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powerpc: Use LOAD_REG_IMMEDIATE only for constants on 64-bit

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Using LOAD_REG_IMMEDIATE to get the address of kernel symbols
generates 5 instructions where LOAD_REG_ADDR can do it in one,
and will generate R_PPC64_ADDR16_* relocations in the output when
we get to making the kernel as a position-independent executable,
which we'd rather not have to handle.  This changes various bits
of assembly code to use LOAD_REG_ADDR when we need to get the
address of a symbol, or to use suitable position-independent code
for cases where we can't access the TOC for various reasons, or
if we're not running at the address we were linked at.

It also cleans up a few minor things; there's no reason to save and
restore SRR0/1 around RTAS calls, __mmu_off can get the return
address from LR more conveniently than the caller can supply it in
R4 (and we already assume elsewhere that EA == RA if the MMU is on
in early boot), and enable_64b_mode was using 5 instructions where
2 would do.

Signed-off-by: Paul Mackerras <paulus@samba.org>
This commit is contained in:
Paul Mackerras
2008-08-30 11:41:12 +10:00
parent 1f6a93e4c3
commit e31aa453bb
6 changed files with 111 additions and 127 deletions
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4
arch/powerpc/kernel/cpu_setup_ppc970.S
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@@ -110,7 +110,7 @@ load_hids:
isync
/* Save away cpu state */
LOAD_REG_IMMEDIATE(r5,cpu_state_storage)
LOAD_REG_ADDR(r5,cpu_state_storage)
/* Save HID0,1,4 and 5 */
mfspr r3,SPRN_HID0
@@ -134,7 +134,7 @@ _GLOBAL(__restore_cpu_ppc970)
rldicl. r0,r0,4,63
beqlr
LOAD_REG_IMMEDIATE(r5,cpu_state_storage)
LOAD_REG_ADDR(r5,cpu_state_storage)
/* Before accessing memory, we make sure rm_ci is clear */
li r0,0
mfspr r3,SPRN_HID4