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authorMatthias Schiffer <mschiffer@universe-factory.net>2018-03-24 17:57:49 +0100
committerPaul Burton <paul.burton@mips.com>2018-06-19 15:00:12 -0700
commit6fb8656646f996d1eef42e6d56203c4915cb9e08 (patch)
tree782be6f9af41e298651cbb679a5d83bfc2d5de4e /arch
parent2a027b47dba6b77ab8c8e47b589ae9bbc5ac6175 (diff)
downloadlinux-6fb8656646f996d1eef42e6d56203c4915cb9e08.tar.bz2
mips: ftrace: fix static function graph tracing
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+
Diffstat (limited to 'arch')
-rw-r--r--arch/mips/kernel/mcount.S27
1 files changed, 12 insertions, 15 deletions
diff --git a/arch/mips/kernel/mcount.S b/arch/mips/kernel/mcount.S
index f2ee7e1e3342..cff52b283e03 100644
--- a/arch/mips/kernel/mcount.S
+++ b/arch/mips/kernel/mcount.S
@@ -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