user/sven/linux.git/init/main.c, branch v4.4.265

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

2020-05-20T06:11:54Z

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

init: initialize jump labels before command line option parsing

2019-05-16T17:45:06Z

[ 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

kaiser: stack map PAGE_SIZE at THREAD_SIZE-PAGE_SIZE

2018-01-05T14:44:23Z

Kaiser only needs to map one page of the stack; and kernel/fork.c did not build on powerpc (no __PAGE_KERNEL). It's all cleaner if linux/kaiser.h provides kaiser_map_thread_stack() and kaiser_unmap_thread_stack() wrappers around asm/kaiser.h's kaiser_add_mapping() and kaiser_remove_mapping(). And use linux/kaiser.h in init/main.c to avoid the #ifdefs there. Signed-off-by: Hugh Dickins Acked-by: Jiri Kosina Signed-off-by: Greg Kroah-Hartman

KAISER: Kernel Address Isolation

2018-01-05T14:44:23Z

This patch introduces our implementation of KAISER (Kernel Address Isolation to have Side-channels Efficiently Removed), a kernel isolation technique to close hardware side channels on kernel address information. More information about the patch can be found on: https://github.com/IAIK/KAISER From: Richard Fellner From: Daniel Gruss X-Subject: [RFC, PATCH] x86_64: KAISER - do not map kernel in user mode Date: Thu, 4 May 2017 14:26:50 +0200 Link: http://marc.info/?l=linux-kernel&m=149390087310405&w=2 Kaiser-4.10-SHA1: c4b1831d44c6144d3762ccc72f0c4e71a0c713e5 To: To: Cc: Cc: Cc: Michael Schwarz Cc: Richard Fellner Cc: Ingo Molnar Cc: Cc: After several recent works [1,2,3] KASLR on x86_64 was basically considered dead by many researchers. We have been working on an efficient but effective fix for this problem and found that not mapping the kernel space when running in user mode is the solution to this problem [4] (the corresponding paper [5] will be presented at ESSoS17). With this RFC patch we allow anybody to configure their kernel with the flag CONFIG_KAISER to add our defense mechanism. If there are any questions we would love to answer them. We also appreciate any comments! Cheers, Daniel (+ the KAISER team from Graz University of Technology) [1] http://www.ieee-security.org/TC/SP2013/papers/4977a191.pdf [2] https://www.blackhat.com/docs/us-16/materials/us-16-Fogh-Using-Undocumented-CPU-Behaviour-To-See-Into-Kernel-Mode-And-Break-KASLR-In-The-Process.pdf [3] https://www.blackhat.com/docs/us-16/materials/us-16-Jang-Breaking-Kernel-Address-Space-Layout-Randomization-KASLR-With-Intel-TSX.pdf [4] https://github.com/IAIK/KAISER [5] https://gruss.cc/files/kaiser.pdf [patch based also on https://raw.githubusercontent.com/IAIK/KAISER/master/KAISER/0001-KAISER-Kernel-Address-Isolation.patch] Signed-off-by: Richard Fellner Signed-off-by: Moritz Lipp Signed-off-by: Daniel Gruss Signed-off-by: Michael Schwarz Acked-by: Jiri Kosina Signed-off-by: Hugh Dickins Signed-off-by: Greg Kroah-Hartman

kmod: use system_unbound_wq instead of khelper

2015-09-10T20:29:01Z

We need to launch the usermodehelper kernel threads with the widest affinity and this is partly why we use khelper. This workqueue has unbound properties and thus a wide affinity inherited by all its children. Now khelper also has special properties that we aren't much interested in: ordered and singlethread. There is really no need about ordering as all we do is creating kernel threads. This can be done concurrently. And singlethread is a useless limitation as well. The workqueue engine already proposes generic unbound workqueues that don't share these useless properties and handle well parallel jobs. The only worrysome specific is their affinity to the node of the current CPU. It's fine for creating the usermodehelper kernel threads but those inherit this affinity for longer jobs such as requesting modules. This patch proposes to use these node affine unbound workqueues assuming that a node is sufficient to handle several parallel usermodehelper requests. Signed-off-by: Frederic Weisbecker Cc: Rik van Riel Reviewed-by: Oleg Nesterov Cc: Christoph Lameter Cc: Tejun Heo Cc: Rusty Russell Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

fs, file table: reinit files_stat.max_files after deferred memory initialisation

2015-08-07T01:39:40Z

Dave Hansen reported the following; My laptop has been behaving strangely with 4.2-rc2. Once I log in to my X session, I start getting all kinds of strange errors from applications and see this in my dmesg: VFS: file-max limit 8192 reached The problem is that the file-max is calculated before memory is fully initialised and miscalculates how much memory the kernel is using. This patch recalculates file-max after deferred memory initialisation. Note that using memory hotplug infrastructure would not have avoided this problem as the value is not recalculated after memory hot-add. 4.1: files_stat.max_files = 6582781 4.2-rc2: files_stat.max_files = 8192 4.2-rc2 patched: files_stat.max_files = 6562467 Small differences with the patch applied and 4.1 but not enough to matter. Signed-off-by: Mel Gorman Reported-by: Dave Hansen Cc: Nicolai Stange Cc: Dave Hansen Cc: Alex Ng Cc: Fengguang Wu Cc: Peter Zijlstra (Intel) Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: meminit: finish initialisation of struct pages before basic setup

