kernel/linux.git/scripts/link-vmlinux.sh, branch v6.19.11

Merge tag 'tracepoints-v6.19' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

2025-12-05T17:37:41+00:00

Pull unused tracepoints update from Steven Rostedt: "Detect unused tracepoints. If a tracepoint is defined but never used (TRACE_EVENT() created but no trace_() called), it can take up to or more than 5K of memory each. This can add up as there are around a hundred unused tracepoints with various configs. That is 500K of wasted memory. Add a make build parameter of "UT=1" to have the build warn if an unused tracepoint is detected in the build. This allows detection of unused tracepoints to be upstream so that outreachy and the mentoring project can have new developers look for fixing them, without having these warnings suddenly show up when someone upgrades their kernel. When all known unused tracepoints are removed, then the "UT=1" build parameter can be removed and unused tracepoints will always warn. This will catch new unused tracepoints after the current ones have been removed. Summary: - Separate out elf functions from sorttable.c Move out the ELF parsing functions from sorttable.c so that the tracing tooling can use it. - Add a tracepoint verifier tool to the build process If "UT=1" is added to the kernel command line, any unused tracepoints will trigger a warning at build time. - Do not warn about unused tracepoints for tracepoints that are exported There are sever cases where a tracepoint is created by the kernel and used by modules. Since there's no easy way to detect if these are truly unused since the users are in modules, if a tracepoint is exported, assume it will eventually be used by a module. Note, there's not many exported tracepoints so this should not be a problem to ignore them. - Have building of modules also detect unused tracepoints Do not only check the main vmlinux for unused tracepoints, also check modules. If a module is defining a tracepoint it should be using it. - Add the tracepoint-update program to the ignore file The new tracepoint-update program needs to be ignored by git" * tag 'tracepoints-v6.19' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: scripts: add tracepoint-update to the list of ignores files tracing: Add warnings for unused tracepoints for modules tracing: Allow tracepoint-update.c to work with modules tracepoint: Do not warn for unused event that is exported tracing: Add a tracepoint verification check at build time sorttable: Move ELF parsing into scripts/elf-parse.[ch]

