MIPS: add dynamic relocation support
The code handles relocation entries with the
following relocation types only:
mips32: R_MIPS_REL32
mips64: R_MIPS_REL+R_MIPS_64
xburst: R_MIPS_REL32
Other relocation entries are skipped without
processing. The code must be extended if other
relocation types must be supported.
Add -pie to LDFLAGS_FINAL to generate the .rel.dyn
fixup table, which will be applied to the relocated
image before transferring control to it.
The CONFIG_NEEDS_MANUAL_RELOC is not needed
after the patch, so remove that as well.
Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Signed-off-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
diff --git a/arch/mips/cpu/mips32/start.S b/arch/mips/cpu/mips32/start.S
index 649c0bb..76abbaa 100644
--- a/arch/mips/cpu/mips32/start.S
+++ b/arch/mips/cpu/mips32/start.S
@@ -201,6 +201,8 @@
jr t0
nop
+ .word __rel_dyn_end
+ .word __rel_dyn_start
.word __image_copy_end
.word _GLOBAL_OFFSET_TABLE_
.word num_got_entries
@@ -227,6 +229,32 @@
blt t2, t3, 1b
addi t4, 4
+ /* Update dynamic relocations */
+ lw t1, -16(t0) # t1 <-- __rel_dyn_start
+ lw t2, -20(t0) # t2 <-- __rel_dyn_end
+
+ b 2f # skip first reserved entry
+ addi t1, 8
+
+1:
+ lw t3, -4(t1) # t3 <-- relocation info
+
+ sub t3, 3
+ bnez t3, 2f # skip non R_MIPS_REL32 entries
+ nop
+
+ lw t3, -8(t1) # t3 <-- location to fix up in FLASH
+
+ lw t4, 0(t3) # t4 <-- original pointer
+ add t4, s1 # t4 <-- adjusted pointer
+
+ add t3, s1 # t3 <-- location to fix up in RAM
+ sw t4, 0(t3)
+
+2:
+ blt t1, t2, 1b
+ addi t1, 8 # each rel.dyn entry is 8 bytes
+
/*
* Clear BSS
*