[PATCH] powerpc: split ftrace bits into a separate file
Steven Rostedt
rostedt at goodmis.org
Wed Nov 23 01:46:17 AEDT 2016
On Tue, 22 Nov 2016 15:25:32 +0530
"Naveen N. Rao" <naveen.n.rao at linux.vnet.ibm.com> wrote:
> No functional changes.
Should have a better change log though. Why did you do this?
I'm personally fine with this, as long as the powerpc maintainers are
too.
-- Steve
>
> Signed-off-by: Naveen N. Rao <naveen.n.rao at linux.vnet.ibm.com>
> ---
> arch/powerpc/kernel/Makefile | 2 +
> arch/powerpc/kernel/entry_32.S | 107 -----------
> arch/powerpc/kernel/entry_64.S | 380 --------------------------------------
> arch/powerpc/kernel/ftrace_32.S | 118 ++++++++++++
> arch/powerpc/kernel/ftrace_64.S | 391 ++++++++++++++++++++++++++++++++++++++++
> 5 files changed, 511 insertions(+), 487 deletions(-)
> create mode 100644 arch/powerpc/kernel/ftrace_32.S
> create mode 100644 arch/powerpc/kernel/ftrace_64.S
>
> diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
> index 26b5a5e..298c98d 100644
> --- a/arch/powerpc/kernel/Makefile
> +++ b/arch/powerpc/kernel/Makefile
> @@ -112,6 +112,8 @@ obj64-$(CONFIG_AUDIT) += compat_audit.o
>
> obj-$(CONFIG_PPC_IO_WORKAROUNDS) += io-workarounds.o
>
> +obj32-$(CONFIG_FUNCTION_TRACER) += ftrace_32.o
> +obj64-$(CONFIG_FUNCTION_TRACER) += ftrace_64.o
> obj-$(CONFIG_DYNAMIC_FTRACE) += ftrace.o
> obj-$(CONFIG_FUNCTION_GRAPH_TRACER) += ftrace.o
> obj-$(CONFIG_FTRACE_SYSCALLS) += ftrace.o
> diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
> index 3841d74..5b30eb9 100644
> --- a/arch/powerpc/kernel/entry_32.S
> +++ b/arch/powerpc/kernel/entry_32.S
> @@ -31,7 +31,6 @@
> #include <asm/ppc_asm.h>
> #include <asm/asm-offsets.h>
> #include <asm/unistd.h>
> -#include <asm/ftrace.h>
> #include <asm/ptrace.h>
> #include <asm/export.h>
>
> @@ -1304,109 +1303,3 @@ machine_check_in_rtas:
> /* XXX load up BATs and panic */
>
> #endif /* CONFIG_PPC_RTAS */
> -
> -#ifdef CONFIG_FUNCTION_TRACER
> -#ifdef CONFIG_DYNAMIC_FTRACE
> -_GLOBAL(mcount)
> -_GLOBAL(_mcount)
> - /*
> - * It is required that _mcount on PPC32 must preserve the
> - * link register. But we have r0 to play with. We use r0
> - * to push the return address back to the caller of mcount
> - * into the ctr register, restore the link register and
> - * then jump back using the ctr register.