tracing: Add a tracepoint verification check at build time

2025-10-24T20:43:14+00:00

If a tracepoint is defined via DECLARE_TRACE() or TRACE_EVENT() but never called (via the trace_() function), its metadata is still around in memory and not discarded. When created via TRACE_EVENT() the situation is worse because the TRACE_EVENT() creates metadata that can be around 5k per trace event. Having unused trace events causes several thousand of wasted bytes. Add a verifier that injects a string of the name of the tracepoint it calls that is added to the discarded section "__tracepoint_check". For every builtin tracepoint, its name (which is saved in the in-memory section "__tracepoint_strings") will have its name also in the "__tracepoint_check" section if it is used. Add a new program that is run on build called tracepoint-update. This is executed on the vmlinux.o before the __tracepoint_check section is discarded (the section is discarded before vmlinux is created). This program will create an array of each string in the __tracepoint_check section and then sort it. Then it will walk the strings in the __tracepoint_strings section and do a binary search to check if its name is in the __tracepoint_check section. If it is not, then it is unused and a warning is printed. Note, this currently only handles tracepoints that are builtin and not in modules. Enabling this currently with a given config produces: warning: tracepoint 'sched_move_numa' is unused. warning: tracepoint 'sched_stick_numa' is unused. warning: tracepoint 'sched_swap_numa' is unused. warning: tracepoint 'pelt_hw_tp' is unused. warning: tracepoint 'pelt_irq_tp' is unused. warning: tracepoint 'rcu_preempt_task' is unused. warning: tracepoint 'rcu_unlock_preempted_task' is unused. warning: tracepoint 'xdp_bulk_tx' is unused. warning: tracepoint 'xdp_redirect_map' is unused. warning: tracepoint 'xdp_redirect_map_err' is unused. warning: tracepoint 'vma_mas_szero' is unused. warning: tracepoint 'vma_store' is unused. warning: tracepoint 'hugepage_set_pmd' is unused. warning: tracepoint 'hugepage_set_pud' is unused. warning: tracepoint 'hugepage_update_pmd' is unused. warning: tracepoint 'hugepage_update_pud' is unused. warning: tracepoint 'block_rq_remap' is unused. warning: tracepoint 'xhci_dbc_handle_event' is unused. warning: tracepoint 'xhci_dbc_handle_transfer' is unused. warning: tracepoint 'xhci_dbc_gadget_ep_queue' is unused. warning: tracepoint 'xhci_dbc_alloc_request' is unused. warning: tracepoint 'xhci_dbc_free_request' is unused. warning: tracepoint 'xhci_dbc_queue_request' is unused. warning: tracepoint 'xhci_dbc_giveback_request' is unused. warning: tracepoint 'tcp_ao_wrong_maclen' is unused. warning: tracepoint 'tcp_ao_mismatch' is unused. warning: tracepoint 'tcp_ao_key_not_found' is unused. warning: tracepoint 'tcp_ao_rnext_request' is unused. warning: tracepoint 'tcp_ao_synack_no_key' is unused. warning: tracepoint 'tcp_ao_snd_sne_update' is unused. warning: tracepoint 'tcp_ao_rcv_sne_update' is unused. Some of the above is totally unused but others are not used due to their "trace_" functions being inside configs, in which case, the defined tracepoints should also be inside those same configs. Others are architecture specific but defined in generic code, where they should either be moved to the architecture or be surrounded by #ifdef for the architectures they are for. This tool could be updated to process modules in the future. I'd like to thank Mathieu Desnoyers for suggesting using strings instead of pointers, as using pointers in vmlinux.o required handling relocations and it required implementing almost a full feature linker to do so. To enable this check, run the build with: make UT=1 Note, when all the existing unused tracepoints are removed from the build, the "UT=1" will be removed and this will always be enabled when tracepoints are configured to warn on any new tracepoints. The reason this isn't always enabled now is because it will introduce a lot of warnings for the current unused tracepoints, and all bisects would end at this commit for those warnings. Link: https://lore.kernel.org/all/20250528114549.4d8a5e03@gandalf.local.home/ Cc: Masami Hiramatsu Cc: Mark Rutland Cc: Mathieu Desnoyers Cc: Andrew Morton Cc: Arnd Bergmann Cc: Masahiro Yamada Cc: Nathan Chancellor Cc: Nicolas Schier Cc: Nick Desaulniers Cc: Catalin Marinas Cc: Linus Torvalds Cc: Randy Dunlap Cc: Stephen Rothwell Link: https://lore.kernel.org/20251022004452.920728129@kernel.org Suggested-by: Mathieu Desnoyers # for using strings instead of pointers Signed-off-by: Steven Rostedt (Google)

kbuild,objtool: Defer objtool validation step for CONFIG_KLP_BUILD

2025-10-14T21:50:19+00:00

In preparation for klp-build, defer objtool validation for CONFIG_KLP_BUILD kernels until the final pre-link archive (e.g., vmlinux.o, module-foo.o) is built. This will simplify the process of generating livepatch modules. Delayed objtool is generally preferred anyway, and is already standard for IBT and LTO. Eventually the per-translation-unit mode will be phased out. Acked-by: Petr Mladek Tested-by: Joe Lawrence Signed-off-by: Josh Poimboeuf

kbuild: vmlinux.unstripped should always depend on .vmlinux.export.o

2025-09-24T16:10:45+00:00

Since .vmlinux.export.c is used to add generated by modpost modaliases for builtin modules the .vmlinux.export.o is no longer optional and should always be created. The generation of this file is not dependent on CONFIG_MODULES. Signed-off-by: Alexey Gladkov Reviewed-by: Nicolas Schier Link: https://patch.msgid.link/0e63a9c7741fe8217e4fd7c60afcf057ffa2ef5a.1758182101.git.legion@kernel.org Signed-off-by: Nathan Chancellor

