kernel/linux.git/init, branch v4.4.269

init/Kconfig: make COMPILE_TEST depend on HAS_IOMEM

2021-04-10T11:01:58+00:00

commit ea29b20a828511de3348334e529a3d046a180416 upstream. I read the commit log of the following two: - bc083a64b6c0 ("init/Kconfig: make COMPILE_TEST depend on !UML") - 334ef6ed06fa ("init/Kconfig: make COMPILE_TEST depend on !S390") Both are talking about HAS_IOMEM dependency missing in many drivers. So, 'depends on HAS_IOMEM' seems the direct, sensible solution to me. This does not change the behavior of UML. UML still cannot enable COMPILE_TEST because it does not provide HAS_IOMEM. The current dependency for S390 is too strong. Under the condition of CONFIG_PCI=y, S390 provides HAS_IOMEM, hence can enable COMPILE_TEST. I also removed the meaningless 'default n'. Link: https://lkml.kernel.org/r/20210224140809.1067582-1-masahiroy@kernel.org Signed-off-by: Masahiro Yamada Cc: Heiko Carstens Cc: Guenter Roeck Cc: Arnd Bergmann Cc: Kees Cook Cc: Daniel Borkmann Cc: Johannes Weiner Cc: KP Singh Cc: Nathan Chancellor Cc: Nick Terrell Cc: Quentin Perret Cc: Valentin Schneider Cc: "Enrico Weigelt, metux IT consult" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Cc: Guenter Roeck Signed-off-by: Greg Kroah-Hartman

init/Kconfig: make COMPILE_TEST depend on !S390

2021-04-10T11:01:58+00:00

commit 334ef6ed06fa1a54e35296b77b693bcf6d63ee9e upstream. While allmodconfig and allyesconfig build for s390 there are also various bots running compile tests with randconfig, where PCI is disabled. This reveals that a lot of drivers should actually depend on HAS_IOMEM. Adding this to each device driver would be a never ending story, therefore just disable COMPILE_TEST for s390. The reasoning is more or less the same as described in commit bc083a64b6c0 ("init/Kconfig: make COMPILE_TEST depend on !UML"). Reported-by: kernel test robot Suggested-by: Arnd Bergmann Signed-off-by: Heiko Carstens Cc: Guenter Roeck Signed-off-by: Greg Kroah-Hartman

init/Kconfig: make COMPILE_TEST depend on !UML

2021-04-10T11:01:58+00:00

commit bc083a64b6c035135c0f80718f9e9192cc0867c6 upstream. UML is a bit special since it does not have iomem nor dma. That means a lot of drivers will not build if they miss a dependency on HAS_IOMEM. s390 used to have the same issues but since it gained PCI support UML is the only stranger. We are tired of patching dozens of new drivers after every merge window just to un-break allmod/yesconfig UML builds. One could argue that a decent driver has to know on what it depends and therefore a missing HAS_IOMEM dependency is a clear driver bug. But the dependency not obvious and not everyone does UML builds with COMPILE_TEST enabled when developing a device driver. A possible solution to make these builds succeed on UML would be providing stub functions for ioremap() and friends which fail upon runtime. Another one is simply disabling COMPILE_TEST for UML. Since it is the least hassle and does not force use to fake iomem support let's do the latter. Link: http://lkml.kernel.org/r/1466152995-28367-1-git-send-email-richard@nod.at Signed-off-by: Richard Weinberger Acked-by: Arnd Bergmann Cc: Al Viro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Cc: Guenter Roeck Signed-off-by: Greg Kroah-Hartman

printk: reduce LOG_BUF_SHIFT range for H8300

2020-11-10T09:22:13+00:00

[ Upstream commit 550c10d28d21bd82a8bb48debbb27e6ed53262f6 ] The .bss section for the h8300 is relatively small. A value of CONFIG_LOG_BUF_SHIFT that is larger than 19 will create a static printk ringbuffer that is too large. Limit the range appropriately for the H8300. Reported-by: kernel test robot Signed-off-by: John Ogness Reviewed-by: Sergey Senozhatsky Acked-by: Steven Rostedt (VMware) Signed-off-by: Petr Mladek Link: https://lore.kernel.org/r/20200812073122.25412-1-john.ogness@linutronix.de Signed-off-by: Sasha Levin