> - */
> - mflr r0
> - mtctr r0
> - lwz r0, 4(r1)
> - mtlr r0
> - bctr
> -
> -_GLOBAL(ftrace_caller)
> - MCOUNT_SAVE_FRAME
> - /* r3 ends up with link register */
> - subi r3, r3, MCOUNT_INSN_SIZE
> -.globl ftrace_call
> -ftrace_call:
> - bl ftrace_stub
> - nop
> -#ifdef CONFIG_FUNCTION_GRAPH_TRACER
> -.globl ftrace_graph_call
> -ftrace_graph_call:
> - b ftrace_graph_stub
> -_GLOBAL(ftrace_graph_stub)
> -#endif
> - MCOUNT_RESTORE_FRAME
> - /* old link register ends up in ctr reg */
> - bctr
> -#else
> -_GLOBAL(mcount)
> -_GLOBAL(_mcount)
> -
> - MCOUNT_SAVE_FRAME
> -
> - subi r3, r3, MCOUNT_INSN_SIZE
> - LOAD_REG_ADDR(r5, ftrace_trace_function)
> - lwz r5,0(r5)
> -
> - mtctr r5
> - bctrl
> - nop
> -
> -#ifdef CONFIG_FUNCTION_GRAPH_TRACER
> - b ftrace_graph_caller
> -#endif
> - MCOUNT_RESTORE_FRAME
> - bctr
> -#endif
> -EXPORT_SYMBOL(_mcount)
> -
> -_GLOBAL(ftrace_stub)
> - blr
> -
> -#ifdef CONFIG_FUNCTION_GRAPH_TRACER
> -_GLOBAL(ftrace_graph_caller)
> - /* load r4 with local address */
> - lwz r4, 44(r1)
> - subi r4, r4, MCOUNT_INSN_SIZE
> -
> - /* Grab the LR out of the caller stack frame */
> - lwz r3,52(r1)
> -
> - 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)
> -
> - MCOUNT_RESTORE_FRAME
> - /* old link register ends up in ctr reg */
> - bctr
> -
> -_GLOBAL(return_to_handler)
> - /* need to save return values */
> - stwu r1, -32(r1)
> - stw r3, 20(r1)
> - stw r4, 16(r1)
> - stw r31, 12(r1)
> - mr r31, r1
> -
> - bl ftrace_return_to_handler
> - nop
> -
> - /* return value has real return address */
> - mtlr r3
> -
> - lwz r3, 20(r1)
> - lwz r4, 16(r1)
> - lwz r31,12(r1)
> - lwz r1, 0(r1)
> -
> - /* Jump back to real return address */
> - blr
> -#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
> -
> -#endif /* CONFIG_FUNCTION_TRACER */
> diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
> index 6432d4b..9b541d2 100644
> --- a/arch/powerpc/kernel/entry_64.S
> +++ b/arch/powerpc/kernel/entry_64.S
> @@ -20,7 +20,6 @@
>
> #include <linux/errno.h>
> #include <linux/err.h>
> -#include <linux/magic.h>
> #include <asm/unistd.h>
> #include <asm/processor.h>
> #include <asm/page.h>
> @@ -33,7 +32,6 @@
> #include <asm/bug.h>
> #include <asm/ptrace.h>
> #include <asm/irqflags.h>
> -#include <asm/ftrace.h>
> #include <asm/hw_irq.h>
> #include <asm/context_tracking.h>
> #include <asm/tm.h>
> @@ -1173,381 +1171,3 @@ _GLOBAL(enter_prom)
> ld r0,16(r1)
> mtlr r0
> blr
> -
> -#ifdef CONFIG_FUNCTION_TRACER
> -#ifdef CONFIG_DYNAMIC_FTRACE
> -_GLOBAL(mcount)
> -_GLOBAL(_mcount)
> -EXPORT_SYMBOL(_mcount)
> - mflr r12
> - mtctr r12
> - mtlr r0
> - bctr
> -
> -#ifndef CC_USING_MPROFILE_KERNEL
> -_GLOBAL_TOC(ftrace_caller)
> - /* Taken from output of objdump from lib64/glibc */
> - mflr r3
> - ld r11, 0(r1)
> - stdu r1, -112(r1)
> - std r3, 128(r1)
> - ld r4, 16(r11)
> - subi r3, r3, MCOUNT_INSN_SIZE
> -.globl ftrace_call
> -ftrace_call:
> - bl ftrace_stub
> - nop
> -#ifdef CONFIG_FUNCTION_GRAPH_TRACER
> -.globl ftrace_graph_call
> -ftrace_graph_call:
> - b ftrace_graph_stub
> -_GLOBAL(ftrace_graph_stub)
> -#endif
> - ld r0, 128(r1)
> - mtlr r0
> - addi r1, r1, 112
> -
> -#else /* CC_USING_MPROFILE_KERNEL */
> -/*
> - *
> - * ftrace_caller() is the function that replaces _mcount() when ftrace is
> - * active.
> - *
> - * We arrive here after a function A calls function B, and we are the trace
> - * function for B. When we enter r1 points to A's stack frame, B has not yet
> - * had a chance to allocate one yet.