Merge tag 'kbuild-v6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

2025-04-05T22:46:50+00:00

Pull Kbuild updates from Masahiro Yamada: - Improve performance in gendwarfksyms - Remove deprecated EXTRA_*FLAGS and KBUILD_ENABLE_EXTRA_GCC_CHECKS - Support CONFIG_HEADERS_INSTALL for ARCH=um - Use more relative paths to sources files for better reproducibility - Support the loong64 Debian architecture - Add Kbuild bash completion - Introduce intermediate vmlinux.unstripped for architectures that need static relocations to be stripped from the final vmlinux - Fix versioning in Debian packages for -rc releases - Treat missing MODULE_DESCRIPTION() as an error - Convert Nios2 Makefiles to use the generic rule for built-in DTB - Add debuginfo support to the RPM package * tag 'kbuild-v6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (40 commits) kbuild: rpm-pkg: build a debuginfo RPM kconfig: merge_config: use an empty file as initfile nios2: migrate to the generic rule for built-in DTB rust: kbuild: skip `--remap-path-prefix` for `rustdoc` kbuild: pacman-pkg: hardcode module installation path kbuild: deb-pkg: don't set KBUILD_BUILD_VERSION unconditionally modpost: require a MODULE_DESCRIPTION() kbuild: make all file references relative to source root x86: drop unnecessary prefix map configuration kbuild: deb-pkg: add comment about future removal of KDEB_COMPRESS kbuild: Add a help message for "headers" kbuild: deb-pkg: remove "version" variable in mkdebian kbuild: deb-pkg: fix versioning for -rc releases Documentation/kbuild: Fix indentation in modules.rst example x86: Get rid of Makefile.postlink kbuild: Create intermediate vmlinux build with relocations preserved kbuild: Introduce Kconfig symbol for linking vmlinux with relocations kbuild: link-vmlinux.sh: Make output file name configurable kbuild: do not generate .tmp_vmlinux*.map when CONFIG_VMLINUX_MAP=y Revert "kheaders: Ignore silly-rename files" ...

Merge tag 'trace-sorttable-v6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

2025-03-27T22:44:34+00:00

Pull tracing / sorttable updates from Steven Rostedt: - Implement arm64 build time sorting of the mcount location table When gcc is used to build arm64, the mcount_loc section is all zeros in the vmlinux elf file. The addresses are stored in the Elf_Rela location. To sort at build time, an array is allocated and the addresses are added to it via the content of the mcount_loc section as well as he Elf_Rela data. After sorting, the information is put back into the Elf_Rela which now has the section sorted. - Make sorting of mcount location table for arm64 work with clang as well When clang is used, the mcount_loc section contains the addresses, unlike the gcc build. An array is still created and the sorting works for both methods. - Remove weak functions from the mcount_loc section Have the sorttable code pass in the data of functions defined via 'nm -S' which shows the functions as well as their sizes. Using this information the sorttable code can determine if a function in the mcount_loc section was weak and overridden. If the function is not found, it is set to be zero. On boot, when the mcount_loc section is read and the ftrace table is created, if the address in the mcount_loc is not in the kernel core text then it is removed and not added to the ftrace_filter_functions (the functions that can be attached by ftrace callbacks). - Update and fix the reporting of how much data is used for ftrace functions On boot, a report of how many pages were used by the ftrace table as well as how they were grouped (the table holds a list of sections that are groups of pages that were able to be allocated). The removing of the weak functions required the accounting to be updated. * tag 'trace-sorttable-v6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: scripts/sorttable: Allow matches to functions before function entry scripts/sorttable: Use normal sort if theres no relocs in the mcount section ftrace: Check against is_kernel_text() instead of kaslr_offset() ftrace: Test mcount_loc addr before calling ftrace_call_addr() ftrace: Have ftrace pages output reflect freed pages ftrace: Update the mcount_loc check of skipped entries scripts/sorttable: Zero out weak functions in mcount_loc table scripts/sorttable: Always use an array for the mcount_loc sorting scripts/sorttable: Have mcount rela sort use direct values arm64: scripts/sorttable: Implement sorting mcount_loc at boot for arm64

kbuild: link-vmlinux.sh: Make output file name configurable

2025-03-16T15:29:45+00:00

In order to introduce an intermediate, non-stripped vmlinux build that can be used by other build steps as an input, pass the output file name to link-vmlinux.sh via its command line. Signed-off-by: Ard Biesheuvel Signed-off-by: Masahiro Yamada