x86: Fix early boot crash on gcc-10, third try

2020-05-20T06:11:54+00:00

commit a9a3ed1eff3601b63aea4fb462d8b3b92c7c1e7e upstream. ... or the odyssey of trying to disable the stack protector for the function which generates the stack canary value. The whole story started with Sergei reporting a boot crash with a kernel built with gcc-10: Kernel panic — not syncing: stack-protector: Kernel stack is corrupted in: start_secondary CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.6.0-rc5—00235—gfffb08b37df9 #139 Hardware name: Gigabyte Technology Co., Ltd. To be filled by O.E.M./H77M—D3H, BIOS F12 11/14/2013 Call Trace: dump_stack panic ? start_secondary __stack_chk_fail start_secondary secondary_startup_64 -—-[ end Kernel panic — not syncing: stack—protector: Kernel stack is corrupted in: start_secondary This happens because gcc-10 tail-call optimizes the last function call in start_secondary() - cpu_startup_entry() - and thus emits a stack canary check which fails because the canary value changes after the boot_init_stack_canary() call. To fix that, the initial attempt was to mark the one function which generates the stack canary with: __attribute__((optimize("-fno-stack-protector"))) ... start_secondary(void *unused) however, using the optimize attribute doesn't work cumulatively as the attribute does not add to but rather replaces previously supplied optimization options - roughly all -fxxx options. The key one among them being -fno-omit-frame-pointer and thus leading to not present frame pointer - frame pointer which the kernel needs. The next attempt to prevent compilers from tail-call optimizing the last function call cpu_startup_entry(), shy of carving out start_secondary() into a separate compilation unit and building it with -fno-stack-protector, was to add an empty asm(""). This current solution was short and sweet, and reportedly, is supported by both compilers but we didn't get very far this time: future (LTO?) optimization passes could potentially eliminate this, which leads us to the third attempt: having an actual memory barrier there which the compiler cannot ignore or move around etc. That should hold for a long time, but hey we said that about the other two solutions too so... Reported-by: Sergei Trofimovich Signed-off-by: Borislav Petkov Tested-by: Kalle Valo Cc: Link: https://lkml.kernel.org/r/20200314164451.346497-1-slyfox@gentoo.org Signed-off-by: Greg Kroah-Hartman

Stop the ad-hoc games with -Wno-maybe-initialized

2020-05-20T06:11:49+00:00

commit 78a5255ffb6a1af189a83e493d916ba1c54d8c75 upstream. We have some rather random rules about when we accept the "maybe-initialized" warnings, and when we don't. For example, we consider it unreliable for gcc versions < 4.9, but also if -O3 is enabled, or if optimizing for size. And then various kernel config options disabled it, because they know that they trigger that warning by confusing gcc sufficiently (ie PROFILE_ALL_BRANCHES). And now gcc-10 seems to be introducing a lot of those warnings too, so it falls under the same heading as 4.9 did. At the same time, we have a very straightforward way to _enable_ that warning when wanted: use "W=2" to enable more warnings. So stop playing these ad-hoc games, and just disable that warning by default, with the known and straight-forward "if you want to work on the extra compiler warnings, use W=123". Would it be great to have code that is always so obvious that it never confuses the compiler whether a variable is used initialized or not? Yes, it would. In a perfect world, the compilers would be smarter, and our source code would be simpler. That's currently not the world we live in, though. Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

kbuild: compute false-positive -Wmaybe-uninitialized cases in Kconfig

2020-05-20T06:11:49+00:00

commit b303c6df80c9f8f13785aa83a0471fca7e38b24d upstream. Since -Wmaybe-uninitialized was introduced by GCC 4.7, we have patched various false positives: - commit e74fc973b6e5 ("Turn off -Wmaybe-uninitialized when building with -Os") turned off this option for -Os. - commit 815eb71e7149 ("Kbuild: disable 'maybe-uninitialized' warning for CONFIG_PROFILE_ALL_BRANCHES") turned off this option for CONFIG_PROFILE_ALL_BRANCHES - commit a76bcf557ef4 ("Kbuild: enable -Wmaybe-uninitialized warning for "make W=1"") turned off this option for GCC < 4.9 Arnd provided more explanation in https://lkml.org/lkml/2017/3/14/903 I think this looks better by shifting the logic from Makefile to Kconfig. Link: https://github.com/ClangBuiltLinux/linux/issues/350 Signed-off-by: Masahiro Yamada Reviewed-by: Nathan Chancellor Tested-by: Nick Desaulniers Signed-off-by: Greg Kroah-Hartman

sched/core: Add try_get_task_stack() and put_task_stack()

