kernel.git/arch/x86/kernel/time.c, branch linux-4.14.y

x86_64: Fix jiffies ODR violation

2020-06-20T08:25:00Z

commit d8ad6d39c35d2b44b3d48b787df7f3359381dcbf upstream. 'jiffies' and 'jiffies_64' are meant to alias (two different symbols that share the same address). Most architectures make the symbols alias to the same address via a linker script assignment in their arch//kernel/vmlinux.lds.S: jiffies = jiffies_64; which is effectively a definition of jiffies. jiffies and jiffies_64 are both forward declared for all architectures in include/linux/jiffies.h. jiffies_64 is defined in kernel/time/timer.c. x86_64 was peculiar in that it wasn't doing the above linker script assignment, but rather was: 1. defining jiffies in arch/x86/kernel/time.c instead via the linker script. 2. overriding the symbol jiffies_64 from kernel/time/timer.c in arch/x86/kernel/vmlinux.lds.s via 'jiffies_64 = jiffies;'. As Fangrui notes: In LLD, symbol assignments in linker scripts override definitions in object files. GNU ld appears to have the same behavior. It would probably make sense for LLD to error "duplicate symbol" but GNU ld is unlikely to adopt for compatibility reasons. This results in an ODR violation (UB), which seems to have survived thus far. Where it becomes harmful is when; 1. -fno-semantic-interposition is used: As Fangrui notes: Clang after LLVM commit 5b22bcc2b70d ("[X86][ELF] Prefer to lower MC_GlobalAddress operands to .Lfoo$local") defaults to -fno-semantic-interposition similar semantics which help -fpic/-fPIC code avoid GOT/PLT when the referenced symbol is defined within the same translation unit. Unlike GCC -fno-semantic-interposition, Clang emits such relocations referencing local symbols for non-pic code as well. This causes references to jiffies to refer to '.Ljiffies$local' when jiffies is defined in the same translation unit. Likewise, references to jiffies_64 become references to '.Ljiffies_64$local' in translation units that define jiffies_64. Because these differ from the names used in the linker script, they will not be rewritten to alias one another. 2. Full LTO Full LTO effectively treats all source files as one translation unit, causing these local references to be produced everywhere. When the linker processes the linker script, there are no longer any references to jiffies_64' anywhere to replace with 'jiffies'. And thus '.Ljiffies$local' and '.Ljiffies_64$local' no longer alias at all. In the process of porting patches enabling Full LTO from arm64 to x86_64, spooky bugs have been observed where the kernel appeared to boot, but init doesn't get scheduled. Avoid the ODR violation by matching other architectures and define jiffies only by linker script. For -fno-semantic-interposition + Full LTO, there is no longer a global definition of jiffies for the compiler to produce a local symbol which the linker script won't ensure aliases to jiffies_64. Fixes: 40747ffa5aa8 ("asmlinkage: Make jiffies visible") Reported-by: Nathan Chancellor Reported-by: Alistair Delva Debugged-by: Nick Desaulniers Debugged-by: Sami Tolvanen Suggested-by: Fangrui Song Signed-off-by: Bob Haarman Signed-off-by: Thomas Gleixner Tested-by: Sedat Dilek # build+boot on Reviewed-by: Andi Kleen Reviewed-by: Josh Poimboeuf Cc: stable@vger.kernel.org Link: https://github.com/ClangBuiltLinux/linux/issues/852 Link: https://lkml.kernel.org/r/20200602193100.229287-1-inglorion@google.com Signed-off-by: Greg Kroah-Hartman

