kernel/arch/mips/vdso, branch linux-5.1.y

MIPS: VDSO: Include $(ccflags-vdso) in o32,n32 .lds builds

2019-01-29T19:50:58Z

When generating vdso-o32.lds & vdso-n32.lds for use with programs running as compat ABIs under 64b kernels, we previously haven't included the compiler flags that are supposedly common to all ABIs - ie. those in the ccflags-vdso variable. This is problematic in cases where we need to provide the -m%-float flag in order to ensure that we don't attempt to use a floating point ABI that's incompatible with the target CPU & ABI. For example a toolchain using current gcc trunk configured --with-fp-32=xx fails to build a 64r6el_defconfig kernel with the following error: cc1: error: '-march=mips1' requires '-mfp32' make[2]: *** [arch/mips/vdso/Makefile:135: arch/mips/vdso/vdso-o32.lds] Error 1 Include $(ccflags-vdso) for the compat VDSO .lds builds, just as it is included for the native VDSO .lds & when compiling objects for the compat VDSOs. This ensures we consistently provide the -msoft-float flag amongst others, avoiding the problem by ensuring we're agnostic to the toolchain defaults. Signed-off-by: Paul Burton Fixes: ebb5e78cc634 ("MIPS: Initial implementation of a VDSO") Cc: linux-mips@vger.kernel.org Cc: Kevin Hilman Cc: Guenter Roeck Cc: Maciej W . Rozycki Cc: stable@vger.kernel.org # v4.4+

MIPS: VDSO: Use same -m%-float cflag as the kernel proper

2019-01-29T19:50:41Z

The MIPS VDSO build currently doesn't provide the -msoft-float flag to the compiler as the kernel proper does. This results in an attempt to use the compiler's default floating point configuration, which can be problematic in cases where this is incompatible with the target CPU's -march= flag. For example decstation_defconfig fails to build using toolchains in which gcc was configured --with-fp-32=xx with the following error: LDS arch/mips/vdso/vdso.lds cc1: error: '-march=r3000' requires '-mfp32' make[2]: *** [scripts/Makefile.build:379: arch/mips/vdso/vdso.lds] Error 1 The kernel proper avoids this error because we build with the -msoft-float compiler flag, rather than using the compiler's default. Pass this flag through to the VDSO build so that it too becomes agnostic to the toolchain's floating point configuration. Note that this is filtered out from KBUILD_CFLAGS rather than simply always using -msoft-float such that if we switch the kernel to use -mno-float in the future the VDSO will automatically inherit the change. The VDSO doesn't actually include any floating point code, and its .MIPS.abiflags section is already manually generated to specify that it's compatible with any floating point ABI. As such this change should have no effect on the resulting VDSO, apart from fixing the build failure for affected toolchains. Signed-off-by: Paul Burton Reported-by: Kevin Hilman Reported-by: Guenter Roeck Tested-by: Kevin Hilman References: https://lore.kernel.org/linux-mips/1477843551-21813-1-git-send-email-linux@roeck-us.net/ References: https://kernelci.org/build/id/5c4e4ae059b5142a249ad004/logs/ Fixes: ebb5e78cc634 ("MIPS: Initial implementation of a VDSO") Cc: Maciej W. Rozycki Cc: linux-mips@vger.kernel.org Cc: stable@vger.kernel.org # v4.4+

MIPS: Enable Undefined Behavior Sanitizer UBSAN

2018-11-20T20:23:06Z

Select ARCH_HAS_UBSAN_SANITIZE_ALL in order to allow the user to enable CONFIG_UBSAN_SANITIZE_ALL and instrument the entire kernel for ubsan checks. We exclude the VDSO from this because its build doesn't include the __ubsan_handle_*() functions that the kernel proper defines in from lib/ubsan.c, and the VDSO would have no sane way to report errors even if it had definitions of these functions. Signed-off-by: Hassan Naveed Reviewed-by: Paul Burton Signed-off-by: Paul Burton Patchwork: https://patchwork.linux-mips.org/patch/21179/ Cc:

kbuild: replace cc-name test with CONFIG_CC_IS_CLANG

2018-11-02T13:49:00Z

Evaluating cc-name invokes the compiler every time even when you are not compiling anything, like 'make help'. This is not efficient. The compiler type has been already detected in the Kconfig stage. Use CONFIG_CC_IS_CLANG, instead. Signed-off-by: Masahiro Yamada Acked-by: Michael Ellerman (powerpc) Acked-by: Paul Burton (MIPS) Acked-by: Joel Stanley