> - *
> - * Additionally r2 may point either to the TOC for A, or B, depending on
> - * whether B did a TOC setup sequence before calling us.
> - *
> - * On entry the LR points back to the _mcount() call site, and r0 holds the
> - * saved LR as it was on entry to B, ie. the original return address at the
> - * call site in A.
> - *
> - * Our job is to save the register state into a struct pt_regs (on the stack)
> - * and then arrange for the ftrace function to be called.
> - */
> -_GLOBAL(ftrace_caller)
> - /* Save the original return address in A's stack frame */
> - std r0,LRSAVE(r1)
> -
> - /* Create our stack frame + pt_regs */
> - stdu r1,-SWITCH_FRAME_SIZE(r1)
> -
> - /* Save all gprs to pt_regs */
> - SAVE_8GPRS(0,r1)
> - SAVE_8GPRS(8,r1)
> - SAVE_8GPRS(16,r1)
> - SAVE_8GPRS(24,r1)
> -
> - /* Load special regs for save below */
> - mfmsr r8
> - mfctr r9
> - mfxer r10
> - mfcr r11
> -
> - /* Get the _mcount() call site out of LR */
> - mflr r7
> - /* Save it as pt_regs->nip & pt_regs->link */
> - std r7, _NIP(r1)
> - std r7, _LINK(r1)
> -
> - /* Save callee's TOC in the ABI compliant location */
> - std r2, 24(r1)
> - ld r2,PACATOC(r13) /* get kernel TOC in r2 */
> -
> - addis r3,r2,function_trace_op at toc@ha
> - addi r3,r3,function_trace_op at toc@l
> - ld r5,0(r3)
> -
> -#ifdef CONFIG_LIVEPATCH
> - 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 */
> - mr r4, r0
> -
> - /* Save special regs */
> - std r8, _MSR(r1)
> - std r9, _CTR(r1)
> - std r10, _XER(r1)
> - std r11, _CCR(r1)
> -
> - /* Load &pt_regs in r6 for call below */
> - addi r6, r1 ,STACK_FRAME_OVERHEAD
> -
> - /* ftrace_call(r3, r4, r5, r6) */
> -.globl ftrace_call
> -ftrace_call:
> - bl ftrace_stub
> - nop
> -
> - /* Load ctr with the possibly modified NIP */
> - ld r3, _NIP(r1)
> - mtctr r3
> -#ifdef CONFIG_LIVEPATCH
> - cmpd r14,r3 /* has NIP been altered? */
> -#endif
> -
> - /* Restore gprs */
> - REST_8GPRS(0,r1)
> - REST_8GPRS(8,r1)
> - REST_8GPRS(16,r1)
> - REST_8GPRS(24,r1)
> -
> - /* Restore callee's TOC */
> - ld r2, 24(r1)
> -
> - /* Pop our stack frame */
> - addi r1, r1, SWITCH_FRAME_SIZE
> -
> - /* Restore original LR for return to B */
> - ld r0, LRSAVE(r1)
> - mtlr r0
> -
> -#ifdef CONFIG_LIVEPATCH
> - /* Based on the cmpd above, if the NIP was altered handle livepatch */
> - bne- livepatch_handler
> -#endif
> -
> -#ifdef CONFIG_FUNCTION_GRAPH_TRACER
> - stdu r1, -112(r1)
> -.globl ftrace_graph_call
> -ftrace_graph_call:
> - b ftrace_graph_stub
> -_GLOBAL(ftrace_graph_stub)
> - addi r1, r1, 112
> -#endif
> -
> - ld r0,LRSAVE(r1) /* restore callee's lr at _mcount site */
> - mtlr r0
> - bctr /* jump after _mcount site */
> -#endif /* CC_USING_MPROFILE_KERNEL */
> -
> -_GLOBAL(ftrace_stub)
> - blr
> -
> -#ifdef CONFIG_LIVEPATCH
> - /*
> - * This function runs in the mcount context, between two functions. As
> - * such it can only clobber registers which are volatile and used in
> - * function linkage.
