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| author | Anton Blanchard | 2014-02-12 07:17:05 +0100 |
|---|---|---|
| committer | Benjamin Herrenschmidt | 2014-02-17 01:19:37 +0100 |
| commit | a0a4419e302fedb548d56129e02130347810f892 (patch) | |
| tree | ce833699bd698a3a037387d518f158a926572ac4 | |
| parent | mm: Use ptep/pmdp_set_numa() for updating _PAGE_NUMA bit (diff) | |
| download | kernel-qcow2-linux-a0a4419e302fedb548d56129e02130347810f892.tar.gz kernel-qcow2-linux-a0a4419e302fedb548d56129e02130347810f892.tar.xz kernel-qcow2-linux-a0a4419e302fedb548d56129e02130347810f892.zip | |
powerpc: Link VDSOs at 0x0
perf is failing to resolve symbols in the VDSO. A while (1)
gettimeofday() loop shows:
93.99% [vdso] [.] 0x00000000000005e0
3.12% test [.] 00000037.plt_call.gettimeofday@@GLIBC_2.18
2.81% test [.] main
The reason for this is that we are linking our VDSO shared libraries
at 1MB, which is a little weird. Even though this is uncommon, Alan
points out that it is valid and we should probably fix perf userspace.
Regardless, I can't see a reason why we are doing this. The code
is all position independent and we never rely on the VDSO ending
up at 1M (and we never place it there on 64bit tasks).
Changing our link address to 0x0 fixes perf VDSO symbol resolution:
73.18% [vdso] [.] 0x000000000000060c
12.39% [vdso] [.] __kernel_gettimeofday
3.58% test [.] 00000037.plt_call.gettimeofday@@GLIBC_2.18
2.94% [vdso] [.] __kernel_datapage_offset
2.90% test [.] main
We still have some local symbol resolution issues that will be
fixed in a subsequent patch.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
| -rw-r--r-- | arch/powerpc/include/asm/vdso.h | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/arch/powerpc/include/asm/vdso.h b/arch/powerpc/include/asm/vdso.h index 0d9cecddf8a4..c53f5f6d1761 100644 --- a/arch/powerpc/include/asm/vdso.h +++ b/arch/powerpc/include/asm/vdso.h @@ -4,11 +4,11 @@ #ifdef __KERNEL__ /* Default link addresses for the vDSOs */ -#define VDSO32_LBASE 0x100000 -#define VDSO64_LBASE 0x100000 +#define VDSO32_LBASE 0x0 +#define VDSO64_LBASE 0x0 /* Default map addresses for 32bit vDSO */ -#define VDSO32_MBASE VDSO32_LBASE +#define VDSO32_MBASE 0x100000 #define VDSO_VERSION_STRING LINUX_2.6.15 |