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2019-09-15um: Add SPDX headers for files in arch/um/os-LinuxAlex Dewar1-1/+1
Convert files to use SPDX header. All files are licensed under the GPLv2. Signed-off-by: Alex Dewar <alex.dewar@gmx.co.uk> Signed-off-by: Richard Weinberger <richard@nod.at>
2019-09-15um: Implement TRACE_IRQFLAGS_SUPPORTJohannes Berg1-12/+32
UML enables TRACE_IRQFLAGS_SUPPORT but doesn't actually implement it. It seems to have been added for lockdep support, but that can't actually really work well without IRQ flags tracing, as is also very noisily reported when enabling CONFIG_DEBUG_LOCKDEP. Implement it now. Fixes: 711553efa5b8 ("[PATCH] uml: declare in Kconfig our partial LOCKDEP support") Signed-off-by: Johannes Berg <johannes.berg@intel.com> Signed-off-by: Richard Weinberger <richard@nod.at>
2019-09-15um: Avoid using uninitialized regsJohannes Berg1-0/+3
In timer_real_alarm_handler(), regs is only initialized if the context argument is non-NULL, also initialize in the other case. Signed-off-by: Johannes Berg <johannes.berg@intel.com> Acked-by: Anton Ivanov <anton.ivanov@cambridgegreys.co.uk> Signed-off-by: Richard Weinberger <richard@nod.at>
2019-09-15um: Remove sig_info[SIGALRM]Johannes Berg1-2/+1
This entry is misleading, the actual signal handler is another one that never uses sig_info. Also remove the SIGALRM if inside sig_handler() for the same reason. Signed-off-by: Johannes Berg <johannes.berg@intel.com> Acked-by: Anton Ivanov <anton.ivanov@cambridgegreys.co.uk> Signed-off-by: Richard Weinberger <richard@nod.at>
2019-05-07um: Revert to using stack for pt_regs in signal handlingAnton Ivanov1-20/+8
Reverts commit b6024b21fec8367ef961a771cc9dde31f1831965 and adjusts default stack sizing to cope with larger size of floating point save registers on the newer Intel CPUs. b6024b21fec8367ef961a771cc9dde31f1831965 replaced storing the register state on the stack with kmalloc-ed storage. That has a number of issues and a panic if that fails. 1. kmalloc/ATOMIC can fail. There was a latent hard crash in all interrupt and fault handling as a result. 2. kmalloc in the interrupt path introduces a considerable performance penalty for networking ~ 14% on iperf. This commit restores uml to a stable state until a better solution is found. Signed-off-by: Anton Ivanov <anton.ivanov@cambridgegreys.com> Signed-off-by: Richard Weinberger <richard@nod.at>
2018-03-29um: Compile with modern headersJason A. Donenfeld1-0/+1
Recent libcs have gotten a bit more strict, so we actually need to include the right headers and use the right types. This enables UML to compile again. Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> Cc: stable@vger.kernel.org Signed-off-by: Richard Weinberger <richard@nod.at>
2018-02-19um: Use POSIX ucontext_t instead of struct ucontextKrzysztof Mazur1-1/+1
glibc 2.26 removed the 'struct ucontext' to "improve" POSIX compliance and break programs, including User Mode Linux. Fix User Mode Linux by using POSIX ucontext_t. This fixes: arch/um/os-Linux/signal.c: In function 'hard_handler': arch/um/os-Linux/signal.c:163:22: error: dereferencing pointer to incomplete type 'struct ucontext' mcontext_t *mc = &uc->uc_mcontext; arch/x86/um/stub_segv.c: In function 'stub_segv_handler': arch/x86/um/stub_segv.c:16:13: error: dereferencing pointer to incomplete type 'struct ucontext' &uc->uc_mcontext); Cc: stable@vger.kernel.org Signed-off-by: Krzysztof Mazur <krzysiek@podlesie.net> Signed-off-by: Richard Weinberger <richard@nod.at>
2016-08-04um: Fix possible deadlock in sig_handler_common()Richard Weinberger1-2/+3
We are in atomic context and must not sleep. Sleeping here is possible since malloc() maps to kmalloc() with GFP_KERNEL. Cc: stable@vger.kernel.org Fixes: b6024b21 ("um: extend fpstate to _xstate to support YMM registers") Signed-off-by: Richard Weinberger <richard@nod.at>
2016-05-21um: extend fpstate to _xstate to support YMM registersEli Cooper1-8/+20
Extends fpstate to _xstate, in order to hold AVX/YMM registers. To avoid oversized stack frame, the following functions have been refactored by using malloc. - sig_handler_common - timer_real_alarm_handler Signed-off-by: Eli Cooper <elicooper@gmx.com>
2016-01-10um: Prevent IRQ handler reentrancyAnton Ivanov1-1/+15
