diff options
| author | Vasily Gorbik <gor@linux.ibm.com> | 2018-08-06 16:17:46 +0300 |
|---|---|---|
| committer | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2018-08-16 05:38:38 +0300 |
| commit | 2f4df0017baedd535254d987c6b10f855f1fb11f (patch) | |
| tree | c035a8d2357ee4c54b584a3ba4153d4673fa057f | |
| parent | 07d0408120216b60625c9a5b8012d1c3a907984d (diff) | |
| download | linux-2f4df0017baedd535254d987c6b10f855f1fb11f.tar.xz | |
tracing: Add -mcount-nop option support
-mcount-nop gcc option generates the calls to the profiling functions
as nops which allows to avoid patching mcount jump with NOP instructions
initially.
-mcount-nop gcc option will be activated if platform selects
HAVE_NOP_MCOUNT and gcc actually supports it.
In addition to that CC_USING_NOP_MCOUNT is defined and could be used by
architectures to adapt ftrace patching behavior.
Link: http://lkml.kernel.org/r/patch-3.thread-aa7b8d.git-e02ed2dc082b.your-ad-here.call-01533557518-ext-9465@work.hours
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
| -rw-r--r-- | Makefile | 6 | ||||
| -rw-r--r-- | kernel/trace/Kconfig | 5 | ||||
| -rw-r--r-- | kernel/trace/ftrace.c | 2 |
3 files changed, 13 insertions, 0 deletions
@@ -749,6 +749,12 @@ ifdef CONFIG_FTRACE_MCOUNT_RECORD CC_FLAGS_FTRACE += -mrecord-mcount export CC_USING_RECORD_MCOUNT := 1 endif + ifdef CONFIG_HAVE_NOP_MCOUNT + ifeq ($(call cc-option-yn, -mnop-mcount),y) + CC_FLAGS_FTRACE += -mnop-mcount + CC_FLAGS_USING += -DCC_USING_NOP_MCOUNT + endif + endif endif ifdef CONFIG_HAVE_FENTRY ifeq ($(call cc-option-yn, -mfentry),y) diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig index 036cec1fcd24..fd6754b88f87 100644 --- a/kernel/trace/Kconfig +++ b/kernel/trace/Kconfig @@ -47,6 +47,11 @@ config HAVE_FENTRY help Arch supports the gcc options -pg with -mfentry +config HAVE_NOP_MCOUNT + bool + help + Arch supports the gcc options -pg with -mrecord-mcount and -nop-mcount + config HAVE_C_RECORDMCOUNT bool help diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 48b5b466ec7a..468e8527e979 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -2950,12 +2950,14 @@ static int ftrace_update_code(struct module *mod, struct ftrace_page *new_pgs) p = &pg->records[i]; p->flags = rec_flags; +#ifndef CC_USING_NOP_MCOUNT /* * Do the initial record conversion from mcount jump * to the NOP instructions. */ if (!ftrace_code_disable(mod, p)) break; +#endif update_cnt++; } |