- May 21, 2016
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Jiri Slaby authored
We need to call exit_thread from copy_process in a fail path. So make it accept task_struct as a parameter. [v2] * s390: exit_thread_runtime_instr doesn't make sense to be called for non-current tasks. * arm: fix the comment in vfp_thread_copy * change 'me' to 'tsk' for task_struct * now we can change only archs that actually have exit_thread [akpm@linux-foundation.org: coding-style fixes] Signed-off-by:
Jiri Slaby <jslaby@suse.cz> Cc: "David S. Miller" <davem@davemloft.net> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: "James E.J. Bottomley" <jejb@parisc-linux.org> Cc: Aurelien Jacquiot <a-jacquiot@ti.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chen Liqin <liqin.linux@gmail.com> Cc: Chris Metcalf <cmetcalf@mellanox.com> Cc: Chris Zankel <chris@zankel.net> Cc: David Howells <dhowells@redhat.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Guan Xuetao <gxt@mprc.pku.edu.cn> Cc: Haavard Skinnemoen <hskinnemoen@gmail.com> Cc: Hans-Christian Egtvedt <egtvedt@samfundet.no> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Helge Deller <deller@gmx.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: James Hogan <james.hogan@imgtec.com> Cc: Jeff Dike <jdike@addtoit.com> Cc: Jesper Nilsson <jesper.nilsson@axis.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Jonas Bonn <jonas@southpole.se> Cc: Koichi Yasutake <yasutake.koichi@jp.panasonic.com> Cc: Lennox Wu <lennox.wu@gmail.com> Cc: Ley Foon Tan <lftan@altera.com> Cc: Mark Salter <msalter@redhat.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Matt Turner <mattst88@gmail.com> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Michal Simek <monstr@monstr.eu> Cc: Mikael Starvik <starvik@axis.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Rich Felker <dalias@libc.org> Cc: Richard Henderson <rth@twiddle.net> Cc: Richard Kuo <rkuo@codeaurora.org> Cc: Richard Weinberger <richard@nod.at> Cc: Russell King <linux@arm.linux.org.uk> Cc: Steven Miao <realmz6@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Tony Luck <tony.luck@intel.com> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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- Mar 10, 2016
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Andy Lutomirski authored
The first instruction of the SYSENTER entry runs on its own tiny stack. That stack can be used if a #DB or NMI is delivered before the SYSENTER prologue switches to a real stack. We have code in place to prevent us from overflowing the tiny stack. For added paranoia, add a canary to the stack and check it in do_debug() -- that way, if something goes wrong with the #DB logic, we'll eventually notice. Signed-off-by:
Andy Lutomirski <luto@kernel.org> Cc: Andrew Cooper <andrew.cooper3@citrix.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/6ff9a806f39098b166dc2c41c1db744df5272f29.1457578375.git.luto@kernel.org Signed-off-by:
Ingo Molnar <mingo@kernel.org>
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- Jan 29, 2016
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Michael S. Tsirkin authored
The following commit: f8e617f4 ("sched/idle/x86: Optimize unnecessary mwait_idle() resched IPIs") adds memory barriers around clflush(), but this seems wrong for UP since barrier() has no effect on clflush(). We really want MFENCE, so switch to mb() instead. Signed-off-by:
Michael S. Tsirkin <mst@redhat.com> Acked-by:
Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Davidlohr Bueso <dbueso@suse.de> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Len Brown <len.brown@intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <bitbucket@online.de> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: virtualization <virtualization@lists.linux-foundation.org> Link: http://lkml.kernel.org/r/1453921746-16178-5-git-send-email-mst@redhat.com Signed-off-by:
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- Oct 31, 2015
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Andy Lutomirski authored
thread.vm86 points to per-task information -- the pointer should not be copied on clone. Fixes: d4ce0f26 ("x86/vm86: Move fields from 'struct kernel_vm86_struct' to 'struct vm86'") Signed-off-by:
Thomas Gleixner <tglx@linutronix.de>
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- Oct 20, 2015
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Andrey Ryabinin authored
get_wchan() is racy by design, it may access volatile stack of running task, thus it may access redzone in a stack frame and cause KASAN to warn about this. Use READ_ONCE_NOCHECK() to silence these warnings. Reported-by:
Sasha Levin <sasha.levin@oracle.com> Signed-off-by:
Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Alexander Potapenko <glider@google.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andrey Konovalov <andreyknvl@google.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Kostya Serebryany <kcc@google.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wolfram Gloger <wmglo@dent.med.uni-muenchen.de> Cc: kasan-dev <kasan-dev@googlegroups.com> Link: http://lkml.kernel.org/r/1445243838-17763-3-git-send-email-aryabinin@virtuozzo.com Signed-off-by:
