Re: [PATCH v7 04/10] ppc64 ftrace_with_regs configuration variables
From: Petr Mladek <pmladek@suse.com>
Date: 2016-02-05 16:18:39
Also in:
linuxppc-dev
Subsystem:
the rest, tracing · Maintainers:
Linus Torvalds, Steven Rostedt, Masami Hiramatsu
On Fri 2016-02-05 09:48:03, Steven Rostedt wrote:
quoted hunk ↗ jump to hunk
On Fri, 5 Feb 2016 15:05:17 +0100 Petr Mladek [off-list ref] wrote:quoted
On Mon 2016-01-25 16:29:54, Torsten Duwe wrote:quoted
diff --git a/arch/powerpc/kernel/ftrace.c b/arch/powerpc/kernel/ftrace.c index ef8b916..29b7014 100644 --- a/arch/powerpc/kernel/ftrace.c +++ b/arch/powerpc/kernel/ftrace.c@@ -28,6 +28,11 @@ #ifdef CONFIG_DYNAMIC_FTRACE +#if defined(CONFIG_DYNAMIC_FTRACE_WITH_REGS) && defined(CONFIG_PPC64) && \ + !defined(CC_USING_MPROFILE_KERNEL) +#error "DYNAMIC_FTRACE_WITH_REGS requires working -mprofile-kernel" +#endifCONFIG_DYNAMIC_FTRACE_WITH_REGS is automatically enabled when both CONFIG_DYNAMIC_FTRACE and HAVE_DYNAMIC_FTRACE_WITH_REGS are enabled. Therefore it is not possible to build kernel with broken gcc and DYNAMIC_FTRACE. IMHO, we need to allow to explicitely disable DYNAMIC_FTRACE_WITH_REGS if the compiler is broken to get around this build error. We either need to define DYNAMIC_FTRACE_WITH_REGS as a proper bool with description, help text, ... Or we need a way to explicitely disable HAVE_DYNAMIC_FTRACE_WITH_REGS. Or something like this.You mean something like this? (not tested) -- Stevediff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig index e45db6b0d878..19377bacebfc 100644 --- a/kernel/trace/Kconfig +++ b/kernel/trace/Kconfig@@ -470,6 +470,19 @@ config DYNAMIC_FTRACE_WITH_REGS def_bool y depends on DYNAMIC_FTRACE depends on HAVE_DYNAMIC_FTRACE_WITH_REGS + depends on !DISABLE_DYNAMIC_FTRACE_WITH_REGS + +config DISABLE_DYNAMIC_FTRACE_WITH_REGS + bool "Force build to not have function tracer pass in registers" + depends on DYNAMIC_FTRACE + depends on HAVE_DYNAMIC_FTRACE_WITH_REGS + help + If the architecture supports passing in registers to the function + tracer, then that is automatically enabled. But there may be some + compilers out there that are broken and cause this to fail. + This option makes the build think that the architecture does not + support the register passing and allows the build to work even + with compilers that do not support the feature.g
s/feature.g/feature/
config FUNCTION_PROFILER bool "Kernel function profiler"
It works but the extra option and reverse logic makes things even more complicated. Whem I think about it, the change below does similar job and looks more strightforwad:
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index a138f6d..de6dab0 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig@@ -449,7 +449,7 @@ config PROBE_EVENTS def_bool n config DYNAMIC_FTRACE - bool "enable/disable function tracing dynamically" + bool "Enable/Disable function tracing dynamically" depends on FUNCTION_TRACER depends on HAVE_DYNAMIC_FTRACE default y
@@ -472,9 +472,17 @@ config DYNAMIC_FTRACE otherwise has native performance as long as no tracing is active. config DYNAMIC_FTRACE_WITH_REGS - def_bool y + bool "Pass registers to function tracer" depends on DYNAMIC_FTRACE depends on HAVE_DYNAMIC_FTRACE_WITH_REGS + default y + help + This option enables passing the current state of processor + registers to the function tracer. It allows to do a more + detailed analyze and print more information. + + Say Y here if you are unsure. The only exception is if + you want to pass a build error caused by a broken compiler. config FUNCTION_PROFILER bool "Kernel function profiler"
I made "enable/disable" uppercase because it looked weird in context of other descritions. Best Regards, Petr