The existing IRQ handler design in UML does not prevent reentrancy This is mitigated by fd-enable/fd-disable semantics for the IO portion of the UML subsystem. The timer, however, can and is re-entered resulting in very deep stack usage and occasional stack exhaustion. This patch prevents this by checking if there is a timer interrupt in-flight before processing any pending timer interrupts. Signed-off-by: Anton Ivanov <aivanov@brocade.com> Signed-off-by: Richard Weinberger <richard@nod.at>
2015-11-06um: Switch clocksource to hrtimersAnton Ivanov1-19/+22
UML is using an obsolete itimer call for all timers and "polls" for kernel space timer firing in its userspace portion resulting in a long list of bugs and incorrect behaviour(s). It also uses ITIMER_VIRTUAL for its timer which results in the timer being dependent on it running and the cpu load. This patch fixes this by moving to posix high resolution timers firing off CLOCK_MONOTONIC and relaying the timer correctly to the UML userspace. Fixes: - crashes when hosts suspends/resumes - broken userspace timers - effecive ~40Hz instead of what they should be. Note - this modifies skas behavior by no longer setting an itimer per clone(). Timer events are relayed instead. - kernel network packet scheduling disciplines - tcp behaviour especially under load - various timer related corner cases Finally, overall responsiveness of userspace is better. Signed-off-by: Thomas Meyer <thomas@m3y3r.de> Signed-off-by: Anton Ivanov <aivanov@brocade.com> [rw: massaged commit message] Signed-off-by: Richard Weinberger <richard@nod.at>
2015-06-25um: Do not use __ptr_t type for stack_t's .ss pointerHans-Werner Hilse1-3/+5
__ptr_t type is a glibc-specific type, while the generally documented type is a void*. That's what other C libraries use, too. Signed-off-by: Hans-Werner Hilse <hwhilse@gmail.com> Signed-off-by: Richard Weinberger <richard@nod.at>
2013-11-17um: Make stack trace reliable against kernel mode faultsRichard Weinberger1-0/+8
As UML uses an alternative signal stack we cannot use the current stack pointer for stack dumping if UML itself dies by SIGSEGV. To bypass this issue we save regs taken from mcontext in our segv handler into thread_struct and use these regs to obtain the stack pointer in show_stack(). Signed-off-by: Richard Weinberger <richard@nod.at>
2013-07-19um: siginfo cleanupRichard Weinberger1-4/+4
Currently we use both struct siginfo and siginfo_t. Let's use struct siginfo internally to avoid ongoing compiler warning. We are allowed to do so because struct siginfo and siginfo_t are equivalent. Signed-off-by: Richard Weinberger <richard@nod.at>
2013-03-11um: fix build failure due to mess-up of sig_info protorypeSergei Trofimovich1-1/+1
arch/um/os-Linux/signal.c:18:8: error: conflicting types for 'sig_info' In file included from /home/slyfox/linux-2.6/arch/um/os-Linux/signal.c:12:0: arch/um/include/shared/as-layout.h:64:15: note: previous declaration of 'sig_info' was here Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org> CC: Jeff Dike <jdike@addtoit.com> CC: Richard Weinberger <richard@nod.at> CC: "Martin Pärtel" <martin.partel@gmail.com> CC: Al Viro <viro@zeniv.linux.org.uk> CC: user-mode-linux-devel@lists.sourceforge.net CC: user-mode-linux-user@lists.sourceforge.net CC: linux-kernel@vger.kernel.org Signed-off-by: Richard Weinberger <richard@nod.at>
2012-10-09um: get rid of pointless include "..." where include <...> will doAl Viro1-4/+4
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Richard Weinberger <richard@nod.at>
2012-08-02um: pass siginfo to guest processMartin Pärtel1-11/+15
UML guest processes now get correct siginfo_t for SIGTRAP, SIGFPE, SIGILL and SIGBUS. Specifically, si_addr and si_code are now correct where previously they were si_addr = NULL and si_code = 128. Signed-off-by: Martin Pärtel <martin.partel@gmail.com> Signed-off-by: Richard Weinberger <richard@nod.at>
2011-11-02um: sysdep/barrier.h is not used for anythingAl Viro1-1/+0
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Richard Weinberger <richard@nod.at>
2011-11-02um: shared/process.h is empty now; kill itAl Viro1-1/+0
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Richard Weinberger <richard@nod.at>
2011-11-02um: finish conversion to mcontext_tAl Viro1-3/+3
now we don't mix host and guest signal frame layouts anymore; moreover, we don't need host's struct sigcontext at all. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Richard Weinberger <richard@nod.at>
