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2014-05-13ARC: !PREEMPT: Ensure Return to kernel mode is IRQ safeVineet Gupta
commit 8aa9e85adac609588eeec356e5a85059b3b819ba upstream. There was a very small race window where resume to kernel mode from a Exception Path (or pure kernel mode which is true for most of ARC exceptions anyways), was not disabling interrupts in restore_regs, clobbering the exception regs Anton found the culprit call flow (after many sleepless nights) | 1. we got a Trap from user land | 2. started to service it. | 3. While doing some stuff on user-land memory (I think it is padzero()), | we got a DataTlbMiss | 4. On return from it we are taking "resume_kernel_mode" path | 5. NEED_RESHED is not set, so we go to "return from exception" path in | restore regs. | 6. there seems to be IRQ happening Signed-off-by: Vineet Gupta <vgupta@synopsys.com> Cc: Anton Kolesov <Anton.Kolesov@synopsys.com> Cc: Francois Bedard <Francois.Bedard@synopsys.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-05-13ARC: Entry Handler tweaks: Optimize away redundant IRQ_DISABLE_SAVEVineet Gupta
commit fce16bc35ae4a45634f3dc348d8d297a25c277cf upstream. In the exception return path, for both U/K cases, intr are already disabled (for various existing reasons). So when we drop down to @restore_regs, we need not redo that. There was subtle issue - when intr were NOT being disabled for ret-to-kernel-but-no-preemption case - now fixed by moving the IRQ_DISABLE further up in @resume_kernel_mode. So what do we gain: * Shaves off a few insn in return path. * Eliminates the need for IRQ_DISABLE_SAVE assembler macro for ARCv2 hence allows for entry code sharing. Signed-off-by: Vineet Gupta <vgupta@synopsys.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-05-13ARC: Entry Handler tweaks: Simplify branch for in-kernel preemptionVineet Gupta
commit 147aece29b15051173eb1e767018135361cdba89 upstream. Signed-off-by: Vineet Gupta <vgupta@synopsys.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-08-29ARC: gdbserver breakage in Big-Endian configuration #1Vineet Gupta
[Based on mainline commit 502a0c775c7f0a: "ARC: pt_regs update #5"] gdbserver needs @stop_pc, served by ptrace, but fetched from pt_regs differently, based on in_brkpt_traps(), which in turn relies on additional machine state in pt_regs->event bitfield. unsigned long orig_r8:16, event:16; For big endian config, this macro was returning false, despite being in breakpoint Trap exception, causing wrong @stop_pc to be returned to gdb. Issue #1: In BE, @event above is at offset 2 in word, while a STW insn at offset 0 was used to update it. Resort to using ST insn which updates the half-word at right location. Issue #2: The union involving bitfields causes all the members to be laid out at offset 0. So with fix #1 above, ASM was now updating at offset 2, "C" code was still referencing at offset 0. Fixed by wrapping bitfield in a struct. Reported-by: Noam Camus <noamc@ezchip.com> Tested-by: Anton Kolesov <akolesov@synopsys.com> Signed-off-by: Vineet Gupta <vgupta@synopsys.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-05-07ARC: unaligned access emulation broken if callee-reg dest of LD/STVineet Gupta
The fixup code correctly updates the callee-regs on stack, but fails to unwind it into actual register file. Thus userspace won't see the update. Reported-by: Noam Camus <noamc@ezchip.com> Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
2013-05-07ARC: unaligned access emulation error handling consolidationVineet Gupta
If CONFIG_ARC_MISALIGN_ACCESS is not enabled, or if the fixup fails, call the same error handler: same signal/si_code to user (SIGBUS) Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
2013-03-20ARC: Fix the typo in event identifier flags used by ptraceVineet Gupta
orig_r8_IS_EXCPN and orig_r8_IS_BRKPT were same values due to a copy/paste error. Although it looks bad and is wrong, it really doesn't affect gdb working. orig_r8_IS_BRKPT is the one relevant to debugging (breakpoints), since it is used to provide EFA vs. ERET to a ptrace "stop_pc" request. So when gdb has inserted a breakpoint, orig_r8_IS_BRKPT is already set, and anything else (i.e. orig_r8_IS_EXCPN) becoming same as it, really doesn't hurt gdb. The corollary case, could be nasty but nobody uses the ptrace "stop_pc" request in that case Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
2013-03-11ARC: ABIv3: fork/vfork wrappers not needed in "no-legacy-syscall" ABIVineet Gupta
When switching to clone() only ABI - I missed out pruning the low level asm syscall wrappers Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
2013-02-15ARC: Fix pt_orig_r8 accessVineet Gupta
Syscall restarting fixes made pt_regs->orig_r8 a short word, which was not reflected in the assembler code - thus could potentially break gdb debugging. Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
2013-02-15ARC: Support for single cycle Close Coupled Mem (CCM)Vineet Gupta
