From c691b4b83b6a348f7b9d13c36916e73c2e1d85e4 Mon Sep 17 00:00:00 2001 From: Christophe Leroy Date: Tue, 20 Aug 2019 14:34:12 +0000 Subject: powerpc: rewrite LOAD_REG_IMMEDIATE() as an intelligent macro 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 Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/d60ce8dd3a383c7adbfc322bf1d53d81724a6000.1566311636.git.christophe.leroy@c-s.fr --- arch/powerpc/kernel/head_64.S | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/powerpc/kernel/head_64.S') 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: -- cgit v1.2.3-59-g8ed1b