2011-11-02um: start switching the references to host mcontext_t to its userland typeAl Viro1-19/+16
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Richard Weinberger <richard@nod.at>
2011-11-02um: take userland definition of barrier() to user.hAl Viro1-3/+0
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Richard Weinberger <richard@nod.at>
2011-11-02um: fill the handlers array at build timeAl Viro1-4/+13
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Richard Weinberger <richard@nod.at>
2011-11-02um: simplify set_handler()Al Viro1-11/+11
For one thing, we always block the same signals (IRQ ones - IO, WINCH, VTALRM), so there's no need to pass sa_mask elements in arguments. For another, the flags depend only on whether it's an IRQ signal or not (we add SA_RESTART for them). Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Richard Weinberger <richard@nod.at>
2011-11-02um: don't bother blocking SIGARLM and SIGUSR1Al Viro1-1/+1
We used to generate those, but we hadn't done that for a long time. No need to bother blocking them for signal handlers. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Richard Weinberger <richard@nod.at>
2011-11-02um: merge hard_handler() instances, switch to use of SA_SIGINFOAl Viro1-4/+8
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Richard Weinberger <richard@nod.at>
2011-11-02um: -include user.h for USER_OBJ, trim includesAl Viro1-1/+0
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Richard Weinberger <richard@nod.at>
2008-07-24UML: make several more things staticWANG Cong1-1/+1
- Make some variables and functions static, since they don't need to be global. - Remove an unused function - arch/um/kernel/time.c::sched_clock(). - Clean the style a bit as complained by checkpatch.pl. Cc: Jeff Dike <jdike@addtoit.com> Signed-off-by: WANG Cong <wangcong@zeuux.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-05-13uml: track and make up lost ticksJeff Dike1-0/+1
Alarm delivery could be noticably late in the !CONFIG_NOHZ case because lost ticks weren't being taken into account. This is now treated more carefully, with the time between ticks being calculated and the appropriate number of ticks delivered to the timekeeping system. Cc: Nix <nix@esperi.org.uk> Signed-off-by: Jeff Dike <jdike@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-08uml: style fixes in arch/um/os-LinuxJeff Dike1-1/+1
Style changes under arch/um/os-Linux: include trimming CodingStyle fixes some printks needed severity indicators make_tempfile turns out not to be used outside of mem.c, so it is now static. Its declaration in tempfile.h is no longer needed, and tempfile.h itself is no longer needed. create_tmp_file was also made static. checkpatch moans about an EXPORT_SYMBOL in user_syms.c which is part of a macro definition - this is copying a bit of kernel infrastructure into the libc side of UML because the kernel headers can't be included there. Signed-off-by: Jeff Dike <jdike@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05uml: signal handling tidyingJeff Dike1-21/+12
This patch tidies the signal handling code slightly. pending is renamed to signals_pending for symmetry with signals_enabled. remove_sigstack was unused, so can be deleted. The value of change_sig was never used, so it is now void and the return value is not calculated any more. Signed-off-by: Jeff Dike <jdike@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05uml: clean up sig_handler_common_skasJeff Dike1-45/+18
sig_handler_common_skas needs significant modernization, starting with its name and storage class. There is no need to hide the true type of the sigcontext pointer, so the void * dummy parameter can be replaced with a sigcontext *sc. The array of uml_pt_regs structs used in the page fault case are gone, replaced by a local variable. This is also used in the non-segfault case instead of the copy in the task_struct. Since it's local, the special handling of the is_user flag can go away. There hasn't been any special treatment of SIGUSR1 in ages, so the line that enables it can be deleted. The special treatment of SIGSEGV similarly goes away, but to compensate, SA_NODEFER is added to sa_mask when registering a signal handler. Signed-off-by: Jeff Dike <jdike@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05uml: move sig_handler_common_skasJeff Dike1-0/+62
