diff options
| 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/kernel/entry.S | |
| parent | d3e75ff14bc1453c4762428395aac9953a023efc (diff) | |
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/kernel/entry.S')
| -rw-r--r-- | arch/ia64/kernel/entry.S | 51 |
1 files changed, 51 insertions, 0 deletions
diff --git a/arch/ia64/kernel/entry.S b/arch/ia64/kernel/entry.S index c2f7d798e2a..e0be92a6abb 100644 --- a/arch/ia64/kernel/entry.S +++ b/arch/ia64/kernel/entry.S @@ -1406,6 +1406,56 @@ GLOBAL_ENTRY(unw_init_running) END(unw_init_running) #ifdef CONFIG_FUNCTION_TRACER +#ifdef CONFIG_DYNAMIC_FTRACE +GLOBAL_ENTRY(_mcount) + br ftrace_stub +END(_mcount) + +.here: + br.ret.sptk.many b0 + +GLOBAL_ENTRY(ftrace_caller) + alloc out0 = ar.pfs, 8, 0, 4, 0 + mov out3 = r0 + ;; + mov out2 = b0 + add r3 = 0x20, r3 + mov out1 = r1; + br.call.sptk.many b0 = ftrace_patch_gp + //this might be called from module, so we must patch gp +ftrace_patch_gp: + movl gp=__gp + mov b0 = r3 + ;; +.global ftrace_call; +ftrace_call: +{ + .mlx + nop.m 0x0 + movl r3 = .here;; +} + alloc loc0 = ar.pfs, 4, 4, 2, 0 + ;; + mov loc1 = b0 + mov out0 = b0 + mov loc2 = r8 + mov loc3 = r15 + ;; + adds out0 = -MCOUNT_INSN_SIZE, out0 + mov out1 = in2 + mov b6 = r3 + + br.call.sptk.many b0 = b6 + ;; + mov ar.pfs = loc0 + mov b0 = loc1 + mov r8 = loc2 + mov r15 = loc3 + br ftrace_stub + ;; +END(ftrace_caller) + +#else GLOBAL_ENTRY(_mcount) movl r2 = ftrace_stub movl r3 = ftrace_trace_function;; @@ -1435,6 +1485,7 @@ GLOBAL_ENTRY(_mcount) br ftrace_stub ;; END(_mcount) +#endif GLOBAL_ENTRY(ftrace_stub) mov r3 = b0 |