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- Sep 30, 2015
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Thomas Gleixner authored
The stack layout and the functionality is identical. Use the 64bit version for all of x86. Signed-off-by:
Borislav Petkov <bp@alien8.de> Reviewed-by:
Dmitry Vyukov <dvyukov@google.com> Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Andrey Konovalov <andreyknvl@google.com> Cc: Kostya Serebryany <kcc@google.com> Cc: Alexander Potapenko <glider@google.com> Cc: kasan-dev <kasan-dev@googlegroups.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Sasha Levin <sasha.levin@oracle.com> Cc: Wolfram Gloger <wmglo@dent.med.uni-muenchen.de> Link: http://lkml.kernel.org/r/20150930083302.779694618@linutronix.de Signed-off-by:
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- Aug 20, 2015
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Jisheng Zhang authored
Commit b253149b ("sched/idle/x86: Restore mwait_idle() to fix boot hangs, to improve power savings and to improve performance") restores mwait_idle(), but the trace_cpu_idle related calls are missing. This causes powertop on my old desktop powered by Intel Core2 E6550 to report zero wakeups and zero events. Add them back to restore the proper behaviour. Fixes: b253149b ("sched/idle/x86: Restore mwait_idle() to ...") Signed-off-by:
Jisheng Zhang <jszhang@marvell.com> Cc: <len.brown@intel.com> Cc: stable@vger.kernel.org # 4.1 Link: http://lkml.kernel.org/r/1440046479-4262-1-git-send-email-jszhang@marvell.com Signed-off-by:
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- Aug 13, 2015
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Ashok Raj authored
kexec could boot a kernel that could be legacy with no knowledge of LMCE. Hence we should make sure we clear LMCE optin before kexec reboot. Signed-off-by:
Ashok Raj <ashok.raj@intel.com> Signed-off-by:
Borislav Petkov <bp@suse.de> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Aravind Gopalakrishnan <Aravind.Gopalakrishnan@amd.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Tony Luck <tony.luck@intel.com> Cc: linux-edac <linux-edac@vger.kernel.org> Link: http://lkml.kernel.org/r/1439396985-12812-9-git-send-email-bp@alien8.de Signed-off-by:
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- Jul 31, 2015
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Brian Gerst authored
Allocate a separate structure for the vm86 fields. Signed-off-by:
Brian Gerst <brgerst@gmail.com> Acked-by:
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- Jul 18, 2015
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Ingo Molnar authored
Don't burden architectures without dynamic task_struct sizing with the overhead of dynamic sizing. Also optimize the x86 code a bit by caching task_struct_size. Acked-and-Tested-by:
Dave Hansen <dave.hansen@linux.intel.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Dave Hansen <dave@sr71.net> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1437128892-9831-3-git-send-email-mingo@kernel.org Signed-off-by:
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Dave Hansen authored
The FPU rewrite removed the dynamic allocations of 'struct fpu'. But, this potentially wastes massive amounts of memory (2k per task on systems that do not have AVX-512 for instance). Instead of having a separate slab, this patch just appends the space that we need to the 'task_struct' which we dynamically allocate already. This saves from doing an extra slab allocation at fork(). The only real downside here is that we have to stick everything and the end of the task_struct. But, I think the BUILD_BUG_ON()s I stuck in there should keep that from being too fragile. Signed-off-by:
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- May 27, 2015
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Huang Rui authored
A single "default" is fine. Signed-off-by:
Huang Rui <ray.huang@amd.com> [ Fix another typo and reflow comment. ] Signed-off-by:
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- May 19, 2015
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Ingo Molnar authored
Do it like all other high level FPU state handling functions: they only know about struct fpu, not about the task. (Also remove a dead prototype while at it.) Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: -
Ingo Molnar authored
