Merge remote-tracking branch 'arm64/for-next/neon-softirqs-disabled' into kvmarm...

Signed-off-by: Marc Zyngier <maz@kernel.org>

diff --cc arch/arm64/include/asm/assembler.h
index 34ddd8a,6ac38f7..ad9ccc4
--- 1/arch/arm64/include/asm/assembler.h
--- 2/arch/arm64/include/asm/assembler.h
+++ b/arch/arm64/include/asm/assembler.h
@@@ -15,7 -15,7 +15,8 @@@
  #include <asm-generic/export.h>
  
  #include <asm/asm-offsets.h>
+ #include <asm/alternative.h>
 +#include <asm/asm-bug.h>
  #include <asm/cpufeature.h>
  #include <asm/cputype.h>
  #include <asm/debug-monitors.h>
@@@ -705,95 -701,25 +714,33 @@@ USER(\label, ic ivau, \tmp2)                    // inval
        isb
  .endm
  
- /*
-  * Check whether to yield to another runnable task from kernel mode NEON code
-  * (which runs with preemption disabled).
-  *
-  * if_will_cond_yield_neon
-  *        // pre-yield patchup code
-  * do_cond_yield_neon
-  *        // post-yield patchup code
-  * endif_yield_neon    <label>
-  *
-  * where <label> is optional, and marks the point where execution will resume
-  * after a yield has been performed. If omitted, execution resumes right after
-  * the endif_yield_neon invocation. Note that the entire sequence, including
-  * the provided patchup code, will be omitted from the image if
-  * CONFIG_PREEMPTION is not defined.
-  *
-  * As a convenience, in the case where no patchup code is required, the above
-  * sequence may be abbreviated to
-  *
-  * cond_yield_neon <label>
-  *
-  * Note that the patchup code does not support assembler directives that change
-  * the output section, any use of such directives is undefined.
-  *
-  * The yield itself consists of the following:
-  * - Check whether the preempt count is exactly 1 and a reschedule is also
-  *   needed. If so, calling of preempt_enable() in kernel_neon_end() will
-  *   trigger a reschedule. If it is not the case, yielding is pointless.
-  * - Disable and re-enable kernel mode NEON, and branch to the yield fixup
-  *   code.
-  *
-  * This macro sequence may clobber all CPU state that is not guaranteed by the
-  * AAPCS to be preserved across an ordinary function call.
-  */
- 
-       .macro          cond_yield_neon, lbl
-       if_will_cond_yield_neon
-       do_cond_yield_neon
-       endif_yield_neon        \lbl
-       .endm
- 
-       .macro          if_will_cond_yield_neon
- #ifdef CONFIG_PREEMPTION
-       get_current_task        x0
-       ldr             x0, [x0, #TSK_TI_PREEMPT]
-       sub             x0, x0, #PREEMPT_DISABLE_OFFSET
-       cbz             x0, .Lyield_\@
-       /* fall through to endif_yield_neon */
-       .subsection     1
- .Lyield_\@ :
- #else
-       .section        ".discard.cond_yield_neon", "ax"
- #endif
-       .endm
- 
-       .macro          do_cond_yield_neon
-       bl              kernel_neon_end
-       bl              kernel_neon_begin
-       .endm
- 
-       .macro          endif_yield_neon, lbl
-       .ifnb           \lbl
-       b               \lbl
-       .else
-       b               .Lyield_out_\@
-       .endif
-       .previous
- .Lyield_out_\@ :
-       .endm
- 
 +.macro set_sctlr_el1, reg
 +      set_sctlr sctlr_el1, \reg
 +.endm
 +
 +.macro set_sctlr_el2, reg
 +      set_sctlr sctlr_el2, \reg
 +.endm
 +
        /*
-        * Check whether preempt-disabled code should yield as soon as it
-        * is able. This is the case if re-enabling preemption a single
-        * time results in a preempt count of zero, and the TIF_NEED_RESCHED
-        * flag is set. (Note that the latter is stored negated in the
-        * top word of the thread_info::preempt_count field)
+        * Check whether preempt/bh-disabled asm code should yield as soon as
+        * it is able. This is the case if we are currently running in task
+        * context, and either a softirq is pending, or the TIF_NEED_RESCHED
+        * flag is set and re-enabling preemption a single time would result in
+        * a preempt count of zero. (Note that the TIF_NEED_RESCHED flag is
+        * stored negated in the top word of the thread_info::preempt_count
+        * field)
         */
-       .macro          cond_yield, lbl:req, tmp:req
- #ifdef CONFIG_PREEMPTION
+       .macro          cond_yield, lbl:req, tmp:req, tmp2:req
        get_current_task \tmp
        ldr             \tmp, [\tmp, #TSK_TI_PREEMPT]
+       /*
+        * If we are serving a softirq, there is no point in yielding: the
+        * softirq will not be preempted no matter what we do, so we should
+        * run to completion as quickly as we can.
+        */
+       tbnz            \tmp, #SOFTIRQ_SHIFT, .Lnoyield_\@
+ #ifdef CONFIG_PREEMPTION
        sub             \tmp, \tmp, #PREEMPT_DISABLE_OFFSET
        cbz             \tmp, \lbl
  #endif

diff --cc arch/arm64/kernel/asm-offsets.c
Simple merge