Re: [PATCH v6 08/15] arm64: disable function graph tracing with SCS
From: Will Deacon <will@kernel.org>
Date: 2020-01-16 17:40:53
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On Fri, Dec 06, 2019 at 02:13:44PM -0800, Sami Tolvanen wrote:
quoted hunk ↗ jump to hunk
The graph tracer hooks returns by modifying frame records on the (regular) stack, but with SCS the return address is taken from the shadow stack, and the value in the frame record has no effect. As we don't currently have a mechanism to determine the corresponding slot on the shadow stack (and to pass this through the ftrace infrastructure), for now let's disable the graph tracer when SCS is enabled. Signed-off-by: Sami Tolvanen <samitolvanen@google.com> Reviewed-by: Kees Cook <redacted> Reviewed-by: Mark Rutland <mark.rutland@arm.com> --- arch/arm64/Kconfig | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index b1b4476ddb83..49e5f94ff4af 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig@@ -149,7 +149,7 @@ 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
I think this is the wrong way around, as we support the graph tracer today and so I think SHADOW_CALL_STACK should depend on !GRAPH_TRACER and possibly even EXPERT until this is resolved. Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel