Merge branch 'linux-2.6'

1 files changed, 198 insertions, 0 deletions

diff --git a/arch/sh/kernel/cpu/sh5/switchto.S b/arch/sh/kernel/cpu/sh5/switchto.S
new file mode 100644
index 000000000000..45c351b0f1ba
--- /dev/null
+++ b/arch/sh/kernel/cpu/sh5/switchto.S
@@ -0,0 +1,198 @@
+/*
+ * arch/sh/kernel/cpu/sh5/switchto.S
+ *
+ * sh64 context switch
+ *
+ * Copyright (C) 2004  Richard Curnow
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+*/
+
+        .section .text..SHmedia32,"ax"
+        .little
+
+        .balign 32
+
+        .type sh64_switch_to,@function
+        .global sh64_switch_to
+        .global __sh64_switch_to_end
+sh64_switch_to:
+
+/* Incoming args
+   r2 - prev
+   r3 - &prev->thread
+   r4 - next
+   r5 - &next->thread
+
+   Outgoing results
+   r2 - last (=prev) : this just stays in r2 throughout
+
+   Want to create a full (struct pt_regs) on the stack to allow backtracing
+   functions to work.  However, we only need to populate the callee-save
+   register slots in this structure; since we're a function our ancestors must
+   have themselves preserved all caller saved state in the stack.  This saves
+   some wasted effort since we won't need to look at the values.
+
+   In particular, all caller-save registers are immediately available for
+   scratch use.
+
+*/
+
+#define FRAME_SIZE (76*8 + 8)
+
+        movi    FRAME_SIZE, r0
+        sub.l   r15, r0, r15
+        ! Do normal-style register save to support backtrace
+
+        st.l    r15,   0, r18   ! save link reg
+        st.l    r15,   4, r14   ! save fp
+        add.l   r15, r63, r14   ! setup frame pointer
+
+        ! hopefully this looks normal to the backtrace now.
+
+        addi.l  r15,   8, r1    ! base of pt_regs
+        addi.l  r1,   24, r0    ! base of pt_regs.regs
+        addi.l  r0, (63*8), r8  ! base of pt_regs.trregs
+
+        /* Note : to be fixed?
+           struct pt_regs is really designed for holding the state on entry
+           to an exception, i.e. pc,sr,regs etc.  However, for the context
+           switch state, some of this is not required.  But the unwinder takes
+           struct pt_regs * as an arg so we have to build this structure
+           to allow unwinding switched tasks in show_state() */
+
+        st.q    r0, ( 9*8), r9
+        st.q    r0, (10*8), r10
+        st.q    r0, (11*8), r11
+        st.q    r0, (12*8), r12
+        st.q    r0, (13*8), r13
+        st.q    r0, (14*8), r14 ! for unwind, want to look as though we took a trap at
+        ! the point where the process is left in suspended animation, i.e. current
+        ! fp here, not the saved one.
+        st.q    r0, (16*8), r16
+
+        st.q    r0, (24*8), r24
+        st.q    r0, (25*8), r25
+        st.q    r0, (26*8), r26
+        st.q    r0, (27*8), r27
+        st.q    r0, (28*8), r28
+        st.q    r0, (29*8), r29
+        st.q    r0, (30*8), r30
+        st.q    r0, (31*8), r31
+        st.q    r0, (32*8), r32
+        st.q    r0, (33*8), r33
+        st.q    r0, (34*8), r34
+        st.q    r0, (35*8), r35
+
+        st.q    r0, (44*8), r44
+        st.q    r0, (45*8), r45
+        st.q    r0, (46*8), r46
+        st.q    r0, (47*8), r47
+        st.q    r0, (48*8), r48
+        st.q    r0, (49*8), r49
+        st.q    r0, (50*8), r50
+        st.q    r0, (51*8), r51
+        st.q    r0, (52*8), r52
+        st.q    r0, (53*8), r53
+        st.q    r0, (54*8), r54
+        st.q    r0, (55*8), r55
+        st.q    r0, (56*8), r56
+        st.q    r0, (57*8), r57
+        st.q    r0, (58*8), r58
+        st.q    r0, (59*8), r59
+
+        ! do this early as pta->gettr has no pipeline forwarding (=> 5 cycle latency)
+        ! Use a local label to avoid creating a symbol that will confuse the !
