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linux-next/arch/x86/purgatory/Makefile

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License cleanup: add SPDX GPL-2.0 license identifier to files with no license Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-01 22:07:57 +08:00
# SPDX-License-Identifier: GPL-2.0
objtool: Mark non-standard object files and directories Code which runs outside the kernel's normal mode of operation often does unusual things which can cause a static analysis tool like objtool to emit false positive warnings: - boot image - vdso image - relocation - realmode - efi - head - purgatory - modpost Set OBJECT_FILES_NON_STANDARD for their related files and directories, which will tell objtool to skip checking them. It's ok to skip them because they don't affect runtime stack traces. Also skip the following code which does the right thing with respect to frame pointers, but is too "special" to be validated by a tool: - entry - mcount Also skip the test_nx module because it modifies its exception handling table at runtime, which objtool can't understand. Fortunately it's just a test module so it doesn't matter much. Currently objtool is the only user of OBJECT_FILES_NON_STANDARD, but it might eventually be useful for other tools. Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Bernd Petrovitsch <bernd@petrovitsch.priv.at> Cc: Borislav Petkov <bp@alien8.de> Cc: Chris J Arges <chris.j.arges@canonical.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Michal Marek <mmarek@suse.cz> Cc: Namhyung Kim <namhyung@gmail.com> Cc: Pedro Alves <palves@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: live-patching@vger.kernel.org Link: http://lkml.kernel.org/r/366c080e3844e8a5b6a0327dc7e8c2b90ca3baeb.1456719558.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-02-29 12:22:34 +08:00
OBJECT_FILES_NON_STANDARD := y
purgatory-y := purgatory.o stack.o setup-x86_$(BITS).o sha256.o entry64.o string.o
targets += $(purgatory-y)
PURGATORY_OBJS = $(addprefix $(obj)/,$(purgatory-y))
x86/purgatory: Do not use __builtin_memcpy and __builtin_memset Implementing memcpy and memset in terms of __builtin_memcpy and __builtin_memset is problematic. GCC at -O2 will replace calls to the builtins with calls to memcpy and memset (but will generate an inline implementation at -Os). Clang will replace the builtins with these calls regardless of optimization level. $ llvm-objdump -dr arch/x86/purgatory/string.o | tail 0000000000000339 memcpy: 339: 48 b8 00 00 00 00 00 00 00 00 movabsq $0, %rax 000000000000033b: R_X86_64_64 memcpy 343: ff e0 jmpq *%rax 0000000000000345 memset: 345: 48 b8 00 00 00 00 00 00 00 00 movabsq $0, %rax 0000000000000347: R_X86_64_64 memset 34f: ff e0 Such code results in infinite recursion at runtime. This is observed when doing kexec. Instead, reuse an implementation from arch/x86/boot/compressed/string.c. This requires to implement a stub function for warn(). Also, Clang may lower memcmp's that compare against 0 to bcmp's, so add a small definition, too. See also: commit 5f074f3e192f ("lib/string.c: implement a basic bcmp") Fixes: 8fc5b4d4121c ("purgatory: core purgatory functionality") Reported-by: Vaibhav Rustagi <vaibhavrustagi@google.com> Debugged-by: Vaibhav Rustagi <vaibhavrustagi@google.com> Debugged-by: Manoj Gupta <manojgupta@google.com> Suggested-by: Alistair Delva <adelva@google.com> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Vaibhav Rustagi <vaibhavrustagi@google.com> Cc: stable@vger.kernel.org Link: https://bugs.chromium.org/p/chromium/issues/detail?id=984056 Link: https://lkml.kernel.org/r/20190807221539.94583-1-ndesaulniers@google.com
2019-08-08 06:15:32 +08:00
$(obj)/string.o: $(srctree)/arch/x86/boot/compressed/string.c FORCE
$(call if_changed_rule,cc_o_c)
$(obj)/sha256.o: $(srctree)/lib/sha256.c FORCE
$(call if_changed_rule,cc_o_c)
LDFLAGS_purgatory.ro := -e purgatory_start -r --no-undefined -nostdlib -z nodefaultlib
targets += purgatory.ro
KASAN_SANITIZE := n
KCOV_INSTRUMENT := n
