Changeset a7961271 in mainline for kernel/arch/sparc64/src/trap/trap_table.S

Timestamp:

2006-08-26T18:42:11Z (18 years ago)

Author:

Jakub Jermar <jakub@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

c8ea4a8b

Parents:

f47fd19

Message:

sparc64 work.
Bunch of changes in preparation for sparc64 mm and userspace support.
Fix alignment of hardcoded_* variables in linker script.

File:

• kernel/arch/sparc64/src/trap/trap_table.S (modified) (9 diffs)

kernel/arch/sparc64/src/trap/trap_table.S

@@ -33 +33 @@
 .register %g2, #scratch
 .register %g3, #scratch
-.register %g6, #scratch
-.register %g7, #scratch 
 
 .text
@@ -204 +202 @@
 .global spill_0_normal
 spill_0_normal:
-        SPILL_NORMAL_HANDLER
+        SPILL_NORMAL_HANDLER_KERNEL
 
 /* TT = 0xc0, TL = 0, fill_0_normal handler */
@@ -210 +208 @@
 .global fill_0_normal
 fill_0_normal:
-        FILL_NORMAL_HANDLER
+        FILL_NORMAL_HANDLER_KERNEL
 
 /*
@@ -268 +266 @@
 .global spill_0_normal_high
 spill_0_normal_high:
-        SPILL_NORMAL_HANDLER
+        SPILL_NORMAL_HANDLER_KERNEL
 
 /* TT = 0xc0, TL > 0, fill_0_normal handler */
@@ -274 +272 @@
 .global fill_0_normal_high
 fill_0_normal_high:
-        FILL_NORMAL_HANDLER
+        FILL_NORMAL_HANDLER_KERNEL
 
 
@@ -280 +278 @@
  *
  * This trap handler makes arrangements to make calling of scheduler() from
- * within a trap context possible. It is guaranteed to function only when traps
- * are not nested (i.e. for TL=1).
+ * within a trap context possible. It is called from several other trap
+ * handlers.
  *
- * Every trap handler on TL=1 that makes a call to the scheduler needs to
- * be based on this function. The reason behind it is that the nested
- * trap levels and the automatic saving of the interrupted context by hardware
- * does not work well together with scheduling (i.e. a thread cannot be rescheduled
- * with TL>0). Therefore it is necessary to eliminate the effect of trap levels
- * by software and save the necessary state on the kernel stack.
- *
- * Note that for traps with TL>1, more state needs to be saved. This function
- * is therefore not going to work when TL>1.
- *
- * The caller is responsible for doing SAVE and allocating
- * PREEMPTIBLE_HANDLER_STACK_FRAME_SIZE bytes on the stack.
+ * This function can be entered either with interrupt globals or alternate globals.
+ * Memory management trap handlers are obliged to switch to one of those global sets
+ * prior to calling this function. Register window management functions are not
+ * allowed to modify the alternate global registers.
  *
  * Input registers:
- *      %l0             Address of function to call.
- * Output registers:
- *       %l1 - %l7      Copy of %g1 - %g7
+ *      %g1             Address of function to call.
+ *      %g2             Argument for the function.
+ *      %g6             Pre-set as kernel stack base if trap from userspace.
+ *      %g7             Reserved.
  */
 .global preemptible_handler
 preemptible_handler:
-        /*
-         * Save TSTATE, TPC, TNPC and PSTATE aside.
+        rdpr %tstate, %g3
+        andcc %g3, TSTATE_PRIV_BIT, %g0         ! if this trap came from the privileged mode...
+        bnz 0f                                  ! ...skip setting of kernel stack and primary context
+        nop
+
+        /*
+         * Switch to kernel stack. The old stack is
+         * automatically saved in the old window's %sp
+         * and the new window's %fp.
+         */
+        save %g6, -PREEMPTIBLE_HANDLER_STACK_FRAME_SIZE, %sp
+
+        /*
+         * Mark the CANSAVE windows as OTHER windows.
+         * Set CLEANWIN to NWINDOW-1 so that clean_window traps do not occur.
+         */
+        rdpr %cansave, %l0
+        wrpr %l0, %otherwin
+        wrpr %g0, %cansave
+        wrpr %g0, NWINDOW-1, %cleanwin
+
+        /*
+         * Switch to primary context 0.
+         */
+        mov VA_PRIMARY_CONTEXT_REG, %l0
+        stxa %g0, [%l0] ASI_DMMU
+        set kernel_image_start, %l0
+        flush %l0
+
+        ba 1f
+        nop
+
+0:
+        save %sp, -PREEMPTIBLE_HANDLER_STACK_FRAME_SIZE, %sp
+
+        /*
+         * At this moment, we are using the kernel stack 
+         * and have successfully allocated a register window.
+         */
+1:
+
+        /*
+         * Copy arguments.
+         */
+        mov %g1, %l0
+        mov %g2, %o0
+
+        /*
+         * Save TSTATE, TPC and TNPC aside.
          */
         rdpr %tstate, %g1
         rdpr %tpc, %g2
         rdpr %tnpc, %g3
-        rdpr %pstate, %g4
 
