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Subject[PATCH 2/3] powerpc/ftrace: Enable HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
Date
This associates entries in the ftrace_ret_stack with corresponding stack
frames, enabling more robust stack unwinding. Also update the only user
of ftrace_graph_ret_addr() to pass the stack pointer.

Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
---
arch/powerpc/include/asm/asm-prototypes.h | 3 ++-
arch/powerpc/include/asm/ftrace.h | 2 ++
arch/powerpc/kernel/stacktrace.c | 2 +-
arch/powerpc/kernel/trace/ftrace.c | 5 +++--
arch/powerpc/kernel/trace/ftrace_32.S | 1 +
arch/powerpc/kernel/trace/ftrace_64_mprofile.S | 1 +
arch/powerpc/kernel/trace/ftrace_64_pg.S | 1 +
7 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/include/asm/asm-prototypes.h b/arch/powerpc/include/asm/asm-prototypes.h
index 49196d35e3bb..8561498e653c 100644
--- a/arch/powerpc/include/asm/asm-prototypes.h
+++ b/arch/powerpc/include/asm/asm-prototypes.h
@@ -134,7 +134,8 @@ extern int __ucmpdi2(u64, u64);

/* tracing */
void _mcount(void);
-unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip);
+unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip,
+ unsigned long sp);

void pnv_power9_force_smt4_catch(void);
void pnv_power9_force_smt4_release(void);
diff --git a/arch/powerpc/include/asm/ftrace.h b/arch/powerpc/include/asm/ftrace.h
index 3dfb80b86561..f54a08a2cd70 100644
--- a/arch/powerpc/include/asm/ftrace.h
+++ b/arch/powerpc/include/asm/ftrace.h
@@ -8,6 +8,8 @@
#define MCOUNT_ADDR ((unsigned long)(_mcount))
#define MCOUNT_INSN_SIZE 4 /* sizeof mcount call */

+#define HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
+
#ifdef __ASSEMBLY__

/* Based off of objdump optput from glibc */
diff --git a/arch/powerpc/kernel/stacktrace.c b/arch/powerpc/kernel/stacktrace.c
index 1e2276963f6d..e2a46cfed5fd 100644
--- a/arch/powerpc/kernel/stacktrace.c
+++ b/arch/powerpc/kernel/stacktrace.c
@@ -182,7 +182,7 @@ static int __save_stack_trace_tsk_reliable(struct task_struct *tsk,
* FIXME: IMHO these tests do not belong in
* arch-dependent code, they are generic.
*/
- ip = ftrace_graph_ret_addr(tsk, &graph_idx, ip, NULL);
+ ip = ftrace_graph_ret_addr(tsk, &graph_idx, ip, stack);
#ifdef CONFIG_KPROBES
/*
* Mark stacktraces with kretprobed functions on them
diff --git a/arch/powerpc/kernel/trace/ftrace.c b/arch/powerpc/kernel/trace/ftrace.c
index be1ca98fce5c..7ea0ca044b65 100644
--- a/arch/powerpc/kernel/trace/ftrace.c
+++ b/arch/powerpc/kernel/trace/ftrace.c
@@ -944,7 +944,8 @@ int ftrace_disable_ftrace_graph_caller(void)
* Hook the return address and push it in the stack of return addrs
* in current thread info. Return the address we want to divert to.
*/
-unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip)
+unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip,
+ unsigned long sp)
{
unsigned long return_hooker;

@@ -956,7 +957,7 @@ unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip)

return_hooker = ppc_function_entry(return_to_handler);

- if (!function_graph_enter(parent, ip, 0, NULL))
+ if (!function_graph_enter(parent, ip, 0, (unsigned long *)sp))
parent = return_hooker;
out:
return parent;
diff --git a/arch/powerpc/kernel/trace/ftrace_32.S b/arch/powerpc/kernel/trace/ftrace_32.S
index 183f608efb81..e023ae59c429 100644
--- a/arch/powerpc/kernel/trace/ftrace_32.S
+++ b/arch/powerpc/kernel/trace/ftrace_32.S
@@ -50,6 +50,7 @@ _GLOBAL(ftrace_stub)

#ifdef CONFIG_FUNCTION_GRAPH_TRACER
_GLOBAL(ftrace_graph_caller)
+ addi r5, r1, 48
/* load r4 with local address */
lwz r4, 44(r1)
subi r4, r4, MCOUNT_INSN_SIZE
diff --git a/arch/powerpc/kernel/trace/ftrace_64_mprofile.S b/arch/powerpc/kernel/trace/ftrace_64_mprofile.S
index 74acbf16a666..f9fd5f743eba 100644
--- a/arch/powerpc/kernel/trace/ftrace_64_mprofile.S
+++ b/arch/powerpc/kernel/trace/ftrace_64_mprofile.S
@@ -294,6 +294,7 @@ _GLOBAL(ftrace_graph_caller)
std r2, 24(r1)
ld r2, PACATOC(r13) /* get kernel TOC in r2 */

+ addi r5, r1, 112
mfctr r4 /* ftrace_caller has moved local addr here */
std r4, 40(r1)
mflr r3 /* ftrace_caller has restored LR from stack */
diff --git a/arch/powerpc/kernel/trace/ftrace_64_pg.S b/arch/powerpc/kernel/trace/ftrace_64_pg.S
index e41a7d13c99c..6708e24db0ab 100644
--- a/arch/powerpc/kernel/trace/ftrace_64_pg.S
+++ b/arch/powerpc/kernel/trace/ftrace_64_pg.S
@@ -41,6 +41,7 @@ _GLOBAL(ftrace_stub)

#ifdef CONFIG_FUNCTION_GRAPH_TRACER
_GLOBAL(ftrace_graph_caller)
+ addi r5, r1, 112
/* load r4 with local address */
ld r4, 128(r1)
subi r4, r4, MCOUNT_INSN_SIZE
--
2.23.0
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