mips: ftrace: fix static function graph tracing (6fb86566) · Commits · 戴 / test

ftrace_graph_caller was never run after calling ftrace_trace_function, breaking the function graph tracer. Fix this, bringing it in line with the x86 implementation. While we're at it, also streamline the control flow of _mcount a bit to reduce the number of branches. This issue was reported before: https://www.linux-mips.org/archives/linux-mips/2014-11/msg00295.html Signed-off-by:

Matthias Schiffer <mschiffer@universe-factory.net> Tested-by:

Matt Redfearn <matt.redfearn@mips.com> Patchwork: https://patchwork.linux-mips.org/patch/18929/ Signed-off-by:

Paul Burton <paul.burton@mips.com> Cc: stable@vger.kernel.org # v3.17+

arch/mips/kernel/mcount.S

+12 −15

Original line number	Diff line number	Diff line
		@@ -119,10 +119,20 @@ NESTED(_mcount, PT_SIZE, ra)
		EXPORT_SYMBOL(_mcount)
		PTR_LA t1, ftrace_stub
		PTR_L t2, ftrace_trace_function /* Prepare t2 for (1) */
		bne t1, t2, static_trace
		beq t1, t2, fgraph_trace
		nop

		MCOUNT_SAVE_REGS

		move a0, ra /* arg1: self return address */
		jalr t2 /* (1) call ftrace_trace_function /
		move a1, AT /* arg2: parent's return address */

		MCOUNT_RESTORE_REGS

		fgraph_trace:
		#ifdef CONFIG_FUNCTION_GRAPH_TRACER
		PTR_LA t1, ftrace_stub
		PTR_L t3, ftrace_graph_return
		bne t1, t3, ftrace_graph_caller
		nop
		@@ -131,24 +141,11 @@ EXPORT_SYMBOL(_mcount)
		bne t1, t3, ftrace_graph_caller
		nop
		#endif
		b ftrace_stub
		#ifdef CONFIG_32BIT
		addiu sp, sp, 8
		#else
		nop
		#endif

		static_trace:
		MCOUNT_SAVE_REGS

		move a0, ra /* arg1: self return address */
		jalr t2 /* (1) call ftrace_trace_function /
		move a1, AT /* arg2: parent's return address */

		MCOUNT_RESTORE_REGS
		#ifdef CONFIG_32BIT
		addiu sp, sp, 8
		#endif

		.globl ftrace_stub
		ftrace_stub:
		RETURN_BACK

Admin message