lkml.org 
[lkml]   [2018]   [Jul]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 4.4 036/105] mips: ftrace: fix static function graph tracing
Date
4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

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

commit 6fb8656646f996d1eef42e6d56203c4915cb9e08 upstream.

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+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/mips/kernel/mcount.S | 27 ++++++++++++---------------
1 file changed, 12 insertions(+), 15 deletions(-)

--- a/arch/mips/kernel/mcount.S
+++ b/arch/mips/kernel/mcount.S
@@ -116,10 +116,20 @@ ftrace_stub:
NESTED(_mcount, PT_SIZE, ra)
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
@@ -128,24 +138,11 @@ NESTED(_mcount, PT_SIZE, ra)
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

\
 
 \ /
  Last update: 2018-07-01 20:33    [W:0.225 / U:1.716 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site