powerpc/ftrace: directly call of function graph tracer by ftrace caller

Modify function graph tracer to be handled directly by the standard
ftrace caller.

This is made possible as powerpc now supports
CONFIG_DYNAMIC_FTRACE_WITH_ARGS.

This change simplifies the call of function graph ftrace.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/04d196585ff81bde06a000bd9c633a33a5b21130.1640017960.git.christophe.leroy@csgroup.eu

diff --git a/arch/powerpc/include/asm/ftrace.h b/arch/powerpc/include/asm/ftrace.h
index 45c3d6f..70b4570 100644 (file)
--- a/arch/powerpc/include/asm/ftrace.h
+++ b/arch/powerpc/include/asm/ftrace.h
@@ -38,6 +38,12 @@ static __always_inline void ftrace_instruction_pointer_set(struct ftrace_regs *f
 {
        regs_set_return_ip(&fregs->regs, ip);
 }
+
+struct ftrace_ops;
+
+#define ftrace_graph_func ftrace_graph_func
+void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
+                      struct ftrace_ops *op, struct ftrace_regs *fregs);
 #endif
 #endif /* __ASSEMBLY__ */
 

diff --git a/arch/powerpc/kernel/trace/ftrace.c b/arch/powerpc/kernel/trace/ftrace.c
index ce67376..74a176e 100644 (file)
--- a/arch/powerpc/kernel/trace/ftrace.c
+++ b/arch/powerpc/kernel/trace/ftrace.c
@@ -917,6 +917,9 @@ static int ftrace_modify_ftrace_graph_caller(bool enable)
        unsigned long stub = (unsigned long)(&ftrace_graph_stub);
        ppc_inst_t old, new;
 
+       if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_ARGS))
+               return 0;
+
        old = ftrace_call_replace(ip, enable ? stub : addr, 0);
        new = ftrace_call_replace(ip, enable ? addr : stub, 0);
 
@@ -955,6 +958,14 @@ unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip,
 out:
        return parent;
 }
+
+#ifdef CONFIG_DYNAMIC_FTRACE_WITH_ARGS
+void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
+                      struct ftrace_ops *op, struct ftrace_regs *fregs)
+{
+       fregs->regs.link = prepare_ftrace_return(parent_ip, ip, fregs->regs.gpr[1]);
+}
+#endif
 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
 
 #ifdef PPC64_ELF_ABI_v1

diff --git a/arch/powerpc/kernel/trace/ftrace_32.S b/arch/powerpc/kernel/trace/ftrace_32.S
index c4055b4..2b425da 100644 (file)
--- a/arch/powerpc/kernel/trace/ftrace_32.S
+++ b/arch/powerpc/kernel/trace/ftrace_32.S
@@ -59,13 +59,6 @@ ftrace_call:
        mtlr    r0
 
        addi    r1, r1, INT_FRAME_SIZE
-ftrace_caller_common:
-#ifdef CONFIG_FUNCTION_GRAPH_TRACER
-.globl ftrace_graph_call
-ftrace_graph_call:
-       b       ftrace_graph_stub
-_GLOBAL(ftrace_graph_stub)
-#endif
        /* old link register ends up in ctr reg */
        bctr
 
@@ -135,52 +128,10 @@ ftrace_regs_call:
 
