Changeset 414f59c in mainline

Timestamp:

2005-12-01T20:27:22Z (19 years ago)

Author:

Jakub Jermar <jakub@…>

Branches:

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

Children:

8ac5fe7

Parents:

22e10ab

Message:

sparc64 work.
The context_save/context_restore needed two other improvements.
First, storing of %fp because of window_fills.
Second, flushing all active windows before CONTEXT_LOAD to make CWP - 1 the overlap window.

Files:

• arch/sparc64/include/context.h (modified) (2 diffs)
• arch/sparc64/include/context_offset.h (modified) (1 diff)
• arch/sparc64/src/context.S (modified) (2 diffs)
• tools/sparc64/gencontext.c (modified) (1 diff)

arch/sparc64/include/context.h

@@ -48 +48 @@
 #endif
 
-#define context_set(c, _pc, stack, size)                                                                \
-        (c)->pc = ((__address) _pc) - 8;                                                                \
-        (c)->sp = ((__address) stack) + ALIGN((size), STACK_ALIGNMENT) - (STACK_BIAS + SP_DELTA)
+#define context_set(c, _pc, stack, size)                                                                \
+        (c)->pc = ((__address) _pc) - 8;                                                                \
+        (c)->sp = ((__address) stack) + ALIGN((size), STACK_ALIGNMENT) - (STACK_BIAS + SP_DELTA);       \
+        (c)->fp = -STACK_BIAS
+        
 
 /*
@@ -65 +67 @@
         __address sp;           /* %o6 */
         __address pc;           /* %o7 */
+        __address fp;
         ipl_t ipl;
 };

arch/sparc64/include/context_offset.h

@@ -8 +8 @@
 #define OFFSET_SP  0x28
 #define OFFSET_PC  0x30
+#define OFFSET_FP  0x38

arch/sparc64/src/context.S

@@ -29 +29 @@
 #include <arch/context_offset.h>
 #include <arch/stack.h>
+
+/**
+ * Both context_save_arch() and context_restore_arch() are
+ * leaf-optimized procedures. Both of them touch %sp and
+ * %fp and thus break SCD 2.4 compliance. However, these
+ * functions are special enough to be allowed this
+ * kind of behavior. Moreover, this kind of optimization
+ * is very important and prevents any window spill/
+ * fill/clean traps in these very core kernel functions.
+ */
         
 .text   
@@ -36 +46 @@
 
 .macro CONTEXT_STORE r
-        stx %o1, [\r + OFFSET_I1]
-        stx %o2, [\r + OFFSET_I2]
-        stx %o3, [\r + OFFSET_I3]
-        stx %o4, [\r + OFFSET_I4]
-        stx %o5, [\r + OFFSET_I5]
+        stx %o1, [\r + OFFSET_O1]
+        stx %o2, [\r + OFFSET_O2]
+        stx %o3, [\r + OFFSET_O3]
+        stx %o4, [\r + OFFSET_O4]
+        stx %o5, [\r + OFFSET_O5]
         stx %o7, [\r + OFFSET_PC]
         stx %sp, [\r + OFFSET_SP]
+        stx %fp, [\r + OFFSET_FP]
 .endm
 
 .macro CONTEXT_LOAD r
-        ldx [\r + OFFSET_I1], %o1
-        ldx [\r + OFFSET_I2], %o2
-        ldx [\r + OFFSET_I3], %o3
-        ldx [\r + OFFSET_I4], %o4
-        ldx [\r + OFFSET_I5], %o5
+        ldx [\r + OFFSET_O1], %o1
+        ldx [\r + OFFSET_O2], %o2
+        ldx [\r + OFFSET_O3], %o3
+        ldx [\r + OFFSET_O4], %o4
+        ldx [\r + OFFSET_O5], %o5
         ldx [\r + OFFSET_PC], %o7
         ldx [\r + OFFSET_SP], %sp
+        ldx [\r + OFFSET_FP], %fp
 .endm
 
-        
 context_save_arch:
         CONTEXT_STORE %o0
-
-        # context_save returns 1
         retl
-        mov 1, %o0
+        mov 1, %o0              ! context_save_arch returns 1
 
 context_restore_arch:
+        #
+        # Flush all active windows.
+        # This is essential, because CONTEXT_LOAD overwrites
+        # %sp of CWP - 1 with the value written to %fp of CWP.
+        # Flushing all active windows mitigates this problem
+        # as CWP - 1 becomes the overlap window.
+        #
+        flushw
+        
         CONTEXT_LOAD %o0
-
-        # context_restore returns 0
         retl
-        xor %o0, %o0, %o0
+        xor %o0, %o0, %o0       ! context_restore_arch returns 0

tools/sparc64/gencontext.c

@@ -35 +35 @@
         fprintf(f,"#define OFFSET_SP  0x%x\n",((int)&pctx->sp) - (int )pctx);
         fprintf(f,"#define OFFSET_PC  0x%x\n",((int)&pctx->pc) - (int )pctx);
+        fprintf(f,"#define OFFSET_FP  0x%x\n",((int)&pctx->fp) - (int )pctx);
 
         fclose(f);