drop_fpu() and fpu_reset_state() are similar in functionality and in scope, yet this is not apparent from their names. drop_fpu() deactivates FPU contents (both the fpregs and the fpstate), but leaves register contents intact in the eager-FPU case, mostly as an optimization. It disables fpregs in the lazy FPU case. The drop_fpu() method can be used to destroy FPU state in an optimized way, when we know that a new state will be loaded before user-space might see any remains of the old FPU state: - such as in sys_exit()'s exit_thread() where we know this task won't execute any user-space instructions anymore and the next context switch cleans up the FPU. The old FPU state might still be around in the eagerfpu case but won't be saved. - in __restore_xstate_sig(), where we use drop_fpu() before copying a new state into the fpstate and activating that one. No user-pace instructions can execute between those steps. - in sys_execve()'s fpu__clear(): there we use drop_fpu() in the !eagerfpu case, where it's equivalent to a full reinit. fpu_reset_state() is a stronger version of drop_fpu(): both in the eagerfpu and the lazy-FPU case it guarantees that fpregs are reinitialized to init state. This method is used in cases where we need a full reset: - handle_signal() uses fpu_reset_state() to reset the FPU state to init before executing a user-space signal handler. While we have already saved the original FPU state at this point, and always restore the original state, the signal handling code still has to do this reinit, because signals may interrupt any user-space instruction, and the FPU might be in various intermediate states (such as an unbalanced x87 stack) that is not immediately usable for general C signal handler code. - __restore_xstate_sig() uses fpu_reset_state() when the signal frame has no FP context. Since the signal handler may have modified the FPU state, it gets reset back to init state. - in another branch __restore_xstate_sig() uses fpu_reset_state() to handle a restoration error: when restore_user_xstate() fails to restore FPU state and we might have inconsistent FPU data, fpu_reset_state() is used to reset it back to a known good state. - __kernel_fpu_end() uses fpu_reset_state() in an error branch. This is in a 'must not trigger' error branch, so on bug-free kernels this never triggers. - fpu__restore() uses fpu_reset_state() in an error path as well: if the fpstate was set up with invalid FPU state (via ptrace or via a signal handler), then it's reset back to init state. - likewise, the scheduler's switch_fpu_finish() uses it in a restoration error path too. Move both drop_fpu() and fpu_reset_state() to the fpu__*() namespace and harmonize their naming with their function: fpu__drop() fpu__reset() This clearly shows that both methods operate on the full state of the FPU, just like fpu__restore(). Also add comments to explain what each function does. Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: -
Ingo Molnar authored
Now that we always allocate the FPU context as part of task_struct there's no need for separate allocations - remove them and their primary failure handling code. ( Note that there's still secondary error codes that have become superfluous, those will be removed in separate patches. ) Move the somewhat misplaced setup_xstate_comp() call to the core. Reviewed-by:
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Ingo Molnar authored
This unifies all the FPU related header files under a unified, hiearchical naming scheme: - asm/fpu/types.h: FPU related data types, needed for 'struct task_struct', widely included in almost all kernel code, and hence kept as small as possible. - asm/fpu/api.h: FPU related 'public' methods exported to other subsystems. - asm/fpu/internal.h: FPU subsystem internal methods - asm/fpu/xsave.h: XSAVE support internal methods (Also standardize the header guard in asm/fpu/internal.h.) Reviewed-by: -
Ingo Molnar authored
The primary purpose of this function is to clear the current task's FPU before an exec(), to not leak information from the previous task, and to allow the new task to start with freshly initialized FPU registers. Rename the function to reflect this primary purpose. Reviewed-by:
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Ingo Molnar authored
Migrate this function to pure 'struct fpu' usage. Reviewed-by:
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Ingo Molnar authored
Migrate this function to pure 'struct fpu' usage. Reviewed-by:
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Ingo Molnar authored
Introduce fpu__copy() and use it in arch_dup_task_struct(), thus moving another chunk of FPU logic to fpu/core.c. Reviewed-by:
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Ingo Molnar authored
This code was historically in process.c, now we have FPU core internals in fpu/core.c instead - move it there. Reviewed-by:
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Ingo Molnar authored
flush_thread() open codes a lot of FPU internals - create a separate function for it in fpu/core.c. Turns out that this does not hurt performance: text data bss dec hex filename 11843039 1884440 1130496 14857975 e2b6f7 vmlinux.before 11843039 1884440 1130496 14857975 e2b6f7 vmlinux.after and since this is a slowpath clarity comes first anyway. We can reconsider inlining decisions after the FPU code has been cleaned up. Reviewed-by:
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Ingo Molnar authored
