linux.git/arch/s390/include/asm/processor.h, branch v5.5

s390: always inline disabled_wait

2019-11-30T09:52:44+00:00

disabled_wait uses _THIS_IP_ and assumes that compiler would inline it.
Make sure this assumption is always correct by utilizing __always_inline.

Reviewed-by: Heiko Carstens 
Signed-off-by: Vasily Gorbik

s390: always inline current_stack_pointer()

2019-10-31T16:20:54+00:00

This function must be inlined since any caller expects the current
stack pointer; which wouldn't be true if the function isn't inlined.

Signed-off-by: Heiko Carstens 
Signed-off-by: Vasily Gorbik

s390/base: remove unused s390_base_mcck_handler

2019-09-03T11:53:56+00:00

s390_base_mcck_handler was used during system reset if diag308 set was
not available. But after commit d485235b0054 ("s390: assume diag308 set
always works") is a dead code and could be removed.

Acked-by: Heiko Carstens 
Signed-off-by: Vasily Gorbik

arch: replace _BITUL() in kernel-space headers with BIT()

2019-07-17T02:23:22+00:00

Now that BIT() can be used from assembly code, we can safely replace
_BITUL() with equivalent BIT().

UAPI headers are still required to use _BITUL(), but there is no more
reason to use it in kernel headers.  BIT() is shorter.

Link: http://lkml.kernel.org/r/20190609153941.17249-2-yamada.masahiro@socionext.com
Signed-off-by: Masahiro Yamada 
Cc: Heiko Carstens 
Cc: Vasily Gorbik 
Cc: Christian Borntraeger 
Cc: Vineet Gupta 
Cc: Catalin Marinas 
Cc: Will Deacon 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

processor: get rid of cpu_relax_yield

2019-06-15T10:25:55+00:00

stop_machine is the only user left of cpu_relax_yield. Given that it
now has special semantics which are tied to stop_machine introduce a
weak stop_machine_yield function which architectures can override, and
get rid of the generic cpu_relax_yield implementation.

Acked-by: Peter Zijlstra (Intel) 
Acked-by: Thomas Gleixner 
Signed-off-by: Heiko Carstens

s390: improve wait logic of stop_machine

2019-06-15T10:25:52+00:00

The stop_machine loop to advance the state machine and to wait for all
affected CPUs to check-in calls cpu_relax_yield in a tight loop until
the last missing CPUs acknowledged the state transition.

On a virtual system where not all logical CPUs are backed by real CPUs
all the time it can take a while for all CPUs to check-in. With the
current definition of cpu_relax_yield a diagnose 0x44 is done which
tells the hypervisor to schedule *some* other CPU. That can be any
CPU and not necessarily one of the CPUs that need to run in order to
advance the state machine. This can lead to a pretty bad diagnose 0x44
storm until the last missing CPU finally checked-in.

Replace the undirected cpu_relax_yield based on diagnose 0x44 with a
directed yield. Each CPU in the wait loop will pick up the next CPU
in the cpumask of stop_machine. The diagnose 0x9c is used to tell the
hypervisor to run this next CPU instead of the current one. If there
is only a limited number of real CPUs backing the virtual CPUs we
end up with the real CPUs passed around in a round-robin fashion.

[heiko.carstens@de.ibm.com]:
    Use cpumask_next_wrap as suggested by Peter Zijlstra.

Signed-off-by: Martin Schwidefsky 
Acked-by: Peter Zijlstra (Intel) 
Acked-by: Thomas Gleixner 
Signed-off-by: Heiko Carstens

s390: simplify disabled_wait

2019-05-02T11:54:11+00:00

The disabled_wait() function uses its argument as the PSW address when
it stops the CPU with a wait PSW that is disabled for interrupts.
The different callers sometimes use a specific number like 0xdeadbeef
to indicate a specific failure, the early boot code uses 0 and some
other calls sites use __builtin_return_address(0).

At the time a dump is created the current PSW and the registers of a
CPU are written to lowcore to make them avaiable to the dump analysis
tool. For a CPU stopped with disabled_wait the PSW and the registers
do not really make sense together, the PSW address does not point to
the function the registers belong to.

Simplify disabled_wait() by using _THIS_IP_ for the PSW address and
drop the argument to the function.

Signed-off-by: Martin Schwidefsky

s390/unwind: introduce stack unwind API

2019-05-02T11:54:11+00:00

Rework the dump_trace() stack unwinder interface to support different
unwinding algorithms. The new interface looks like this:

	struct unwind_state state;
	unwind_for_each_frame(&state, task, regs, start_stack)
		do_something(state.sp, state.ip, state.reliable);

The unwind_bc.c file contains the implementation for the classic
back-chain unwinder.

One positive side effect of the new code is it now handles ftraced
functions gracefully. It prints the real name of the return function
instead of 'return_to_handler'.

Signed-off-by: Martin Schwidefsky

s390: make __load_psw_mask work with clang

2019-04-11T11:36:52+00:00

clang fails to use the %O and %R inline assembly modifiers
the same way as gcc, leading to build failures with every use
of __load_psw_mask():

/tmp/nmi-4a9f80.s: Assembler messages:
/tmp/nmi-4a9f80.s:571: Error: junk at end of line: `+8(160(%r11))'
/tmp/nmi-4a9f80.s:626: Error: junk at end of line: `+8(160(%r11))'

Replace these with a more conventional way of passing the addresses
that should work with both clang and gcc.

Signed-off-by: Arnd Bergmann 
Signed-off-by: Martin Schwidefsky

s390: fine-tune stack switch helper

2019-04-11T11:36:45+00:00

The CALL_ON_STACK helper currently does not work with clang and for
calls without arguments. It does not initialize r2 although the constraint
is "+&d". Rework the CALL_FMT_x and the CALL_ON_STACK macros to work
with clang and produce optimal code in all cases.

Reported-by: Arnd Bergmann 
Signed-off-by: Martin Schwidefsky