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author | AKASHI Takahiro <takahiro.akashi@linaro.org> | 2014-04-30 18:54:33 +0900 |
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committer | Will Deacon <will.deacon@arm.com> | 2014-05-29 09:08:08 +0100 |
commit | 819e50e25d0ce8a75f5cba815416a6a8573655c4 (patch) | |
tree | 006f9d7dc3f97f47709430357651a83ffdc1f86d /arch/arm64/kernel/ftrace.c | |
parent | af64d2aa872a174772ffc00e2558083f70193acb (diff) | |
download | linux-stable-819e50e25d0ce8a75f5cba815416a6a8573655c4.tar.gz linux-stable-819e50e25d0ce8a75f5cba815416a6a8573655c4.tar.bz2 linux-stable-819e50e25d0ce8a75f5cba815416a6a8573655c4.zip |
arm64: Add ftrace support
This patch implements arm64 specific part to support function tracers,
such as function (CONFIG_FUNCTION_TRACER), function_graph
(CONFIG_FUNCTION_GRAPH_TRACER) and function profiler
(CONFIG_FUNCTION_PROFILER).
With 'function' tracer, all the functions in the kernel are traced with
timestamps in ${sysfs}/tracing/trace. If function_graph tracer is
specified, call graph is generated.
The kernel must be compiled with -pg option so that _mcount() is inserted
at the beginning of functions. This function is called on every function's
entry as long as tracing is enabled.
In addition, function_graph tracer also needs to be able to probe function's
exit. ftrace_graph_caller() & return_to_handler do this by faking link
register's value to intercept function's return path.
More details on architecture specific requirements are described in
Documentation/trace/ftrace-design.txt.
Reviewed-by: Ganapatrao Kulkarni <ganapatrao.kulkarni@cavium.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'arch/arm64/kernel/ftrace.c')
-rw-r--r-- | arch/arm64/kernel/ftrace.c | 64 |
1 files changed, 64 insertions, 0 deletions
diff --git a/arch/arm64/kernel/ftrace.c b/arch/arm64/kernel/ftrace.c new file mode 100644 index 000000000000..a559ab86999b --- /dev/null +++ b/arch/arm64/kernel/ftrace.c @@ -0,0 +1,64 @@ +/* + * arch/arm64/kernel/ftrace.c + * + * Copyright (C) 2013 Linaro Limited + * Author: AKASHI Takahiro <takahiro.akashi@linaro.org> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + +#include <linux/ftrace.h> +#include <linux/swab.h> +#include <linux/uaccess.h> + +#include <asm/cacheflush.h> +#include <asm/ftrace.h> +#include <asm/insn.h> + +#ifdef CONFIG_FUNCTION_GRAPH_TRACER +/* + * function_graph tracer expects ftrace_return_to_handler() to be called + * on the way back to parent. For this purpose, this function is called + * in _mcount() or ftrace_caller() to replace return address (*parent) on + * the call stack to return_to_handler. + * + * Note that @frame_pointer is used only for sanity check later. + */ +void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr, + unsigned long frame_pointer) +{ + unsigned long return_hooker = (unsigned long)&return_to_handler; + unsigned long old; + struct ftrace_graph_ent trace; + int err; + + if (unlikely(atomic_read(¤t->tracing_graph_pause))) + return; + + /* + * Note: + * No protection against faulting at *parent, which may be seen + * on other archs. It's unlikely on AArch64. + */ + old = *parent; + *parent = return_hooker; + + trace.func = self_addr; + trace.depth = current->curr_ret_stack + 1; + + /* Only trace if the calling function expects to */ + if (!ftrace_graph_entry(&trace)) { + *parent = old; + return; + } + + err = ftrace_push_return_trace(old, self_addr, &trace.depth, + frame_pointer); + if (err == -EBUSY) { + *parent = old; + return; + } +} +#endif /* CONFIG_FUNCTION_GRAPH_TRACER */ |