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644e0e8dc7
x86_64 has had fentry support for some time. I did not add support to x86_32 as I was unsure if it will be used much in the future. It is still very much used, and there's issues with function graph tracing with gcc playing around with the mcount frames, causing function graph to panic. The fentry code does not have this issue, and is able to cope as there is no frame to mess up. Note, this only adds support for fentry when DYNAMIC_FTRACE is set. There's really no reason to not have that set, because the performance of the machine drops significantly when it's not enabled. Keep !DYNAMIC_FTRACE around to test it off, as there's still some archs that have FTRACE but not DYNAMIC_FTRACE. Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org> Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com> Reviewed-by: Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/20170323143446.052202377@goodmis.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
248 lines
5.0 KiB
ArmAsm
248 lines
5.0 KiB
ArmAsm
/*
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* Copyright (C) 2017 Steven Rostedt, VMware Inc.
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*/
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#include <linux/linkage.h>
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#include <asm/page_types.h>
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#include <asm/segment.h>
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#include <asm/export.h>
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#include <asm/ftrace.h>
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#ifdef CONFIG_FUNCTION_TRACER
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#ifdef CC_USING_FENTRY
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# define function_hook __fentry__
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EXPORT_SYMBOL(__fentry__)
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#else
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# define function_hook mcount
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EXPORT_SYMBOL(mcount)
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#endif
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#ifdef CONFIG_DYNAMIC_FTRACE
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/* mcount uses a frame pointer even if CONFIG_FRAME_POINTER is not set */
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#if !defined(CC_USING_FENTRY) || defined(CONFIG_FRAME_POINTER)
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# define USING_FRAME_POINTER
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#endif
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#ifdef USING_FRAME_POINTER
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# define MCOUNT_FRAME 1 /* using frame = true */
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#else
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# define MCOUNT_FRAME 0 /* using frame = false */
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#endif
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ENTRY(function_hook)
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ret
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END(function_hook)
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ENTRY(ftrace_caller)
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#ifdef USING_FRAME_POINTER
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# ifdef CC_USING_FENTRY
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/*
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* Frame pointers are of ip followed by bp.
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* Since fentry is an immediate jump, we are left with
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* parent-ip, function-ip. We need to add a frame with
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* parent-ip followed by ebp.
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*/
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pushl 4(%esp) /* parent ip */
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pushl %ebp
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movl %esp, %ebp
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pushl 2*4(%esp) /* function ip */
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# endif
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/* For mcount, the function ip is directly above */
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pushl %ebp
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movl %esp, %ebp
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#endif
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pushl %eax
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pushl %ecx
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pushl %edx
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pushl $0 /* Pass NULL as regs pointer */
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#ifdef USING_FRAME_POINTER
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/* Load parent ebp into edx */
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movl 4*4(%esp), %edx
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#else
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/* There's no frame pointer, load the appropriate stack addr instead */
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lea 4*4(%esp), %edx
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#endif
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movl (MCOUNT_FRAME+4)*4(%esp), %eax /* load the rip */
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/* Get the parent ip */
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movl 4(%edx), %edx /* edx has ebp */
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movl function_trace_op, %ecx
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subl $MCOUNT_INSN_SIZE, %eax
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.globl ftrace_call
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ftrace_call:
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call ftrace_stub
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addl $4, %esp /* skip NULL pointer */
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popl %edx
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popl %ecx
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popl %eax
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#ifdef USING_FRAME_POINTER
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popl %ebp
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# ifdef CC_USING_FENTRY
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addl $4,%esp /* skip function ip */
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popl %ebp /* this is the orig bp */
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addl $4, %esp /* skip parent ip */
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# endif
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#endif
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.Lftrace_ret:
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER
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.globl ftrace_graph_call
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ftrace_graph_call:
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jmp ftrace_stub
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#endif
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/* This is weak to keep gas from relaxing the jumps */
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WEAK(ftrace_stub)
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ret
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END(ftrace_caller)
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ENTRY(ftrace_regs_caller)
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/*
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* i386 does not save SS and ESP when coming from kernel.
