnop as an option to --mcount

2022-11-18T08:00:16+00:00

Some architectures (powerpc) may not support ftrace locations being nop'ed out at build time. Introduce CONFIG_HAVE_OBJTOOL_NOP_MCOUNT for objtool, as a means for architectures to enable nop'ing of ftrace locations. Add --mnop as an option to objtool --mcount, to indicate support for the same. Also, make sure that --mnop can be passed as an option to objtool only when --mcount is passed. Tested-by: Naveen N. Rao Reviewed-by: Naveen N. Rao Acked-by: Josh Poimboeuf Reviewed-by: Christophe Leroy Signed-off-by: Sathvika Vasireddy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20221114175754.1131267-12-sv@linux.ibm.com

x86/ibt: Implement FineIBT

2022-11-01T12:44:10+00:00

Implement an alternative CFI scheme that merges both the fine-grained nature of kCFI but also takes full advantage of the coarse grained hardware CFI as provided by IBT. To contrast: kCFI is a pure software CFI scheme and relies on being able to read text -- specifically the instruction *before* the target symbol, and does the hash validation *before* doing the call (otherwise control flow is compromised already). FineIBT is a software and hardware hybrid scheme; by ensuring every branch target starts with a hash validation it is possible to place the hash validation after the branch. This has several advantages: o the (hash) load is avoided; no memop; no RX requirement. o IBT WAIT-FOR-ENDBR state is a speculation stop; by placing the hash validation in the immediate instruction after the branch target there is a minimal speculation window and the whole is a viable defence against SpectreBHB. o Kees feels obliged to mention it is slightly more vulnerable when the attacker can write code. Obviously this patch relies on kCFI, but additionally it also relies on the padding from the call-depth-tracking patches. It uses this padding to place the hash-validation while the call-sites are re-written to modify the indirect target to be 16 bytes in front of the original target, thus hitting this new preamble. Notably, there is no hardware that needs call-depth-tracking (Skylake) and supports IBT (Tigerlake and onwards). Suggested-by: Joao Moreira (Intel) Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Kees Cook Link: https://lore.kernel.org/r/20221027092842.634714496@infradead.org

x86: Add prefix symbols for function padding

2022-11-01T12:44:09+00:00

When code is compiled with: -fpatchable-function-entry=${PADDING_BYTES},${PADDING_BYTES} functions will have PADDING_BYTES of NOP in front of them. Unwinders and other things that symbolize code locations will typically attribute these bytes to the preceding function. Given that these bytes nominally belong to the following symbol this mis-attribution is confusing. Inspired by the fact that CFI_CLANG emits __cfi_##name symbols to claim these bytes, use objtool to emit __pfx_##name symbols to do the same when CFI_CLANG is not used. This then shows the callthunk for symbol 'name' as: __pfx_##name+0x6/0x10 Signed-off-by: Peter Zijlstra (Intel) Tested-by: Yujie Liu Link: https://lkml.kernel.org/r/20221028194453.592512209@infradead.org