x86/time: Correct the attribute on jiffies' definition

2018-11-10T15:48:36Z

commit 53c13ba8ed39e89f21a0b98f4c8a241bb44e483d upstream. Clang warns that the declaration of jiffies in include/linux/jiffies.h doesn't match the definition in arch/x86/time/kernel.c: arch/x86/kernel/time.c:29:42: warning: section does not match previous declaration [-Wsection] __visible volatile unsigned long jiffies __cacheline_aligned = INITIAL_JIFFIES; ^ ./include/linux/cache.h:49:4: note: expanded from macro '__cacheline_aligned' __section__(".data..cacheline_aligned"))) ^ ./include/linux/jiffies.h:81:31: note: previous attribute is here extern unsigned long volatile __cacheline_aligned_in_smp __jiffy_arch_data jiffies; ^ ./arch/x86/include/asm/cache.h:20:2: note: expanded from macro '__cacheline_aligned_in_smp' __page_aligned_data ^ ./include/linux/linkage.h:39:29: note: expanded from macro '__page_aligned_data' #define __page_aligned_data __section(.data..page_aligned) __aligned(PAGE_SIZE) ^ ./include/linux/compiler_attributes.h:233:56: note: expanded from macro '__section' #define __section(S) __attribute__((__section__(#S))) ^ 1 warning generated. The declaration was changed in commit 7c30f352c852 ("jiffies.h: declare jiffies and jiffies_64 with ____cacheline_aligned_in_smp") but wasn't updated here. Make them match so Clang no longer warns. Fixes: 7c30f352c852 ("jiffies.h: declare jiffies and jiffies_64 with ____cacheline_aligned_in_smp") Signed-off-by: Nathan Chancellor Signed-off-by: Thomas Gleixner Cc: Borislav Petkov Cc: "H. Peter Anvin" Cc: Nick Desaulniers Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20181013005311.28617-1-natechancellor@gmail.com Signed-off-by: Greg Kroah-Hartman

x86: Don't include linux/irq.h from asm/hardirq.h

2018-08-15T16:12:58Z

commit 447ae316670230d7d29430e2cbf1f5db4f49d14c upstream The next patch in this series will have to make the definition of irq_cpustat_t available to entering_irq(). Inclusion of asm/hardirq.h into asm/apic.h would cause circular header dependencies like asm/smp.h asm/apic.h asm/hardirq.h linux/irq.h linux/topology.h linux/smp.h asm/smp.h or linux/gfp.h linux/mmzone.h asm/mmzone.h asm/mmzone_64.h asm/smp.h asm/apic.h asm/hardirq.h linux/irq.h linux/irqdesc.h linux/kobject.h linux/sysfs.h linux/kernfs.h linux/idr.h linux/gfp.h and others. This causes compilation errors because of the header guards becoming effective in the second inclusion: symbols/macros that had been defined before wouldn't be available to intermediate headers in the #include chain anymore. A possible workaround would be to move the definition of irq_cpustat_t into its own header and include that from both, asm/hardirq.h and asm/apic.h. However, this wouldn't solve the real problem, namely asm/harirq.h unnecessarily pulling in all the linux/irq.h cruft: nothing in asm/hardirq.h itself requires it. Also, note that there are some other archs, like e.g. arm64, which don't have that #include in their asm/hardirq.h. Remove the linux/irq.h #include from x86' asm/hardirq.h. Fix resulting compilation errors by adding appropriate #includes to *.c files as needed. Note that some of these *.c files could be cleaned up a bit wrt. to their set of #includes, but that should better be done from separate patches, if at all. Signed-off-by: Nicolai Stange Signed-off-by: Thomas Gleixner Signed-off-by: Greg Kroah-Hartman

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

x86/time: Make setup_default_timer_irq() static

2017-06-13T06:42:09Z

This function isn't used outside of time.c, so let's mark it static. Signed-off-by: Dou Liyang Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1497321029-29049-1-git-send-email-douly.fnst@cn.fujitsu.com Signed-off-by: Ingo Molnar

x86/asm/entry: Change all 'user_mode_vm()' calls to 'user_mode()'

2015-03-23T10:14:17Z

user_mode_vm() and user_mode() are now the same. Change all callers of user_mode_vm() to user_mode(). The next patch will remove the definition of user_mode_vm. Signed-off-by: Andy Lutomirski Cc: Borislav Petkov Cc: Brad Spengler Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/43b1f57f3df70df5a08b0925897c660725015554.1426728647.git.luto@kernel.org [ Merged to a more recent kernel. ] Signed-off-by: Ingo Molnar

x86_64/vdso: Remove jiffies from the vvar page

2014-10-28T10:22:13Z

I think that the jiffies vvar was once used for the vgetcpu cache. That code is long gone, so let's just make jiffies be a normal variable. Signed-off-by: Andy Lutomirski Link: http://lkml.kernel.org/r/fcfee6f8749af14d96373a9e2656354ad0b95499.1411494540.git.luto@amacapital.net Signed-off-by: Ingo Molnar

