linux-dev/arch/powerpc/platforms/pseries/hvCall.S, branch linus/master

powerpc/64s: avoid reloading (H)SRR registers if they are still valid

2021-06-24T14:06:55Z

When an interrupt is taken, the SRR registers are set to return to where it left off. Unless they are modified in the meantime, or the return address or MSR are modified, there is no need to reload these registers when returning from interrupt. Introduce per-CPU flags that track the validity of SRR and HSRR registers. These are cleared when returning from interrupt, when using the registers for something else (e.g., OPAL calls), when adjusting the return address or MSR of a context, and when context switching (which changes the return address and MSR). This improves the performance of interrupt returns. Signed-off-by: Nicholas Piggin [mpe: Fold in fixup patch from Nick] Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20210617155116.2167984-5-npiggin@gmail.com

powerpc/pseries: Fix hcall tracing recursion in pv queued spinlocks

2021-05-12T01:07:38Z

The paravit queued spinlock slow path adds itself to the queue then calls pv_wait to wait for the lock to become free. This is implemented by calling H_CONFER to donate cycles. When hcall tracing is enabled, this H_CONFER call can lead to a spin lock being taken in the tracing code, which will result in the lock to be taken again, which will also go to the slow path because it queues behind itself and so won't ever make progress. An example trace of a deadlock: __pv_queued_spin_lock_slowpath trace_clock_global ring_buffer_lock_reserve trace_event_buffer_lock_reserve trace_event_buffer_reserve trace_event_raw_event_hcall_exit __trace_hcall_exit plpar_hcall_norets_trace __pv_queued_spin_lock_slowpath trace_clock_global ring_buffer_lock_reserve trace_event_buffer_lock_reserve trace_event_buffer_reserve trace_event_raw_event_rcu_dyntick rcu_irq_exit irq_exit __do_irq call_do_irq do_IRQ hardware_interrupt_common_virt Fix this by introducing plpar_hcall_norets_notrace(), and using that to make SPLPAR virtual processor dispatching hcalls by the paravirt spinlock code. Signed-off-by: Nicholas Piggin Reviewed-by: Naveen N. Rao Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20210508101455.1578318-2-npiggin@gmail.com

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152

2019-05-30T18:26:32Z

Based on 1 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license as published by the free software foundation either version 2 of the license or at your option any later version extracted by the scancode license scanner the SPDX license identifier GPL-2.0-or-later has been chosen to replace the boilerplate/reference in 3029 file(s). Signed-off-by: Thomas Gleixner Reviewed-by: Allison Randal Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de Signed-off-by: Greg Kroah-Hartman

jump_label: move 'asm goto' support test to Kconfig

2019-01-06T00:46:51Z

Currently, CONFIG_JUMP_LABEL just means "I _want_ to use jump label". The jump label is controlled by HAVE_JUMP_LABEL, which is defined like this: #if defined(CC_HAVE_ASM_GOTO) && defined(CONFIG_JUMP_LABEL) # define HAVE_JUMP_LABEL #endif We can improve this by testing 'asm goto' support in Kconfig, then make JUMP_LABEL depend on CC_HAS_ASM_GOTO. Ugly #ifdef HAVE_JUMP_LABEL will go away, and CONFIG_JUMP_LABEL will match to the real kernel capability. Signed-off-by: Masahiro Yamada Acked-by: Michael Ellerman (powerpc) Tested-by: Sedat Dilek

powerpc: clean inclusions of asm/feature-fixups.h

2018-07-30T12:48:17Z

files not using feature fixup don't need asm/feature-fixups.h files using feature fixup need asm/feature-fixups.h Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman

powerpc/asm: Convert .llong directives to .8byte

2017-08-31T04:26:47Z

.llong is an undocumented PPC specific directive. The generic equivalent is .quad, but even better (because it's self describing) is .8byte. Convert all .llong directives to .8byte. Signed-off-by: Tobin C. Harding Signed-off-by: Michael Ellerman

powerpc, jump_label: Include linux/jump_label.h to get HAVE_JUMP_LABEL define

2015-04-09T07:40:29Z

Commit 1bc9e47aa8e4 ("powerpc/jump_label: Use HAVE_JUMP_LABEL") converted uses of CONFIG_JUMP_LABEL to HAVE_JUMP_LABEL in some assembly files. HAVE_JUMP_LABEL is defined in linux/jump_label.h, so we need to include this or we always get the non jump label fallback code. Signed-off-by: Anton Blanchard Acked-by: Michael Ellerman Acked-by: Peter Zijlstra (Intel) Cc: Andrew Morton Cc: Linus Torvalds Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: benh@kernel.crashing.org Cc: catalin.marinas@arm.com Cc: davem@davemloft.net Cc: heiko.carstens@de.ibm.com Cc: jbaron@akamai.com Cc: linux@arm.linux.org.uk Cc: linuxppc-dev@lists.ozlabs.org Cc: liuj97@gmail.com Cc: mgorman@suse.de Cc: mmarek@suse.cz Cc: paulus@samba.org Cc: ralf@linux-mips.org Cc: rostedt@goodmis.org Cc: schwidefsky@de.ibm.com Cc: will.deacon@arm.com Fixes: 1bc9e47aa8e4 ("powerpc/jump_label: Use HAVE_JUMP_LABEL") Link: http://lkml.kernel.org/r/1428551492-21977-3-git-send-email-anton@samba.org Signed-off-by: Ingo Molnar

powerpc/jump_label: Use HAVE_JUMP_LABEL

2014-11-09T22:59:30Z

Commit d4fe0965e208 ("powerpc/jump_label: use HAVE_JUMP_LABEL?") missed a few conversions. Change the remaining uses of CONFIG_JUMP_LABEL to HAVE_JUMP_LABEL. Signed-off-by: Anton Blanchard Signed-off-by: Michael Ellerman

powerpc/pseries: Optimise hcall tracepoints

2014-07-11T06:06:03Z

Now that we execute the hcall tracepoint entry and exit code out of line, we can use the same stack across both functions. Signed-off-by: Anton Blanchard Signed-off-by: Benjamin Herrenschmidt

powerpc/pseries: Use jump labels for hcall tracepoints

2014-07-11T06:05:58Z

hcall tracepoints add quite a few instructions to our hcall path: plpar_hcall: mr r2,r2 mfcr r0 stw r0,8(r1) b 164 <---- start ld r12,0(r2) std r12,32(r1) cmpdi r12,0 beq 164 <---- end ... We have an unconditional branch that gets noped out during boot and a load/compare/branch. We also store the tracepoint value to the stack for the hcall_exit path to use. By using jump labels we can simplify this to just a single nop that gets replaced with a branch when the tracepoint is enabled: plpar_hcall: mr r2,r2 mfcr r0 stw r0,8(r1) nop <---- ... If jump labels are not enabled, we fall back to the old method. Signed-off-by: Anton Blanchard Signed-off-by: Benjamin Herrenschmidt