powerpc/ftrace: Prepare PPC64's ftrace_caller() for CONFIG_DYNAMIC_FTRACE_WITH_ARGS

In order to implement CONFIG_DYNAMIC_FTRACE_WITH_ARGS, change ftrace_caller()
to handle LIVEPATCH the same way as frace_caller_regs().

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/850817333cc76593699032e8e9a70d8c36e1af1e.1640017960.git.christophe.leroy@csgroup.eu

diff --git a/arch/powerpc/kernel/trace/ftrace_64_mprofile.S b/arch/powerpc/kernel/trace/ftrace_64_mprofile.S
index d636fc755f608e7aaf069134bd313387b9c22eac..f6f7878192735c210b141010b87652c77fec1411 100644 (file)
--- a/arch/powerpc/kernel/trace/ftrace_64_mprofile.S
+++ b/arch/powerpc/kernel/trace/ftrace_64_mprofile.S
@@ -172,14 +172,19 @@ _GLOBAL(ftrace_caller)
        addi    r3, r3, function_trace_op@toc@l
        ld      r5, 0(r3)
 
+#ifdef CONFIG_LIVEPATCH_64
+       SAVE_GPR(14, r1)
+       mr      r14,r7          /* remember old NIP */
+#endif
        /* Calculate ip from nip-4 into r3 for call below */
        subi    r3, r7, MCOUNT_INSN_SIZE
 
        /* Put the original return address in r4 as parent_ip */
+       std     r0, _LINK(r1)
        mr      r4, r0
 
-       /* Set pt_regs to NULL */
-       li      r6, 0
+       /* Load &pt_regs in r6 for call below */
+       addi    r6, r1 ,STACK_FRAME_OVERHEAD
 
        /* ftrace_call(r3, r4, r5, r6) */
 .globl ftrace_call
@@ -189,6 +194,10 @@ ftrace_call:
 
        ld      r3, _NIP(r1)
        mtctr   r3
+#ifdef CONFIG_LIVEPATCH_64
+       cmpd    r14, r3         /* has NIP been altered? */
+       REST_GPR(14, r1)
+#endif
 
        /* Restore gprs */
        REST_GPRS(3, 10, r1)
@@ -196,13 +205,17 @@ ftrace_call:
        /* Restore callee's TOC */
        ld      r2, 24(r1)
 
+       /* Restore possibly modified LR */
+       ld      r0, _LINK(r1)
+       mtlr    r0
+
        /* Pop our stack frame */
        addi    r1, r1, SWITCH_FRAME_SIZE
 
-       /* Reload original LR */
-       ld      r0, LRSAVE(r1)
-       mtlr    r0
-
+#ifdef CONFIG_LIVEPATCH_64
+        /* 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