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Message-ID: <20100315170054.31593.3153.stgit@localhost6.localdomain6> Date: Mon, 15 Mar 2010 13:00:54 -0400 From: Masami Hiramatsu <mhiramat@...hat.com> To: Ingo Molnar <mingo@...e.hu>, lkml <linux-kernel@...r.kernel.org> Cc: systemtap <systemtap@...rces.redhat.com>, DLE <dle-develop@...ts.sourceforge.net>, Masami Hiramatsu <mhiramat@...hat.com>, Dieter Ries <mail@...terries.net>, Ingo Molnar <mingo@...e.hu>, Ananth N Mavinakayanahalli <ananth@...ibm.com>, OGAWA Hirofumi <hirofumi@...l.parknet.co.jp> Subject: [PATCH -tip v3] kprobes: Hide CONFIG_OPTPROBES and set if arch support optimized kprobes Hide CONFIG_OPTPROBES and set if the arch supports optimized kprobes (IOW, HAVE_OPTPROBES=y), since this option doesn't change the major behavior of kprobes, and workarounds for minor changes are documented. Signed-off-by: Masami Hiramatsu <mhiramat@...hat.com> Cc: Dieter Ries <mail@...terries.net> Cc: Ingo Molnar <mingo@...e.hu> Cc: Ananth N Mavinakayanahalli <ananth@...ibm.com> Cc: OGAWA Hirofumi <hirofumi@...l.parknet.co.jp> --- Documentation/kprobes.txt | 10 ++-------- arch/Kconfig | 9 ++------- 2 files changed, 4 insertions(+), 15 deletions(-) diff --git a/Documentation/kprobes.txt b/Documentation/kprobes.txt index 2f9115c..61c291c 100644 --- a/Documentation/kprobes.txt +++ b/Documentation/kprobes.txt @@ -165,8 +165,8 @@ the user entry_handler invocation is also skipped. 1.4 How Does Jump Optimization Work? -If you configured your kernel with CONFIG_OPTPROBES=y (currently -this option is supported on x86/x86-64, non-preemptive kernel) and +If your kernel is built with CONFIG_OPTPROBES=y (currently this flag +is automatically set 'y' on x86/x86-64, non-preemptive kernel) and the "debug.kprobes_optimization" kernel parameter is set to 1 (see sysctl(8)), Kprobes tries to reduce probe-hit overhead by using a jump instruction instead of a breakpoint instruction at each probepoint. @@ -271,8 +271,6 @@ tweak the kernel's execution path, you need to suppress optimization, using one of the following techniques: - Specify an empty function for the kprobe's post_handler or break_handler. or -- Config CONFIG_OPTPROBES=n. - or - Execute 'sysctl -w debug.kprobes_optimization=n' 2. Architectures Supported @@ -307,10 +305,6 @@ it useful to "Compile the kernel with debug info" (CONFIG_DEBUG_INFO), so you can use "objdump -d -l vmlinux" to see the source-to-object code mapping. -If you want to reduce probing overhead, set "Kprobes jump optimization -support" (CONFIG_OPTPROBES) to "y". You can find this option under the -"Kprobes" line. - 4. API Reference The Kprobes API includes a "register" function and an "unregister" diff --git a/arch/Kconfig b/arch/Kconfig index e5eb133..f06010f 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -42,15 +42,10 @@ config KPROBES If in doubt, say "N". config OPTPROBES - bool "Kprobes jump optimization support (EXPERIMENTAL)" - default y - depends on KPROBES + def_bool y + depends on KPROBES && HAVE_OPTPROBES depends on !PREEMPT - depends on HAVE_OPTPROBES select KALLSYMS_ALL - help - This option will allow kprobes to optimize breakpoint to - a jump for reducing its overhead. config HAVE_EFFICIENT_UNALIGNED_ACCESS bool -- Masami Hiramatsu e-mail: mhiramat@...hat.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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