This patch moves sig_handler_common_skas from arch/um/os-Linux/skas/trap.c to its only caller in arch/um/os-Linux/signal.c. trap.c is now empty, so it can be removed. This is code movement only - the significant cleanup needed here is done in the next patch. Signed-off-by: Jeff Dike <jdike@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05uml: use barrier() instead of mb()Jeff Dike1-20/+8
signals_enabled and pending have requirements on the order in which they are modified. This used to be done by declaring them volatile and putting an mb() where the ordering requirements were in effect. After getting a better (I hope) understanding of how to do this correctly, the volatile declarations are gone and the mb()'s replaced by barrier()'s. One of the mb()'s was deleted because I see no problematic writes that could be re-ordered past that point. Signed-off-by: Jeff Dike <jdike@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05uml: tidy kern_util.hJeff Dike1-0/+1
Tidy kern_util.h. It turns out that most of the function declarations aren't used, so they can go away. os.h no longer includes kern_util.h, so files which got it through os.h now need to include it directly. A number of other files never needed it, so these includes are deleted. The structure which was used to pass signal handlers from the kernel side to the userspace side is gone. Instead, the handlers are declared here, and used directly from libc code. This allows arch/um/os-Linux/trap.c to be deleted, with its remnants being moved to arch/um/os-Linux/skas/trap.c. arch/um/os-Linux/tty.c had its inclusions changed, and it needed some style attention, so it got tidied. Signed-off-by: Jeff Dike <jdike@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05uml: code tidying under arch/um/os-LinuxWANG Cong1-1/+2
This patch contains varied fixes and improvements for some files under arch/um/os-Linux/, such as a typo fix in a perror message, a missing argument fix for a printf, some constifying for pointers and so on. [ jdike - made sigprocmask failure return -errno instead of -1 ] Signed-off-by: WANG Cong <xiyou.wangcong@gmail.com> Signed-off-by: Jeff Dike <jdike@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-16uml: eliminate SIGALRMJeff Dike1-21/+7
Now that ITIMER_REAL is no longer used, there is no need for any use of SIGALRM whatsoever. This patch removes all mention of it. In addition, real_alarm_handler took a signal argument which is now always SIGVTALRM. So, that is gone. Signed-off-by: Jeff Dike <jdike@linux.intel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-16uml: eliminate interrupts in the idle loopJeff Dike1-3/+0
Now, the idle loop now longer needs SIGALRM firing - it can just sleep for the requisite amount of time and fake a timer interrupt when it finishes. Any use of ITIMER_REAL now goes away. disable_timer only turns off ITIMER_VIRTUAL. switch_timers is no longer needed, so it, and all calls, goes away. disable_timer now returns the amount of time remaining on the timer. default_idle uses this to tell idle_sleep how long to sleep. idle_sleep will call alarm_handler if nanosleep returns 0, which is the case if it didn't return early due to an interrupt. Otherwise, it just returns. Signed-off-by: Jeff Dike <jdike@linux.intel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-16uml: separate timer initializationJeff Dike1-0/+10
Move timer signal initialization from init_irq_signals to a new function, timer_init. Signed-off-by: Jeff Dike <jdike@linux.intel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-16uml: fix timer switchingJeff Dike1-6/+3
Fix up the switching between virtual and real timers. The idle loop sleeps, so the timer at that point must be real time. At all other times, the timer must be virtual. Even when userspace is running, and the kernel is asleep, the virtual timer is correct because the process timer will be running and the process timer will be firing. The timer switch used to be in the context switch and timer handler code. This is moved to the idle loop and the signal handler, making it much more clear why it is happening. switch_timers now returns the old timer type so that it may be restored. The signal handler uses this in order to restore the previous timer type when it returns. Signed-off-by: Jeff Dike <jdike@linux.intel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-16uml: style fixes pass 3Jeff Dike1-45/+51