MIPS: VDSO: Force link endianness

2018-08-07T23:16:13Z

When building the VDSO with clang it appears to invoke ld without specifying endianness, even though clang itself was provided with a -EB or -EL flag. This results in the build failing due to a mismatch between the objects that are the input to ld, and the output it is attempting to create: VDSO arch/mips/vdso/vdso.so.dbg.raw mips-linux-ld: arch/mips/vdso/elf.o: compiled for a big endian system and target is little endian mips-linux-ld: arch/mips/vdso/elf.o: endianness incompatible with that of the selected emulation mips-linux-ld: failed to merge target specific data of file arch/mips/vdso/elf.o ... Work around this problem by explicitly specifying the link endianness using -Wl,-EB or -Wl,-EL when -EB or -EL are part of KBUILD_CFLAGS. This resolves the build failure when using clang, and doesn't have any negative effect on gcc. Signed-off-by: Paul Burton

MIPS: vdso: Allow clang's --target flag in VDSO cflags

2018-08-06T22:53:33Z

The MIPS VDSO code filters out a subset of known-good flags from KBUILD_CFLAGS to use when building VDSO libraries. When we build using clang we need to allow the --target flag through, otherwise we'll generally attempt to build the VDSO for the architecture of the build machine rather than for MIPS. Signed-off-by: Paul Burton Patchwork: https://patchwork.linux-mips.org/patch/20154/ Cc: James Hogan Cc: Ralf Baechle Cc: linux-mips@linux-mips.org

MIPS: genvdso: Remove GOT checks

2018-08-06T22:28:46Z

Our genvdso tool performs some rather paranoid checking that the VDSO library isn't attempting to make use of a GOT by constraining the number of entries that the GOT is allowed to contain to the minimum 2 entries that are always generated by binutils. Unfortunately lld prior to revision 334390 generates a third entry, which is unused & thus harmless but falls foul of genvdso's checks & causes the build to fail. Since we already check that the VDSO contains no relocations it seems reasonable to presume that it also doesn't contain use of a GOT, which would involve relocations. Thus rather than attempting to work around this issue by allowing 3 GOT entries when using lld, simply remove the GOT checks which seem overly paranoid. Signed-off-by: Paul Burton Patchwork: https://patchwork.linux-mips.org/patch/20152/ Cc: James Hogan Cc: Ralf Baechle Cc: linux-mips@linux-mips.org

MIPS: VDSO: Prevent use of smp_processor_id()

2018-07-28T02:36:16Z

VDSO code should not be using smp_processor_id(), since it is executed in user mode. Introduce a VDSO-specific path which will cause a compile-time or link-time error (depending upon support for __compiletime_error) if the VDSO ever incorrectly attempts to use smp_processor_id(). [Matt Redfearn : Move before change to smp_processor_id in series] Signed-off-by: Paul Burton Signed-off-by: Matt Redfearn Patchwork: https://patchwork.linux-mips.org/patch/17932/ Cc: Ralf Baechle Cc: James Hogan Cc: linux-mips@linux-mips.org

MIPS: VDSO: Replace __mips_isa_rev with MIPS_ISA_REV

2018-03-09T11:22:48Z

Remove the need to check that __mips_isa_rev is defined by using the newly added MIPS_ISA_REV. Signed-off-by: Matt Redfearn Cc: Ralf Baechle Cc: Paul Burton Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/18678/ Signed-off-by: James Hogan

License cleanup: add SPDX GPL-2.0 license identifier to files with no license

2017-11-02T10:10:55Z

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 Reviewed-by: Philippe Ombredanne Reviewed-by: Thomas Gleixner Signed-off-by: Greg Kroah-Hartman