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6a06bdbf7f
The function graph helper function prepare_ftrace_return() which does the work to hijack the parent pointer has that parent pointer as its first parameter. Instead, if we make it the second parameter and have ip as the first parameter (self_addr), then it can use the %rdi from save_mcount_regs that loads it already. Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1411262304010.3961@nanos Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
327 lines
7.4 KiB
ArmAsm
327 lines
7.4 KiB
ArmAsm
/*
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* linux/arch/x86_64/mcount_64.S
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*
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* Copyright (C) 2014 Steven Rostedt, Red Hat Inc
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*/
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#include <linux/linkage.h>
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#include <asm/ptrace.h>
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#include <asm/ftrace.h>
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.code64
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.section .entry.text, "ax"
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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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#else
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# define function_hook mcount
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#endif
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/* All cases save the original rbp (8 bytes) */
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#ifdef CONFIG_FRAME_POINTER
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# ifdef CC_USING_FENTRY
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/* Save parent and function stack frames (rip and rbp) */
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# define MCOUNT_FRAME_SIZE (8+16*2)
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# else
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/* Save just function stack frame (rip and rbp) */
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# define MCOUNT_FRAME_SIZE (8+16)
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# endif
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#else
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/* No need to save a stack frame */
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# define MCOUNT_FRAME_SIZE 8
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#endif /* CONFIG_FRAME_POINTER */
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/* Size of stack used to save mcount regs in save_mcount_regs */
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#define MCOUNT_REG_SIZE (SS+8 + MCOUNT_FRAME_SIZE)
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/*
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* gcc -pg option adds a call to 'mcount' in most functions.
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* When -mfentry is used, the call is to 'fentry' and not 'mcount'
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* and is done before the function's stack frame is set up.
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* They both require a set of regs to be saved before calling
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* any C code and restored before returning back to the function.
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*
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* On boot up, all these calls are converted into nops. When tracing
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* is enabled, the call can jump to either ftrace_caller or
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* ftrace_regs_caller. Callbacks (tracing functions) that require
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* ftrace_regs_caller (like kprobes) need to have pt_regs passed to
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* it. For this reason, the size of the pt_regs structure will be
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* allocated on the stack and the required mcount registers will
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* be saved in the locations that pt_regs has them in.
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*/
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/*
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* @added: the amount of stack added before calling this
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*
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* After this is called, the following registers contain:
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*
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* %rdi - holds the address that called the trampoline
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* %rsi - holds the parent function (traced function's return address)
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* %rdx - holds the original %rbp
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*/
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.macro save_mcount_regs added=0
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/* Always save the original rbp */
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pushq %rbp
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#ifdef CONFIG_FRAME_POINTER
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/*
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* Stack traces will stop at the ftrace trampoline if the frame pointer
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* is not set up properly. If fentry is used, we need to save a frame
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* pointer for the parent as well as the function traced, because the
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* fentry is called before the stack frame is set up, where as mcount
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* is called afterward.
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*/
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#ifdef CC_USING_FENTRY
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/* Save the parent pointer (skip orig rbp and our return address) */
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pushq \added+8*2(%rsp)
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pushq %rbp
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movq %rsp, %rbp
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/* Save the return address (now skip orig rbp, rbp and parent) */
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pushq \added+8*3(%rsp)
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#else
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/* Can't assume that rip is before this (unless added was zero) */
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pushq \added+8(%rsp)
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#endif
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pushq %rbp
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movq %rsp, %rbp
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#endif /* CONFIG_FRAME_POINTER */
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/*
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* We add enough stack to save all regs.
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*/
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subq $(MCOUNT_REG_SIZE - MCOUNT_FRAME_SIZE), %rsp
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movq %rax, RAX(%rsp)
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movq %rcx, RCX(%rsp)
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movq %rdx, RDX(%rsp)
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movq %rsi, RSI(%rsp)
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movq %rdi, RDI(%rsp)
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movq %r8, R8(%rsp)
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movq %r9, R9(%rsp)
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/*
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* Save the original RBP. Even though the mcount ABI does not
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* require this, it helps out callers.
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*/
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movq MCOUNT_REG_SIZE-8(%rsp), %rdx
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movq %rdx, RBP(%rsp)
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/* Copy the parent address into %rsi (second parameter) */
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#ifdef CC_USING_FENTRY
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movq MCOUNT_REG_SIZE+8+\added(%rsp), %rsi
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#else
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/* %rdx contains original %rbp */
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movq 8(%rdx), %rsi
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#endif
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/* Move RIP to its proper location */
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movq MCOUNT_REG_SIZE+\added(%rsp), %rdi
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movq %rdi, RIP(%rsp)
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/*
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* Now %rdi (the first parameter) has the return address of
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* where ftrace_call returns. But the callbacks expect the
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* address of the call itself.