Use fpstate_free() directly to manage FPU state. Only process.c was using this method, so this is a speedup as well, as it removes the extra function call and related clobbers. Reviewed-by:
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Ingo Molnar authored
Fix a minor header file dependency bug in asm/fpu-internal.h: it relies on i387.h but does not include it. All users of fpu-internal.h included it explicitly. Also remove unnecessary includes, to reduce compilation time. This also makes it easier to use it as a standalone header file for FPU internals, such as an upcoming C module in arch/x86/kernel/fpu/. Reviewed-by:
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Ingo Molnar authored
This field is kept separate from the main FPU state structure for no good reason. Reviewed-by:
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Ingo Molnar authored
Use the fpu__*() namespace. Reviewed-by:
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Ingo Molnar authored
Use the fpu__*() namespace for fpstate_alloc() as well. Also add a comment about FPU state alignment. Reviewed-by:
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Ingo Molnar authored
Most init_fpu() users don't want the register-saving aspect of the function, they are calling it for 'current' and when FPU registers are not allocated and initialized yet. Split out a simplified API that does just that (and add debug-checks for these conditions): fpstate_alloc_init(). Use it where appropriate. Reviewed-by:
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- May 06, 2015
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Bobby Powers authored
The following commit: f893959b ("x86/fpu: Don't abuse drop_init_fpu() in flush_thread()") removed drop_init_fpu() usage from flush_thread(). This seems to break things for me - the Go 1.4 test suite fails all over the place with floating point comparision errors (offending commit found through bisection). The functional change was that flush_thread() after this commit only calls restore_init_xstate() when both use_eager_fpu() and !used_math() are true. drop_init_fpu() (now fpu_reset_state()) calls restore_init_xstate() regardless of whether current used_math() - apply the same logic here. Switch used_math() -> tsk_used_math(tsk) to consistently use the grabbed tsk instead of current, like in the rest of flush_thread(). Tested-by:
Dave Hansen <dave.hansen@intel.com> Signed-off-by:
Bobby Powers <bobbypowers@gmail.com> Signed-off-by:
Oleg Nesterov <oleg@redhat.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Pekka Riikonen <priikone@iki.fi> Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com> Cc: Rik van Riel <riel@redhat.com> Cc: Suresh Siddha <sbsiddha@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes: f893959b ("x86/fpu: Don't abuse drop_init_fpu() in flush_thread()") Link: http://lkml.kernel.org/r/1430147441-9820-1-git-send-email-bobbypowers@gmail.com Signed-off-by:
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- May 05, 2015
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Marc Dionne authored
Commit 75182b16 ("x86/asm/entry: Switch all C consumers of kernel_stack to this_cpu_sp0()") changed current_thread_info to use this_cpu_sp0, and indirectly made it rely on init_tss which was exported with EXPORT_PER_CPU_SYMBOL_GPL. As a result some macros and inline functions such as set/get_fs, test_thread_flag and variants have been made unusable for external modules. Make cpu_tss exported with EXPORT_PER_CPU_SYMBOL so that these functions are accessible again, as they were previously. Signed-off-by:
Marc Dionne <marc.dionne@your-file-system.com> Acked-by:
Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/1430763404-21221-1-git-send-email-marc.dionne@your-file-system.com Signed-off-by:
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- Apr 03, 2015
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Thomas Gleixner authored
Replace the clockevents_notify() call with an explicit function call. Signed-off-by:
Rafael J. Wysocki <rafael.j.wysocki@intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/8569669.lgxIty9PKW@vostro.rjw.lan Signed-off-by:
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Thomas Gleixner authored
Replace the clockevents_notify() call with an explicit function call. Signed-off-by:
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- Mar 23, 2015
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Oleg Nesterov authored
flush_thread() -> drop_init_fpu() is suboptimal and confusing. It does drop_fpu() or restore_init_xstate() depending on !use_eager_fpu(). But flush_thread() too checks eagerfpu right after that, and if it is true then restore_init_xstate() just burns CPU for no reason. We are going to load init_xstate_buf again after we set used_math()/user_has_fpu(), until then the FPU state can't survive after switch_to(). Remove it, and change the "if (!use_eager_fpu())" to call drop_fpu(). While at it, clean up the tsk/current usage. Signed-off-by:
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Oleg Nesterov authored
