linux/Documentation/core-api, branch v5.14

module: add printk formats to add module build ID to stacktraces

2021-07-08T18:48:22Z

Let's make kernel stacktraces easier to identify by including the build ID[1] of a module if the stacktrace is printing a symbol from a module. This makes it simpler for developers to locate a kernel module's full debuginfo for a particular stacktrace. Combined with scripts/decode_stracktrace.sh, a developer can download the matching debuginfo from a debuginfod[2] server and find the exact file and line number for the functions plus offsets in a stacktrace that match the module. This is especially useful for pstore crash debugging where the kernel crashes are recorded in something like console-ramoops and the recovery kernel/modules are different or the debuginfo doesn't exist on the device due to space concerns (the debuginfo can be too large for space limited devices). Originally, I put this on the %pS format, but that was quickly rejected given that %pS is used in other places such as ftrace where build IDs aren't meaningful. There was some discussions on the list to put every module build ID into the "Modules linked in:" section of the stacktrace message but that quickly becomes very hard to read once you have more than three or four modules linked in. It also provides too much information when we don't expect each module to be traversed in a stacktrace. Having the build ID for modules that aren't important just makes things messy. Splitting it to multiple lines for each module quickly explodes the number of lines printed in an oops too, possibly wrapping the warning off the console. And finally, trying to stash away each module used in a callstack to provide the ID of each symbol printed is cumbersome and would require changes to each architecture to stash away modules and return their build IDs once unwinding has completed. Instead, we opt for the simpler approach of introducing new printk formats '%pS[R]b' for "pointer symbolic backtrace with module build ID" and '%pBb' for "pointer backtrace with module build ID" and then updating the few places in the architecture layer where the stacktrace is printed to use this new format. Before: Call trace: lkdtm_WARNING+0x28/0x30 [lkdtm] direct_entry+0x16c/0x1b4 [lkdtm] full_proxy_write+0x74/0xa4 vfs_write+0xec/0x2e8 After: Call trace: lkdtm_WARNING+0x28/0x30 [lkdtm 6c2215028606bda50de823490723dc4bc5bf46f9] direct_entry+0x16c/0x1b4 [lkdtm 6c2215028606bda50de823490723dc4bc5bf46f9] full_proxy_write+0x74/0xa4 vfs_write+0xec/0x2e8 [akpm@linux-foundation.org: fix build with CONFIG_MODULES=n, tweak code layout] [rdunlap@infradead.org: fix build when CONFIG_MODULES is not set] Link: https://lkml.kernel.org/r/20210513171510.20328-1-rdunlap@infradead.org [akpm@linux-foundation.org: make kallsyms_lookup_buildid() static] [cuibixuan@huawei.com: fix build error when CONFIG_SYSFS is disabled] Link: https://lkml.kernel.org/r/20210525105049.34804-1-cuibixuan@huawei.com Link: https://lkml.kernel.org/r/20210511003845.2429846-6-swboyd@chromium.org Link: https://fedoraproject.org/wiki/Releases/FeatureBuildId [1] Link: https://sourceware.org/elfutils/Debuginfod.html [2] Signed-off-by: Stephen Boyd Signed-off-by: Bixuan Cui Signed-off-by: Randy Dunlap Cc: Jiri Olsa Cc: Alexei Starovoitov Cc: Jessica Yu Cc: Evan Green Cc: Hsin-Yi Wang Cc: Petr Mladek Cc: Steven Rostedt Cc: Sergey Senozhatsky Cc: Andy Shevchenko Cc: Rasmus Villemoes Cc: Matthew Wilcox Cc: Baoquan He Cc: Borislav Petkov Cc: Catalin Marinas Cc: Dave Young Cc: Ingo Molnar Cc: Konstantin Khlebnikov Cc: Sasha Levin Cc: Thomas Gleixner Cc: Vivek Goyal Cc: Will Deacon Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Merge branch 'akpm' (patches from Andrew)

