Andreas Schwab <sch...@linux-m68k.org> writes:
> Andreas Schwab <sch...@linux-m68k.org> writes:
>
>> Anton Blanchard <an...@samba.org> writes:
>>
>>> On 64bit applications the VDSO is the only thing in segment 0. Since the
>>> VDSO
>>> is position independent we can remove the hint and let get_unmapped_area
>>> pick
>>> an area.
>>
>> This breaks gdb. The section table in the VDSO image when mapped into
>> the process no longer contains meaningful values, and gdb rejects it.
>
> The problem is that the load segment requires 64k alignment, but the
> page allocater of course only provides PAGE_SIZE alignment, causing the
> image to be unaligned in memory.
Here is a patch. The disadvantage is that now gdb complains that the
vdso does not contain section headers, because they are no longer
covered by the load segment.
Andreas.
---
>From 003c323c753d8717e58220c9560329882bcfa2c2 Mon Sep 17 00:00:00 2001
From: Andreas Schwab <sch...@linux-m68k.org>
Date: Sat, 3 Oct 2009 16:46:45 +0200
Subject: [PATCH] powerpc: fix unaligned load segment in vdso64
Since the page allocator can only guarantee PAGE_SIZE alignment the load
segment in the vdso object cannot claim more than that alignment. Use 4k
alignment which is the minimum possible page size.
Signed-off-by: Andreas Schwab <sch...@linux-m68k.org>
---
arch/powerpc/kernel/vdso64/Makefile | 2 ++
1 files changed, 2 insertions(+), 0 deletions(-)
diff --git a/arch/powerpc/kernel/vdso64/Makefile
b/arch/powerpc/kernel/vdso64/Makefile
index 79da65d..d4be303 100644
--- a/arch/powerpc/kernel/vdso64/Makefile
+++ b/arch/powerpc/kernel/vdso64/Makefile
@@ -10,7 +10,9 @@ obj-vdso64 := $(addprefix $(obj)/, $(obj-vdso64))
GCOV_PROFILE := n
EXTRA_CFLAGS := -shared -fno-common -fno-builtin
+# Force maximum page size of 4k so that it works with any page size
EXTRA_CFLAGS += -nostdlib -Wl,-soname=linux-vdso64.so.1 \
+ -Wl,-z,max-page-size=4096 \
$(call cc-ldoption, -Wl$(comma)--hash-style=sysv)
EXTRA_AFLAGS := -D__VDSO64__ -s
--
1.6.4.4
--
Andreas Schwab, sch...@linux-m68k.org
GPG Key fingerprint = 58CA 54C7 6D53 942B 1756 01D3 44D5 214B 8276 4ED5
"And now for something completely different."
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