2019-12-21T09:35:04+00:00

commit c6c314a613cd7d03fb97713e0d642b493de42e69 upstream. There are a few places in the kernel that access stack memory belonging to a different task. Before we can start freeing task stacks before the task_struct is freed, we need a way for those code paths to pin the stack. Signed-off-by: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Jann Horn Cc: Josh Poimboeuf Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/17a434f50ad3d77000104f21666575e10a9c1fbd.1474003868.git.luto@kernel.org Signed-off-by: Ingo Molnar Signed-off-by: zhangyi (F) Signed-off-by: Greg Kroah-Hartman

sched/core: Allow putting thread_info into task_struct

2019-12-21T09:35:04+00:00

commit c65eacbe290b8141554c71b2c94489e73ade8c8d upstream. If an arch opts in by setting CONFIG_THREAD_INFO_IN_TASK_STRUCT, then thread_info is defined as a single 'u32 flags' and is the first entry of task_struct. thread_info::task is removed (it serves no purpose if thread_info is embedded in task_struct), and thread_info::cpu gets its own slot in task_struct. This is heavily based on a patch written by Linus. Originally-from: Linus Torvalds Signed-off-by: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Jann Horn Cc: Josh Poimboeuf Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/a0898196f0476195ca02713691a5037a14f2aac5.1473801993.git.luto@kernel.org Signed-off-by: Ingo Molnar Signed-off-by: zhangyi (F) Signed-off-by: Greg Kroah-Hartman

init: initialize jump labels before command line option parsing

2019-05-16T17:45:06+00:00

[ Upstream commit 6041186a32585fc7a1d0f6cfe2f138b05fdc3c82 ] When a module option, or core kernel argument, toggles a static-key it requires jump labels to be initialized early. While x86, PowerPC, and ARM64 arrange for jump_label_init() to be called before parse_args(), ARM does not. Kernel command line: rdinit=/sbin/init page_alloc.shuffle=1 panic=-1 console=ttyAMA0,115200 page_alloc.shuffle=1 ------------[ cut here ]------------ WARNING: CPU: 0 PID: 0 at ./include/linux/jump_label.h:303 page_alloc_shuffle+0x12c/0x1ac static_key_enable(): static key 'page_alloc_shuffle_key+0x0/0x4' used before call to jump_label_init() Modules linked in: CPU: 0 PID: 0 Comm: swapper Not tainted 5.1.0-rc4-next-20190410-00003-g3367c36ce744 #1 Hardware name: ARM Integrator/CP (Device Tree) [] (unwind_backtrace) from [] (show_stack+0x10/0x18) [] (show_stack) from [] (dump_stack+0x18/0x24) [] (dump_stack) from [] (__warn+0xe0/0x108) [] (__warn) from [] (warn_slowpath_fmt+0x44/0x6c) [] (warn_slowpath_fmt) from [] (page_alloc_shuffle+0x12c/0x1ac) [] (page_alloc_shuffle) from [] (shuffle_store+0x28/0x48) [] (shuffle_store) from [] (parse_args+0x1f4/0x350) [] (parse_args) from [] (start_kernel+0x1c0/0x488) Move the fallback call to jump_label_init() to occur before parse_args(). The redundant calls to jump_label_init() in other archs are left intact in case they have static key toggling use cases that are even earlier than option parsing. Link: http://lkml.kernel.org/r/155544804466.1032396.13418949511615676665.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Dan Williams Reported-by: Guenter Roeck Reviewed-by: Kees Cook Cc: Mathieu Desnoyers Cc: Thomas Gleixner Cc: Mike Rapoport Cc: Russell King Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin