Peter Tyser <pty...@xes-inc.com> wrote on 23/09/2009 14:57:19:
>
>
> > > I made the same changes recently, but ran into an "issue" that prevented
> > > me from sending the change upstream. Some boards/arches have the bss at
> > > address 0 and later relocate it, unlike every other NULL pointer. If
> > > you don't fix up the bss address, the board will not function. If you
> > > run readelf on an 83xx u-boot image vs a 85xx u-boot image it should be
> > > more clear what's going on. I was doing my testing on the XPedite5370
> > > fwiw.
> >
> > Ouch, the horror continues :(
>
> Yeah... Its seemingly never ending:)
>
> > > In any case, the change as is would break some other arches. Seems like
> > > the proper workaround would be to "fix" the 85xx (and other arches) link
> > > script to locate the bss similar to the 83xx boards.
> >
> > Yes, something should be done. Does it work for you with a "fixed" linker
> > script?
>
> My "fix" to the linker script was to change:
> __bss_start = .;
> into:
> __bss_start = . | 4;
>
> ie, a big hack, but it did work:) I'll take a peek at a more proper
> link script workaround.
>
> > > It might be nice to consolidate all the ppc relocate code into 1
> > > function while we were at it.
> >
> > Played around a little and this is what I got sofar, possibly
> > WS damged and fixups untested:
>
> Nice! It'd be great to have the magical 20 lines of assembly put into
> some semi-understandable c.
Played some more and got this, running out of time now so
I figured I should post as is in case you (or someone else)
wants to play some more. I will answer questions though.
>From 684443ce6870eac2878026e47cc107fbfcdefc02 Mon Sep 17 00:00:00 2001
From: Joakim Tjernlund <joakim.tjernl...@transmode.se>
Date: Wed, 23 Sep 2009 18:41:44 +0200
Subject: [PATCH] relocation: Use C as much as possible to do relocation.
---
cpu/mpc83xx/start.S | 64 ++++++++++++++++++++++++++++++++------------------
lib_ppc/board.c | 21 ++++++++++++++++-
2 files changed, 61 insertions(+), 24 deletions(-)
diff --git a/cpu/mpc83xx/start.S b/cpu/mpc83xx/start.S
index 868b070..ccd337a 100644
--- a/cpu/mpc83xx/start.S
+++ b/cpu/mpc83xx/start.S
@@ -307,6 +307,39 @@ in_flash:
/* run 1st part of board init code (in Flash)*/
bl board_init_f
+ .globl got_off /* void * got_off(void * ptr) */
+got_off:
+ /* Adds GOT offset to ptr, might be useful for true PIC too */
+ /* Would be great if this could be inline C __asm__ instead */
+#if 1
+ /* Hand coded as we cannot clobber r14 when called from C */
+ mflr r4
+ bl 1f
+ .text 2
+0: .long .LCTOC1-1f
+ .text
+1: mflr r6
+ lwz r0,0b-1b(r6)
+ add r6,r0,r6
+ mtlr r4
+ addi r4,r6,.L__GOT2_TABLE_
+ lwz r5, .L__GOT2_TABLE_(r6)
+ sub r4,r5,r4
+ sub r3,r3,r4
+ blr
+#else
+ /* Use predefined macros instead */
+ mflr r4
+ mr r6,r14 /* GET_GOT clobbers r14 so save it */
+ GET_GOT
+ mtlr r4
+ la r4,GOT(_GOT2_TABLE_) /* addi r4, r14, .L__GOT2_TABLE_ */
+ lwz r5,GOT(_GOT2_TABLE_) /* lwz r5, .L__GOT2_TABLE_(r14) */
+ sub r4,r5,r4
+ sub r3,r3,r4
+ mr r6,r14
+ blr
+#endif
#ifndef CONFIG_NAND_SPL
/*
* Vector Table
@@ -842,8 +875,8 @@ flush_dcache:
.globl relocate_code
relocate_code:
mr r1, r3 /* Set new stack pointer */
- mr r9, r4 /* Save copy of Global Data pointer */
- mr r10, r5 /* Save copy of Destination Address */
+ mr r16, r4 /* Save copy of Global Data pointer */
+ mr r17, r5 /* Save copy of Destination Address */
mr r3, r5 /* Destination Address */
lis r4, config_sys_monitor_b...@h /* Source Address
*/
@@ -860,7 +893,7 @@ relocate_code:
*
* Offset:
*/
- sub r15, r10, r4
+ sub r15, r17, r4
/* First our own GOT */
add r14, r14, r15
@@ -938,7 +971,7 @@ relocate_code:
* We are done. Do not return, instead branch to second part of board
* initialization, now running from RAM.