kbuild: do not generate .tmp_vmlinux*.map when CONFIG_VMLINUX_MAP=y

2025-03-15T12:22:52+00:00

Commit 5cc124720461 ("kbuild: add CONFIG_VMLINUX_MAP expert option") mentioned that "the .map file can be rather large (several MB), and that's a waste of space when one isn't interested in these things." If that is the case, generating map files for the intermediate tmp_vmlinux* files is also a waste of space. It is unlikely that anyone would be interested in the .tmp_vmlinux*.map files. This commit stops passing the -Map= option when linking the .tmp_vmlinux* intermediates. I also hard-coded the file name 'vmlinux.map' instead of ${output}.map because a later commit will introduce vmlinux.unstripped but I want to keep the current name of the map file. Signed-off-by: Masahiro Yamada Acked-by: Ard Biesheuvel

scripts/sorttable: Zero out weak functions in mcount_loc table

2025-02-18T22:12:03+00:00

When a function is annotated as "weak" and is overridden, the code is not removed. If it is traced, the fentry/mcount location in the weak function will be referenced by the "__mcount_loc" section. This will then be added to the available_filter_functions list. Since only the address of the functions are listed, to find the name to show, a search of kallsyms is used. Since kallsyms will return the function by simply finding the function that the address is after but before the next function, an address of a weak function will show up as the function before it. This is because kallsyms does not save names of weak functions. This has caused issues in the past, as now the traced weak function will be listed in available_filter_functions with the name of the function before it. At best, this will cause the previous function's name to be listed twice. At worse, if the previous function was marked notrace, it will now show up as a function that can be traced. Note that it only shows up that it can be traced but will not be if enabled, which causes confusion. https://lore.kernel.org/all/20220412094923.0abe90955e5db486b7bca279@kernel.org/ The commit b39181f7c6907 ("ftrace: Add FTRACE_MCOUNT_MAX_OFFSET to avoid adding weak function") was a workaround to this by checking the function address before printing its name. If the address was too far from the function given by the name then instead of printing the name it would print: __ftrace_invalid_address___ The real issue is that these invalid addresses are listed in the ftrace table look up which available_filter_functions is derived from. A place holder must be listed in that file because set_ftrace_filter may take a series of indexes into that file instead of names to be able to do O(1) lookups to enable filtering (many tools use this method). Even if kallsyms saved the size of the function, it does not remove the need of having these place holders. The real solution is to not add a weak function into the ftrace table in the first place. To solve this, the sorttable.c code that sorts the mcount regions during the build is modified to take a "nm -S vmlinux" input, sort it, and any function listed in the mcount_loc section that is not within a boundary of the function list given by nm is considered a weak function and is zeroed out. Note, this does not mean they will remain zero when booting as KASLR will still shift those addresses. To handle this, the entries in the mcount_loc section will be ignored if they are zero or match the kaslr_offset() value. Before: ~# grep __ftrace_invalid_address___ /sys/kernel/tracing/available_filter_functions | wc -l 551 After: ~# grep __ftrace_invalid_address___ /sys/kernel/tracing/available_filter_functions | wc -l 0 Cc: bpf Cc: Masami Hiramatsu Cc: Mark Rutland Cc: Mathieu Desnoyers Cc: Andrew Morton Cc: Peter Zijlstra Cc: Linus Torvalds Cc: Masahiro Yamada Cc: Nathan Chancellor Cc: Nicolas Schier Cc: Zheng Yejian Cc: Martin Kelly Cc: Christophe Leroy Cc: Josh Poimboeuf Cc: Heiko Carstens Cc: Catalin Marinas Cc: Will Deacon Cc: Vasily Gorbik Cc: Alexander Gordeev Link: https://lore.kernel.org/20250218200022.883095980@goodmis.org Signed-off-by: Steven Rostedt (Google)

kallsyms: Remove KALLSYMS_ABSOLUTE_PERCPU

2025-02-18T09:16:04+00:00

x86-64 was the only user. Signed-off-by: Brian Gerst Signed-off-by: Ingo Molnar Reviewed-by: Ard Biesheuvel Cc: Linus Torvalds Link: https://lore.kernel.org/r/20250123190747.745588-16-brgerst@gmail.com