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* Instead, to get sp, ®s->sp is used (see ptrace.h).
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* Unfortunately, that means eflags must be at the same location
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* as the current return ip is. We move the return ip into the
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* regs->ip location, and move flags into the return ip location.
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*/
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pushl $__KERNEL_CS
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pushl 4(%esp) /* Save the return ip */
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pushl $0 /* Load 0 into orig_ax */
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pushl %gs
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pushl %fs
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pushl %es
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pushl %ds
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pushl %eax
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/* Get flags and place them into the return ip slot */
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pushf
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popl %eax
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movl %eax, 8*4(%esp)
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pushl %ebp
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pushl %edi
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pushl %esi
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pushl %edx
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pushl %ecx
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pushl %ebx
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#ifdef CC_USING_FENTRY
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/* Load 4 off of the parent ip addr into ebp */
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lea 14*4(%esp), %ebp
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#endif
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movl 12*4(%esp), %eax /* Load ip (1st parameter) */
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subl $MCOUNT_INSN_SIZE, %eax /* Adjust ip */
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movl 0x4(%ebp), %edx /* Load parent ip (2nd parameter) */
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movl function_trace_op, %ecx /* Save ftrace_pos in 3rd parameter */
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pushl %esp /* Save pt_regs as 4th parameter */
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GLOBAL(ftrace_regs_call)
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call ftrace_stub
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addl $4, %esp /* Skip pt_regs */
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/* restore flags */
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push 14*4(%esp)
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popf
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/* Move return ip back to its original location */
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movl 12*4(%esp), %eax
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movl %eax, 14*4(%esp)
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popl %ebx
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popl %ecx
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popl %edx
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popl %esi
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popl %edi
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popl %ebp
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popl %eax
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popl %ds
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popl %es
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popl %fs
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popl %gs
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/* use lea to not affect flags */
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lea 3*4(%esp), %esp /* Skip orig_ax, ip and cs */
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jmp .Lftrace_ret
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#else /* ! CONFIG_DYNAMIC_FTRACE */
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ENTRY(function_hook)
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cmpl $__PAGE_OFFSET, %esp
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jb ftrace_stub /* Paging not enabled yet? */
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cmpl $ftrace_stub, ftrace_trace_function
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jnz .Ltrace
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER
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cmpl $ftrace_stub, ftrace_graph_return
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jnz ftrace_graph_caller
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cmpl $ftrace_graph_entry_stub, ftrace_graph_entry
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jnz ftrace_graph_caller
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#endif
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.globl ftrace_stub
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ftrace_stub:
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ret
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/* taken from glibc */
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.Ltrace:
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pushl %eax
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pushl %ecx
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pushl %edx
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movl 0xc(%esp), %eax
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movl 0x4(%ebp), %edx
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subl $MCOUNT_INSN_SIZE, %eax
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call *ftrace_trace_function
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popl %edx
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popl %ecx
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popl %eax
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jmp ftrace_stub
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END(function_hook)
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#endif /* CONFIG_DYNAMIC_FTRACE */
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#endif /* CONFIG_FUNCTION_TRACER */
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER
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ENTRY(ftrace_graph_caller)
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pushl %eax
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pushl %ecx
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pushl %edx
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movl 3*4(%esp), %eax
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/* Even with frame pointers, fentry doesn't have one here */
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#ifdef CC_USING_FENTRY
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lea 4*4(%esp), %edx
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movl $0, %ecx
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#else
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lea 0x4(%ebp), %edx
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movl (%ebp), %ecx
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#endif
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subl $MCOUNT_INSN_SIZE, %eax
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call prepare_ftrace_return
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popl %edx
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popl %ecx
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popl %eax
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ret
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END(ftrace_graph_caller)
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.globl return_to_handler
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return_to_handler:
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pushl %eax
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pushl %edx
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#ifdef CC_USING_FENTRY
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movl $0, %eax
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#else
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movl %ebp, %eax
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#endif
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call ftrace_return_to_handler
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movl %eax, %ecx
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popl %edx
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popl %eax
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jmp *%ecx
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#endif
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