> - *
> - * We get here when a function A, calls another function B, but B has
> - * been live patched with a new function C.
> - *
> - * On entry:
> - * - we have no stack frame and can not allocate one
> - * - LR points back to the original caller (in A)
> - * - CTR holds the new NIP in C
> - * - r0 & r12 are free
> - *
> - * r0 can't be used as the base register for a DS-form load or store, so
> - * we temporarily shuffle r1 (stack pointer) into r0 and then put it back.
> - */
> -livepatch_handler:
> - CURRENT_THREAD_INFO(r12, r1)
> -
> - /* Save stack pointer into r0 */
> - mr r0, r1
> -
> - /* Allocate 3 x 8 bytes */
> - ld r1, TI_livepatch_sp(r12)
> - addi r1, r1, 24
> - std r1, TI_livepatch_sp(r12)
> -
> - /* Save toc & real LR on livepatch stack */
> - std r2, -24(r1)
> - mflr r12
> - std r12, -16(r1)
> -
> - /* Store stack end marker */
> - lis r12, STACK_END_MAGIC at h
> - ori r12, r12, STACK_END_MAGIC at l
> - std r12, -8(r1)
> -
> - /* Restore real stack pointer */
> - mr r1, r0
> -
> - /* Put ctr in r12 for global entry and branch there */
> - mfctr r12
> - bctrl
> -
> - /*
> - * Now we are returning from the patched function to the original
> - * caller A. We are free to use r0 and r12, and we can use r2 until we
> - * restore it.
> - */
> -
> - CURRENT_THREAD_INFO(r12, r1)
> -
> - /* Save stack pointer into r0 */
> - mr r0, r1
> -
> - ld r1, TI_livepatch_sp(r12)
> -
> - /* Check stack marker hasn't been trashed */
> - lis r2, STACK_END_MAGIC at h
> - ori r2, r2, STACK_END_MAGIC at l
> - ld r12, -8(r1)
> -1: tdne r12, r2
> - EMIT_BUG_ENTRY 1b, __FILE__, __LINE__ - 1, 0
> -
> - /* Restore LR & toc from livepatch stack */
> - ld r12, -16(r1)
> - mtlr r12
> - ld r2, -24(r1)
> -
> - /* Pop livepatch stack frame */
> - CURRENT_THREAD_INFO(r12, r0)
> - subi r1, r1, 24
> - std r1, TI_livepatch_sp(r12)
> -
> - /* Restore real stack pointer */
> - mr r1, r0
> -
> - /* Return to original caller of live patched function */
> - blr
> -#endif
> -
> -
> -#else
> -_GLOBAL_TOC(_mcount)
> -EXPORT_SYMBOL(_mcount)
> - /* Taken from output of objdump from lib64/glibc */
> - mflr r3
> - ld r11, 0(r1)
> - stdu r1, -112(r1)
> - std r3, 128(r1)
> - ld r4, 16(r11)
> -
> - subi r3, r3, MCOUNT_INSN_SIZE
> - LOAD_REG_ADDR(r5,ftrace_trace_function)
> - ld r5,0(r5)
> - ld r5,0(r5)
> - mtctr r5
> - bctrl
> - nop
> -
> -
> -#ifdef CONFIG_FUNCTION_GRAPH_TRACER
> - b ftrace_graph_caller
> -#endif
> - ld r0, 128(r1)
> - mtlr r0
> - addi r1, r1, 112
> -_GLOBAL(ftrace_stub)
> - blr
> -
> -#endif /* CONFIG_DYNAMIC_FTRACE */
> -
> -#ifdef CONFIG_FUNCTION_GRAPH_TRACER
> -#ifndef CC_USING_MPROFILE_KERNEL
> -_GLOBAL(ftrace_graph_caller)
> - /* load r4 with local address */
> - ld r4, 128(r1)
> - subi r4, r4, MCOUNT_INSN_SIZE
> -
> - /* Grab the LR out of the caller stack frame */
> - ld r11, 112(r1)
> - ld r3, 16(r11)
> -
> - 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.