2021-07-02T19:08:10Z

Merge more updates from Andrew Morton: "190 patches. Subsystems affected by this patch series: mm (hugetlb, userfaultfd, vmscan, kconfig, proc, z3fold, zbud, ras, mempolicy, memblock, migration, thp, nommu, kconfig, madvise, memory-hotplug, zswap, zsmalloc, zram, cleanups, kfence, and hmm), procfs, sysctl, misc, core-kernel, lib, lz4, checkpatch, init, kprobes, nilfs2, hfs, signals, exec, kcov, selftests, compress/decompress, and ipc" * emailed patches from Andrew Morton : (190 commits) ipc/util.c: use binary search for max_idx ipc/sem.c: use READ_ONCE()/WRITE_ONCE() for use_global_lock ipc: use kmalloc for msg_queue and shmid_kernel ipc sem: use kvmalloc for sem_undo allocation lib/decompressors: remove set but not used variabled 'level' selftests/vm/pkeys: exercise x86 XSAVE init state selftests/vm/pkeys: refill shadow register after implicit kernel write selftests/vm/pkeys: handle negative sys_pkey_alloc() return code selftests/vm/pkeys: fix alloc_random_pkey() to make it really, really random kcov: add __no_sanitize_coverage to fix noinstr for all architectures exec: remove checks in __register_bimfmt() x86: signal: don't do sas_ss_reset() until we are certain that sigframe won't be abandoned hfsplus: report create_date to kstat.btime hfsplus: remove unnecessary oom message nilfs2: remove redundant continue statement in a while-loop kprobes: remove duplicated strong free_insn_page in x86 and s390 init: print out unknown kernel parameters checkpatch: do not complain about positive return values starting with EPOLL checkpatch: improve the indented label test checkpatch: scripts/spdxcheck.py now requires python3 ...

kernel.h: split out kstrtox() and simple_strtox() to a separate header

2021-07-01T18:06:05Z

kernel.h is being used as a dump for all kinds of stuff for a long time. Here is the attempt to start cleaning it up by splitting out kstrtox() and simple_strtox() helpers. At the same time convert users in header and lib folders to use new header. Though for time being include new header back to kernel.h to avoid twisted indirected includes for existing users. [andy.shevchenko@gmail.com: fix documentation references] Link: https://lkml.kernel.org/r/20210615220003.377901-1-andy.shevchenko@gmail.com Link: https://lkml.kernel.org/r/20210611185815.44103-1-andriy.shevchenko@linux.intel.com Signed-off-by: Andy Shevchenko Acked-by: Jonathan Cameron Cc: Francis Laniel Cc: Randy Dunlap Cc: Kars Mulder Cc: Trond Myklebust Cc: Anna Schumaker Cc: "J. Bruce Fields" Cc: Chuck Lever Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Merge tag 'irq-core-2021-06-29' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2021-06-29T19:25:04Z

Pull irq updates from Thomas Gleixner: "Updates for the interrupt subsystem: Core changes: - Cleanup and simplification of common code to invoke the low level interrupt flow handlers when this invocation requires irqdomain resolution. Add the necessary core infrastructure. - Provide a proper interface for modular PMU drivers to set the interrupt affinity. - Add a request flag which allows to exclude interrupts from spurious interrupt detection. Useful especially for IPI handlers which always return IRQ_HANDLED which turns the spurious interrupt detection into a pointless waste of CPU cycles. Driver changes: - Bulk convert interrupt chip drivers to the new irqdomain low level flow handler invocation mechanism. - Add device tree bindings for the Renesas R-Car M3-W+ SoC - Enable modular build of the Qualcomm PDC driver - The usual small fixes and improvements" * tag 'irq-core-2021-06-29' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (38 commits) dt-bindings: interrupt-controller: arm,gic-v3: Describe GICv3 optional properties irqchip: gic-pm: Remove redundant error log of clock bulk irqchip/sun4i: Remove unnecessary oom message irqchip/irq-imx-gpcv2: Remove unnecessary oom message irqchip/imgpdc: Remove unnecessary oom message irqchip/gic-v3-its: Remove unnecessary oom message irqchip/gic-v2m: Remove unnecessary oom message irqchip/exynos-combiner: Remove unnecessary oom message irqchip: Bulk conversion to generic_handle_domain_irq() genirq: Move non-irqdomain handle_domain_irq() handling into ARM's handle_IRQ() genirq: Add generic_handle_domain_irq() helper irqchip/nvic: Convert from handle_IRQ() to handle_domain_irq() irqdesc: Fix __handle_domain_irq() comment genirq: Use irq_resolve_mapping() to implement __handle_domain_irq() and co irqdomain: Introduce irq_resolve_mapping() irqdomain: Protect the linear revmap with RCU irqdomain: Cache irq_data instead of a virq number in the revmap irqdomain: Use struct_size() helper when allocating irqdomain irqdomain: Make normal and nomap irqdomains exclusive powerpc: Move the use of irq_domain_add_nomap() behind a config option ...

