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| author | Shaohua Li <shaohua.li@intel.com> | 2009-01-09 11:29:49 +0800 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-01-14 12:11:31 +0100 |
| commit | a14a07b8018b714e03a39ff2180c66e307ef4238 (patch) | |
| tree | 7c4b9249f862969b80b74e5e11e56480b0e3d15c /arch/ia64/Kconfig | |
| parent | d3e75ff14bc1453c4762428395aac9953a023efc (diff) | |
| download | lwn-a14a07b8018b714e03a39ff2180c66e307ef4238.tar.gz lwn-a14a07b8018b714e03a39ff2180c66e307ef4238.zip | |
ftrace, ia64: IA64 dynamic ftrace support
IA64 dynamic ftrace support.
The original _mcount stub for each function is like:
alloc r40=ar.pfs,12,8,0
mov r43=r0;;
mov r42=b0
mov r41=r1
nop.i 0x0
br.call.sptk.many b0 = _mcount;;
The patch convert it to below for nop:
[MII] nop.m 0x0
mov r3=ip
nop.i 0x0
[MLX] nop.m 0x0
nop.x 0x0;;
This isn't completely nop, as there is one instuction 'mov r3=ip', but
it should be light and harmless for code follow it.
And below is for call
[MII] nop.m 0x0
mov r3=ip
nop.i 0x0
[MLX] nop.m 0x0
brl.many .;;
In this way, only one instruction is changed to convert code between nop
and call. This should meet dyn-ftrace's requirement.
But this requires CPU support brl instruction, so dyn-ftrace isn't
supported for old Itanium system. Assume there are quite few such old
system running.
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/ia64/Kconfig')
| -rw-r--r-- | arch/ia64/Kconfig | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/ia64/Kconfig b/arch/ia64/Kconfig index b992ba447c41..e20c1d45930a 100644 --- a/arch/ia64/Kconfig +++ b/arch/ia64/Kconfig @@ -21,6 +21,8 @@ config IA64 select HAVE_OPROFILE select HAVE_KPROBES select HAVE_KRETPROBES + select HAVE_FTRACE_MCOUNT_RECORD + select HAVE_DYNAMIC_FTRACE if (!ITANIUM) select HAVE_FUNCTION_TRACER select HAVE_DMA_ATTRS select HAVE_KVM |