* Includes mapping of CCMs in address space * Annotations to move arbitrary code/data into CCM * Moving some of the critical code/data into CCM * Runtime detection/reporting Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
2013-02-15ARC: Unaligned access emulationVineet Gupta
ARC700 doesn't natively support unaligned access, but can be emulated -Unaligned Access Exception -Disassembly at the Fault address to find the exact insn (long/short) Also per Arnd's comment, we runtime control it using 2 sysctl knobs: * SYSCTL_ARCH_UNALIGN_ALLOW: Runtime enable/disble * SYSCTL_ARCH_UNALIGN_NO_WARN: Warn on each emulation attempt Originally contributed by Tim Yao <tim.yao@amlogic.com> Signed-off-by: Vineet Gupta <vgupta@synopsys.com> Cc: Tim Yao <tim.yao@amlogic.com> Acked-by: Arnd Bergmann <arnd@arndb.de>
2013-02-15ARC: DWARF2 .debug_frame based stack unwinderVineet Gupta
-Originally written by Rajeshwar Ranga -Derived off of generic unwinder in 2.6.19 and adapted to ARC Signed-off-by: Vineet Gupta <vgupta@synopsys.com> Cc: Rajeshwar Ranga <rajeshwar.ranga@gmail.com>
2013-02-15ARC: SMP supportVineet Gupta
ARC common code to enable a SMP system + ISS provided SMP extensions. ARC700 natively lacks SMP support, hence some of the core features are are only enabled if SoCs have the necessary h/w pixie-dust. This includes: -Inter Processor Interrupts (IPI) -Cache coherency -load-locked/store-conditional ... The low level exception handling would be completely broken in SMP because we don't have hardware assisted stack switching. Thus a fair bit of this code is repurposing the MMU_SCRATCH reg for event handler prologues to keep them re-entrant. Many thanks to Rajeshwar Ranga for his initial "major" contributions to SMP Port (back in 2008), and to Noam Camus and Gilad Ben-Yossef for help with resurrecting that in 3.2 kernel (2012). Note that this platform code is again singleton design pattern - so multiple SMP platforms won't build at the moment - this deficiency is addressed in subsequent patches within this series. Signed-off-by: Vineet Gupta <vgupta@synopsys.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Rajeshwar Ranga <rajeshwar.ranga@gmail.com> Cc: Noam Camus <noamc@ezchip.com> Cc: Gilad Ben-Yossef <gilad@benyossef.com>
2013-02-15ARC: Support for high priority interrupts in the in-core intcVineet Gupta
There is a bit of hack/kludge right now where we disable preemption if a L2 (High prio) IRQ is taken while L1 (Low prio) is active. Need to revisit this Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
2013-02-15ARC: ptrace supportVineet Gupta
Signed-off-by: Vineet Gupta <vgupta@synopsys.com> Acked-by: Arnd Bergmann <arnd@arndb.de>
2013-02-15ARC: [optim] Cache "current" in Register r25Vineet Gupta
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
2013-02-15ARC: [Review] Preparing to fix incorrect syscall restarts due to signalsVineet Gupta
To avoid multiple syscall restarts (multiple signals) or no restart at all (sigreturn), we need just an extra bit of state "literally 1 bit" in struct pt_regs. orig_r8 is the best place to do this, however given the way it is encoded currently, we can't add anything simplistically. Current orig_r8: * syscalls -> 1 to NR_SYSCALLS * Exceptions -> NR_SYSCALLS + 1 * Break-point-> NR_SYSCALLS + 2 In new scheme it is a bit-field * lower short word contains the exact event type (and a new bit to represent restart semantics : if syscall was already / can't be restarted) * upper short word optionally containing the syscall num - needed by likes of tracehooks etc This patch only changes how orig_r8 is organised and nothing should change behaviourily. Signed-off-by: Vineet Gupta <vgupta@synopsys.com> Cc: Al Viro <viro@ZenIV.linux.org.uk>
2013-02-15ARC: Signal handlingVineet Gupta
Includes following fixes courtesy review by Al-Viro * Tracer poke to Callee-regs were lost Before going off into do_signal( ) we save the user-mode callee regs (as they are not saved by default as part of pt_regs). This is to make sure that that a Tracer (if tracing related signal) is able to do likes of PEEKUSR(callee-reg). However in return path we were simply discarding the user-mode callee regs, which would break a POKEUSR(callee-reg) from a tracer. * Issue related to multiple syscall restarts are addressed in next patch Signed-off-by: Vineet Gupta <vgupta@synopsys.com> Cc: Al Viro <viro@ZenIV.linux.org.uk> Acked-by: Jonas Bonn <jonas@southpole.se>
2013-02-11ARC: Process-creation/scheduling/idle-loopVineet Gupta
Signed-off-by: Vineet Gupta <vgupta@synopsys.com> Cc: Al Viro <viro@ZenIV.linux.org.uk> Cc: Thomas Gleixner <tglx@linutronix.de>
2013-02-11ARC: Syscall support (no-legacy-syscall ABI)Vineet Gupta
This includes support for generic clone/for/vfork/execve Signed-off-by: Vineet Gupta <vgupta@synopsys.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Al Viro <viro@ZenIV.linux.org.uk> Acked-by: Arnd Bergmann <arnd@arndb.de>
2013-02-11ARC: Low level IRQ/Trap/Exception HandlingVineet Gupta
Signed-off-by: Vineet Gupta <vgupta@synopsys.com> Cc: Al Viro <viro@ZenIV.linux.org.uk>
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