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Subject[PATCH 1/2] powerpc: rewrite LOAD_REG_IMMEDIATE() as an intelligent macro
Date
Today LOAD_REG_IMMEDIATE() is a basic #define which loads all
parts on a value into a register, including the parts that are NUL.

This means always 2 instructions on PPC32 and always 5 instructions
on PPC64. And those instructions cannot run in parallele as they are
updating the same register.

Ex: LOAD_REG_IMMEDIATE(r1,THREAD_SIZE) in head_64.S results in:

3c 20 00 00 lis r1,0
60 21 00 00 ori r1,r1,0
78 21 07 c6 rldicr r1,r1,32,31
64 21 00 00 oris r1,r1,0
60 21 40 00 ori r1,r1,16384

Rewrite LOAD_REG_IMMEDIATE() with GAS macro in order to skip
the parts that are NUL.

Rename existing LOAD_REG_IMMEDIATE() as LOAD_REG_IMMEDIATE_SYM()
and use that one for loading value of symbols which are not known
at compile time.

Now LOAD_REG_IMMEDIATE(r1,THREAD_SIZE) in head_64.S results in:

38 20 40 00 li r1,16384

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
arch/powerpc/include/asm/ppc_asm.h | 42 +++++++++++++++++++++++++++++++-----
arch/powerpc/kernel/exceptions-64e.S | 10 ++++-----
arch/powerpc/kernel/head_64.S | 2 +-
3 files changed, 43 insertions(+), 11 deletions(-)

diff --git a/arch/powerpc/include/asm/ppc_asm.h b/arch/powerpc/include/asm/ppc_asm.h
index e0637730a8e7..9a7c2ca9b714 100644
--- a/arch/powerpc/include/asm/ppc_asm.h
+++ b/arch/powerpc/include/asm/ppc_asm.h
@@ -311,13 +311,43 @@ GLUE(.,name):
addis reg,reg,(name - 0b)@ha; \
addi reg,reg,(name - 0b)@l;

-#ifdef __powerpc64__
-#ifdef HAVE_AS_ATHIGH
+#if defined(__powerpc64__) && defined(HAVE_AS_ATHIGH)
#define __AS_ATHIGH high
#else
#define __AS_ATHIGH h
#endif
-#define LOAD_REG_IMMEDIATE(reg,expr) \
+
+.macro __LOAD_REG_IMMEDIATE_32 r, x
+ .if (\x) >= 0x8000 || (\x) < -0x8000
+ lis \r, (\x)@__AS_ATHIGH
+ .if (\x) & 0xffff != 0
+ ori \r, \r, (\x)@l
+ .endif
+ .else
+ li \r, (\x)@l
+ .endif
+.endm
+
+.macro __LOAD_REG_IMMEDIATE r, x
+ .if \x & ~0xffffffff != 0
+ __LOAD_REG_IMMEDIATE_32 \r, (\x) >> 32
+ rldicr \r, \r, 32, 31
+ .if (\x) & 0xffff0000 != 0
+ oris \r, \r, (\x)@__AS_ATHIGH
+ .endif
+ .if (\x) & 0xffff != 0
+ oris \r, \r, (\x)@l
+ .endif
+ .else
+ __LOAD_REG_IMMEDIATE_32 \r, \x
+ .endif
+.endm
+
+#ifdef __powerpc64__
+
+#define LOAD_REG_IMMEDIATE(reg, expr) __LOAD_REG_IMMEDIATE reg, expr
+
+#define LOAD_REG_IMMEDIATE_SYM(reg,expr) \
lis reg,(expr)@highest; \
ori reg,reg,(expr)@higher; \
rldicr reg,reg,32,31; \
@@ -335,11 +365,13 @@ GLUE(.,name):

#else /* 32-bit */

-#define LOAD_REG_IMMEDIATE(reg,expr) \
+#define LOAD_REG_IMMEDIATE(reg, expr) __LOAD_REG_IMMEDIATE_32 reg, expr
+
+#define LOAD_REG_IMMEDIATE_SYM(reg,expr) \
lis reg,(expr)@ha; \
addi reg,reg,(expr)@l;

-#define LOAD_REG_ADDR(reg,name) LOAD_REG_IMMEDIATE(reg, name)
+#define LOAD_REG_ADDR(reg,name) LOAD_REG_IMMEDIATE_SYM(reg, name)

#define LOAD_REG_ADDRBASE(reg, name) lis reg,name@ha
#define ADDROFF(name) name@l
diff --git a/arch/powerpc/kernel/exceptions-64e.S b/arch/powerpc/kernel/exceptions-64e.S
index 1cfb3da4a84a..898aae6da167 100644
--- a/arch/powerpc/kernel/exceptions-64e.S
+++ b/arch/powerpc/kernel/exceptions-64e.S
@@ -751,8 +751,8 @@ END_FTR_SECTION_IFSET(CPU_FTR_ALTIVEC)
ld r14,interrupt_base_book3e@got(r15)
ld r15,__end_interrupts@got(r15)
#else
- LOAD_REG_IMMEDIATE(r14,interrupt_base_book3e)
- LOAD_REG_IMMEDIATE(r15,__end_interrupts)
+ LOAD_REG_IMMEDIATE_SYM(r14,interrupt_base_book3e)
+ LOAD_REG_IMMEDIATE_SYM(r15,__end_interrupts)
#endif
cmpld cr0,r10,r14
cmpld cr1,r10,r15
@@ -821,8 +821,8 @@ kernel_dbg_exc:
ld r14,interrupt_base_book3e@got(r15)
ld r15,__end_interrupts@got(r15)
#else
- LOAD_REG_IMMEDIATE(r14,interrupt_base_book3e)
- LOAD_REG_IMMEDIATE(r15,__end_interrupts)
+ LOAD_REG_IMMEDIATE_SYM(r14,interrupt_base_book3e)
+ LOAD_REG_IMMEDIATE_SYM(r15,__end_interrupts)
#endif
cmpld cr0,r10,r14
cmpld cr1,r10,r15
@@ -1449,7 +1449,7 @@ a2_tlbinit_code_start:
a2_tlbinit_after_linear_map:

/* Now we branch the new virtual address mapped by this entry */
- LOAD_REG_IMMEDIATE(r3,1f)
+ LOAD_REG_IMMEDIATE_SYM(r3,1f)
mtctr r3
bctr

diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S
index 91d297e696dd..1fd44761e997 100644
--- a/arch/powerpc/kernel/head_64.S
+++ b/arch/powerpc/kernel/head_64.S
@@ -635,7 +635,7 @@ __after_prom_start:
sub r5,r5,r11
#else
/* just copy interrupts */
- LOAD_REG_IMMEDIATE(r5, FIXED_SYMBOL_ABS_ADDR(__end_interrupts))
+ LOAD_REG_IMMEDIATE_SYM(r5, FIXED_SYMBOL_ABS_ADDR(__end_interrupts))
#endif
b 5f
3:
--
2.13.3
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