2015-07-01T02:44:56Z

Waiman Long reported that 24TB machines hit OOM during basic setup when struct page initialisation was deferred. One approach is to initialise memory on demand but it interferes with page allocator paths. This patch creates dedicated threads to initialise memory before basic setup. It then blocks on a rw_semaphore until completion as a wait_queue and counter is overkill. This may be slower to boot but it's simplier overall and also gets rid of a section mangling which existed so kswapd could do the initialisation. [akpm@linux-foundation.org: include rwsem.h, use DECLARE_RWSEM, fix comment, remove unneeded cast] Signed-off-by: Mel Gorman Cc: Waiman Long Cc: Dave Hansen Cc: Scott Norton Tested-by: Daniel J Blueman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Merge tag 'driver-core-4.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

2015-06-26T22:07:37Z

Pull driver core updates from Greg KH: "Here is the driver core / firmware changes for 4.2-rc1. A number of small changes all over the place in the driver core, and in the firmware subsystem. Nothing really major, full details in the shortlog. Some of it is a bit of churn, given that the platform driver probing changes was found to not work well, so they were reverted. All of these have been in linux-next for a while with no reported issues" * tag 'driver-core-4.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (31 commits) Revert "base/platform: Only insert MEM and IO resources" Revert "base/platform: Continue on insert_resource() error" Revert "of/platform: Use platform_device interface" Revert "base/platform: Remove code duplication" firmware: add missing kfree for work on async call fs: sysfs: don't pass count == 0 to bin file readers base:dd - Fix for typo in comment to function driver_deferred_probe_trigger(). base/platform: Remove code duplication of/platform: Use platform_device interface base/platform: Continue on insert_resource() error base/platform: Only insert MEM and IO resources firmware: use const for remaining firmware names firmware: fix possible use after free on name on asynchronous request firmware: check for file truncation on direct firmware loading firmware: fix __getname() missing failure check drivers: of/base: move of_init to driver_init drivers/base: cacheinfo: fix annoying typo when DT nodes are absent sysfs: disambiguate between "error code" and "failure" in comments driver-core: fix build for !CONFIG_MODULES driver-core: make __device_attach() static ...

ACPI / init: Switch over platform to the ACPI mode later

2015-06-10T21:51:27Z

Commit 73f7d1ca3263 "ACPI / init: Run acpi_early_init() before timekeeping_init()" moved the ACPI subsystem initialization, including the ACPI mode enabling, to an earlier point in the initialization sequence, to allow the timekeeping subsystem use ACPI early. Unfortunately, that resulted in boot regressions on some systems and the early ACPI initialization was moved toward its original position in the kernel initialization code by commit c4e1acbb35e4 "ACPI / init: Invoke early ACPI initialization later". However, that turns out to be insufficient, as boot is still broken on the Tyan S8812 mainboard. To fix that issue, split the ACPI early initialization code into two pieces so the majority of it still located in acpi_early_init() and the part switching over the platform into the ACPI mode goes into a new function, acpi_subsystem_init(), executed at the original early ACPI initialization spot. That fixes the Tyan S8812 boot problem, but still allows ACPI tables to be loaded earlier which is useful to the EFI code in efi_enter_virtual_mode(). Link: https://bugzilla.kernel.org/show_bug.cgi?id=97141 Fixes: 73f7d1ca3263 "ACPI / init: Run acpi_early_init() before timekeeping_init()" Reported-and-tested-by: Marius Tolzmann Signed-off-by: Rafael J. Wysocki Acked-by: Toshi Kani Reviewed-by: Hanjun Guo Reviewed-by: Lee, Chun-Yi

module: add extra argument for parse_params() callback

2015-05-20T07:25:24Z

This adds an extra argument onto parse_params() to be used as a way to make the unused callback a bit more useful and generic by allowing the caller to pass on a data structure of its choice. An example use case is to allow us to easily make module parameters for every module which we will do next. @ parse @ identifier name, args, params, num, level_min, level_max; identifier unknown, param, val, doing; type s16; @@ extern char *parse_args(const char *name, char *args, const struct kernel_param *params, unsigned num, s16 level_min, s16 level_max, + void *arg, int (*unknown)(char *param, char *val, const char *doing + , void *arg )); @ parse_mod @ identifier name, args, params, num, level_min, level_max; identifier unknown, param, val, doing; type s16; @@ char *parse_args(const char *name, char *args, const struct kernel_param *params, unsigned num, s16 level_min, s16 level_max, + void *arg, int (*unknown)(char *param, char *val, const char *doing + , void *arg )) { ... } @ parse_args_found @ expression R, E1, E2, E3, E4, E5, E6; identifier func; @@ ( R = parse_args(E1, E2, E3, E4, E5, E6, + NULL, func); | R = parse_args(E1, E2, E3, E4, E5, E6, + NULL, &func); | R = parse_args(E1, E2, E3, E4, E5, E6, + NULL, NULL); | parse_args(E1, E2, E3, E4, E5, E6, + NULL, func); | parse_args(E1, E2, E3, E4, E5, E6, + NULL, &func); | parse_args(E1, E2, E3, E4, E5, E6, + NULL, NULL); ) @ parse_args_unused depends on parse_args_found @ identifier parse_args_found.func; @@ int func(char *param, char *val, const char *unused + , void *arg ) { ... } @ mod_unused depends on parse_args_found @ identifier parse_args_found.func; expression A1, A2, A3; @@ - func(A1, A2, A3); + func(A1, A2, A3, NULL); Generated-by: Coccinelle SmPL Cc: cocci@systeme.lip6.fr Cc: Tejun Heo Cc: Arjan van de Ven Cc: Greg Kroah-Hartman Cc: Rusty Russell Cc: Christoph Hellwig Cc: Felipe Contreras Cc: Ewan Milne Cc: Jean Delvare Cc: Hannes Reinecke Cc: Jani Nikula Cc: linux-kernel@vger.kernel.org Reviewed-by: Tejun Heo Acked-by: Rusty Russell Signed-off-by: Luis R. Rodriguez Signed-off-by: Greg Kroah-Hartman