x86/purgatory: Change compiler flags from -mcmodel=kernel to -mcmodel=large to fix kexec relocation errors The last change to this Makefile caused relocation errors when loading a kdump kernel. Restore -mcmodel=large (not -mcmodel=kernel), -ffreestanding, and -fno-zero-initialized-bsss, without reverting to the former practice of resetting KBUILD_CFLAGS. Purgatory.ro is a standalone binary that is not linked against the rest of the kernel. Its image is copied into an array that is linked to the kernel, and from there kexec relocates it wherever it desires. With the previous change to compiler flags, the error "kexec: Overflow in relocation type 11 value 0x11fffd000" was encountered when trying to load the crash kernel. This is from kexec code trying to relocate the purgatory.ro object. From the error message, relocation type 11 is R_X86_64_32S. The x86_64 ABI says: "The R_X86_64_32 and R_X86_64_32S relocations truncate the computed value to 32-bits. The linker must verify that the generated value for the R_X86_64_32 (R_X86_64_32S) relocation zero-extends (sign-extends) to the original 64-bit value." This type of relocation doesn't work when kexec chooses to place the purgatory binary in memory that is not reachable with 32 bit addresses. The compiler flag -mcmodel=kernel allows those type of relocations to be emitted, so revert to using -mcmodel=large as was done before. Also restore the -ffreestanding and -fno-zero-initialized-bss flags because they are appropriate for a stand alone piece of object code which doesn't explicitly zero the bss, and one other report has said undefined symbols are encountered without -ffreestanding. These identical compiler flag changes need to happen for every object that becomes part of the purgatory.ro object, so gather them together first into PURGATORY_CFLAGS_REMOVE and PURGATORY_CFLAGS, and then apply them to each of the objects that have C source. Do not apply any of these flags to kexec-purgatory.o, which is not part of the standalone object but part of the kernel proper. Tested-by: Vaibhav Rustagi <vaibhavrustagi@google.com> Tested-by: Andreas Smas <andreas@lonelycoder.com> Signed-off-by: Steve Wahl <steve.wahl@hpe.com> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Cc: Borislav Petkov <bp@alien8.de> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: None Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: clang-built-linux@googlegroups.com Cc: dimitri.sivanich@hpe.com Cc: mike.travis@hpe.com Cc: russ.anderson@hpe.com Fixes: b059f801a937 ("x86/purgatory: Use CFLAGS_REMOVE rather than reset KBUILD_CFLAGS") Link: https://lkml.kernel.org/r/20190905202346.GA26595@swahl-linux Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-09-06 04:23:46 +08:00
# These are adjustments to the compiler flags used for objects that
# make up the standalone purgatory.ro
PURGATORY_CFLAGS_REMOVE := -mcmodel=kernel
PURGATORY_CFLAGS := -mcmodel=large -ffreestanding -fno-zero-initialized-in-bss
# Default KBUILD_CFLAGS can have -pg option set when FTRACE is enabled. That
# in turn leaves some undefined symbols like __fentry__ in purgatory and not
# sure how to relocate those.
ifdef CONFIG_FUNCTION_TRACER
x86/purgatory: Change compiler flags from -mcmodel=kernel to -mcmodel=large to fix kexec relocation errors The last change to this Makefile caused relocation errors when loading a kdump kernel. Restore -mcmodel=large (not -mcmodel=kernel), -ffreestanding, and -fno-zero-initialized-bsss, without reverting to the former practice of resetting KBUILD_CFLAGS. Purgatory.ro is a standalone binary that is not linked against the rest of the kernel. Its image is copied into an array that is linked to the kernel, and from there kexec relocates it wherever it desires. With the previous change to compiler flags, the error "kexec: Overflow in relocation type 11 value 0x11fffd000" was encountered when trying to load the crash kernel. This is from kexec code trying to relocate the purgatory.ro object. From the error message, relocation type 11 is R_X86_64_32S. The x86_64 ABI says: "The R_X86_64_32 and R_X86_64_32S relocations truncate the computed value to 32-bits. The linker must verify that the generated value for the R_X86_64_32 (R_X86_64_32S) relocation zero-extends (sign-extends) to the original 64-bit value." This type of relocation doesn't work when kexec chooses to place the purgatory binary in memory that is not reachable with 32 bit addresses. The compiler flag -mcmodel=kernel allows those type of relocations to be emitted, so revert to using -mcmodel=large as was done before. Also restore the -ffreestanding and -fno-zero-initialized-bss flags because they are appropriate for a stand alone piece of object code which doesn't explicitly zero the bss, and one other report has said undefined symbols are encountered without -ffreestanding. These identical compiler flag changes need to happen for every object that becomes part of the purgatory.ro object, so gather them together first into PURGATORY_CFLAGS_REMOVE and PURGATORY_CFLAGS, and then apply them to each of the objects that have C source. Do not apply any of these flags to kexec-purgatory.o, which is not part of the standalone object but part of the kernel proper. Tested-by: Vaibhav Rustagi <vaibhavrustagi@google.com> Tested-by: Andreas Smas <andreas@lonelycoder.com> Signed-off-by: Steve Wahl <steve.wahl@hpe.com> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Cc: Borislav Petkov <bp@alien8.de> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: None Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: clang-built-linux@googlegroups.com Cc: dimitri.sivanich@hpe.com Cc: mike.travis@hpe.com Cc: russ.anderson@hpe.com Fixes: b059f801a937 ("x86/purgatory: Use CFLAGS_REMOVE rather than reset KBUILD_CFLAGS") Link: https://lkml.kernel.org/r/20190905202346.GA26595@swahl-linux Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-09-06 04:23:46 +08:00