x86: Fix non-PC platform kernel crash on boot due to NULL dereference

2014-08-25T20:36:57Z

Upstream commit: 95d76acc7518d5 ("x86, irq: Count legacy IRQs by legacy_pic->nr_legacy_irqs instead of NR_IRQS_LEGACY") removed reserved interrupts for the platforms that do not have a legacy IOAPIC. Which breaks the boot on Intel MID platforms such as Medfield: BUG: unable to handle kernel NULL pointer dereference at 0000003a IP: [] setup_irq+0xf/0x4d [ 0.000000] *pdpt = 0000000000000000 *pde = 9bbf32453167e510 The culprit is an uncoditional setting of IRQ2 which is used as cascade IRQ on legacy platforms. It seems we have to check if we have enough legacy IRQs reserved before we can call setup_irq(). The fix adds such check in native_init_IRQ() and in setup_default_timer_irq(). Signed-off-by: Andy Shevchenko Reviewed-by: Jiang Liu Reviewed-by: Thomas Gleixner Cc: David Cohen Link: http://lkml.kernel.org/r/1405931920-12871-1-git-send-email-andriy.shevchenko@linux.intel.com Signed-off-by: Ingo Molnar

Merge branch 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2014-04-01T18:22:57Z

Pull irq code updates from Thomas Gleixner: "The irq department proudly presents: - Another tree wide sweep of irq infrastructure abuse. Clear winner of the trainwreck engineering contest was: #include "../../../kernel/irq/settings.h" - Tree wide update of irq_set_affinity() callbacks which miss a cpu online check when picking a single cpu out of the affinity mask. - Tree wide consolidation of interrupt statistics. - Updates to the threaded interrupt infrastructure to allow explicit wakeup of the interrupt thread and a variant of synchronize_irq() which synchronizes only the hard interrupt handler. Both are needed to replace the homebrewn thread handling in the mmc/sdhci code. - New irq chip callbacks to allow proper support for GPIO based irqs. The GPIO based interrupts need to request/release GPIO resources from request/free_irq. - A few new ARM interrupt chips. No revolutionary new hardware, just differently wreckaged variations of the scheme. - Small improvments, cleanups and updates all over the place" I was hoping that that trainwreck engineering contest was a April Fools' joke. But no. * 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (68 commits) irqchip: sun7i/sun6i: Disable NMI before registering the handler ARM: sun7i/sun6i: dts: Fix IRQ number for sun6i NMI controller ARM: sun7i/sun6i: irqchip: Update the documentation ARM: sun7i/sun6i: dts: Add NMI irqchip support ARM: sun7i/sun6i: irqchip: Add irqchip driver for NMI controller genirq: Export symbol no_action() arm: omap: Fix typo in ams-delta-fiq.c m68k: atari: Fix the last kernel_stat.h fallout irqchip: sun4i: Simplify sun4i_irq_ack irqchip: sun4i: Use handle_fasteoi_irq for all interrupts genirq: procfs: Make smp_affinity values go+r softirq: Add linux/irq.h to make it compile again m68k: amiga: Add linux/irq.h to make it compile again irqchip: sun4i: Don't ack IRQs > 0, fix acking of IRQ 0 irqchip: sun4i: Fix a comment about mask register initialization irqchip: sun4i: Fix irq 0 not working genirq: Add a new IRQCHIP_EOI_THREADED flag genirq: Document IRQCHIP_ONESHOT_SAFE flag ARM: sunxi: dt: Convert to the new irq controller compatibles irqchip: sunxi: Change compatibles ...

x86: Remove deprecated IRQF_DISABLED

2014-03-04T20:47:51Z

This patch removes the IRQF_DISABLED flag from x86 architecture code. It's a NOOP since 2.6.35 and it will be removed one day. Signed-off-by: Michael Opdenacker Cc: venki@google.com Link: http://lkml.kernel.org/r/1393965305-17248-1-git-send-email-michael.opdenacker@free-electrons.com Signed-off-by: Thomas Gleixner