[U-Boot] [PATCH 5/5] arm: optimize relocate_code routine

Benoît Thébaudeau
2013-05-14T23:54:11Z

Hi Albert,

On Tuesday, May 14, 2013 10:03:00 PM, Albert ARIBAUD wrote:
> Use section symbols directly
> Drop support for R_ARM_ABS32 record types
> Eliminate unneeded intermediate registers
> Optimize relocation table iteration
>
> Signed-off-by: Albert ARIBAUD <albert.u.boot@aribaud.net>
> ---
> arch/arm/lib/relocate.S | 45 +++++++++++++++------------------------------
> 1 file changed, 15 insertions(+), 30 deletions(-)
>
> diff --git a/arch/arm/lib/relocate.S b/arch/arm/lib/relocate.S
> index 818735c..75ee3b4 100644
> --- a/arch/arm/lib/relocate.S
> +++ b/arch/arm/lib/relocate.S
> @@ -37,51 +37,36 @@
> * This function relocates the monitor code.
> */
> ENTRY(relocate_code)
> - mov r6, r0 /* save addr of destination */
>
> - ldr r0, =__image_copy_start /* r0 <- source start address */
> - subs r9, r6, r0 /* r9 <- relocation offset */
> + ldr r1, =__image_copy_start /* r1 <- source start address */
> + subs r9, r0, r1 /* r9 <- relocation offset */
> beq relocate_done /* skip relocation */
> - mov r1, r6 /* r1 <- scratch for copy loop */
> ldr r2, =__image_copy_end /* r2 <- source end address */
>
> copy_loop:
> - ldmia r0!, {r10-r11} /* copy from source address [r0] */
> - stmia r1!, {r10-r11} /* copy to target address [r1] */
> - cmp r0, r2 /* until source end address [r2] */
> + ldmia r1!, {r10-r11} /* copy from source address [r1] */
> + stmia r0!, {r10-r11} /* copy to target address [r0] */
> + cmp r1, r2 /* until source end address [r2] */
> blo copy_loop
>
> /*
> * fix .rel.dyn relocations
> */
> - ldr r10, =__dynsym_start /* r10 <- sym table ofs */
> ldr r2, =__rel_dyn_start /* r2 <- rel dyn start ofs */
> ldr r3, =__rel_dyn_end /* r3 <- rel dyn end ofs */
> fixloop:
> - ldr r0, [r2] /* r0 <- SRC location to fix up */
> - add r0, r0, r9 /* r0 <- DST location to fix up */
> - ldr r1, [r2, #4]
> - and r7, r1, #0xff
> - cmp r7, #23 /* relative fixup? */
> - beq fixrel
> - cmp r7, #2 /* absolute fixup? */
> - beq fixabs
> - /* ignore unknown type of fixup */
> - b fixnext
> -fixabs:
> - /* absolute fix: set location to (offset) symbol value */
> - mov r1, r1, LSR #4 /* r1 <- symbol index in .dynsym */
> - add r1, r10, r1 /* r1 <- address of symbol in table */
> - ldr r1, [r1, #4] /* r1 <- symbol value */
> - add r1, r1, r9 /* r1 <- relocated sym addr */
> - b fixnext
> -fixrel:
> + ldmia r2!, {r0-r1} /* (r0,r1) <- (SRC location,fixup) */
> + and r1, r1, #0xff /* r1 <- fixup type */
> + cmp r1, #23 /* relative fixup? */
> + bne fixnext
> +
> /* relative fix: increase location by offset */
> - ldr r1, [r0]
> - add r1, r1, r9
> + add r0, r0, r9 /* r0 <- DST location to fix up */
> + ldr r1, [r0] /* r1 <- content to fix up */
> + add r1, r1, r9 /* fix up */
> + str r1, [r0] /* write back fixed-up content */
> +
> fixnext:
> - str r1, [r0]
> - add r2, r2, #8 /* each rel.dyn entry is 8 bytes */
> cmp r2, r3
> blo fixloop

The final state of relocate.S is correct in this series, but it is not correct
at the end of "[PATCH v2 4/4] arm: factorize relocate_code routine" as I pointed
out in the part of my review that you cut in your first reply.

Best regards,
Beno?t