+        ! backtrace
+        pta     .Lsave_pc, tr0
+
+        gettr   tr5, r45
+        gettr   tr6, r46
+        gettr   tr7, r47
+        st.q    r8, (5*8), r45
+        st.q    r8, (6*8), r46
+        st.q    r8, (7*8), r47
+
+        ! Now switch context
+        gettr   tr0, r9
+        st.l    r3, 0, r15      ! prev->thread.sp
+        st.l    r3, 8, r1       ! prev->thread.kregs
+        st.l    r3, 4, r9       ! prev->thread.pc
+        st.q    r1, 0, r9       ! save prev->thread.pc into pt_regs->pc
+
+        ! Load PC for next task (init value or save_pc later)
+        ld.l    r5, 4, r18      ! next->thread.pc
+        ! Switch stacks
+        ld.l    r5, 0, r15      ! next->thread.sp
+        ptabs   r18, tr0
+
+        ! Update current
+        ld.l    r4, 4, r9       ! next->thread_info (2nd element of next task_struct)
+        putcon  r9, kcr0        ! current = next->thread_info
+
+        ! go to save_pc for a reschedule, or the initial thread.pc for a new process
+        blink   tr0, r63
+
+        ! Restore (when we come back to a previously saved task)
+.Lsave_pc:
+        addi.l  r15, 32, r0     ! r0 = next's regs
+        addi.l  r0, (63*8), r8  ! r8 = next's tr_regs
+
+        ld.q    r8, (5*8), r45
+        ld.q    r8, (6*8), r46
+        ld.q    r8, (7*8), r47
+        ptabs   r45, tr5
+        ptabs   r46, tr6
+        ptabs   r47, tr7
+
+        ld.q    r0, ( 9*8), r9
+        ld.q    r0, (10*8), r10
+        ld.q    r0, (11*8), r11
+        ld.q    r0, (12*8), r12
+        ld.q    r0, (13*8), r13
+        ld.q    r0, (14*8), r14
+        ld.q    r0, (16*8), r16
+
+        ld.q    r0, (24*8), r24
+        ld.q    r0, (25*8), r25
+        ld.q    r0, (26*8), r26
+        ld.q    r0, (27*8), r27
+        ld.q    r0, (28*8), r28
+        ld.q    r0, (29*8), r29
+        ld.q    r0, (30*8), r30
+        ld.q    r0, (31*8), r31
+        ld.q    r0, (32*8), r32
+        ld.q    r0, (33*8), r33
+        ld.q    r0, (34*8), r34
+        ld.q    r0, (35*8), r35
+
+        ld.q    r0, (44*8), r44
+        ld.q    r0, (45*8), r45
+        ld.q    r0, (46*8), r46
+        ld.q    r0, (47*8), r47
+        ld.q    r0, (48*8), r48
+        ld.q    r0, (49*8), r49
+        ld.q    r0, (50*8), r50
+        ld.q    r0, (51*8), r51
+        ld.q    r0, (52*8), r52
+        ld.q    r0, (53*8), r53
+        ld.q    r0, (54*8), r54
+        ld.q    r0, (55*8), r55
+        ld.q    r0, (56*8), r56
+        ld.q    r0, (57*8), r57
+        ld.q    r0, (58*8), r58
+        ld.q    r0, (59*8), r59
+
+        ! epilogue
+        ld.l    r15, 0, r18
+        ld.l    r15, 4, r14
+        ptabs   r18, tr0
+        movi    FRAME_SIZE, r0
+        add     r15, r0, r15
+        blink   tr0, r63
+__sh64_switch_to_end:
+.LFE1:
+        .size   sh64_switch_to,.LFE1-sh64_switch_to
+