PURGATORY_CFLAGS_REMOVE += $(CC_FLAGS_FTRACE)
endif
ifdef CONFIG_STACKPROTECTOR
x86/purgatory: Change compiler flags from -mcmodel=kernel to -mcmodel=large to fix kexec relocation errors The last change to this Makefile caused relocation errors when loading a kdump kernel. Restore -mcmodel=large (not -mcmodel=kernel), -ffreestanding, and -fno-zero-initialized-bsss, without reverting to the former practice of resetting KBUILD_CFLAGS. Purgatory.ro is a standalone binary that is not linked against the rest of the kernel. Its image is copied into an array that is linked to the kernel, and from there kexec relocates it wherever it desires. With the previous change to compiler flags, the error "kexec: Overflow in relocation type 11 value 0x11fffd000" was encountered when trying to load the crash kernel. This is from kexec code trying to relocate the purgatory.ro object. From the error message, relocation type 11 is R_X86_64_32S. The x86_64 ABI says: "The R_X86_64_32 and R_X86_64_32S relocations truncate the computed value to 32-bits. The linker must verify that the generated value for the R_X86_64_32 (R_X86_64_32S) relocation zero-extends (sign-extends) to the original 64-bit value." This type of relocation doesn't work when kexec chooses to place the purgatory binary in memory that is not reachable with 32 bit addresses. The compiler flag -mcmodel=kernel allows those type of relocations to be emitted, so revert to using -mcmodel=large as was done before. Also restore the -ffreestanding and -fno-zero-initialized-bss flags because they are appropriate for a stand alone piece of object code which doesn't explicitly zero the bss, and one other report has said undefined symbols are encountered without -ffreestanding. These identical compiler flag changes need to happen for every object that becomes part of the purgatory.ro object, so gather them together first into PURGATORY_CFLAGS_REMOVE and PURGATORY_CFLAGS, and then apply them to each of the objects that have C source. Do not apply any of these flags to kexec-purgatory.o, which is not part of the standalone object but part of the kernel proper. Tested-by: Vaibhav Rustagi <vaibhavrustagi@google.com> Tested-by: Andreas Smas <andreas@lonelycoder.com> Signed-off-by: Steve Wahl <steve.wahl@hpe.com> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Cc: Borislav Petkov <bp@alien8.de> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: None Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: clang-built-linux@googlegroups.com Cc: dimitri.sivanich@hpe.com Cc: mike.travis@hpe.com Cc: russ.anderson@hpe.com Fixes: b059f801a937 ("x86/purgatory: Use CFLAGS_REMOVE rather than reset KBUILD_CFLAGS") Link: https://lkml.kernel.org/r/20190905202346.GA26595@swahl-linux Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-09-06 04:23:46 +08:00
PURGATORY_CFLAGS_REMOVE += -fstack-protector
endif
ifdef CONFIG_STACKPROTECTOR_STRONG
x86/purgatory: Change compiler flags from -mcmodel=kernel to -mcmodel=large to fix kexec relocation errors The last change to this Makefile caused relocation errors when loading a kdump kernel. Restore -mcmodel=large (not -mcmodel=kernel), -ffreestanding, and -fno-zero-initialized-bsss, without reverting to the former practice of resetting KBUILD_CFLAGS. Purgatory.ro is a standalone binary that is not linked against the rest of the kernel. Its image is copied into an array that is linked to the kernel, and from there kexec relocates it wherever it desires. With the previous change to compiler flags, the error "kexec: Overflow in relocation type 11 value 0x11fffd000" was encountered when trying to load the crash kernel. This is from kexec code trying to relocate the purgatory.ro object. From the error message, relocation type 11 is R_X86_64_32S. The x86_64 ABI says: "The R_X86_64_32 and R_X86_64_32S relocations truncate the computed value to 32-bits. The linker must verify that the generated value for the R_X86_64_32 (R_X86_64_32S) relocation zero-extends (sign-extends) to the original 64-bit value." This type of