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| author | Daniel Schwierzeck <daniel.schwierzeck@gmail.com> | 2013-02-12 22:22:13 +0100 |
|---|---|---|
| committer | Daniel Schwierzeck <daniel.schwierzeck@gmail.com> | 2013-02-12 22:22:13 +0100 |
| commit | 696a3b2a5368360c149335e2a35b8900a78f47fa (patch) | |
| tree | ebad9e8ee6bfd035c5b9b10a965ae77f129df305 /arch/mips | |
| parent | eea8a320e1299cbd76d3ffd9a1fe0e0d3313268b (diff) | |
| download | u-boot-imx-696a3b2a5368360c149335e2a35b8900a78f47fa.zip u-boot-imx-696a3b2a5368360c149335e2a35b8900a78f47fa.tar.gz u-boot-imx-696a3b2a5368360c149335e2a35b8900a78f47fa.tar.bz2 | |
MIPS: start.S: optimize BSS initialization
Get the start and end address for clearing BSS from the newly
introduced symbols __bss_start and __bss_end. After GOT is
relocated, those symbols are already pointing to the correct
addresses.
Also optimize the loop by moving the address incrementation
to the delay slot to avoid the initial sub instruction.
Signed-off-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
Diffstat (limited to 'arch/mips')
| -rw-r--r-- | arch/mips/cpu/mips32/start.S | 20 | ||||
| -rw-r--r-- | arch/mips/cpu/mips64/start.S | 20 | ||||
| -rw-r--r-- | arch/mips/cpu/xburst/start.S | 23 |
3 files changed, 35 insertions, 28 deletions
diff --git a/arch/mips/cpu/mips32/start.S b/arch/mips/cpu/mips32/start.S index 7373d4e..cd8b914 100644 --- a/arch/mips/cpu/mips32/start.S +++ b/arch/mips/cpu/mips32/start.S @@ -228,17 +228,19 @@ in_ram: blt t2, t3, 1b addi t4, 4 - /* Clear BSS */ - lw t1, -12(t0) # t1 <-- uboot_end_data - lw t2, -8(t0) # t2 <-- uboot_end - add t1, s1 # adjust pointers - add t2, s1 + /* + * Clear BSS + * + * GOT is now relocated. Thus __bss_start and __bss_end can be + * accessed directly via $gp. + */ + la t1, __bss_start # t1 <-- __bss_start + la t2, __bss_end # t2 <-- __bss_end - sub t1, 4 1: - addi t1, 4 - bltl t1, t2, 1b - sw zero, 0(t1) + sw zero, 0(t1) + blt t1, t2, 1b + addi t1, 4 move a0, s0 # a0 <-- gd la t9, board_init_r diff --git a/arch/mips/cpu/mips64/start.S b/arch/mips/cpu/mips64/start.S index c0ae41a..ba4ca4d 100644 --- a/arch/mips/cpu/mips64/start.S +++ b/arch/mips/cpu/mips64/start.S @@ -220,17 +220,19 @@ in_ram: blt t2, t3, 1b daddi t8, 8 - /* Clear BSS */ - ld t1, -24(t0) # t1 <-- uboot_end_data - ld t2, -16(t0) # t2 <-- uboot_end - dadd t1, s1 # adjust pointers - dadd t2, s1 + /* + * Clear BSS + * + * GOT is now relocated. Thus __bss_start and __bss_end can be + * accessed directly via $gp. + */ + dla t1, __bss_start # t1 <-- __bss_start + dla t2, __bss_end # t2 <-- __bss_end - dsub t1, 8 1: - daddi t1, 8 - bltl t1, t2, 1b - sd zero, 0(t1) + sd zero, 0(t1) + blt t1, t2, 1b + daddi t1, 8 move a0, s0 # a0 <-- gd dla t9, board_init_r diff --git a/arch/mips/cpu/xburst/start.S b/arch/mips/cpu/xburst/start.S index 50b7fb1..bd9390a 100644 --- a/arch/mips/cpu/xburst/start.S +++ b/arch/mips/cpu/xburst/start.S @@ -143,16 +143,19 @@ in_ram: blt t2, t3, 1b addi t4, 4 - /* Clear BSS */ - lw t1, -12(t0) # t1 <-- uboot_end_data - lw t2, -8(t0) # t2 <-- uboot_end - add t1, t6 # adjust pointers - add t2, t6 - - sub t1, 4 -1: addi t1, 4 - bltl t1, t2, 1b - sw zero, 0(t1) + /* + * Clear BSS + * + * GOT is now relocated. Thus __bss_start and __bss_end can be + * accessed directly via $gp. + */ + la t1, __bss_start # t1 <-- __bss_start + la t2, __bss_end # t2 <-- __bss_end + +1: + sw zero, 0(t1) + blt t1, t2, 1b + addi t1, 4 move a0, a1 # a0 <-- gd la t9, board_init_r |