ftrace: Prepare ftrace_64_mprofile.S for reuse by PPC32

Naveen N. Rao Mon, 14 Feb 2022 09:52:56 -0800

Christophe Leroy wrote:

PPC64 mprofile versions and PPC32 are very similar.


Modify PPC64 version so that if can be reused for PPC32.

Signed-off-by: Christophe Leroy <christophe.le...@csgroup.eu>
---
 .../powerpc/kernel/trace/ftrace_64_mprofile.S | 73 +++++++++++++------
 1 file changed, 51 insertions(+), 22 deletions(-)

While I agree that ppc32 and -mprofile-kernel ftrace code are verysimilar, I think this patch adds way too many #ifdefs. IMHO, this

makes the resultant code quite difficult to follow.


- Naveen


diff --git a/arch/powerpc/kernel/trace/ftrace_64_mprofile.S 
b/arch/powerpc/kernel/trace/ftrace_64_mprofile.S
index 6071e0122797..56da60e98327 100644
--- a/arch/powerpc/kernel/trace/ftrace_64_mprofile.S
+++ b/arch/powerpc/kernel/trace/ftrace_64_mprofile.S
@@ -34,13 +34,16 @@
  */
 _GLOBAL(ftrace_regs_caller)
        /* Save the original return address in A's stack frame */
-       std     r0,LRSAVE(r1)
+#ifdef CONFIG_MPROFILE_KERNEL
+       PPC_STL r0,LRSAVE(r1)
+#endif

/* Create our stack frame + pt_regs */

-       stdu    r1,-SWITCH_FRAME_SIZE(r1)
+       PPC_STLU        r1,-SWITCH_FRAME_SIZE(r1)

/* Save all gprs to pt_regs */

        SAVE_GPR(0, r1)
+#ifdef CONFIG_PPC64
        SAVE_GPRS(2, 11, r1)

/* Ok to continue? */

@@ -49,10 +52,13 @@ _GLOBAL(ftrace_regs_caller)
        beq     ftrace_no_trace

SAVE_GPRS(12, 31, r1)

+#else
+       stmw    r2, GPR2(r1)
+#endif

/* Save previous stack pointer (r1) */

        addi    r8, r1, SWITCH_FRAME_SIZE
-       std     r8, GPR1(r1)
+       PPC_STL r8, GPR1(r1)

/* Load special regs for save below */

        mfmsr   r8
@@ -63,10 +69,11 @@ _GLOBAL(ftrace_regs_caller)
        /* Get the _mcount() call site out of LR */
        mflr    r7
        /* Save it as pt_regs->nip */
-       std     r7, _NIP(r1)
+       PPC_STL r7, _NIP(r1)
        /* Save the read LR in pt_regs->link */
-       std     r0, _LINK(r1)
+       PPC_STL r0, _LINK(r1)

+#ifdef CONFIG_PPC64

        /* Save callee's TOC in the ABI compliant location */
        std     r2, 24(r1)
        ld      r2,PACATOC(r13) /* get kernel TOC in r2 */
@@ -74,8 +81,12 @@ _GLOBAL(ftrace_regs_caller)
        addis   r3,r2,function_trace_op@toc@ha
        addi    r3,r3,function_trace_op@toc@l
        ld      r5,0(r3)
+#else
+       lis     r3,function_trace_op@ha
+       lwz     r5,function_trace_op@l(r3)
+#endif

-#ifdef CONFIG_LIVEPATCH

+#ifdef CONFIG_LIVEPATCH_64
        mr      r14,r7          /* remember old NIP */
 #endif
        /* Calculate ip from nip-4 into r3 for call below */
@@ -85,10 +96,10 @@ _GLOBAL(ftrace_regs_caller)
        mr      r4, r0

/* Save special regs */

-       std     r8, _MSR(r1)
-       std     r9, _CTR(r1)
-       std     r10, _XER(r1)
-       std     r11, _CCR(r1)
+       PPC_STL r8, _MSR(r1)
+       PPC_STL r9, _CTR(r1)
+       PPC_STL r10, _XER(r1)
+       PPC_STL r11, _CCR(r1)

/* Load &pt_regs in r6 for call below */

        addi    r6, r1 ,STACK_FRAME_OVERHEAD
@@ -100,27 +111,32 @@ ftrace_regs_call:
        nop

/* Load ctr with the possibly modified NIP */

-       ld      r3, _NIP(r1)
+       PPC_LL  r3, _NIP(r1)
        mtctr   r3
-#ifdef CONFIG_LIVEPATCH
+#ifdef CONFIG_LIVEPATCH_64
        cmpd    r14, r3         /* has NIP been altered? */
 #endif

