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MIPS: start.S: simplify relocation offset calculation

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The current code uses four instructions and a
temporary register to calculate the relocation
offset and to adjust the gp register.

The relocation offset can be calculated directly
from the CONFIG_SYS_MONITOR_BASE constant and from
the destination address. The resulting offset can
be used to adjust the gp pointer.

This approach makes the code a bit simpler because
it needs two instructions only.

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Cc: Daniel Schwierzeck <daniel.schwierzeck@googlemail.com>
This commit is contained in:
Gabor Juhos 2013-01-24 06:27:54 +00:00 • committed by Daniel Schwierzeck
parent b2fe86f887
commit 248fe03f53
2 changed files with 6 additions and 18 deletions
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12
arch/mips/cpu/mips32/start.S
View file

@ -283,19 +283,13 @@ relocate_code:
move s2, a2 # save destination address in s2
li t0, CONFIG_SYS_MONITOR_BASE
sub s1, s2, t0 # s1 <-- relocation offset
la t3, in_ram
lw t2, -12(t3) # t2 <-- uboot_end_data
move t1, a2
/*
* Fix $gp:
*
* New $gp = (Old $gp - CONFIG_SYS_MONITOR_BASE) + Destination Address
*/
move t6, gp
sub gp, CONFIG_SYS_MONITOR_BASE
add gp, a2 # gp now adjusted
sub s1, gp, t6 # s1 <-- relocation offset
add gp, s1 # adjust gp
/*
* t0 = source address

12
arch/mips/cpu/mips64/start.S
View file

@ -162,19 +162,13 @@ relocate_code:
move s2, a2 # save destination address in s2
dli t0, CONFIG_SYS_MONITOR_BASE
dsub s1, s2, t0 # s1 <-- relocation offset
dla t3, in_ram
ld t2, -24(t3) # t2 <-- uboot_end_data
move t1, a2
/*
* Fix $gp:
*
* New $gp = (Old $gp - CONFIG_SYS_MONITOR_BASE) + Destination Address
*/
move t8, gp
dsub gp, CONFIG_SYS_MONITOR_BASE
dadd gp, a2 # gp now adjusted
dsub s1, gp, t8 # s1 <-- relocation offset
dadd gp, s1 # adjust gp
/*
* t0 = source address