powerpc: Use LOAD_REG_IMMEDIATE only for constants on 64-bit
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>
diff --git a/arch/powerpc/kernel/misc.S b/arch/powerpc/kernel/misc.S
index 85cb6f3..2d29752 100644
--- a/arch/powerpc/kernel/misc.S
+++ b/arch/powerpc/kernel/misc.S
@@ -31,11 +31,14 @@
mflr r0
bl 1f
1: mflr r3
- LOAD_REG_IMMEDIATE(r4,1b)
+ PPC_LL r4,(2f-1b)(r3)
subf r3,r4,r3
mtlr r0
blr
+ .align 3
+2: PPC_LONG 1b
+
/*
* add_reloc_offset(x) returns x + reloc_offset().
*/
@@ -43,12 +46,15 @@
mflr r0
bl 1f
1: mflr r5
- LOAD_REG_IMMEDIATE(r4,1b)
+ PPC_LL r4,(2f-1b)(r5)
subf r5,r4,r5
add r3,r3,r5
mtlr r0
blr
+ .align 3
+2: PPC_LONG 1b
+
_GLOBAL(kernel_execve)
li r0,__NR_execve
sc