> - */
> - ld r11, 112(r1)
> - std r3, 16(r11)
> -
> - ld r0, 128(r1)
> - mtlr r0
> - addi r1, r1, 112
> - blr
> -
> -#else /* CC_USING_MPROFILE_KERNEL */
> -_GLOBAL(ftrace_graph_caller)
> - /* 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 */
> -
> - 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 /* CC_USING_MPROFILE_KERNEL */
> -
> -_GLOBAL(return_to_handler)
> - /* need to save return values */
> - std r4, -32(r1)
> - std r3, -24(r1)
> - /* save TOC */
> - std r2, -16(r1)
> - std r31, -8(r1)
> - mr r31, r1
> - stdu r1, -112(r1)
> -
> - /*
> - * We might be called from a module.
> - * Switch to our TOC to run inside the core kernel.
> - */
> - ld r2, PACATOC(r13)
> -
> - bl ftrace_return_to_handler
> - nop
> -
> - /* return value has real return address */
> - mtlr r3
> -
> - ld r1, 0(r1)
> - ld r4, -32(r1)
> - ld r3, -24(r1)
> - ld r2, -16(r1)
> - ld r31, -8(r1)
> -
> - /* Jump back to real return address */
> - blr
> -#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
> -#endif /* CONFIG_FUNCTION_TRACER */
> diff --git a/arch/powerpc/kernel/ftrace_32.S b/arch/powerpc/kernel/ftrace_32.S
> new file mode 100644
> index 0000000..afef2c0
> --- /dev/null
> +++ b/arch/powerpc/kernel/ftrace_32.S
> @@ -0,0 +1,118 @@
> +/*
> + * Split from entry_32.S
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License
> + * as published by the Free Software Foundation; either version
> + * 2 of the License, or (at your option) any later version.
> + */
> +
> +#include <linux/magic.h>
> +#include <asm/reg.h>
> +#include <asm/ppc_asm.h>
> +#include <asm/asm-offsets.h>
> +#include <asm/ftrace.h>
> +#include <asm/export.h>
> +
> +#ifdef CONFIG_DYNAMIC_FTRACE
> +_GLOBAL(mcount)
> +_GLOBAL(_mcount)
> + /*
> + * It is required that _mcount on PPC32 must preserve the
> + * link register. But we have r0 to play with. We use r0
> + * to push the return address back to the caller of mcount
> + * into the ctr register, restore the link register and
> + * then jump back using the ctr register.
> + */
> + mflr r0
> + mtctr r0
> + lwz r0, 4(r1)
> + mtlr r0
> + bctr
> +
> +_GLOBAL(ftrace_caller)
> + MCOUNT_SAVE_FRAME
> + /* r3 ends up with link register */
> + subi r3, r3, MCOUNT_INSN_SIZE
> +.globl ftrace_call
> +ftrace_call:
> + bl ftrace_stub
> + nop
> +#ifdef CONFIG_FUNCTION_GRAPH_TRACER
> +.globl ftrace_graph_call
> +ftrace_graph_call:
> + b ftrace_graph_stub
> +_GLOBAL(ftrace_graph_stub)
> +#endif
> + MCOUNT_RESTORE_FRAME
> + /* old link register ends up in ctr reg */
> + bctr
> +#else
> +_GLOBAL(mcount)
> +_GLOBAL(_mcount)
> +
> + MCOUNT_SAVE_FRAME
> +
> + subi r3, r3, MCOUNT_INSN_SIZE
> + LOAD_REG_ADDR(r5, ftrace_trace_function)
> + lwz r5,0(r5)
> +
> + mtctr r5
> + bctrl
> + nop
> +
> +#ifdef CONFIG_FUNCTION_GRAPH_TRACER
> + b ftrace_graph_caller
> +#endif
> + MCOUNT_RESTORE_FRAME
> + bctr
> +#endif
> +EXPORT_SYMBOL(_mcount)
> +
> +_GLOBAL(ftrace_stub)
> + blr
> +
> +#ifdef CONFIG_FUNCTION_GRAPH_TRACER
