[PATCH] ppc: Don't do relative branches from relocated memory

[Andreas Färber]

On startup, OpenBIOS copies exception vectors to 0x00000000.
Therefore jumps cannot be performed relative to the compile-time address
to outside the relocated exception vectors.

QEMU's g3beige and mac99 did not run into this so far, but prep does.

Signed-off-by: Andreas Färber <andreas.faerber(a)web.de>
---
 arch/ppc/qemu/start.S |    4 +++-
 1 Datei geändert, 3 Zeilen hinzugefügt(+), 1 Zeile entfernt(-)

diff --git a/arch/ppc/qemu/start.S b/arch/ppc/qemu/start.S
index 5c86d74..66987a0 100644
--- a/arch/ppc/qemu/start.S
+++ b/arch/ppc/qemu/start.S
@@ -302,7 +302,9 @@ trap_error:
 	bctr
 
 VECTOR( 0x100, "SRE" ):
-        b       _entry
+    LOAD_REG_IMMEDIATE(r3, _entry)
+    mtctr r3
+    bctr
 
 ILLEGAL_VECTOR( 0x200 )
 
-- 
1.7.10.4

[PATCH] ppc: Don't do relative branches from relocated memory

[Alexander Graf]

On 24.02.2013, at 23:32, Andreas Färber wrote:

  On startup, OpenBIOS copies exception vectors to
0x00000000.
 Therefore jumps cannot be performed relative to the compile-time address
 to outside the relocated exception vectors.
 
 QEMU's g3beige and mac99 did not run into this so far, but prep does.
 
 Signed-off-by: Andreas Färber <andreas.faerber(a)web.de>
This sounds wrong. You shouldn't get to 0x100 in RAM. It's the reset vector!


Alex

  ---
 arch/ppc/qemu/start.S |    4 +++-
 1 Datei geändert, 3 Zeilen hinzugefügt(+), 1 Zeile entfernt(-)
 
 diff --git a/arch/ppc/qemu/start.S b/arch/ppc/qemu/start.S
 index 5c86d74..66987a0 100644
 --- a/arch/ppc/qemu/start.S
 +++ b/arch/ppc/qemu/start.S
 @@ -302,7 +302,9 @@ trap_error:
 	bctr
 
 VECTOR( 0x100, "SRE" ):
 -        b       _entry
 +    LOAD_REG_IMMEDIATE(r3, _entry)
 +    mtctr r3
 +    bctr
 
 ILLEGAL_VECTOR( 0x200 )
 
 -- 
 1.7.10.4