user/sven/linux.git/kernel/ksysfs.c, branch v6.1.70

kexec: turn all kexec_mutex acquisitions into trylocks

2022-09-12T04:55:06Z

Patch series "kexec, panic: Making crash_kexec() NMI safe", v4. This patch (of 2): Most acquistions of kexec_mutex are done via mutex_trylock() - those were a direct "translation" from: 8c5a1cf0ad3a ("kexec: use a mutex for locking rather than xchg()") there have however been two additions since then that use mutex_lock(): crash_get_memory_size() and crash_shrink_memory(). A later commit will replace said mutex with an atomic variable, and locking operations will become atomic_cmpxchg(). Rather than having those mutex_lock() become while (atomic_cmpxchg(&lock, 0, 1)), turn them into trylocks that can return -EBUSY on acquisition failure. This does halve the printable size of the crash kernel, but that's still neighbouring 2G for 32bit kernels which should be ample enough. Link: https://lkml.kernel.org/r/20220630223258.4144112-1-vschneid@redhat.com Link: https://lkml.kernel.org/r/20220630223258.4144112-2-vschneid@redhat.com Signed-off-by: Valentin Schneider Cc: Arnd Bergmann Cc: "Eric W . Biederman" Cc: Juri Lelli Cc: Luis Claudio R. Goncalves Cc: Miaohe Lin Cc: Petr Mladek Cc: Sebastian Andrzej Siewior Cc: Thomas Gleixner Cc: Baoquan He Signed-off-by: Andrew Morton

kernel/ksysfs.c: use helper macro __ATTR_RW

2022-03-24T02:00:33Z

Use helper macro __ATTR_RW to define kobj_attribute to make code more clear. Minor readability improvement. Link: https://lkml.kernel.org/r/20220222112034.48298-1-linmiaohe@huawei.com Signed-off-by: Miaohe Lin Cc: Greg Kroah-Hartman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 170

2019-05-30T18:26:39Z

Based on 1 normalized pattern(s): this file is release under the gplv2 extracted by the scancode license scanner the SPDX license identifier GPL-2.0-only has been chosen to replace the boilerplate/reference in 1 file(s). Signed-off-by: Thomas Gleixner Reviewed-by: Richard Fontana Reviewed-by: Kate Stewart Reviewed-by: Armijn Hemel Reviewed-by: Allison Randal Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190527070034.216732358@linutronix.de Signed-off-by: Greg Kroah-Hartman

kexec: move vmcoreinfo out of the kernel's .bss section

2017-07-12T23:25:59Z

As Eric said, "what we need to do is move the variable vmcoreinfo_note out of the kernel's .bss section. And modify the code to regenerate and keep this information in something like the control page. Definitely something like this needs a page all to itself, and ideally far away from any other kernel data structures. I clearly was not watching closely the data someone decided to keep this silly thing in the kernel's .bss section." This patch allocates extra pages for these vmcoreinfo_XXX variables, one advantage is that it enhances some safety of vmcoreinfo, because vmcoreinfo now is kept far away from other kernel data structures. Link: http://lkml.kernel.org/r/1493281021-20737-1-git-send-email-xlpang@redhat.com Signed-off-by: Xunlei Pang Tested-by: Michael Holzheu Reviewed-by: Juergen Gross Suggested-by: Eric Biederman Cc: Benjamin Herrenschmidt Cc: Dave Young Cc: Hari Bathini Cc: Mahesh Salgaonkar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

kernel/ksysfs.c: constify attribute_group structures.

2017-07-10T23:32:34Z

attribute_groups are not supposed to change at runtime. All functions working with attribute_groups provided by work with const attribute_group. So mark the non-const structs as const. File size before: text data bss dec hex filename 1120 544 16 1680 690 kernel/ksysfs.o File size After adding 'const': text data bss dec hex filename 1160 480 16 1656 678 kernel/ksysfs.o Link: http://lkml.kernel.org/r/aa224b3cc923fdbb3edd0c41b2c639c85408c9e8.1498737347.git.arvind.yadav.cs@gmail.com Signed-off-by: Arvind Yadav Acked-by: Kees Cook Cc: Russell King Cc: Dave Young Cc: Hari Bathini Cc: Petr Tesarik Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

