csky: ftrace call graph supported.

With csky-gcc -pg -mbacktrace, ftrace call graph supported.

Signed-off-by: Guo Ren <ren_guo@c-sky.com>

diff --git a/arch/csky/Kconfig b/arch/csky/Kconfig
index 0b9a290c015748144cd5ca7a530b5de43c849094..6e814772d72e52bd069c9c27a8da22af7896cad1 100644 (file)
--- a/arch/csky/Kconfig
+++ b/arch/csky/Kconfig
@@ -30,6 +30,7 @@ config CSKY
        select GENERIC_SMP_IDLE_THREAD
        select HAVE_ARCH_TRACEHOOK
        select HAVE_FUNCTION_TRACER
+       select HAVE_FUNCTION_GRAPH_TRACER
        select HAVE_GENERIC_DMA_COHERENT
        select HAVE_KERNEL_GZIP
        select HAVE_KERNEL_LZO

diff --git a/arch/csky/abiv2/mcount.S b/arch/csky/abiv2/mcount.S
index 73377d5ddd18c7bb715e0d05fa7324fc6dc080c6..c633379956f5c3671333ab4f4b4d080becfa6bde 100644 (file)
--- a/arch/csky/abiv2/mcount.S
+++ b/arch/csky/abiv2/mcount.S
@@ -2,23 +2,123 @@
 // Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
 
 #include <linux/linkage.h>
+#include <asm/ftrace.h>
 
-ENTRY (_mcount)
-       subi    sp, 20
+/*
+ * csky-gcc with -pg will put the following asm after prologue:
+ *      push   r15
+ *      jsri   _mcount
+ *
+ * stack layout after mcount_enter in _mcount():
+ *
+ * current sp => 0:+-------+
+ *                 | a0-a3 | -> must save all argument regs
+ *             +16:+-------+
+ *                 | lr    | -> _mcount lr (instrumente function's pc)
+ *             +20:+-------+
+ *                 | fp=r8 | -> instrumented function fp
+ *             +24:+-------+
+ *                 | plr   | -> instrumented function lr (parent's pc)
+ *                 +-------+
+ */
+
+.macro mcount_enter
+       subi    sp, 24
        stw     a0, (sp, 0)
        stw     a1, (sp, 4)
        stw     a2, (sp, 8)
        stw     a3, (sp, 12)
        stw     lr, (sp, 16)
-       mov     a1, lr
-       ldw     a0, (sp, 20)
-       jsri    csky_mcount
+       stw     r8, (sp, 20)
+.endm
+
+.macro mcount_exit
        ldw     a0, (sp, 0)
        ldw     a1, (sp, 4)
        ldw     a2, (sp, 8)
        ldw     a3, (sp, 12)
        ldw     t1, (sp, 16)
-       ldw     lr, (sp, 20)
-       addi    sp, 24
+       ldw     r8, (sp, 20)
+       ldw     lr, (sp, 24)
+       addi    sp, 28
        jmp     t1
-END (_mcount)
+.endm
+
+.macro save_return_regs
+       subi    sp, 16
+       stw     a0, (sp, 0)
+       stw     a1, (sp, 4)
+       stw     a2, (sp, 8)
+       stw     a3, (sp, 12)
+.endm
+
+.macro restore_return_regs
+       mov     lr, a0
+       ldw     a0, (sp, 0)
+       ldw     a1, (sp, 4)
+       ldw     a2, (sp, 8)
+       ldw     a3, (sp, 12)
+       addi    sp, 16
+.endm
+
+ENTRY(ftrace_stub)
+       jmp     lr
+END(ftrace_stub)
+
+ENTRY(_mcount)
+       mcount_enter
+
+       /* r26 is link register, only used with jsri translation */
+       lrw     r26, ftrace_trace_function
+       ldw     r26, (r26, 0)
+       lrw     a1, ftrace_stub
+       cmpne   r26, a1
+       bf      skip_ftrace
+
+       mov     a0, lr
+       subi    a0, MCOUNT_INSN_SIZE
+       ldw     a1, (sp, 24)
+
+       jsr     r26
+
+#ifndef CONFIG_FUNCTION_GRAPH_TRACER
+skip_ftrace:
+       mcount_exit
+#else
+skip_ftrace:
+       lrw     a0, ftrace_graph_return
+       ldw     a0, (a0, 0)
+       lrw     a1, ftrace_stub
+       cmpne   a0, a1
+       bt      ftrace_graph_caller
+
+       lrw     a0, ftrace_graph_entry
+       ldw     a0, (a0, 0)
+       lrw     a1, ftrace_graph_entry_stub
+       cmpne   a0, a1
+       bt      ftrace_graph_caller
+
+       mcount_exit
+#endif
+END(_mcount)
+
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+ENTRY(ftrace_graph_caller)
+       mov     a0, sp
+       addi    a0, 24
+       ldw     a1, (sp, 16)
+       subi    a1, MCOUNT_INSN_SIZE
+       mov     a2, r8
+       lrw     r26, prepare_ftrace_return
+       jsr     r26
+       mcount_exit
+END(ftrace_graph_caller)
+
+ENTRY(return_to_handler)
+       save_return_regs
+       mov     a0, r8
+       jsri    ftrace_return_to_handler
+       restore_return_regs
+       jmp     lr
+END(return_to_handler)
+#endif

