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Message-ID: <201910312056.E3315F0F@keescook> Date: Thu, 31 Oct 2019 20:58:00 -0700 From: Kees Cook <keescook@...omium.org> To: samitolvanen@...gle.com Cc: Will Deacon <will@...nel.org>, Catalin Marinas <catalin.marinas@....com>, Steven Rostedt <rostedt@...dmis.org>, Masami Hiramatsu <mhiramat@...nel.org>, Ard Biesheuvel <ard.biesheuvel@...aro.org>, Dave Martin <Dave.Martin@....com>, Laura Abbott <labbott@...hat.com>, Mark Rutland <mark.rutland@....com>, Nick Desaulniers <ndesaulniers@...gle.com>, Jann Horn <jannh@...gle.com>, Miguel Ojeda <miguel.ojeda.sandonis@...il.com>, Masahiro Yamada <yamada.masahiro@...ionext.com>, clang-built-linux@...glegroups.com, kernel-hardening@...ts.openwall.com, linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org Subject: Re: [PATCH v3 11/17] arm64: disable function graph tracing with SCS On Thu, Oct 31, 2019 at 09:46:31AM -0700, samitolvanen@...gle.com wrote: > With CONFIG_FUNCTION_GRAPH_TRACER, function return addresses are > modified in ftrace_graph_caller and prepare_ftrace_return to redirect > control flow to ftrace_return_to_handler. This is incompatible with > SCS. IIRC, the argument was to disable these on a per-arch basis instead of doing it as a "depends on !SHADOW_CALL_STACK" in the top-level function graph tracer Kconfig? (I'm just thinking ahead to doing this again for other architectures, though, I guess, there is much more work than just that for, say, x86.) Regardless: Reviewed-by: Kees Cook <keescook@...omium.org> -Kees > > Signed-off-by: Sami Tolvanen <samitolvanen@...gle.com> > --- > arch/arm64/Kconfig | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > index e7b57a8a5531..42867174920f 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -148,7 +148,7 @@ config ARM64 > select HAVE_FTRACE_MCOUNT_RECORD > select HAVE_FUNCTION_TRACER > select HAVE_FUNCTION_ERROR_INJECTION > - select HAVE_FUNCTION_GRAPH_TRACER > + select HAVE_FUNCTION_GRAPH_TRACER if !SHADOW_CALL_STACK > select HAVE_GCC_PLUGINS > select HAVE_HW_BREAKPOINT if PERF_EVENTS > select HAVE_IRQ_TIME_ACCOUNTING > -- > 2.24.0.rc0.303.g954a862665-goog > -- Kees Cook
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