[PATCH] ftrace: arm64: remove static ftrace

[Steven Rostedt]

On Tue, 22 Nov 2022 16:36:24 +0000
Mark Rutland <mark.rutland at arm.com> wrote:

> The build test robot pointer out that there's a build failure when:
> 
>   CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS=y
>   CONFIG_DYNAMIC_FTRACE_WITH_ARGS=n
> 
> ... due to some mismatched ifdeffery, some of which checks
> CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS, and some of which checks
> CONFIG_DYNAMIC_FTRACE_WITH_ARGS, leading to some missing definitions expected
> by the core code when CONFIG_DYNAMIC_FTRACE=n and consequently
> CONFIG_DYNAMIC_FTRACE_WITH_ARGS=n.
> 
> There's really not much point in supporting CONFIG_DYNAMIC_FTRACE=n (AKA
> static ftrace). All supported toolchains allow us to implement
> DYNAMIC_FTRACE, distributions all prefer DYNAMIC_FTRACE, and both
> powerpc and s390 removed support for static ftrace in commits:
> 
>   0c0c52306f4792a4 ("powerpc: Only support DYNAMIC_FTRACE not static")
>   5d6a0163494c78ad ("s390/ftrace: enforce DYNAMIC_FTRACE if FUNCTION_TRACER is selected")
> 
> ... and according to Steven, static ftrace is only supported on x86 to
> allow testing that the core code still functions in this configuration.
> 
> Given that, let's simplify matters by removing arm64's support for
> static ftrace. This avoids the problem originally reported, and leaves
> us with less code to maintain.
> 
> Fixes: 26299b3f6ba26bfc ("ftrace: arm64: move from REGS to ARGS")
> Link: https://lore.kernel.org/r/202211212249.livTPi3Y-lkp@intel.com
> Suggested-by: Steven Rostedt <rostedt at goodmis.org>
> Signed-off-by: Mark Rutland <mark.rutland at arm.com>
> Cc: Will Deacon <will at kernel.org>
> Cc: Catalin Marinas <catalin.marinas at arm.com>

Acked-by: Steven Rostedt (Google) <rostedt at goodmis.org>

-- Steve