diff --git a/arch/csky/include/asm/ftrace.h b/arch/csky/include/asm/ftrace.h
index 1d22a1787b8b9c725b0ee18e342d2c21ab8ea2f5..7547c45312a8e60b144a8e95db73dcee03116791 100644 (file)
--- a/arch/csky/include/asm/ftrace.h
+++ b/arch/csky/include/asm/ftrace.h
@@ -4,6 +4,10 @@
 #ifndef __ASM_CSKY_FTRACE_H
 #define __ASM_CSKY_FTRACE_H
 
-extern void _mcount(unsigned long from_pc);
+#define MCOUNT_INSN_SIZE 4
+
+#define HAVE_FUNCTION_GRAPH_FP_TEST
+
+#define HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
 
 #endif /* __ASM_CSKY_FTRACE_H */

diff --git a/arch/csky/kernel/ftrace.c b/arch/csky/kernel/ftrace.c
index ad054f7190f9ea8be8ebb0dc618c56a29190c977..274c431f18103971996b97a8bf7f704bc0c0736c 100644 (file)
--- a/arch/csky/kernel/ftrace.c
+++ b/arch/csky/kernel/ftrace.c
@@ -4,21 +4,47 @@
 #include <linux/ftrace.h>
 #include <linux/uaccess.h>
 
-extern void (*ftrace_trace_function)(unsigned long, unsigned long,
-                                    struct ftrace_ops*, struct pt_regs*);
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
+                          unsigned long frame_pointer)
+{
+       unsigned long return_hooker = (unsigned long)&return_to_handler;
+       unsigned long old;
 
+       if (unlikely(atomic_read(&current->tracing_graph_pause)))
+               return;
 
-noinline void __naked ftrace_stub(unsigned long ip, unsigned long parent_ip,
-                                 struct ftrace_ops *op, struct pt_regs *regs)
-{
-       asm volatile ("\n");
-}
+       old = *parent;
 
-noinline void csky_mcount(unsigned long from_pc, unsigned long self_pc)
-{
-       if (ftrace_trace_function != ftrace_stub)
-               ftrace_trace_function(self_pc, from_pc, NULL, NULL);
+       if (!function_graph_enter(old, self_addr,
+                       *(unsigned long *)frame_pointer, parent)) {
+               /*
+                * For csky-gcc function has sub-call:
+                * subi sp,     sp, 8
+                * stw  r8,     (sp, 0)
+                * mov  r8,     sp
+                * st.w r15,    (sp, 0x4)
+                * push r15
+                * jl   _mcount
+                * We only need set *parent for resume
+                *
+                * For csky-gcc function has no sub-call:
+                * subi sp,     sp, 4
+                * stw  r8,     (sp, 0)
+                * mov  r8,     sp
+                * push r15
+                * jl   _mcount
+                * We need set *parent and *(frame_pointer + 4) for resume,
+                * because lr is resumed twice.
+                */
+               *parent = return_hooker;
+               frame_pointer += 4;
+               if (*(unsigned long *)frame_pointer == old)
+                       *(unsigned long *)frame_pointer = return_hooker;
+       }
 }
+#endif
 
 /* _mcount is defined in abi's mcount.S */
+extern void _mcount(void);
 EXPORT_SYMBOL(_mcount);