*/
- addi r0, r10, in_ram - _start + EXC_OFF_SYS_RESET
+ addi r0, r17, in_ram - _start + EXC_OFF_SYS_RESET
mtlr r0
blr
@@ -950,24 +983,9 @@ in_ram:
* Adjust got2 pointers, no need to check for 0, this code
* already puts a few entries in the table.
*/
- la r3,GOT(_GOT2_TABLE_)
- li r4,__got2_entr...@sectoff@l
- lwz r5,GOT(_GOT2_TABLE_)
- sub r5,r3,r5
- mr r30,r5
- bl __eabi_convert
-
-#ifndef CONFIG_NAND_SPL
- /*
- * Now adjust the fixups and the pointers to the fixups
- * in case we need to move ourselves again.
- */
- lwz r3,GOT(_FIXUP_TABLE_)
+ li r3,__got2_entr...@sectoff@l
li r4,__fixup_entr...@sectoff@l
- mr r5,r30
- bl __eabi_uconvert
-#endif
-
+ bl __do_eabi_reloc
clear_bss:
/*
* Now clear BSS segment
@@ -997,8 +1015,8 @@ clear_bss:
bne 5b
6:
- mr r3, r9 /* Global Data pointer */
- mr r4, r10 /* Destination Address */
+ mr r3, r16 /* Global Data pointer */
+ mr r4, r17 /* Destination Address */
bl board_init_r
#ifndef CONFIG_NAND_SPL
diff --git a/lib_ppc/board.c b/lib_ppc/board.c
index 0afc7c3..2a9b16e 100644
--- a/lib_ppc/board.c
+++ b/lib_ppc/board.c
@@ -147,7 +147,9 @@ static ulong mem_malloc_brk = 0;
* Utilities *
************************************************************************
*/
-
+extern unsigned long *_GOT2_TABLE_;
+extern unsigned long *_FIXUP_TABLE_;
+extern void * got_off(void*);
/* Relocate the .got2 pointers. */
void __eabi_convert(unsigned long *low, unsigned long len,
unsigned long addend)
@@ -178,6 +180,23 @@ void __eabi_uconvert(unsigned long *low, unsigned long len,
*v2p = val2;
}
}
+void __do_eabi_reloc(unsigned long got2_len, unsigned long fixup_len)
+{
+ unsigned long addend = (unsigned long)got_off(NULL);
+ unsigned long *low;
+
+ low = (unsigned long *)(*_GOT2_TABLE_ + addend);
+ printf("GOT2:%lx, addend:%lx low:%p\n",
+ *_GOT2_TABLE_, addend, low);
+ __eabi_convert(low, got2_len, addend);
+
+#ifndef CONFIG_NAND_SPL
+ low = (unsigned long *)(*_FIXUP_TABLE_ + addend);
+ printf("FIXUP:%lx, addend:%lx low:%p\n",
+ *_FIXUP_TABLE_, addend, low);
+ __eabi_uconvert(low, fixup_len, addend);
+#endif
+}
/*
* The Malloc area is immediately below the monitor copy in DRAM
--
1.6.4.4
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