/* Restore gprs */

-       REST_GPR(0, r1)
+#ifdef CONFIG_PPC64
        REST_GPRS(2, 31, r1)
+#else
+       lmw     r2, GPR2(r1)
+#endif

/* Restore possibly modified LR */

-       ld      r0, _LINK(r1)
+       PPC_LL  r0, _LINK(r1)
        mtlr    r0

+#ifdef CONFIG_PPC64

        /* Restore callee's TOC */
        ld      r2, 24(r1)
+#endif

/* Pop our stack frame */

        addi r1, r1, SWITCH_FRAME_SIZE

-#ifdef CONFIG_LIVEPATCH

+#ifdef CONFIG_LIVEPATCH_64
         /* Based on the cmpd above, if the NIP was altered handle livepatch */
        bne-    livepatch_handler
 #endif
@@ -129,6 +145,7 @@ ftrace_regs_call:
 _GLOBAL(ftrace_stub)
        blr

+#ifdef CONFIG_PPC64

 ftrace_no_trace:
        mflr    r3
        mtctr   r3
@@ -136,25 +153,31 @@ ftrace_no_trace:
        addi    r1, r1, SWITCH_FRAME_SIZE
        mtlr    r0
        bctr
+#endif

_GLOBAL(ftrace_caller)

        /* Save the original return address in A's stack frame */
-       std     r0, LRSAVE(r1)
+#ifdef CONFIG_MPROFILE_KERNEL
+       PPC_STL r0, LRSAVE(r1)
+#endif

/* Create our stack frame + pt_regs */

-       stdu    r1, -SWITCH_FRAME_SIZE(r1)
+       PPC_STLU        r1, -SWITCH_FRAME_SIZE(r1)

/* Save all gprs to pt_regs */

        SAVE_GPRS(3, 10, r1)

+#ifdef CONFIG_PPC64

        lbz     r3, PACA_FTRACE_ENABLED(r13)
        cmpdi   r3, 0
        beq     ftrace_no_trace
+#endif

/* Get the _mcount() call site out of LR */

        mflr    r7
-       std     r7, _NIP(r1)
+       PPC_STL     r7, _NIP(r1)

+#ifdef CONFIG_PPC64

        /* Save callee's TOC in the ABI compliant location */
        std     r2, 24(r1)
        ld      r2, PACATOC(r13)        /* get kernel TOC in r2 */
@@ -162,6 +185,10 @@ _GLOBAL(ftrace_caller)
        addis   r3, r2, function_trace_op@toc@ha
        addi    r3, r3, function_trace_op@toc@l
        ld      r5, 0(r3)
+#else
+       lis     r3,function_trace_op@ha
+       lwz     r5,function_trace_op@l(r3)
+#endif

#ifdef CONFIG_LIVEPATCH_64

        SAVE_GPR(14, r1)
@@ -171,7 +198,7 @@ _GLOBAL(ftrace_caller)
        subi    r3, r7, MCOUNT_INSN_SIZE

/* Put the original return address in r4 as parent_ip */

-       std     r0, _LINK(r1)
+       PPC_STL r0, _LINK(r1)
        mr      r4, r0

/* Load &pt_regs in r6 for call below */

@@ -183,7 +210,7 @@ ftrace_call:
        bl      ftrace_stub
        nop

- ld r3, _NIP(r1)

+       PPC_LL  r3, _NIP(r1)
        mtctr   r3
 #ifdef CONFIG_LIVEPATCH_64
        cmpd    r14, r3         /* has NIP been altered? */
@@ -193,11 +220,13 @@ ftrace_call:
        /* Restore gprs */
        REST_GPRS(3, 10, r1)

+#ifdef CONFIG_PPC64

        /* Restore callee's TOC */
        ld      r2, 24(r1)
+#endif

/* Restore possibly modified LR */

-       ld      r0, _LINK(r1)
+       PPC_LL  r0, _LINK(r1)
        mtlr    r0

/* Pop our stack frame */

@@ -209,7 +238,7 @@ ftrace_call:
 #endif
        bctr                    /* jump after _mcount site */

-#ifdef CONFIG_LIVEPATCH

+#ifdef CONFIG_LIVEPATCH_64
        /*
         * This function runs in the mcount context, between two functions. As
         * such it can only clobber registers which are volatile and used in
--
2.33.1

Re: [PATCH v2 12/13] powerpc/ftrace: Prepare ftrace_64_mprofile.S for reuse by PPC32

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