[PATCH] powerpc: Cleanup LOADADDR etc. asm macros
This patch consolidates the variety of macros used for loading 32 or
64-bit constants in assembler (LOADADDR, LOADBASE, SET_REG_TO_*). The
idea is to make the set of macros consistent across 32 and 64 bit and
to make it more obvious which is the appropriate one to use in a given
situation. The new macros and their semantics are described in the
comments in ppc_asm.h.
In the process, we change several places that were unnecessarily using
immediate loads on ppc64 to use the GOT/TOC. Likewise we cleanup a
couple of places where we were clumsily subtracting PAGE_OFFSET with
asm instructions to use assemble-time arithmetic or the toreal() macro
instead.
Signed-off-by: David Gibson <dwg@au1.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/include/asm-powerpc/ppc_asm.h b/include/asm-powerpc/ppc_asm.h
index 0dc798d..ab8688d 100644
--- a/include/asm-powerpc/ppc_asm.h
+++ b/include/asm-powerpc/ppc_asm.h
@@ -156,52 +156,56 @@
#endif
/*
- * LOADADDR( rn, name )
- * loads the address of 'name' into 'rn'
+ * LOAD_REG_IMMEDIATE(rn, expr)
+ * Loads the value of the constant expression 'expr' into register 'rn'
+ * using immediate instructions only. Use this when it's important not
+ * to reference other data (i.e. on ppc64 when the TOC pointer is not
+ * valid).
*
- * LOADBASE( rn, name )
- * loads the address (possibly without the low 16 bits) of 'name' into 'rn'
- * suitable for base+disp addressing
+ * LOAD_REG_ADDR(rn, name)
+ * Loads the address of label 'name' into register 'rn'. Use this when
+ * you don't particularly need immediate instructions only, but you need
+ * the whole address in one register (e.g. it's a structure address and
+ * you want to access various offsets within it). On ppc32 this is
+ * identical to LOAD_REG_IMMEDIATE.
+ *
+ * LOAD_REG_ADDRBASE(rn, name)
+ * ADDROFF(name)
+ * LOAD_REG_ADDRBASE loads part of the address of label 'name' into
+ * register 'rn'. ADDROFF(name) returns the remainder of the address as
+ * a constant expression. ADDROFF(name) is a signed expression < 16 bits
+ * in size, so is suitable for use directly as an offset in load and store
+ * instructions. Use this when loading/storing a single word or less as:
+ * LOAD_REG_ADDRBASE(rX, name)
+ * ld rY,ADDROFF(name)(rX)
*/
#ifdef __powerpc64__
-#define LOADADDR(rn,name) \
- lis rn,name##@highest; \
- ori rn,rn,name##@higher; \
- rldicr rn,rn,32,31; \
- oris rn,rn,name##@h; \
- ori rn,rn,name##@l
+#define LOAD_REG_IMMEDIATE(reg,expr) \
+ lis (reg),(expr)@highest; \
+ ori (reg),(reg),(expr)@higher; \
+ rldicr (reg),(reg),32,31; \
+ oris (reg),(reg),(expr)@h; \
+ ori (reg),(reg),(expr)@l;
-#define LOADBASE(rn,name) \
- ld rn,name@got(r2)
+#define LOAD_REG_ADDR(reg,name) \
+ ld (reg),name@got(r2)
-#define OFF(name) 0
-
-#define SET_REG_TO_CONST(reg, value) \
- lis reg,(((value)>>48)&0xFFFF); \
- ori reg,reg,(((value)>>32)&0xFFFF); \
- rldicr reg,reg,32,31; \
- oris reg,reg,(((value)>>16)&0xFFFF); \
- ori reg,reg,((value)&0xFFFF);
-
-#define SET_REG_TO_LABEL(reg, label) \
- lis reg,(label)@highest; \
- ori reg,reg,(label)@higher; \
- rldicr reg,reg,32,31; \
- oris reg,reg,(label)@h; \
- ori reg,reg,(label)@l;
+#define LOAD_REG_ADDRBASE(reg,name) LOAD_REG_ADDR(reg,name)
+#define ADDROFF(name) 0
/* offsets for stack frame layout */
#define LRSAVE 16
#else /* 32-bit */
-#define LOADADDR(rn,name) \
- lis rn,name@ha; \
- addi rn,rn,name@l
-#define LOADBASE(rn,name) \
- lis rn,name@ha
+#define LOAD_REG_IMMEDIATE(reg,expr) \
+ lis (reg),(expr)@ha; \
+ addi (reg),(reg),(expr)@l;
-#define OFF(name) name@l
+#define LOAD_REG_ADDR(reg,name) LOAD_REG_IMMEDIATE(reg, name)
+
+#define LOAD_REG_ADDRBASE(reg, name) lis (reg),name@ha
+#define ADDROFF(name) name@l
/* offsets for stack frame layout */
#define LRSAVE 4