output befor patch when HAVE_FUNCTION_TRACER is enable
------------= ---------------------------------------------------------
#> insmod b= acktrace.ko
=3D=3D=3D=3D[ backtrace testing ]=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D
Testing a backtrace from process context.
The following trace is a kernel self test and not a bug!
Testing a backt= race.
The following trace is a kernel self test and not a bug!
Call T= race:
[<802e5164>] dump_stack+0x1c/0x50
[<802e5164>] dump= _stack+0x1c/0x50
=3D=3D=3D=3D[ end of backtrace testing ]=3D=3D=3D=3D
-------------------= -----------------------------------
above shows the wrong back trcae

output after patch when HAVE_FUNCTION_TRACER is enable
------------= ----------------------------------------------------------
=3D=3D=3D=3D[= backtrace testing ]=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
Testing a backtrac= e from process context.
The following trace is a kernel self test and not a bug!
Testing a backt= race.
The following trace is a kernel self test and not a bug!
Call T= race:
[<802eb1a4>] dump_stack+0x20/0x54
[<c003405c>] back= trace_test_timer+0x5c/0x74 [sisc_backtrcae]
[<c00340dc>] init_module+0x68/0xa0 [sisc_backtrcae]
[<80000508&= gt;] do_one_initcall+0x108/0x1f0
[<8006d4c4>] sys_init_module+0x1a= 10/0x1c74
[<8000b038>] stack_done+0x20/0x40
-------------------= -----------------------------------------------

get_frame_info() is used to fetch the frame information from the
fu= nction.
However,
1. this function just considers the first stack adju= stment for frame
size.
2. On finding the save_lr instruction, it retu= rns.
It doesn't handle the ftrace condition.

If Dynamic Frace "CONFIG_DYNAMIC_FTRACE" is enabled, the ins= trumentation
code is:
=A0- jal <ftrace_caller>
=A0- addiu sp= ,sp,-8
Thus, the current Frame Size of function is increased by 8 for Ft= race.

Signed-off-by: Akhilesh Kumar <akhilesh.lxr@gmail.com>

---
=A0arch/mips/kernel/process.c |=A0=A0 67
+++++++++++++++++++= +++++++++++++++++++++++++
=A01 files changed, 67 insertions(+), 0 deleti= ons(-)

diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.cindex 7955409..df72738 100644
--- a/arch/mips/kernel/process.c
+++ = b/arch/mips/kernel/process.c
@@ -290,12 +290,45 @@=A0 static inline int = is_sp_move_ins(union
mips_instruction *ip)
=A0 return 0;
=A0}

+#ifdef CONFIG_DYNAMIC_FTRACE
+/*
+ * To create the jal <>= instruction from mcount.
+ * taken from:
+ * - arch/mips/kernel/ftra= ce.c
+ */
+#define ADDR_MASK 0x03ffffff=A0=A0=A0 /*=A0 op_code|addr := 31...26|25 ....0 */
+#define JAL 0x0c000000=A0=A0=A0=A0=A0 /* jump & link: ip --> ra, ju= mp to target */
+#define INSN_JAL(addr)=A0 \
+=A0=A0=A0=A0=A0 ((unsig= ned int)(JAL | (((addr) >> 2) & ADDR_MASK)))
+
+/*
+ * W= e assume jal <mcount>/<ftrace_caller> to be present in
+ * first JAL_MAX_OFFSET instructions.
+ * Increment this, if its otherw= ise
+ */
+#define JAL_MAX_OFFSET 16U
+#define MCOUNT_STACK_INST 0x= 27bdfff8 /* addiu=A0=A0 sp,sp,-8 */
+
+/*
+ * If Dynamic Ftrace is= enabled, ftrace_caller is the trace function.
+ * Otherwise its - mcount
+ */
+extern void=A0 ftrace_caller(void);<= br>+#endif /* CONFIG_DYNAMIC_FTRACE */
+
=A0static int get_frame_info= (struct mips_frame_info *info)
=A0{
=A0 union mips_instruction *ip = =3D info->func;
=A0 unsigned max_insns =3D info->func_size / sizeof(union mips_instructi= on);
=A0 unsigned i;

+#ifdef CONFIG_DYNAMIC_FTRACE
+ unsigned max_prolog_inst =3D max_in= sns;
+ int jal_found =3D 0;
+ /* instruction corresponding to jal <= ;_mcount>/<ftrace_caller> */
+ int jal_mcount =3D 0;
+#endif=
+
=A0 info->pc_offset =3D -1;
=A0 info->frame_size =3D 0;

--e89a8ff1c89c74179f04c6d58d84--