Formatting changes in the files which have been changed in the course of folding foo_skas functions into their callers. These include: copyright updates header file trimming style fixes adding severity to printks These changes should be entirely non-functional. Signed-off-by: Jeff Dike <jdike@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-16uml: remove code made redundant by CHOOSE_MODE removalJeff Dike1-3/+2
This patch makes a number of simplifications enabled by the removal of CHOOSE_MODE. There were lots of functions that looked like int foo(args){ foo_skas(args); } The bodies of foo_skas are now folded into foo, and their declarations (and sometimes entire header files) are deleted. In addition, the union uml_pt_regs, which was a union between the tt and skas register formats, is now a struct, with the tt-mode arm of the union being removed. It turns out that usr2_handler was unused, so it is gone. Signed-off-by: Jeff Dike <jdike@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-16uml: throw out CHOOSE_MODEJeff Dike1-4/+2
The next stage after removing code which depends on CONFIG_MODE_TT is removing the CHOOSE_MODE abstraction, which provided both compile-time and run-time branching to either tt-mode or skas-mode code. This patch removes choose-mode.h and all inclusions of it, and replaces all CHOOSE_MODE invocations with the skas branch. This leaves a number of trivial functions which will be dealt with in a later patch. There are some changes in the uaccess and tls support which go somewhat beyond this and eliminate some of the now-redundant functions. Signed-off-by: Jeff Dike <jdike@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-09-19uml: fix irqstack crashJeff Dike1-2/+2
This patch fixes a crash caused by an interrupt coming in when an IRQ stack is being torn down. When this happens, handle_signal will loop, setting up the IRQ stack again because the tearing down had finished, and handling whatever signals had come in. However, to_irq_stack returns a mask of pending signals to be handled, plus bit zero is set if the IRQ stack was already active, and thus shouldn't be torn down. This causes a problem because when handle_signal goes around the loop, sig will be zero, and to_irq_stack will duly set bit zero in the returned mask, faking handle_signal into believing that it shouldn't tear down the IRQ stack and return thread_info pointers back to their original values. This will eventually cause a crash, as the IRQ stack thread_info will continue pointing to the original task_struct and an interrupt will look into it after it has been freed. The fix is to stop passing a signal number into to_irq_stack. Rather, the pending signals mask is initialized beforehand with the bit for sig already set. References to sig in to_irq_stack can be replaced with references to the mask. [akpm@linux-foundation.org: use UL] Signed-off-by: Jeff Dike <jdike@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-11uml: iRQ stacksJeff Dike1-0/+40
Add a separate IRQ stack. This differs from i386 in having the entire interrupt run on a separate stack rather than starting on the normal kernel stack and switching over once some preparation has been done. The underlying mechanism, is of course, sigaltstack. Another difference is that interrupts that happen in userspace are handled on the normal kernel stack. These cause a wait wakeup instead of a signal delivery so there is no point in trying to switch stacks for these. There's no other stuff on the stack, so there is no extra stack consumption. This quirk makes it possible to have the entire interrupt run on a separate stack - process preemption (and calls to schedule()) happens on a normal kernel stack. If we enable CONFIG_PREEMPT, this will need to be rethought. The IRQ stack for CPU 0 is declared in the same way as the initial kernel stack. IRQ stacks for other CPUs will be allocated dynamically. An extra field was added to the thread_info structure. When the active thread_info is copied to the IRQ stack, the real_thread field points back to the original stack. This makes it easy to tell where to copy the thread_info struct back to when the interrupt is finished. It also serves as a marker of a nested interrupt. It is NULL for the first interrupt on the stack, and non-NULL for any nested interrupts. Care is taken to behave correctly if a second interrupt comes in when the thread_info structure is being set up or taken down. I could just