        /* Pop our stack frame */
        addi r1, r1, INT_FRAME_SIZE
-
-       b       ftrace_caller_common
-
-#ifdef CONFIG_FUNCTION_GRAPH_TRACER
-_GLOBAL(ftrace_graph_caller)
-       stwu    r1,-48(r1)
-       stw     r3, 12(r1)
-       stw     r4, 16(r1)
-       stw     r5, 20(r1)
-       stw     r6, 24(r1)
-       stw     r7, 28(r1)
-       stw     r8, 32(r1)
-       stw     r9, 36(r1)
-       stw     r10,40(r1)
-
-       addi    r5, r1, 48
-       mfctr   r4              /* ftrace_caller has moved local addr here */
-       stw     r4, 44(r1)
-       mflr    r3              /* ftrace_caller has restored LR from stack */
-       subi    r4, r4, MCOUNT_INSN_SIZE
-
-       bl      prepare_ftrace_return
-       nop
-
-        /*
-         * prepare_ftrace_return gives us the address we divert to.
-         * Change the LR in the callers stack frame to this.
-         */
-       stw     r3,52(r1)
-       mtlr    r3
-       lwz     r0,44(r1)
-       mtctr   r0
-
-       lwz     r3, 12(r1)
-       lwz     r4, 16(r1)
-       lwz     r5, 20(r1)
-       lwz     r6, 24(r1)
-       lwz     r7, 28(r1)
-       lwz     r8, 32(r1)
-       lwz     r9, 36(r1)
-       lwz     r10,40(r1)
-
-       addi    r1, r1, 48
-
+       /* old link register ends up in ctr reg */
        bctr
 
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
 _GLOBAL(return_to_handler)
        /* need to save return values */
        stwu    r1, -16(r1)

diff --git a/arch/powerpc/kernel/trace/ftrace_64_mprofile.S b/arch/powerpc/kernel/trace/ftrace_64_mprofile.S
index f6f7878..6071e01 100644 (file)
--- a/arch/powerpc/kernel/trace/ftrace_64_mprofile.S
+++ b/arch/powerpc/kernel/trace/ftrace_64_mprofile.S
@@ -124,15 +124,6 @@ ftrace_regs_call:
         /* Based on the cmpd above, if the NIP was altered handle livepatch */
        bne-    livepatch_handler
 #endif
-
-ftrace_caller_common:
-#ifdef CONFIG_FUNCTION_GRAPH_TRACER
-.globl ftrace_graph_call
-ftrace_graph_call:
-       b       ftrace_graph_stub
-_GLOBAL(ftrace_graph_stub)
-#endif
-
        bctr                    /* jump after _mcount site */
 
 _GLOBAL(ftrace_stub)
@@ -216,8 +207,7 @@ ftrace_call:
         /* Based on the cmpd above, if the NIP was altered handle livepatch */
        bne-    livepatch_handler
 #endif
-       /* Handle function_graph or go back */
-       b       ftrace_caller_common
+       bctr                    /* jump after _mcount site */
 
 #ifdef CONFIG_LIVEPATCH
        /*
@@ -286,55 +276,3 @@ livepatch_handler:
        /* Return to original caller of live patched function */
        blr
 #endif /* CONFIG_LIVEPATCH */
-
-#ifdef CONFIG_FUNCTION_GRAPH_TRACER
-_GLOBAL(ftrace_graph_caller)
-       stdu    r1, -112(r1)
-       /* with -mprofile-kernel, parameter regs are still alive at _mcount */
-       std     r10, 104(r1)
-       std     r9, 96(r1)
-       std     r8, 88(r1)
-       std     r7, 80(r1)
-       std     r6, 72(r1)
-       std     r5, 64(r1)
-       std     r4, 56(r1)
-       std     r3, 48(r1)
-
-       /* Save callee's TOC in the ABI compliant location */
-       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 */
-       subi    r4, r4, MCOUNT_INSN_SIZE
-
-       bl      prepare_ftrace_return
-       nop
-
-       /*
-        * prepare_ftrace_return gives us the address we divert to.
-        * Change the LR to this.
-        */
-       mtlr    r3
-
-       ld      r0, 40(r1)
-       mtctr   r0
-       ld      r10, 104(r1)
-       ld      r9, 96(r1)
-       ld      r8, 88(r1)
-       ld      r7, 80(r1)
-       ld      r6, 72(r1)
-       ld      r5, 64(r1)
-       ld      r4, 56(r1)
-       ld      r3, 48(r1)
-
-       /* Restore callee's TOC */
-       ld      r2, 24(r1)
-
-       addi    r1, r1, 112
-       mflr    r0
-       std     r0, LRSAVE(r1)
-       bctr
-#endif /* CONFIG_FUNCTION_GRAPH_TRACER */