         /*
@@ -316 +353 @@
          * the kernel stack of THREAD locked in DTLB.
          */
-        stx %g1, [%fp + STACK_BIAS + SAVED_TSTATE]
-        stx %g2, [%fp + STACK_BIAS + SAVED_TPC]
-        stx %g3, [%fp + STACK_BIAS + SAVED_TNPC]
-        stx %g4, [%fp + STACK_BIAS + SAVED_PSTATE]
+        stx %g1, [%sp + PREEMPTIBLE_HANDLER_STACK_FRAME_SIZE + STACK_BIAS + SAVED_TSTATE]
+        stx %g2, [%sp + PREEMPTIBLE_HANDLER_STACK_FRAME_SIZE + STACK_BIAS + SAVED_TPC]
+        stx %g3, [%sp + PREEMPTIBLE_HANDLER_STACK_FRAME_SIZE + STACK_BIAS + SAVED_TNPC]
         
-        /*
-         * Write 0 to TL.
-         */
         wrpr %g0, 0, %tl
-        
-        /*
-         * Alter PSTATE.
-         * - switch to normal globals.
-         */
-        and %g4, ~(PSTATE_AG_BIT|PSTATE_IG_BIT|PSTATE_MG_BIT), %g4
-        wrpr %g4, 0, %pstate
-         
-        /*
-         * Save the normal globals.
-         */
+        wrpr %g0, PSTATE_PRIV_BIT, %pstate
         SAVE_GLOBALS
         
         /*
-         * Call the higher-level handler.
-         */
-        mov %fp, %o1                            ! calculate istate address
+         * Call the higher-level handler and pass istate as second parameter.
+         */
         call %l0
-        add %o1, STACK_BIAS + SAVED_PSTATE, %o1 ! calculate istate address
-        
-        /*
-         * Restore       the normal global register set.
-         */
+        add %sp, PREEMPTIBLE_HANDLER_STACK_FRAME_SIZE + STACK_BIAS + SAVED_TNPC, %o1
+
         RESTORE_GLOBALS
-        
-        /*
-         * Restore PSTATE from saved copy.
-         * Alternate/Interrupt/MM globals become active.
-         */
-        ldx [%fp + STACK_BIAS + SAVED_PSTATE], %l4
-        wrpr %l4, 0, %pstate
-        
-        /*
-         * Write 1 to TL.
-         */
+        wrpr %g0, PSTATE_AG_BIT | PSTATE_PRIV_BIT, %pstate
         wrpr %g0, 1, %tl
         
@@ -365 +374 @@
          * Read TSTATE, TPC and TNPC from saved copy.
          */
-        ldx [%fp + STACK_BIAS + SAVED_TSTATE], %g1
-        ldx [%fp + STACK_BIAS + SAVED_TPC], %g2
-        ldx [%fp + STACK_BIAS + SAVED_TNPC], %g3
-
-        /*
-         * Do restore to match the save instruction from the top-level handler.
-         */
-        restore
-
-        /*
-         * On execution of the RETRY instruction, CWP will be restored from the TSTATE
-         * register. However, because of scheduling, it is possible that CWP in the saved
-         * TSTATE is different from the current CWP. The following chunk of code fixes
-         * CWP in the saved copy of TSTATE.
-         */
-        rdpr %cwp, %g4          ! read current CWP
-        and %g1, ~0x1f, %g1     ! clear CWP field in saved TSTATE
-        or %g1, %g4, %g1        ! write current CWP to TSTATE
-        
+        ldx [%sp + PREEMPTIBLE_HANDLER_STACK_FRAME_SIZE + STACK_BIAS + SAVED_TSTATE], %g1
+        ldx [%sp + PREEMPTIBLE_HANDLER_STACK_FRAME_SIZE + STACK_BIAS + SAVED_TPC], %g2
+        ldx [%sp + PREEMPTIBLE_HANDLER_STACK_FRAME_SIZE + STACK_BIAS + SAVED_TNPC], %g3
+
         /*
          * Restore TSTATE, TPC and TNPC from saved copies.
@@ -390 +384 @@
         wrpr %g2, 0, %tpc
         wrpr %g3, 0, %tnpc
-         
-        /*
-         * Return from interrupt.
-         */
+
+        /*
+         * If OTHERWIN is zero, then all the userspace windows have been
+         * spilled to kernel memory (i.e. register window buffer). If
+         * OTHERWIN is non-zero, then some userspace windows are still
+         * valid. Others might have been spilled. However, the CWP pointer
+         * needs no fixing because the scheduler had not been called.
+         */
+        rdpr %otherwin, %l0
+        brnz %l0, 0f
+        nop
+
+        /*
+         * OTHERWIN == 0
+         */
+
+        /*
+         * If TSTATE.CWP + 1 == CWP, then we still do not have to fix CWP.
+         */
+        and %g1, TSTATE_CWP_MASK, %l0
+        inc %l0
+        and %l0, TSTATE_CWP_MASK, %l0   ! %l0 mod NWINDOW
+        rdpr %cwp, %l1
+        cmp %l0, %l1
+        bz 0f                           ! CWP is ok
+        nop
+
+        /*
+         * Fix CWP.
+         */
+        mov %fp, %g1
+        flushw
+        wrpr %l0, 0, %cwp
+        mov %g1, %fp
+        
+        /*
+         * OTHERWIN != 0 or fall-through from the OTHERWIN == 0 case.
+         */
+0:
+        ! TODO: restore register windows from register window memory buffer
+
+        restore
         retry