user/sven/linux.git/scripts/mod/modpost.c, branch v4.9.272

modpost: skip ELF local symbols during section mismatch check

2019-12-21T09:41:17Z

[ Upstream commit a4d26f1a0958bb1c2b60c6f1e67c6f5d43e2647b ] During development of a serial console driver with a gcc 8.2.0 toolchain for RISC-V, the following modpost warning appeared: ---- WARNING: vmlinux.o(.data+0x19b10): Section mismatch in reference from the variable .LANCHOR1 to the function .init.text:sifive_serial_console_setup() The variable .LANCHOR1 references the function __init sifive_serial_console_setup() If the reference is valid then annotate the variable with __init* or __refdata (see linux/init.h) or name the variable: *_template, *_timer, *_sht, *_ops, *_probe, *_probe_one, *_console ---- ".LANCHOR1" is an ELF local symbol, automatically created by gcc's section anchor generation code: https://gcc.gnu.org/onlinedocs/gccint/Anchored-Addresses.html https://gcc.gnu.org/git/?p=gcc.git;a=blob;f=gcc/varasm.c;h=cd9591a45617464946dcf9a126dde277d9de9804;hb=9fb89fa845c1b2e0a18d85ada0b077c84508ab78#l7473 This was verified by compiling the kernel with -fno-section-anchors and observing that the ".LANCHOR1" ELF local symbol disappeared, and modpost no longer warned about the section mismatch. The serial driver code idiom triggering the warning is standard Linux serial driver practice that has a specific whitelist inclusion in modpost.c. I'm neither a modpost nor an ELF expert, but naively, it doesn't seem useful for modpost to report section mismatch warnings caused by ELF local symbols by default. Local symbols have compiler-generated names, and thus bypass modpost's whitelisting algorithm, which relies on the presence of a non-autogenerated symbol name. This increases the likelihood that false positive warnings will be generated (as in the above case). Thus, disable section mismatch reporting on ELF local symbols. The rationale here is similar to that of commit 2e3a10a1551d ("ARM: avoid ARM binutils leaking ELF local symbols") and of similar code already present in modpost.c: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/scripts/mod/modpost.c?h=v4.19-rc4&id=7876320f88802b22d4e2daf7eb027dd14175a0f8#n1256 This third version of the patch implements a suggestion from Masahiro Yamada to restructure the code as an additional pattern matching step inside secref_whitelist(), and further improves the patch description. Signed-off-by: Paul Walmsley Signed-off-by: Paul Walmsley Acked-by: Sam Ravnborg Signed-off-by: Masahiro Yamada Signed-off-by: Sasha Levin

modpost: validate symbol names also in find_elf_symbol

2019-02-12T18:44:52Z

[ Upstream commit 5818c683a619c534c113e1f66d24f636defc29bc ] If an ARM mapping symbol shares an address with a valid symbol, find_elf_symbol can currently return the mapping symbol instead, as the symbol is not validated. This can result in confusing warnings: WARNING: vmlinux.o(.text+0x18f4028): Section mismatch in reference from the function set_reset_devices() to the variable .init.text:$x.0 This change adds a call to is_valid_name to find_elf_symbol, similarly to how it's already used in find_elf_symbol2. Signed-off-by: Sami Tolvanen Signed-off-by: Masahiro Yamada Signed-off-by: Sasha Levin

scripts: modpost: check memory allocation results

2018-09-15T07:42:57Z

[ Upstream commit 1f3aa9002dc6a0d59a4b599b4fc8f01cf43ef014 ] Fix missing error check for memory allocation functions in scripts/mod/modpost.c. Fixes kernel bugzilla #200319: https://bugzilla.kernel.org/show_bug.cgi?id=200319 Signed-off-by: Randy Dunlap Cc: Yuexing Wang Signed-off-by: Masahiro Yamada Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

module/retpoline: Warn about missing retpoline in module

2018-02-13T11:35:58Z

(cherry picked from commit caf7501a1b4ec964190f31f9c3f163de252273b8) There's a risk that a kernel which has full retpoline mitigations becomes vulnerable when a module gets loaded that hasn't been compiled with the right compiler or the right option. To enable detection of that mismatch at module load time, add a module info string "retpoline" at build time when the module was compiled with retpoline support. This only covers compiled C source, but assembler source or prebuilt object files are not checked. If a retpoline enabled kernel detects a non retpoline protected module at load time, print a warning and report it in the sysfs vulnerability file. [ tglx: Massaged changelog ] Signed-off-by: Andi Kleen Signed-off-by: Thomas Gleixner Cc: David Woodhouse Cc: gregkh@linuxfoundation.org Cc: torvalds@linux-foundation.org Cc: jeyu@kernel.org Cc: arjan@linux.intel.com Link: https://lkml.kernel.org/r/20180125235028.31211-1-andi@firstfloor.org Signed-off-by: David Woodhouse Signed-off-by: Greg Kroah-Hartman

