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authorBenjamin Herrenschmidt <benh@kernel.crashing.org>2006-10-20 11:47:18 +1000
committerPaul Mackerras <paulus@samba.org>2006-10-25 11:54:07 +1000
commit0909c8c2d547e45ca50e2492b08ec93a37b35237 (patch)
tree23e66e1dc9a5bd674ba1375b5fccd2cb0d5787a8 /arch/ppc/kernel
parent7aeb732428fc8e2ecae6d432873770c12f04a979 (diff)
downloadlinux-linaro-stable-0909c8c2d547e45ca50e2492b08ec93a37b35237.tar.gz
[POWERPC] Support feature fixups in vdso's
This patch reworks the feature fixup mecanism so vdso's can be fixed up. The main issue was that the construct: .long label (or .llong on 64 bits) will not work in the case of a shared library like the vdso. It will generate an empty placeholder in the fixup table along with a reloc, which is not something we can deal with in the vdso. The idea here (thanks Alan Modra !) is to instead use something like: 1: .long label - 1b That is, the feature fixup tables no longer contain addresses of bits of code to patch, but offsets of such code from the fixup table entry itself. That is properly resolved by ld when building the .so's. I've modified the fixup mecanism generically to use that method for the rest of the kernel as well. Another trick is that the 32 bits vDSO included in the 64 bits kernel need to have a table in the 64 bits format. However, gas does not support 32 bits code with a statement of the form: .llong label - 1b (Or even just .llong label) That is, it cannot emit the right fixup/relocation for the linker to use to assign a 32 bits address to an .llong field. Thus, in the specific case of the 32 bits vdso built as part of the 64 bits kernel, we are using a modified macro that generates: .long 0xffffffff .llong label - 1b Note that is assumes that the value is negative which is enforced by the .lds (those offsets are always negative as the .text is always before the fixup table and gas doesn't support emiting the reloc the other way around). Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Paul Mackerras <paulus@samba.org>
Diffstat (limited to 'arch/ppc/kernel')
-rw-r--r--arch/ppc/kernel/setup.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/ppc/kernel/setup.c b/arch/ppc/kernel/setup.c
index 41a640f16bdd..27faeca2c7a2 100644
--- a/arch/ppc/kernel/setup.c
+++ b/arch/ppc/kernel/setup.c
@@ -314,7 +314,7 @@ early_init(int r3, int r4, int r5)
* that depend on which cpu we have.
*/
spec = identify_cpu(offset);
- do_feature_fixups(offset, spec->cpu_features,
+ do_feature_fixups(spec->cpu_features,
PTRRELOC(&__start___ftr_fixup),
PTRRELOC(&__stop___ftr_fixup));