relocation doesn't work when kexec chooses to place the purgatory binary in memory that is not reachable with 32 bit addresses. The compiler flag -mcmodel=kernel allows those type of relocations to be emitted, so revert to using -mcmodel=large as was done before. Also restore the -ffreestanding and -fno-zero-initialized-bss flags because they are appropriate for a stand alone piece of object code which doesn't explicitly zero the bss, and one other report has said undefined symbols are encountered without -ffreestanding. These identical compiler flag changes need to happen for every object that becomes part of the purgatory.ro object, so gather them together first into PURGATORY_CFLAGS_REMOVE and PURGATORY_CFLAGS, and then apply them to each of the objects that have C source. Do not apply any of these flags to kexec-purgatory.o, which is not part of the standalone object but part of the kernel proper. Tested-by: Vaibhav Rustagi <vaibhavrustagi@google.com> Tested-by: Andreas Smas <andreas@lonelycoder.com> Signed-off-by: Steve Wahl <steve.wahl@hpe.com> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Cc: Borislav Petkov <bp@alien8.de> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: None Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: clang-built-linux@googlegroups.com Cc: dimitri.sivanich@hpe.com Cc: mike.travis@hpe.com Cc: russ.anderson@hpe.com Fixes: b059f801a937 ("x86/purgatory: Use CFLAGS_REMOVE rather than reset KBUILD_CFLAGS") Link: https://lkml.kernel.org/r/20190905202346.GA26595@swahl-linux Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-09-06 04:23:46 +08:00
PURGATORY_CFLAGS_REMOVE += -fstack-protector-strong
endif
ifdef CONFIG_RETPOLINE
x86/purgatory: Change compiler flags from -mcmodel=kernel to -mcmodel=large to fix kexec relocation errors The last change to this Makefile caused relocation errors when loading a kdump kernel. Restore -mcmodel=large (not -mcmodel=kernel), -ffreestanding, and -fno-zero-initialized-bsss, without reverting to the former practice of resetting KBUILD_CFLAGS. Purgatory.ro is a standalone binary that is not linked against the rest of the kernel. Its image is copied into an array that is linked to the kernel, and from there kexec relocates it wherever it desires. With the previous change to compiler flags, the error "kexec: Overflow in relocation type 11 value 0x11fffd000" was encountered when trying to load the crash kernel. This is from kexec code trying to relocate the purgatory.ro object. From the error message, relocation type 11 is R_X86_64_32S. The x86_64 ABI says: "The R_X86_64_32 and R_X86_64_32S relocations truncate the computed value to 32-bits. The linker must verify that the generated value for the R_X86_64_32 (R_X86_64_32S) relocation zero-extends (sign-extends) to the original 64-bit value." This type of relocation doesn't work when kexec chooses to place the purgatory binary in memory that is not reachable with 32 bit addresses. The compiler flag -mcmodel=kernel allows those type of relocations to be emitted, so revert to using -mcmodel=large as was done before. Also restore the -ffreestanding and -fno-zero-initialized-bss flags because they are appropriate for a stand alone piece of object code which doesn't explicitly zero the bss, and one other report has said undefined symbols are encountered without -ffreestanding. These identical compiler flag changes need to happen for every object that becomes part of the purgatory.ro object, so gather them together first into PURGATORY_CFLAGS_REMOVE and PURGATORY_CFLAGS, and then apply them to each of the objects that have C source. Do not apply any of these flags to kexec-purgatory.o, which is not part of the standalone object but part of the kernel proper. Tested-by: Vaibhav Rustagi <vaibhavrustagi@google.com> Tested-by: Andreas Smas <andreas@lonelycoder.com> Signed-off-by: Steve Wahl <steve.wahl@hpe.com> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Cc: Borislav Petkov <bp@alien8.de> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: None Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: clang-built-linux@googlegroups.com Cc: dimitri.sivanich@hpe.com Cc: mike.travis@hpe.com Cc: russ.anderson@hpe.com Fixes: b059f801a937 ("x86/purgatory: Use CFLAGS_REMOVE rather than reset KBUILD_CFLAGS") Link: https://lkml.kernel.org/r/20190905202346.GA26595@swahl-linux Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-09-06 04:23:46 +08:00
PURGATORY_CFLAGS_REMOVE += $(RETPOLINE_CFLAGS)
endif
