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| author | Christophe Leroy <christophe.leroy@c-s.fr> | 2019-08-20 16:34:12 +0200 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2019-08-27 05:03:36 +0200 |
| commit | c691b4b83b6a348f7b9d13c36916e73c2e1d85e4 (patch) | |
| tree | 86e35a779a1f8eea5dfa32654d4afff910c32aa5 /arch/powerpc/kernel/head_64.S | |
| parent | powerpc/mm: split out early ioremap path. (diff) | |
| download | linux-c691b4b83b6a348f7b9d13c36916e73c2e1d85e4.tar.xz linux-c691b4b83b6a348f7b9d13c36916e73c2e1d85e4.zip | |
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 <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/d60ce8dd3a383c7adbfc322bf1d53d81724a6000.1566311636.git.christophe.leroy@c-s.fr
Diffstat (limited to 'arch/powerpc/kernel/head_64.S')
| -rw-r--r-- | arch/powerpc/kernel/head_64.S | 2 |
1 files changed, 1 insertions, 1 deletions
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: |