Changeset 7ba7c6d in mainline for kernel/arch/sparc64/src

Timestamp:

2006-10-08T20:09:28Z (19 years ago)

Author:

Jakub Jermar <jakub@…>

Branches:

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

Children:

e4398200

Parents:

64c2ad5

Message:

A quote from from SPARC V9 specification:

The Y register is deprecated; it is provided only for compatibility with previous versions
of the architecture. It should not be used in new SPARC-V9 software. It is
recommended that all instructions that reference the Y register (i.e., SMUL,
SMULcc, UMUL, UMULcc, MULScc, SDIV, SDIVcc, UDIV, UDIVcc, RDY, and
WRY) be avoided. See the appropriate pages in Appendix A, “Instruction Definitions,”
for suitable substitute instructions.

Still gcc is generating code which uses Y and some of the instructions above.
This change modifies the preemptible_handler() to preserve the Y register
across preemption.

Location:

kernel/arch/sparc64/src

Files:

• dummy.s (modified) (1 diff)
• trap/trap_table.S (modified) (2 diffs)

kernel/arch/sparc64/src/dummy.s

@@ -34 +34 @@
 .global dummy
 
-cpu_sleep:
-sys_tls_set:
+cpu_sleep:              ! not supported by architecture
+sys_tls_set:            ! not needed on architecture
 
 dummy:

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

@@ -747 +747 @@
         stx %g2, [%sp + PREEMPTIBLE_HANDLER_STACK_FRAME_SIZE + STACK_BIAS + SAVED_TPC]
         stx %g3, [%sp + PREEMPTIBLE_HANDLER_STACK_FRAME_SIZE + STACK_BIAS + SAVED_TNPC]
+
+        /*
+         * Save the Y register.
+         * This register is deprecated according to SPARC V9 specification
+         * and is only present for backward compatibility with previous
+         * versions of the SPARC architecture.
+         * Surprisingly, gcc makes use of this register without a notice.
+         */
+        rd %y, %g4
+        stx %g4, [%sp + PREEMPTIBLE_HANDLER_STACK_FRAME_SIZE + STACK_BIAS + SAVED_Y]
         
         wrpr %g0, 0, %tl
@@ -776 +786 @@
         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 Y.
+         */
+        ldx [%sp + PREEMPTIBLE_HANDLER_STACK_FRAME_SIZE + STACK_BIAS + SAVED_Y], %g4
+        wr %g4, %y
 
         /*