By copying the GOT to the end of the INIT_RAM(dcache)
and relocating it there, it is much esier to
support true PIC on u-boot. This cannot handle
FIXUP so C code that depends on fixups before relocation to RAM
must use LINK_OFF to calculate the difference.
This depends on the upcoming single-pic-base option
to gcc.
---
arch/powerpc/cpu/mpc83xx/start.S | 36 ++++++++++++++++++++++++++++++++++++
1 files changed, 36 insertions(+), 0 deletions(-)
diff --git a/arch/powerpc/cpu/mpc83xx/start.S b/arch/powerpc/cpu/mpc83xx/start.S
index 3d4e288..b24a89a 100644
--- a/arch/powerpc/cpu/mpc83xx/start.S
+++ b/arch/powerpc/cpu/mpc83xx/start.S
@@ -302,6 +302,34 @@ in_flash:
/* Needed for upcoming -msingle-pic-base */
bl _global_offset_tab...@local-4
mflr r30
+#ifdef CONFIG_SYS_TRUE_PIC
+ /*
+ * Copy GOT to cache and relocate it
+ * This assumes there is enough space at the end
+ * INIT_RAM to hold a copy of the GOT.
+ */
+ li r3,0
+ bl link_off /* r3 holds link offset at return */
+ lis r9, (CONFIG_SYS_INIT_RAM_ADDR+CONFIG_SYS_INIT_RAM_END)@h
+ ori r9,r9,(CONFIG_SYS_INIT_RAM_ADDR+CONFIG_SYS_INIT_RAM_END)@l
+ lwz r11,GOT(_GOT2_TABLE_)
+ add r11,r11,r3
+
+ li r4, __got2_entr...@sectoff@l
+ mtctr r4
+ slwi r5,r4,2 /* r4 * 4 */
+ subf r9,r5,r9 /* r9 - r5 */
+
+ subf r10,r9,r11 /* r11 - r9 */
+ subf r30,r10,r30 /* r30 - r10, point PIC(r30) to new GOT */
+ addi r11,r11,-4
+ addi r9,r9,-4
+1: /* copy GOT and add link offset */
+ lwzu r0,4(r11)
+ add r0,r0,r3
+ stwu r0,4(r9)
+ bdnz 1b
+#endif
#endif
/* r3: IMMR */
lis r3, config_sys_i...@h
@@ -869,9 +897,17 @@ relocate_code:
bl _global_offset_tab...@local-4
mflr r30
#endif
+#ifdef CONFIG_SYS_TRUE_PIC
+ li r3, 0
+ bl link_off /* const void * link_off(const void *) */
+#endif
lwz r4, GOT(_start) /* Source Address */
addi r4, r4, -EXC_OFF_SYS_RESET
lwz r5, GOT(__bss_start)
+#ifdef CONFIG_SYS_TRUE_PIC
+ add r4, r4, r3 /* Add link offset */
+ add r5, r5, r3 /* Add link offset */
+#endif
mr r3, r10 /* Destination Address */
sub r5, r5, r4
--
1.7.2.2
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