crash: move crashkernel parsing and vmcore related code under CONFIG_CRASH_CORE

2017-05-09T00:15:11Z

Patch series "kexec/fadump: remove dependency with CONFIG_KEXEC and reuse crashkernel parameter for fadump", v4. Traditionally, kdump is used to save vmcore in case of a crash. Some architectures like powerpc can save vmcore using architecture specific support instead of kexec/kdump mechanism. Such architecture specific support also needs to reserve memory, to be used by dump capture kernel. crashkernel parameter can be a reused, for memory reservation, by such architecture specific infrastructure. This patchset removes dependency with CONFIG_KEXEC for crashkernel parameter and vmcoreinfo related code as it can be reused without kexec support. Also, crashkernel parameter is reused instead of fadump_reserve_mem to reserve memory for fadump. The first patch moves crashkernel parameter parsing and vmcoreinfo related code under CONFIG_CRASH_CORE instead of CONFIG_KEXEC_CORE. The second patch reuses the definitions of append_elf_note() & final_note() functions under CONFIG_CRASH_CORE in IA64 arch code. The third patch removes dependency on CONFIG_KEXEC for firmware-assisted dump (fadump) in powerpc. The next patch reuses crashkernel parameter for reserving memory for fadump, instead of the fadump_reserve_mem parameter. This has the advantage of using all syntaxes crashkernel parameter supports, for fadump as well. The last patch updates fadump kernel documentation about use of crashkernel parameter. This patch (of 5): Traditionally, kdump is used to save vmcore in case of a crash. Some architectures like powerpc can save vmcore using architecture specific support instead of kexec/kdump mechanism. Such architecture specific support also needs to reserve memory, to be used by dump capture kernel. crashkernel parameter can be a reused, for memory reservation, by such architecture specific infrastructure. But currently, code related to vmcoreinfo and parsing of crashkernel parameter is built under CONFIG_KEXEC_CORE. This patch introduces CONFIG_CRASH_CORE and moves the above mentioned code under this config, allowing code reuse without dependency on CONFIG_KEXEC. There is no functional change with this patch. Link: http://lkml.kernel.org/r/149035338104.6881.4550894432615189948.stgit@hbathini.in.ibm.com Signed-off-by: Hari Bathini Acked-by: Dave Young Cc: Fenghua Yu Cc: Tony Luck Cc: Eric Biederman Cc: Mahesh Salgaonkar Cc: Vivek Goyal Cc: Michael Ellerman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

kernel/ksysfs.c: add __ro_after_init to bin_attribute structure

2017-02-25T01:46:56Z

The object notes_attr of type bin_attribute is not modified after getting initailized by ksysfs_init. Apart from initialization in ksysfs_init it is also passed as an argument to the function sysfs_create_bin_file but this argument is of type const. Therefore, add __ro_after_init to its declaration. Link: http://lkml.kernel.org/r/1486839969-16891-1-git-send-email-bhumirks@gmail.com Signed-off-by: Bhumika Goyal Acked-by: Kees Cook Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

kexec: add a kexec_crash_loaded() function

2016-08-02T23:35:30Z

Provide a wrapper function to be used by kernel code to check whether a crash kernel is loaded. It returns the same value that can be seen in /sys/kernel/kexec_crash_loaded by userspace programs. I'm exporting the function, because it will be used by Xen, and it is possible to compile Xen modules separately to enable the use of PV drivers with unmodified bare-metal kernels. Link: http://lkml.kernel.org/r/20160713121955.14969.69080.stgit@hananiah.suse.cz Signed-off-by: Petr Tesarik Cc: Juergen Gross Cc: Josh Triplett Cc: Ingo Molnar Cc: Thomas Gleixner Cc: Eric Biederman Cc: "H. Peter Anvin" Cc: Boris Ostrovsky Cc: "Paul E. McKenney" Cc: Dave Young Cc: David Vrabel Cc: Vivek Goyal Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

kdump: arrange for paddr_vmcoreinfo_note() to return phys_addr_t

2016-08-02T23:35:27Z

On PAE systems (eg, ARM LPAE) the vmcore note may be located above 4GB physical on 32-bit architectures, so we need a wider type than "unsigned long" here. Arrange for paddr_vmcoreinfo_note() to return a phys_addr_t, thereby allowing it to be located above 4GB. This makes no difference for kexec-tools, as they already assume a 64-bit type when reading from this file. Link: http://lkml.kernel.org/r/E1b8koK-0004HS-K9@rmk-PC.armlinux.org.uk Signed-off-by: Russell King Reviewed-by: Pratyush Anand Acked-by: Baoquan He Cc: Keerthy Cc: Vitaly Andrianov Cc: Eric Biederman Cc: Dave Young Cc: Vivek Goyal Cc: Simon Horman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

rcu: Remove TINY_RCU bloat from pointless boot parameters

2015-12-08T00:59:37Z

The rcu_expedited, rcu_normal, and rcu_normal_after_boot kernel boot parameters are pointless in the case of TINY_RCU because in that case synchronous grace periods, both expedited and normal, are no-ops. However, these three symbols contribute several hundred bytes of bloat. This commit therefore uses CPP directives to avoid compiling this code in TINY_RCU kernels. Reported-by: kbuild test robot Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett