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_TABLE_@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_entries@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_IMMR@h @@ -869,9 +897,17 @@ relocate_code: bl _GLOBAL_OFFSET_TABLE_@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