> +_GLOBAL(ftrace_graph_caller)
> + /* load r4 with local address */
> + lwz r4, 44(r1)
> + subi r4, r4, MCOUNT_INSN_SIZE
> +
> + /* Grab the LR out of the caller stack frame */
> + lwz r3,52(r1)
> +
> + 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)
> +
> + MCOUNT_RESTORE_FRAME
> + /* old link register ends up in ctr reg */
> + bctr
> +
> +_GLOBAL(return_to_handler)
> + /* need to save return values */
> + stwu r1, -32(r1)
> + stw r3, 20(r1)
> + stw r4, 16(r1)
> + stw r31, 12(r1)
> + mr r31, r1
> +
> + bl ftrace_return_to_handler
> + nop
> +
> + /* return value has real return address */
> + mtlr r3
> +
> + lwz r3, 20(r1)
> + lwz r4, 16(r1)
> + lwz r31,12(r1)
> + lwz r1, 0(r1)
> +
> + /* Jump back to real return address */
> + blr
> +#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
> diff --git a/arch/powerpc/kernel/ftrace_64.S b/arch/powerpc/kernel/ftrace_64.S
> new file mode 100644
> index 0000000..df47433
> --- /dev/null
> +++ b/arch/powerpc/kernel/ftrace_64.S
> @@ -0,0 +1,391 @@
> +/*
> + * Split from entry_64.S
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License
> + * as published by the Free Software Foundation; either version
> + * 2 of the License, or (at your option) any later version.
> + */
> +
> +#include <linux/magic.h>
> +#include <asm/ppc_asm.h>
> +#include <asm/asm-offsets.h>
> +#include <asm/ftrace.h>
> +#include <asm/ppc-opcode.h>
> +#include <asm/export.h>
> +
> +#ifdef CONFIG_DYNAMIC_FTRACE
> +_GLOBAL(mcount)
> +_GLOBAL(_mcount)
> +EXPORT_SYMBOL(_mcount)
> + mflr r12
> + mtctr r12
> + mtlr r0
> + bctr
> +
> +#ifndef CC_USING_MPROFILE_KERNEL
> +_GLOBAL_TOC(ftrace_caller)
> + /* Taken from output of objdump from lib64/glibc */
> + mflr r3
> + ld r11, 0(r1)
> + stdu r1, -112(r1)
> + std r3, 128(r1)
> + ld r4, 16(r11)
> + subi r3, r3, MCOUNT_INSN_SIZE
> +.globl ftrace_call
> +ftrace_call:
> + bl ftrace_stub
> + nop
> +#ifdef CONFIG_FUNCTION_GRAPH_TRACER
> +.globl ftrace_graph_call
> +ftrace_graph_call:
> + b ftrace_graph_stub
> +_GLOBAL(ftrace_graph_stub)
> +#endif
> + ld r0, 128(r1)
> + mtlr r0
> + addi r1, r1, 112
> +
> +#else /* CC_USING_MPROFILE_KERNEL */
> +/*
> + *
> + * ftrace_caller() is the function that replaces _mcount() when ftrace is
> + * active.
> + *
> + * We arrive here after a function A calls function B, and we are the trace
> + * function for B. When we enter r1 points to A's stack frame, B has not yet
> + * had a chance to allocate one yet.
> + *
> + * Additionally r2 may point either to the TOC for A, or B, depending on
> + * whether B did a TOC setup sequence before calling us.
> + *
> + * On entry the LR points back to the _mcount() call site, and r0 holds the
> + * saved LR as it was on entry to B, ie. the original return address at the
> + * call site in A.
> + *
> + * Our job is to save the register state into a struct pt_regs (on the stack)
> + * and then arrange for the ftrace function to be called.
