1 files changed, 136 insertions, 0 deletions

diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h
index 053d83e8db6f..0bcc98dbba56 100644
--- a/arch/arm64/include/asm/assembler.h
+++ b/arch/arm64/include/asm/assembler.h
@@ -565,4 +565,140 @@ USER(\label, ic	ivau, \tmp2)			// invalidate I line PoU
 #endif
         .endm
 
+        /*
+         * frame_push - Push @regcount callee saved registers to the stack,
+         *              starting at x19, as well as x29/x30, and set x29 to
+         *              the new value of sp. Add @extra bytes of stack space
+         *              for locals.
+         */
+        .macro          frame_push, regcount:req, extra
+        __frame         st, \regcount, \extra
+        .endm
+
+        /*
+         * frame_pop  - Pop the callee saved registers from the stack that were
+         *              pushed in the most recent call to frame_push, as well
+         *              as x29/x30 and any extra stack space that may have been
+         *              allocated.
+         */
+        .macro          frame_pop
+        __frame         ld
+        .endm
+
+        .macro          __frame_regs, reg1, reg2, op, num
+        .if             .Lframe_regcount == \num
+        \op\()r         \reg1, [sp, #(\num + 1) * 8]
+        .elseif         .Lframe_regcount > \num
+        \op\()p         \reg1, \reg2, [sp, #(\num + 1) * 8]
+        .endif
+        .endm
+
+        .macro          __frame, op, regcount, extra=0
+        .ifc            \op, st
+        .if             (\regcount) < 0 || (\regcount) > 10
+        .error          "regcount should be in the range [0 ... 10]"
+        .endif
+        .if             ((\extra) % 16) != 0
+        .error          "extra should be a multiple of 16 bytes"
+        .endif
+        .ifdef          .Lframe_regcount
+        .if             .Lframe_regcount != -1
+        .error          "frame_push/frame_pop may not be nested"
+        .endif
+        .endif
+        .set            .Lframe_regcount, \regcount
+        .set            .Lframe_extra, \extra
+        .set            .Lframe_local_offset, ((\regcount + 3) / 2) * 16
+        stp             x29, x30, [sp, #-.Lframe_local_offset - .Lframe_extra]!
+        mov             x29, sp
+        .endif
+
+        __frame_regs    x19, x20, \op, 1
+        __frame_regs    x21, x22, \op, 3
+        __frame_regs    x23, x24, \op, 5
+        __frame_regs    x25, x26, \op, 7
+        __frame_regs    x27, x28, \op, 9
+
+        .ifc            \op, ld
+        .if             .Lframe_regcount == -1
+        .error          "frame_push/frame_pop may not be nested"
+        .endif
+        ldp             x29, x30, [sp], #.Lframe_local_offset + .Lframe_extra
+        .set            .Lframe_regcount, -1
+        .endif
+        .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_PREEMPT
+ * 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, in which case disabling
+ *   preemption once will make the task preemptible. If this is not the case,
+ *   yielding is pointless.
+ * - Check whether TIF_NEED_RESCHED is set, and if so, disable and re-enable
+ *   kernel mode NEON (which will trigger a reschedule), 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_PREEMPT
+        get_thread_info x0
+        ldr             w1, [x0, #TSK_TI_PREEMPT]
+        ldr             x0, [x0, #TSK_TI_FLAGS]
+        cmp             w1, #PREEMPT_DISABLE_OFFSET
+        csel            x0, x0, xzr, eq
+        tbnz            x0, #TIF_NEED_RESCHED, .Lyield_\@       // needs rescheduling?
+        /* 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
+
 #endif  /* __ASM_ASSEMBLER_H */