Every mcount() call in the MIPS 32-bit kernel is done as follows:

[...]
move at, ra
jal _mcount
addiu sp, sp, -8
[...]

but upon returning from the mcount() function, the stack pointer
is not adjusted properly. This is explained in details in 58b69401c797
(MIPS: Function tracer: Fix broken function tracing).

Commit ad8c396936e3 ("MIPS: Unbreak function tracer for 64-bit kernel.)
fixed the stack manipulation for 64-bit but it didn't fix it completely
for MIPS32.

Cc: <redacted>
Signed-off-by: Markos Chandras <redacted>
---
Changes since v2:
- Also fix the case where the function graph tracer is enabled
Changes since v1:
- Also fix the case where the tracer is actually enabled
---
 arch/mips/kernel/mcount.S | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/arch/mips/kernel/mcount.S b/arch/mips/kernel/mcount.S
index 5d25462de8a6..2d28c117831d 100644
--- a/arch/mips/kernel/mcount.S
+++ b/arch/mips/kernel/mcount.S

@@ -106,6 +106,9 @@ ftrace_graph_call:
 #endif
 
 	MCOUNT_RESTORE_REGS
+#ifdef CONFIG_32BIT
+        addiu sp, sp, 8
+#endif
 	.globl ftrace_stub
 ftrace_stub:
 	RETURN_BACK

@@ -129,7 +132,11 @@ NESTED(_mcount, PT_SIZE, ra)
 	 nop
 #endif
 	b	ftrace_stub
+#ifdef CONFIG_32BIT
+	 addiu sp, sp, 8
+#else
 	 nop
+#endif
 
 static_trace:
 	MCOUNT_SAVE_REGS

@@ -139,6 +146,9 @@ static_trace:
 	 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

-- 
2.1.0