disable interrupts here, but I don't feel like giving up any of the performance gained by not flipping signals on and off. If an interrupt comes in during these critical periods, the handler can't run because it has no idea what shape the stack is in. So, it sets a bit for its signal in a global mask and returns. The outer handler will deal with this signal itself. Atomicity is had with xchg. A nested interrupt that needs to bail out will xchg its signal mask into pending_mask and repeat in case yet another interrupt hit at the same time, until the mask stabilizes. The outermost interrupt will set up the thread_info and xchg a zero into pending_mask when it is done. At this point, nested interrupts will look at ->real_thread and see that no setup needs to be done. They can just continue normally. Similar care needs to be taken when exiting the outer handler. If another interrupt comes in while it is copying the thread_info, it will drop a bit into pending_mask. The outer handler will check this and if it is non-zero, will loop, set up the stack again, and handle the interrupt. Signed-off-by: Jeff Dike <jdike@linux.intel.com> Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-11uml: tidy IRQ codeJeff Dike1-3/+7
Some tidying of the irq code before introducing irq stacks. Mostly style fixes, but the timer handler calls the timer code directly rather than going through the generic sig_handler_common_skas. Signed-off-by: Jeff Dike <jdike@linux.intel.com> Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-07uml: remove user_util.hJeff Dike1-1/+0
user_util.h isn't needed any more, so delete it and remove all includes of it. Signed-off-by: Jeff Dike <jdike@linux.intel.com> Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-03-08[PATCH] um: remove dead code about os_usr1_signal() and os_usr1_process()Paolo 'Blaisorblade' Giarrusso1-5/+0
os_usr1_signal() is totally unused, os_usr1_process() is used only by TT mode. Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Acked-by: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2006-11-03[PATCH] uml: fix I/O hangJeff Dike1-3/+28
Fix a UML hang in which everything would just stop until some I/O happened - a ping, someone whacking the keyboard - at which point everything would start up again as though nothing had happened. The cause was gcc reordering some code which absolutely needed to be executed in the order in the source. When unblock_signals switches signals from off to on, it needs to see if any interrupts had happened in the critical section. The interrupt handlers check signals_enabled - if it is zero, then the handler adds a bit to the "pending" bitmask and returns. unblock_signals checks this mask to see if any signals need to be delivered. The crucial part is this: signals_enabled = 1; save_pending = pending; if(save_pending == 0) return; pending = 0; In order to avoid an interrupt arriving between reading pending and setting it to zero, in which case, the record of the interrupt would be erased, signals are enabled. What happened was that gcc reordered this so that 'save_pending = pending' came before 'signals_enabled = 1', creating a one-instruction window within which an interrupt could arrive, set its bit in pending, and have it be immediately erased. When the I/O workload is purely disk-based, the loss of a block device interrupt stops the entire I/O system because the next block request will wait for the current one to finish. Thus the system hangs until something else causes some I/O to arrive, such as a network packet or console input. The fix to this particular problem is a memory barrier between enabling signals and reading the pending signal mask. An xchg would also probably work. Looking over this code for similar problems led me to do a few more things: - make signals_enabled and pending volatile so that they don't get cached in registers - add an mb() to the return paths of block_signals and unblock_signals so that the modification of signals_enabled doesn't get shuffled into the caller in the event that these are inlined in the future. Signed-off-by: Jeff Dike <jdike@addtoit.com> Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-09-26[PATCH] uml: Remove unused variableJeff Dike1-7/+0
timer_irq_inited was useless, so it is removed. Signed-off-by: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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