From: Olaf Hering <olh@suse•de>
To: linuxppc-dev@ozlabs•org, Paul Mackeras <paulus@samba•org>
Subject: [PATCH] force stackpointer alignment in 64bit kernel
Date: Fri, 3 Mar 2006 20:16:33 +0100 [thread overview]
Message-ID: <20060303191633.GA7792@suse.de> (raw)
In-Reply-To: <20060303165253.GA6494@suse.de>
Fix gcc "bug" #26549 which causes pointers to be truncated.
The address of variable val in prom_init_stdout is passed to prom_getprop.
prom_getprop casts the pointer to u32 and passes it to call_prom in the hope
that OpenFirmware stores something there.
But the pointer is truncated in the lower bits and the expected value is
stored somewhere else.
In my testing I had a stackpointer of 0x0023e6b4. val was at offset 120,
wich has address 0x0023e72c. But the value passed to OF was 0x0023e728.
c00000000040b710: 3b 01 00 78 addi r24,r1,120
...
c00000000040b754: 57 08 00 38 rlwinm r8,r24,0,0,28
...
c00000000040b784: 80 01 00 78 lwz r0,120(r1)
...
c00000000040b798: 90 1b 00 0c stw r0,12(r27)
...
The stackpointer came from 32bit code, which appearently has different
alignment rules than 64bit code. The chain was yaboot -> zImage -> vmlinux
Force the stackpointer to be 16 byte aligned.
Signed-off-by: Olaf Hering <olh@suse•de>
arch/powerpc/kernel/head_64.S | 2 ++
1 files changed, 2 insertions(+)
Index: linux-2.6.16-rc5-olh/arch/powerpc/kernel/head_64.S
===================================================================
--- linux-2.6.16-rc5-olh.orig/arch/powerpc/kernel/head_64.S
+++ linux-2.6.16-rc5-olh/arch/powerpc/kernel/head_64.S
@@ -1547,6 +1547,8 @@ _STATIC(__boot_from_prom)
mr r27,r7
/* Make sure we are running in 64 bits mode */
+ addi r1,r1,16
+ rlwinm r1,r1,0,0,28
bl .enable_64b_mode
/* put a relocation offset into r3 */
next prev parent reply other threads:[~2006-03-03 19:16 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-03-03 13:57 alignment bugs in prom_init Olaf Hering
2006-03-03 14:39 ` Andreas Schwab
2006-03-03 15:27 ` Olaf Hering
2006-03-03 15:50 ` Jerry Van Baren
2006-03-03 16:14 ` Jerry Van Baren
2006-03-03 17:24 ` Olaf Hering
2006-03-03 16:52 ` [PATCH] Workaround gcc bug #26549 which causes pointers to be truncated Olaf Hering
2006-03-03 19:16 ` Olaf Hering [this message]
2006-03-03 19:23 ` [PATCH] force stackpointer alignment in 64bit kernel Olaf Hering
2006-03-03 19:29 ` Segher Boessenkool
2006-03-03 19:32 ` Segher Boessenkool
2006-03-03 20:09 ` Olaf Hering
2006-03-03 20:40 ` Olaf Hering
2006-03-03 23:23 ` Olaf Hering
2006-03-03 23:45 ` Paul Nasrat
2006-03-04 0:09 ` Segher Boessenkool
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