Merge tag 'printk-for-5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux

2021-06-29T19:07:18Z

Pull printk updates from Petr Mladek: - Add %pt[RT]s modifier to vsprintf(). It overrides ISO 8601 separator by using ' ' (space). It produces "YYYY-mm-dd HH:MM:SS" instead of "YYYY-mm-ddTHH:MM:SS". - Correctly parse long row of numbers by sscanf() when using the field width. Add extensive sscanf() selftest. - Generalize re-entrant CPU lock that has already been used to serialize dump_stack() output. It is part of the ongoing printk rework. It will allow to remove the obsoleted printk_safe buffers and introduce atomic consoles. - Some code clean up and sparse warning fixes. * tag 'printk-for-5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux: printk: fix cpu lock ordering lib/dump_stack: move cpu lock to printk.c printk: Remove trailing semicolon in macros random32: Fix implicit truncation warning in prandom_seed_state() lib: test_scanf: Remove pointless use of type_min() with unsigned types selftests: lib: Add wrapper script for test_scanf lib: test_scanf: Add tests for sscanf number conversion lib: vsprintf: Fix handling of number field widths in vsscanf lib: vsprintf: scanf: Negative number must have field width > 1 usb: host: xhci-tegra: Switch to use %ptTs nilfs2: Switch to use %ptTs kdb: Switch to use %ptTs lib/vsprintf: Allow to override ISO 8601 date and time separator

docs: core-api: avoid using ReST :doc:`foo` markup

2021-06-17T19:24:37Z

The :doc:`foo` tag is auto-generated via automarkup.py. So, use the filename at the sources, instead of :doc:`foo`. Signed-off-by: Mauro Carvalho Chehab Link: https://lore.kernel.org/r/d967d490b6655735b7df292f88859b5a1b07d0d7.1623824363.git.mchehab+huawei@kernel.org Signed-off-by: Jonathan Corbet

docs: printk-formats: update size-casting examples

2021-06-14T14:12:01Z

Since commit 72deb455b5ec ("block: remove CONFIG_LBDAF") sector_t and blkcnt_t types are no longer variable in size, making them unsuitable examples for casting to the largest possible type. This patch replaces such examples with cycles_t and blk_status_t types, whose sizes depend on architecture and config options respectively. Signed-off-by: Carlos Llamas Link: https://lore.kernel.org/r/20210609195058.3518943-1-cmllamas@google.com Signed-off-by: Jonathan Corbet

irqdomain: Kill irq_domain_add_legacy_isa

2021-06-10T12:09:17Z

This helper doesn't have a user anymore, let's remove it. Signed-off-by: Marc Zyngier

lib/vsprintf: Allow to override ISO 8601 date and time separator

2021-05-17T10:01:26Z

ISO 8601 defines 'T' as a separator between date and time. Though, some ABIs use time and date with ' ' (space) separator instead. Add a flavour to the %pt specifier to override default separator. Signed-off-by: Andy Shevchenko Reviewed-by: Petr Mladek Reviewed-by: Sergey Senozhatsky Signed-off-by: Petr Mladek Link: https://lore.kernel.org/r/20210511153958.34527-1-andriy.shevchenko@linux.intel.com

Merge tag 'docs-5.13-2' of git://git.lwn.net/linux

2021-05-06T15:33:54Z

Pull documentation fixes from Jonathan Corbet: "A few late-arriving documentation fixes, including some oprofile cleanup, a kernel-doc fix, some regression-reporting updates, and the usual minor fixes" * tag 'docs-5.13-2' of git://git.lwn.net/linux: Enlisted oprofile version line removed oprofiled version output line removed from the list Removed the oprofiled version option docs: reporting-issues.rst: CC subsystem and maintainers on regressions docs: correct URL to bios and kernel developer's guide docs/core-api: Consistent code style docs/zh_CN: Adjust order and content of zh_CN/index.rst Documentation: input: joydev file corrections docs: Fix typo in Documentation/x86/x86_64/5level-paging.rst kernel-doc: Add support for __deprecated