> + */
> +_GLOBAL(ftrace_caller)
> + /* Save the original return address in A's stack frame */
> + std r0,LRSAVE(r1)
> +
> + /* Create our stack frame + pt_regs */
> + stdu r1,-SWITCH_FRAME_SIZE(r1)
> +
> + /* Save all gprs to pt_regs */
> + SAVE_8GPRS(0,r1)
> + SAVE_8GPRS(8,r1)
> + SAVE_8GPRS(16,r1)
> + SAVE_8GPRS(24,r1)
> +
> + /* Load special regs for save below */
> + mfmsr r8
> + mfctr r9
> + mfxer r10
> + mfcr r11
> +
> + /* Get the _mcount() call site out of LR */
> + mflr r7
> + /* Save it as pt_regs->nip & pt_regs->link */
> + std r7, _NIP(r1)
> + std r7, _LINK(r1)
> +
> + /* Save callee's TOC in the ABI compliant location */
> + std r2, 24(r1)
> + ld r2,PACATOC(r13) /* get kernel TOC in r2 */
> +
> + addis r3,r2,function_trace_op at toc@ha
> + addi r3,r3,function_trace_op at toc@l
> + ld r5,0(r3)
> +
> +#ifdef CONFIG_LIVEPATCH
> + 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 */
> + mr r4, r0
> +
> + /* Save special regs */
> + std r8, _MSR(r1)
> + std r9, _CTR(r1)
> + std r10, _XER(r1)
> + std r11, _CCR(r1)
> +
> + /* Load &pt_regs in r6 for call below */
> + addi r6, r1 ,STACK_FRAME_OVERHEAD
> +
> + /* ftrace_call(r3, r4, r5, r6) */
> +.globl ftrace_call
> +ftrace_call:
> + bl ftrace_stub
> + nop
> +
> + /* Load ctr with the possibly modified NIP */
> + ld r3, _NIP(r1)
> + mtctr r3
> +#ifdef CONFIG_LIVEPATCH
> + cmpd r14,r3 /* has NIP been altered? */
> +#endif
> +
> + /* Restore gprs */
> + REST_8GPRS(0,r1)
> + REST_8GPRS(8,r1)
> + REST_8GPRS(16,r1)
> + REST_8GPRS(24,r1)
> +
> + /* Restore callee's TOC */
> + ld r2, 24(r1)
> +
> + /* Pop our stack frame */
> + addi r1, r1, SWITCH_FRAME_SIZE
> +
> + /* Restore original LR for return to B */
> + ld r0, LRSAVE(r1)
> + mtlr r0
> +
> +#ifdef CONFIG_LIVEPATCH
> + /* Based on the cmpd above, if the NIP was altered handle livepatch */
> + bne- livepatch_handler
> +#endif
> +
> +#ifdef CONFIG_FUNCTION_GRAPH_TRACER
> + stdu r1, -112(r1)
> +.globl ftrace_graph_call
> +ftrace_graph_call:
> + b ftrace_graph_stub
> +_GLOBAL(ftrace_graph_stub)
> + addi r1, r1, 112
> +#endif
> +
> + ld r0,LRSAVE(r1) /* restore callee's lr at _mcount site */
> + mtlr r0
> + bctr /* jump after _mcount site */
> +#endif /* CC_USING_MPROFILE_KERNEL */
> +
> +_GLOBAL(ftrace_stub)
> + blr
> +
> +#ifdef CONFIG_LIVEPATCH
> + /*
> + * This function runs in the mcount context, between two functions. As
> + * such it can only clobber registers which are volatile and used in
> + * function linkage.
> + *
> + * We get here when a function A, calls another function B, but B has
> + * been live patched with a new function C.
> + *
> + * On entry:
> + * - we have no stack frame and can not allocate one
> + * - LR points back to the original caller (in A)
> + * - CTR holds the new NIP in C
> + * - r0 & r12 are free
> + *
> + * r0 can't be used as the base register for a DS-form load or store, so
> + * we temporarily shuffle r1 (stack pointer) into r0 and then put it back.
> + */
> +livepatch_handler:
> + CURRENT_THREAD_INFO(r12, r1)
> +
> + /* Save stack pointer into r0 */
> + mr r0, r1
> +
> + /* Allocate 3 x 8 bytes */
> + ld r1, TI_livepatch_sp(r12)
> + addi r1, r1, 24
> + std r1, TI_livepatch_sp(r12)
> +
> + /* Save toc & real LR on livepatch stack */
> + std r2, -24(r1)
> + mflr r12
> + std r12, -16(r1)
> +
> + /* Store stack end marker */
> + lis r12, STACK_END_MAGIC at h
> + ori r12, r12, STACK_END_MAGIC at l
> + std r12, -8(r1)
> +
> + /* Restore real stack pointer */
> + mr r1, r0
> +
> + /* Put ctr in r12 for global entry and branch there */
> + mfctr r12
> + bctrl
> +
> + /*
> + * Now we are returning from the patched function to the original
> + * caller A. We are free to use r0 and r12, and we can use r2 until we
> + * restore it.