x86/purgatory: Change compiler flags from -mcmodel=kernel to -mcmodel=large to fix kexec relocation errors The last change to this Makefile caused relocation errors when loading a kdump kernel. Restore -mcmodel=large (not -mcmodel=kernel), -ffreestanding, and -fno-zero-initialized-bsss, without reverting to the former practice of resetting KBUILD_CFLAGS. Purgatory.ro is a standalone binary that is not linked against the rest of the kernel. Its image is copied into an array that is linked to the kernel, and from there kexec relocates it wherever it desires. With the previous change to compiler flags, the error "kexec: Overflow in relocation type 11 value 0x11fffd000" was encountered when trying to load the crash kernel. This is from kexec code trying to relocate the purgatory.ro object. From the error message, relocation type 11 is R_X86_64_32S. The x86_64 ABI says: "The R_X86_64_32 and R_X86_64_32S relocations truncate the computed value to 32-bits. The linker must verify that the generated value for the R_X86_64_32 (R_X86_64_32S) relocation zero-extends (sign-extends) to the original 64-bit value." This type of relocation doesn't work when kexec chooses to place the purgatory binary in memory that is not reachable with 32 bit addresses. The compiler flag -mcmodel=kernel allows those type of relocations to be emitted, so revert to using -mcmodel=large as was done before. Also restore the -ffreestanding and -fno-zero-initialized-bss flags because they are appropriate for a stand alone piece of object code which doesn't explicitly zero the bss, and one other report has said undefined symbols are encountered without -ffreestanding. These identical compiler flag changes need to happen for every object that becomes part of the purgatory.ro object, so gather them together first into PURGATORY_CFLAGS_REMOVE and PURGATORY_CFLAGS, and then apply them to each of the objects that have C source. Do not apply any of these flags to kexec-purgatory.o, which is not part of the standalone object but part of the kernel proper. Tested-by: Vaibhav Rustagi <vaibhavrustagi@google.com> Tested-by: Andreas Smas <andreas@lonelycoder.com> Signed-off-by: Steve Wahl <steve.wahl@hpe.com> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Cc: Borislav Petkov <bp@alien8.de> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: None Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: clang-built-linux@googlegroups.com Cc: dimitri.sivanich@hpe.com Cc: mike.travis@hpe.com Cc: russ.anderson@hpe.com Fixes: b059f801a937 ("x86/purgatory: Use CFLAGS_REMOVE rather than reset KBUILD_CFLAGS") Link: https://lkml.kernel.org/r/20190905202346.GA26595@swahl-linux Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-09-06 04:23:46 +08:00
CFLAGS_REMOVE_purgatory.o += $(PURGATORY_CFLAGS_REMOVE)
CFLAGS_purgatory.o += $(PURGATORY_CFLAGS)
CFLAGS_REMOVE_sha256.o += $(PURGATORY_CFLAGS_REMOVE)
CFLAGS_sha256.o += $(PURGATORY_CFLAGS)
CFLAGS_REMOVE_string.o += $(PURGATORY_CFLAGS_REMOVE)
CFLAGS_string.o += $(PURGATORY_CFLAGS)
$(obj)/purgatory.ro: $(PURGATORY_OBJS) FORCE
$(call if_changed,ld)
targets += kexec-purgatory.c
quiet_cmd_bin2c = BIN2C $@
cmd_bin2c = $(objtree)/scripts/bin2c kexec_purgatory < $< > $@
$(obj)/kexec-purgatory.c: $(obj)/purgatory.ro FORCE
$(call if_changed,bin2c)
kexec: create a new config option CONFIG_KEXEC_FILE for new syscall Currently new system call kexec_file_load() and all the associated code compiles if CONFIG_KEXEC=y. But new syscall also compiles purgatory code which currently uses gcc option -mcmodel=large. This option seems to be available only gcc 4.4 onwards. Hiding new functionality behind a new config option will not break existing users of old gcc. Those who wish to enable new functionality will require new gcc. Having said that, I am trying to figure out how can I move away from using -mcmodel=large but that can take a while. I think there are other advantages of introducing this new config option. As this option will be enabled only on x86_64, other arches don't have to compile generic kexec code which will never be used. This new code selects CRYPTO=y and CRYPTO_SHA256=y. And all other arches had to do this for CONFIG_KEXEC. Now with introduction of new config option, we can remove crypto dependency from other arches. Now CONFIG_KEXEC_FILE is available only on x86_64. So whereever I had CONFIG_X86_64 defined, I got rid of that. For CONFIG_KEXEC_FILE, instead of doing select CRYPTO=y, I changed it to "depends on CRYPTO=y". This should be safer as "select" is not recursive. Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Cc: Eric Biederman <ebiederm@xmission.com> Cc: H. Peter Anvin <hpa@zytor.com> Tested-by: Shaun Ruffell <sruffell@digium.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-08-30 06:18:46 +08:00
obj-$(CONFIG_KEXEC_FILE) += kexec-purgatory.o