From: Wu Zhangjin <wuzhangjin@xxxxxxxxx> A new option -mmcount-ra-address for gcc 4.5 have been sent by David Daney <ddaney@xxxxxxxxxxxxxxxxxx> in the thread "MIPS: Add option to pass return address location to _mcount", which help to record the location of the return address(ra) for the function graph tracer of MIPS to hijack the return address easier and safer. that option used the $12(t0) register by default, so, we reserve it for it, and use t1,t2,t3 instead of t0,t1,t2. Signed-off-by: Wu Zhangjin <wuzhangjin@xxxxxxxxx> --- arch/mips/kernel/mcount.S | 26 +++++++++++++------------- 1 files changed, 13 insertions(+), 13 deletions(-) diff --git a/arch/mips/kernel/mcount.S b/arch/mips/kernel/mcount.S index bdfef2c..522e91c 100644 --- a/arch/mips/kernel/mcount.S +++ b/arch/mips/kernel/mcount.S @@ -65,8 +65,8 @@ NESTED(ftrace_caller, PT_SIZE, ra) _mcount: b ftrace_stub nop - lw t0, function_trace_stop - bnez t0, ftrace_stub + lw t1, function_trace_stop + bnez t1, ftrace_stub nop MCOUNT_SAVE_REGS @@ -93,21 +93,21 @@ ftrace_stub: #else /* ! CONFIG_DYNAMIC_FTRACE */ NESTED(_mcount, PT_SIZE, ra) - lw t0, function_trace_stop - bnez t0, ftrace_stub + lw t1, function_trace_stop + bnez t1, ftrace_stub nop - PTR_LA t0, ftrace_stub - PTR_L t1, ftrace_trace_function /* Prepare t1 for (1) */ - bne t0, t1, static_trace + PTR_LA t1, ftrace_stub + PTR_L t2, ftrace_trace_function /* Prepare t2 for (1) */ + bne t1, t2, static_trace nop #ifdef CONFIG_FUNCTION_GRAPH_TRACER - PTR_L t2, ftrace_graph_return - bne t0, t2, ftrace_graph_caller + PTR_L t3, ftrace_graph_return + bne t1, t3, ftrace_graph_caller nop - PTR_LA t0, ftrace_graph_entry_stub - PTR_L t2, ftrace_graph_entry - bne t0, t2, ftrace_graph_caller + PTR_LA t1, ftrace_graph_entry_stub + PTR_L t3, ftrace_graph_entry + bne t1, t3, ftrace_graph_caller nop #endif b ftrace_stub @@ -117,7 +117,7 @@ static_trace: MCOUNT_SAVE_REGS move a0, ra /* arg1: next ip, selfaddr */ - jalr t1 /* (1) call *ftrace_trace_function */ + jalr t2 /* (1) call *ftrace_trace_function */ move a1, AT /* arg2: the caller's next ip, parent */ MCOUNT_RESTORE_REGS -- 1.6.2.1