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*/
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subq $MCOUNT_INSN_SIZE, %rdi
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.endm
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.macro restore_mcount_regs
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movq R9(%rsp), %r9
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movq R8(%rsp), %r8
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movq RDI(%rsp), %rdi
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movq RSI(%rsp), %rsi
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movq RDX(%rsp), %rdx
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movq RCX(%rsp), %rcx
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movq RAX(%rsp), %rax
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/* ftrace_regs_caller can modify %rbp */
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movq RBP(%rsp), %rbp
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addq $MCOUNT_REG_SIZE, %rsp
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.endm
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#ifdef CONFIG_DYNAMIC_FTRACE
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ENTRY(function_hook)
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retq
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END(function_hook)
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ENTRY(ftrace_caller)
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/* save_mcount_regs fills in first two parameters */
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save_mcount_regs
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GLOBAL(ftrace_caller_op_ptr)
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/* Load the ftrace_ops into the 3rd parameter */
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movq function_trace_op(%rip), %rdx
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/* regs go into 4th parameter (but make it NULL) */
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movq $0, %rcx
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GLOBAL(ftrace_call)
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call ftrace_stub
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restore_mcount_regs
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/*
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* The copied trampoline must call ftrace_return as it
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* still may need to call the function graph tracer.
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*/
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GLOBAL(ftrace_caller_end)
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GLOBAL(ftrace_return)
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER
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GLOBAL(ftrace_graph_call)
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jmp ftrace_stub
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#endif
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GLOBAL(ftrace_stub)
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retq
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END(ftrace_caller)
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ENTRY(ftrace_regs_caller)
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/* Save the current flags before any operations that can change them */
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pushfq
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/* added 8 bytes to save flags */
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save_mcount_regs 8
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/* save_mcount_regs fills in first two parameters */
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GLOBAL(ftrace_regs_caller_op_ptr)
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/* Load the ftrace_ops into the 3rd parameter */
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movq function_trace_op(%rip), %rdx
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/* Save the rest of pt_regs */
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movq %r15, R15(%rsp)
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movq %r14, R14(%rsp)
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movq %r13, R13(%rsp)
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movq %r12, R12(%rsp)
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movq %r11, R11(%rsp)
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movq %r10, R10(%rsp)
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movq %rbx, RBX(%rsp)
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/* Copy saved flags */
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movq MCOUNT_REG_SIZE(%rsp), %rcx
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movq %rcx, EFLAGS(%rsp)
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/* Kernel segments */
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movq $__KERNEL_DS, %rcx
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movq %rcx, SS(%rsp)
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movq $__KERNEL_CS, %rcx
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movq %rcx, CS(%rsp)
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/* Stack - skipping return address and flags */
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leaq MCOUNT_REG_SIZE+8*2(%rsp), %rcx
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movq %rcx, RSP(%rsp)
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/* regs go into 4th parameter */
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leaq (%rsp), %rcx
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GLOBAL(ftrace_regs_call)
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call ftrace_stub
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/* Copy flags back to SS, to restore them */
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movq EFLAGS(%rsp), %rax
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movq %rax, MCOUNT_REG_SIZE(%rsp)
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/* Handlers can change the RIP */
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movq RIP(%rsp), %rax
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movq %rax, MCOUNT_REG_SIZE+8(%rsp)
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/* restore the rest of pt_regs */
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movq R15(%rsp), %r15
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movq R14(%rsp), %r14
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movq R13(%rsp), %r13
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movq R12(%rsp), %r12
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movq R10(%rsp), %r10
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movq RBX(%rsp), %rbx
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restore_mcount_regs
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/* Restore flags */
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popfq
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/*
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* As this jmp to ftrace_return can be a short jump
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* it must not be copied into the trampoline.
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* The trampoline will add the code to jump
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* to the return.
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*/
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GLOBAL(ftrace_regs_caller_end)
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jmp ftrace_return
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END(ftrace_regs_caller)
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#else /* ! CONFIG_DYNAMIC_FTRACE */
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ENTRY(function_hook)
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cmpq $ftrace_stub, ftrace_trace_function
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jnz trace
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fgraph_trace:
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER
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cmpq $ftrace_stub, ftrace_graph_return
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jnz ftrace_graph_caller
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cmpq $ftrace_graph_entry_stub, ftrace_graph_entry
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jnz ftrace_graph_caller
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#endif
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GLOBAL(ftrace_stub)
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retq
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trace:
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/* save_mcount_regs fills in first two parameters */
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save_mcount_regs
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call *ftrace_trace_function
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restore_mcount_regs
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jmp fgraph_trace
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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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/* Saves rbp into %rdx and fills first parameter */
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save_mcount_regs
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#ifdef CC_USING_FENTRY
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leaq MCOUNT_REG_SIZE+8(%rsp), %rsi
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movq $0, %rdx /* No framepointers needed */
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#else
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/* Save address of the return address of traced function */
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leaq 8(%rdx), %rsi
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/* ftrace does sanity checks against frame pointers */
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movq (%rdx), %rdx
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#endif
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call prepare_ftrace_return
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restore_mcount_regs
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retq
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END(ftrace_graph_caller)
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GLOBAL(return_to_handler)
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subq $24, %rsp
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/* Save the return values */
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movq %rax, (%rsp)
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movq %rdx, 8(%rsp)
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movq %rbp, %rdi
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call ftrace_return_to_handler
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movq %rax, %rdi
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movq 8(%rsp), %rdx
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movq (%rsp), %rax
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addq $24, %rsp
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jmp *%rdi
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#endif
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