> + */
> +
> + CURRENT_THREAD_INFO(r12, r1)
> +
> + /* Save stack pointer into r0 */
> + mr r0, r1
> +
> + ld r1, TI_livepatch_sp(r12)
> +
> + /* Check stack marker hasn't been trashed */
> + lis r2, STACK_END_MAGIC at h
> + ori r2, r2, STACK_END_MAGIC at l
> + ld r12, -8(r1)
> +1: tdne r12, r2
> + EMIT_BUG_ENTRY 1b, __FILE__, __LINE__ - 1, 0
> +
> + /* Restore LR & toc from livepatch stack */
> + ld r12, -16(r1)
> + mtlr r12
> + ld r2, -24(r1)
> +
> + /* Pop livepatch stack frame */
> + CURRENT_THREAD_INFO(r12, r0)
> + subi r1, r1, 24
> + std r1, TI_livepatch_sp(r12)
> +
> + /* Restore real stack pointer */
> + mr r1, r0
> +
> + /* Return to original caller of live patched function */
> + blr
> +#endif
> +
> +
> +#else
> +_GLOBAL_TOC(_mcount)
> +EXPORT_SYMBOL(_mcount)
> + /* Taken from output of objdump from lib64/glibc */
> + mflr r3
> + ld r11, 0(r1)
> + stdu r1, -112(r1)
> + std r3, 128(r1)
> + ld r4, 16(r11)
> +
> + subi r3, r3, MCOUNT_INSN_SIZE
> + LOAD_REG_ADDR(r5,ftrace_trace_function)
> + ld r5,0(r5)
> + ld r5,0(r5)
> + mtctr r5
> + bctrl
> + nop
> +
> +
> +#ifdef CONFIG_FUNCTION_GRAPH_TRACER
> + b ftrace_graph_caller
> +#endif
> + ld r0, 128(r1)
> + mtlr r0
> + addi r1, r1, 112
> +_GLOBAL(ftrace_stub)
> + blr
> +
> +#endif /* CONFIG_DYNAMIC_FTRACE */
> +
> +#ifdef CONFIG_FUNCTION_GRAPH_TRACER
> +#ifndef CC_USING_MPROFILE_KERNEL
> +_GLOBAL(ftrace_graph_caller)
> + /* load r4 with local address */
> + ld r4, 128(r1)
> + subi r4, r4, MCOUNT_INSN_SIZE
> +
> + /* Grab the LR out of the caller stack frame */
> + ld r11, 112(r1)
> + ld r3, 16(r11)
> +
> + 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.
> + */
> + ld r11, 112(r1)
> + std r3, 16(r11)
> +
> + ld r0, 128(r1)
> + mtlr r0
> + addi r1, r1, 112
> + blr
> +
> +#else /* CC_USING_MPROFILE_KERNEL */
> +_GLOBAL(ftrace_graph_caller)
> + /* 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 */
> +
> + 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 /* CC_USING_MPROFILE_KERNEL */
> +
> +_GLOBAL(return_to_handler)
> + /* need to save return values */
> + std r4, -32(r1)
> + std r3, -24(r1)
> + /* save TOC */
> + std r2, -16(r1)
> + std r31, -8(r1)
> + mr r31, r1
> + stdu r1, -112(r1)
> +
> + /*
> + * We might be called from a module.
> + * Switch to our TOC to run inside the core kernel.
> + */
> + ld r2, PACATOC(r13)
> +
> + bl ftrace_return_to_handler
> + nop
> +
> + /* return value has real return address */
> + mtlr r3
> +
> + ld r1, 0(r1)
> + ld r4, -32(r1)
> + ld r3, -24(r1)
> + ld r2, -16(r1)
> + ld r31, -8(r1)
> +
> + /* Jump back to real return address */
> + blr
> +#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
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