kernel.git/arch/sparc/include, branch linux-4.12.y

sparc64: Prevent perf from running during super critical sections

2017-08-11T15:34:00Z

[ Upstream commit fc290a114fc6034b0f6a5a46e2fb7d54976cf87a ] This fixes another cause of random segfaults and bus errors that may occur while running perf with the callgraph option. Critical sections beginning with spin_lock_irqsave() raise the interrupt level to PIL_NORMAL_MAX (14) and intentionally do not block performance counter interrupts, which arrive at PIL_NMI (15). But some sections of code are "super critical" with respect to perf because the perf_callchain_user() path accesses user space and may cause TLB activity as well as faults as it unwinds the user stack. One particular critical section occurs in switch_mm: spin_lock_irqsave(&mm->context.lock, flags); ... load_secondary_context(mm); tsb_context_switch(mm); ... spin_unlock_irqrestore(&mm->context.lock, flags); If a perf interrupt arrives in between load_secondary_context() and tsb_context_switch(), then perf_callchain_user() could execute with the context ID of one process, but with an active TSB for a different process. When the user stack is accessed, it is very likely to incur a TLB miss, since the h/w context ID has been changed. The TLB will then be reloaded with a translation from the TSB for one process, but using a context ID for another process. This exposes memory from one process to another, and since it is a mapping for stack memory, this usually causes the new process to crash quickly. This super critical section needs more protection than is provided by spin_lock_irqsave() since perf interrupts must not be allowed in. Since __tsb_context_switch already goes through the trouble of disabling interrupts completely, we fix this by moving the secondary context load down into this better protected region. Orabug: 25577560 Signed-off-by: Dave Aldridge Signed-off-by: Rob Gardner Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

sparc64: Measure receiver forward progress to avoid send mondo timeout

2017-08-11T15:33:59Z

[ Upstream commit 9d53caec84c7c5700e7c1ed744ea584fff55f9ac ] A large sun4v SPARC system may have moments of intensive xcall activities, usually caused by unmapping many pages on many CPUs concurrently. This can flood receivers with CPU mondo interrupts for an extended period, causing some unlucky senders to hit send-mondo timeout. This problem gets worse as cpu count increases because sometimes mappings must be invalidated on all CPUs, and sometimes all CPUs may gang up on a single CPU. But a busy system is not a broken system. In the above scenario, as long as the receiver is making forward progress processing mondo interrupts, the sender should continue to retry. This patch implements the receiver's forward progress meter by introducing a per cpu counter 'cpu_mondo_counter[cpu]' where 'cpu' is in the range of 0..NR_CPUS. The receiver increments its counter as soon as it receives a mondo and the sender tracks the receiver's counter. If the receiver has stopped making forward progress when the retry limit is reached, the sender declares send-mondo-timeout and panic; otherwise, the receiver is allowed to keep making forward progress. In addition, it's been observed that PCIe hotplug events generate Correctable Errors that are handled by hypervisor and then OS. Hypervisor 'borrows' a guest cpu strand briefly to provide the service. If the cpu strand is simultaneously the only cpu targeted by a mondo, it may not be available for the mondo in 20msec, causing SUN4V mondo timeout. It appears that 1 second is the agreed wait time between hypervisor and guest OS, this patch makes the adjustment. Orabug: 25476541 Orabug: 26417466 Signed-off-by: Jane Chu Reviewed-by: Steve Sistare Reviewed-by: Anthony Yznaga Reviewed-by: Rob Gardner Reviewed-by: Thomas Tai Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

Adding asm-prototypes.h for genksyms to generate crc

2017-07-21T04:59:06Z

[ Upstream commit bdca8cc096203b17ad0ac4e19f50578207e054d2 ] This patch adds the prototypes of assembly defined functions to asm-prototypes.h. Some prototypes are directly added as they are not present in any existing header files. Signed-off-by: Nagarathnam Muthusamy Reviewed-by: Babu Moger Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

arch: remove unused macro/function thread_saved_pc()

2017-06-28T23:13:57Z

The only user of thread_saved_pc() in non-arch-specific code was removed in commit 8243d5597793 ("sched/core: Remove pointless printout in sched_show_task()"). Remove the implementations as well. Some architectures use thread_saved_pc() in their arch-specific code. Leave their thread_saved_pc() intact. Signed-off-by: Tobias Klauser Acked-by: Geert Uytterhoeven Cc: Ingo Molnar Signed-off-by: Linus Torvalds

sparc64: delete old wrap code

2017-06-06T20:45:29Z

The old method that is using xcall and softint to get new context id is deleted, as it is replaced by a method of using per_cpu_secondary_mm without xcall to perform the context wrap. Signed-off-by: Pavel Tatashin Reviewed-by: Bob Picco Reviewed-by: Steven Sistare Signed-off-by: David S. Miller

sparc64: add per-cpu mm of secondary contexts

2017-06-06T20:45:29Z

The new wrap is going to use information from this array to figure out mm's that currently have valid secondary contexts setup. Signed-off-by: Pavel Tatashin Reviewed-by: Bob Picco Reviewed-by: Steven Sistare Signed-off-by: David S. Miller

sparc64: redefine first version

2017-06-06T20:45:28Z

CTX_FIRST_VERSION defines the first context version, but also it defines first context. This patch redefines it to only include the first context version. Signed-off-by: Pavel Tatashin Reviewed-by: Bob Picco Reviewed-by: Steven Sistare Signed-off-by: David S. Miller

sparc64: combine activate_mm and switch_mm

2017-06-06T20:45:28Z

The only difference between these two functions is that in activate_mm we unconditionally flush context. However, there is no need to keep this difference after fixing a bug where cpumask was not reset on a wrap. So, in this patch we combine these. Signed-off-by: Pavel Tatashin Reviewed-by: Bob Picco Reviewed-by: Steven Sistare Signed-off-by: David S. Miller

sparc: Machine description indices can vary

2017-06-06T20:45:03Z

VIO devices were being looked up by their index in the machine description node block, but this often varies over time as devices are added and removed. Instead, store the ID and look up using the type, config handle and ID. Signed-off-by: James Clarke Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=112541 Signed-off-by: David S. Miller

sparc: Fix -Wstringop-overflow warning

2017-05-17T19:07:46Z

Greetings, GCC 7 introduced the -Wstringop-overflow flag to detect buffer overflows in calls to string handling functions [1][2]. Due to the way ``empty_zero_page'' is declared in arch/sparc/include/setup.h, this causes a warning to trigger at compile time in the function mem_init(), which is subsequently converted to an error. The ensuing patch fixes this issue and aligns the declaration of empty_zero_page to that of other architectures. Thank you. Cheers, Orlando. [1] https://gcc.gnu.org/ml/gcc-patches/2016-10/msg02308.html [2] https://gcc.gnu.org/gcc-7/changes.html Signed-off-by: Orlando Arias -------------------------------------------------------------------------------- Signed-off-by: David S. Miller