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authorPaul Mackerras <paulus@samba.org>2008-08-30 11:41:12 +1000
committerPaul Mackerras <paulus@samba.org>2008-09-15 11:08:35 -0700
commite31aa453bbc4886a7bd33e5c2afa526d6f55bd7a (patch)
treefefa13c13d7b1803fdaeb92143f83b1971f0ec8d /arch/powerpc/kernel/entry_64.S
parent1f6a93e4c35e75d547b51f56ba8139ab1a91628c (diff)
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>
Diffstat (limited to 'arch/powerpc/kernel/entry_64.S')
-rw-r--r--arch/powerpc/kernel/entry_64.S16
1 files changed, 7 insertions, 9 deletions
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index 55445f1dba8..fd8b4bae9b0 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -690,10 +690,6 @@ _GLOBAL(enter_rtas)
std r7,_DAR(r1)
mfdsisr r8
std r8,_DSISR(r1)
- mfsrr0 r9
- std r9,_SRR0(r1)
- mfsrr1 r10
- std r10,_SRR1(r1)
/* Temporary workaround to clear CR until RTAS can be modified to
* ignore all bits.
@@ -754,6 +750,10 @@ _STATIC(rtas_return_loc)
mfspr r4,SPRN_SPRG3 /* Get PACA */
clrldi r4,r4,2 /* convert to realmode address */
+ bcl 20,31,$+4
+0: mflr r3
+ ld r3,(1f-0b)(r3) /* get &.rtas_restore_regs */
+
mfmsr r6
li r0,MSR_RI
andc r6,r6,r0
@@ -761,7 +761,6 @@ _STATIC(rtas_return_loc)
mtmsrd r6
ld r1,PACAR1(r4) /* Restore our SP */
- LOAD_REG_IMMEDIATE(r3,.rtas_restore_regs)
ld r4,PACASAVEDMSR(r4) /* Restore our MSR */
mtspr SPRN_SRR0,r3
@@ -769,6 +768,9 @@ _STATIC(rtas_return_loc)
rfid
b . /* prevent speculative execution */
+ .align 3
+1: .llong .rtas_restore_regs
+
_STATIC(rtas_restore_regs)
/* relocation is on at this point */
REST_GPR(2, r1) /* Restore the TOC */
@@ -788,10 +790,6 @@ _STATIC(rtas_restore_regs)
mtdar r7
ld r8,_DSISR(r1)
mtdsisr r8
- ld r9,_SRR0(r1)
- mtsrr0 r9
- ld r10,_SRR1(r1)
- mtsrr1 r10
addi r1,r1,RTAS_FRAME_SIZE /* Unstack our frame */
ld r0,16(r1) /* get return address */