Change flush_thread() to do user_fpu_begin() and restore_init_xstate() instead of math_state_restore(). Note: "TODO: cleanup this horror" is still valid. We do not need init_fpu() at all, we only need fpu_alloc() and memset(0). But this needs other changes, in particular user_fpu_begin() should set used_math(). Signed-off-by:
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- Mar 17, 2015
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Andy Lutomirski authored
x86_32 and x86_64 need slightly different thread_struct::sp0 values, and x86_32's was incorrect for init. This never mattered -- the init thread never runs user code, so we never used thread_struct::sp0 for anything. Fix it and mostly unify them. Signed-off-by:
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- Mar 16, 2015
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Mike Galbraith authored
To fully take advantage of MWAIT, apparently the CLFLUSH instruction needs another quirk on certain CPUs: proper barriers around it on certain machines. On a Q6600 SMP system, pipe-test scheduling performance, cross core, improves significantly: 3.8.13 487.2 KHz 1.000 3.13.0-master 415.5 KHz .852 3.13.0-master+ 415.2 KHz .852 + restore mwait_idle 3.13.0-master++ 488.5 KHz 1.002 + restore mwait_idle + IPI fix Since X86_BUG_CLFLUSH_MONITOR is already a quirk, don't create a separate quirk for the extra smp_mb()s. Signed-off-by:
Mike Galbraith <bitbucket@online.de> Cc: <stable@vger.kernel.org> # 3.10+ Cc: Borislav Petkov <bp@alien8.de> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Ian Malone <ibmalone@gmail.com> Cc: Josh Boyer <jwboyer@redhat.com> Cc: Len Brown <len.brown@intel.com> Cc: Len Brown <lenb@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1390061684.5566.4.camel@marge.simpson.net [ Ported to recent kernel, added comments about the quirk. ] Signed-off-by:
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Len Brown authored
sched/idle/x86: Restore mwait_idle() to fix boot hangs, to improve power savings and to improve performance In Linux-3.9 we removed the mwait_idle() loop: 69fb3676 ("x86 idle: remove mwait_idle() and "idle=mwait" cmdline param") The reasoning was that modern machines should be sufficiently happy during the boot process using the default_idle() HALT loop, until cpuidle loads and either acpi_idle or intel_idle invoke the newer MWAIT-with-hints idle loop. But two machines reported problems: 1. Certain Core2-era machines support MWAIT-C1 and HALT only. MWAIT-C1 is preferred for optimal power and performance. But if they support just C1, cpuidle never loads and so they use the boot-time default idle loop forever. 2. Some laptops will boot-hang if HALT is used, but will boot successfully if MWAIT is used. This appears to be a hidden assumption in BIOS SMI, that is presumably valid on the proprietary OS where the BIOS was validated. https://bugzilla.kernel.org/show_bug.cgi?id=60770 So here we effectively revert the patch above, restoring the mwait_idle() loop. However, we don't bother restoring the idle=mwait cmdline parameter, since it appears to add no value. Maintainer notes: For 3.9, simply revert 69fb3676 for 3.10, patch -F3 applies, fuzz needed due to __cpuinit use in context For 3.11, 3.12, 3.13, this patch applies cleanly Tested-by:
Len Brown <len.brown@intel.com> Acked-by:
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- Mar 06, 2015
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Andy Lutomirski authored
The INIT_TSS is unnecessary. Just define the initial TSS where 'cpu_tss' is defined. While we're at it, merge the 32-bit and 64-bit definitions. The only syntactic change is that 32-bit kernels were computing sp0 as long, but now they compute it as unsigned long. Verified by objdump: the contents and relocations of .data..percpu..shared_aligned are unchanged on 32-bit and 64-bit kernels. Signed-off-by:
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Andy Lutomirski authored
It has nothing to do with init -- there's only one TSS per cpu. Other names considered include: - current_tss: Confusing because we never switch the tss. - singleton_tss: Too long. This patch was generated with 's/init_tss/cpu_tss/g'. Followup patches will fix INIT_TSS and INIT_TSS_IST by hand. Signed-off-by:
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Andy Lutomirski authored
We currently store references to the top of the kernel stack in multiple places: kernel_stack (with an offset) and init_tss.x86_tss.sp0 (no offset). The latter is defined by hardware and is a clean canonical way to find the top of the stack. Add an accessor so we can start using it. This needs minor paravirt tweaks. On native, sp0 defines the top of the kernel stack and is therefore always correct. On Xen and lguest, the hypervisor tracks the top of the stack, but we want to start reading sp0 in the kernel. Fixing this is simple: just update our local copy of sp0 as well as the hypervisor's copy on task switches. Signed-off-by:
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