objtool, modules: Discard objtool annotation sections for modules

2018-01-17T08:38:58Z

commit e390f9a9689a42f477a6073e2e7df530a4c1b740 upstream. The '__unreachable' and '__func_stack_frame_non_standard' sections are only used at compile time. They're discarded for vmlinux but they should also be discarded for modules. Since this is a recurring pattern, prefix the section names with ".discard.". It's a nice convention and vmlinux.lds.h already discards such sections. Also remove the 'a' (allocatable) flag from the __unreachable section since it doesn't make sense for a discarded section. Suggested-by: Linus Torvalds Signed-off-by: Josh Poimboeuf Cc: Jessica Yu Cc: Peter Zijlstra Cc: Thomas Gleixner Fixes: d1091c7fa3d5 ("objtool: Improve detection of BUG() and other dead ends") Link: http://lkml.kernel.org/r/20170301180444.lhd53c5tibc4ns77@treble Signed-off-by: Ingo Molnar [dwmw2: Remove the unreachable part in backporting since it's not here yet] Signed-off-by: David Woodhouse Signed-off-by: Greg Kroah-Hartman

nmi_backtrace: generate one-line reports for idle cpus

2016-10-08T01:46:30Z

When doing an nmi backtrace of many cores, most of which are idle, the output is a little overwhelming and very uninformative. Suppress messages for cpus that are idling when they are interrupted and just emit one line, "NMI backtrace for N skipped: idling at pc 0xNNN". We do this by grouping all the cpuidle code together into a new .cpuidle.text section, and then checking the address of the interrupted PC to see if it lies within that section. This commit suitably tags x86 and tile idle routines, and only adds in the minimal framework for other architectures. Link: http://lkml.kernel.org/r/1472487169-14923-5-git-send-email-cmetcalf@mellanox.com Signed-off-by: Chris Metcalf Acked-by: Peter Zijlstra (Intel) Tested-by: Peter Zijlstra (Intel) Tested-by: Daniel Thompson [arm] Tested-by: Petr Mladek Cc: Aaron Tomlin Cc: Peter Zijlstra (Intel) Cc: "Rafael J. Wysocki" Cc: Russell King Cc: Thomas Gleixner Cc: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

powerpc: Simplify module TOC handling

2016-01-21T03:10:56Z

PowerPC64 uses the symbol .TOC. much as other targets use _GLOBAL_OFFSET_TABLE_. It identifies the value of the GOT pointer (or in powerpc parlance, the TOC pointer). Global offset tables are generally local to an executable or shared library, or in the kernel, module. Thus it does not make sense for a module to resolve a relocation against .TOC. to the kernel's .TOC. value. A module has its own .TOC., and indeed the powerpc64 module relocation processing ignores the kernel value of .TOC. and instead calculates a module-local value. This patch removes code involved in exporting the kernel .TOC., tweaks modpost to ignore an undefined .TOC., and the module loader to twiddle the section symbol so that .TOC. isn't seen as undefined. Note that if the kernel was compiled with -msingle-pic-base then ELFv2 would not have function global entry code setting up r2. In that case the module call stubs would need to be modified to set up r2 using the kernel .TOC. value, requiring some of this code to be reinstated. mpe: Furthermore a change in binutils master (not yet released) causes the current way we handle the TOC to no longer work when building with MODVERSIONS=y and RELOCATABLE=n. The symptom is that modules can not be loaded due to there being no version found for TOC. Cc: stable@vger.kernel.org # 3.16+ Signed-off-by: Alan Modra Signed-off-by: Michael Ellerman

scripts: [modpost] add new sections to white list

2015-10-26T10:08:43Z

In our ARC toolchain the default linker script includes special sections used for code and data located in special fast memory. To avoid warnings we add these sections i.e. .cmem* and .fmt_slot* to white list. Signed-off-by: Noam Camus Cc: Rusty Russell Cc: Quentin Casasnovas Signed-off-by: Rusty Russell

modpost: Add flag -E for making section mismatches fatal

2015-10-06T00:16:21Z

The section mismatch warning can be easy to miss during the kernel build process. Allow it to be marked as fatal to be easily caught and prevent bugs from slipping in. Setting CONFIG_SECTION_MISMATCH_WARN_ONLY=y causes these warnings to be non-fatal, since there are a number of section mismatches when using allmodconfig on some architectures, and we do not want to break these builds by default. Signed-off-by: Nicolas Boichat Change-Id: Ic346706e3297c9f0d790e3552aa94e5cff9897a6 Signed-off-by: Rusty Russell

modpost: abort if a module symbol is too long

2015-08-08T10:22:08Z

Module symbols have a limited length, but currently the build system allows the build finishing even if the driver code contains a too long symbol name, which eventually overflows the modversion_info[] item. The compiler may catch at compiling *.mod.c like CC xxx.mod.o xxx.mod.c:18:16: warning: initializer-string for array of chars is too long but it's merely a warning. This patch adds the check of the symbol length in modpost and stops the build properly. Currently MODULE_NAME_LEN is defined in modpost.c instead of referring to the definition in kernel header because including linux/module.h is messy and we must cover cross-compilation. Signed-off-by: Takashi Iwai Signed-off-by: Rusty Russell