377ccbb483
With the latest gcc compilers, they give a warning if __builtin_return_address() parameter is greater than 0. That is because if it is used by a function called by a top level function (or in the case of the kernel, by assembly), it can try to access stack frames outside the stack and crash the system. The tracing system uses __builtin_return_address() of up to 2! But it is well aware of the dangers that it may have, and has even added precautions to protect against it (see the thunk code in arch/x86/entry/thunk*.S) Linus originally added KBUILD_CFLAGS that would suppress the warning for the entire kernel, as simply adding KBUILD_CFLAGS to the tracing directory wouldn't work. The tracing directory plays a bit with the CFLAGS and requires a little more logic. This adds that special logic to only suppress the warning for the tracing directory. If it is used anywhere else outside of tracing, the warning will still be triggered. Link: http://lkml.kernel.org/r/20160728223043.51996267@grimm.local.home Tested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
77 lines
2.5 KiB
Makefile
77 lines
2.5 KiB
Makefile
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# We are fully aware of the dangers of __builtin_return_address()
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FRAME_CFLAGS := $(call cc-disable-warning,frame-address)
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KBUILD_CFLAGS += $(FRAME_CFLAGS)
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# Do not instrument the tracer itself:
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ifdef CONFIG_FUNCTION_TRACER
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ORIG_CFLAGS := $(KBUILD_CFLAGS)
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KBUILD_CFLAGS = $(subst $(CC_FLAGS_FTRACE),,$(ORIG_CFLAGS))
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ifdef CONFIG_FTRACE_SELFTEST
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# selftest needs instrumentation
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CFLAGS_trace_selftest_dynamic.o = $(CC_FLAGS_FTRACE)
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obj-y += trace_selftest_dynamic.o
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endif
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endif
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# If unlikely tracing is enabled, do not trace these files
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ifdef CONFIG_TRACING_BRANCHES
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KBUILD_CFLAGS += -DDISABLE_BRANCH_PROFILING
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endif
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CFLAGS_trace_benchmark.o := -I$(src)
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CFLAGS_trace_events_filter.o := -I$(src)
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obj-$(CONFIG_TRACE_CLOCK) += trace_clock.o
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obj-$(CONFIG_FUNCTION_TRACER) += libftrace.o
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obj-$(CONFIG_RING_BUFFER) += ring_buffer.o
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obj-$(CONFIG_RING_BUFFER_BENCHMARK) += ring_buffer_benchmark.o
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obj-$(CONFIG_TRACING) += trace.o
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obj-$(CONFIG_TRACING) += trace_output.o
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obj-$(CONFIG_TRACING) += trace_seq.o
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obj-$(CONFIG_TRACING) += trace_stat.o
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obj-$(CONFIG_TRACING) += trace_printk.o
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obj-$(CONFIG_TRACING_MAP) += tracing_map.o
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obj-$(CONFIG_CONTEXT_SWITCH_TRACER) += trace_sched_switch.o
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obj-$(CONFIG_FUNCTION_TRACER) += trace_functions.o
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obj-$(CONFIG_IRQSOFF_TRACER) += trace_irqsoff.o
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obj-$(CONFIG_PREEMPT_TRACER) += trace_irqsoff.o
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obj-$(CONFIG_SCHED_TRACER) += trace_sched_wakeup.o
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obj-$(CONFIG_NOP_TRACER) += trace_nop.o
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obj-$(CONFIG_STACK_TRACER) += trace_stack.o
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obj-$(CONFIG_MMIOTRACE) += trace_mmiotrace.o
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obj-$(CONFIG_FUNCTION_GRAPH_TRACER) += trace_functions_graph.o
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obj-$(CONFIG_TRACE_BRANCH_PROFILING) += trace_branch.o
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obj-$(CONFIG_BLK_DEV_IO_TRACE) += blktrace.o
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ifeq ($(CONFIG_BLOCK),y)
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obj-$(CONFIG_EVENT_TRACING) += blktrace.o
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endif
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obj-$(CONFIG_EVENT_TRACING) += trace_events.o
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obj-$(CONFIG_EVENT_TRACING) += trace_export.o
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obj-$(CONFIG_FTRACE_SYSCALLS) += trace_syscalls.o
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ifeq ($(CONFIG_PERF_EVENTS),y)
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obj-$(CONFIG_EVENT_TRACING) += trace_event_perf.o
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endif
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obj-$(CONFIG_EVENT_TRACING) += trace_events_filter.o
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obj-$(CONFIG_EVENT_TRACING) += trace_events_trigger.o
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obj-$(CONFIG_HIST_TRIGGERS) += trace_events_hist.o
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obj-$(CONFIG_BPF_EVENTS) += bpf_trace.o
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obj-$(CONFIG_KPROBE_EVENT) += trace_kprobe.o
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obj-$(CONFIG_TRACEPOINTS) += power-traces.o
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ifeq ($(CONFIG_PM),y)
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obj-$(CONFIG_TRACEPOINTS) += rpm-traces.o
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endif
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ifeq ($(CONFIG_TRACING),y)
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obj-$(CONFIG_KGDB_KDB) += trace_kdb.o
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endif
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obj-$(CONFIG_PROBE_EVENTS) += trace_probe.o
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obj-$(CONFIG_UPROBE_EVENT) += trace_uprobe.o
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obj-$(CONFIG_TRACEPOINT_BENCHMARK) += trace_benchmark.o
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libftrace-y := ftrace.o
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