351 lines
8.5 KiB
ArmAsm
351 lines
8.5 KiB
ArmAsm
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/* SPDX-License-Identifier: GPL-2.0 */
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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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#include <asm/export.h>
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#include <asm/nospec-branch.h>
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#include <asm/unwind_hints.h>
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#include <asm/frame.h>
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.code64
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.section .text, "ax"
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#ifdef CONFIG_FRAME_POINTER
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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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/* No need to save a stack frame */
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# define MCOUNT_FRAME_SIZE 0
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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 (FRAME_SIZE + 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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#ifdef CONFIG_FRAME_POINTER
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/* Save the original rbp */
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pushq %rbp
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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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/* 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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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 $(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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movq $0, ORIG_RAX(%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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#ifdef CONFIG_FRAME_POINTER
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movq MCOUNT_REG_SIZE-8(%rsp), %rdx
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#else
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movq %rbp, %rdx
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#endif
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movq %rdx, RBP(%rsp)
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/* Copy the parent address into %rsi (second parameter) */
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movq MCOUNT_REG_SIZE+8+\added(%rsp), %rsi
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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 save=0
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/* ftrace_regs_caller or frame pointers require this */
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movq RBP(%rsp), %rbp
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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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addq $MCOUNT_REG_SIZE-\save, %rsp
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.endm
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#ifdef CONFIG_DYNAMIC_FTRACE
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SYM_FUNC_START(__fentry__)
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RET
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SYM_FUNC_END(__fentry__)
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EXPORT_SYMBOL(__fentry__)
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SYM_FUNC_START(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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/* Stack - skipping return address of ftrace_caller */
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leaq MCOUNT_REG_SIZE+8(%rsp), %rcx
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movq %rcx, RSP(%rsp)
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SYM_INNER_LABEL(ftrace_caller_op_ptr, SYM_L_GLOBAL)
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ANNOTATE_NOENDBR
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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 */
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leaq (%rsp), %rcx
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/* Only ops with REGS flag set should have CS register set */
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movq $0, CS(%rsp)
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SYM_INNER_LABEL(ftrace_call, SYM_L_GLOBAL)
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ANNOTATE_NOENDBR
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call ftrace_stub
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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(%rsp)
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restore_mcount_regs
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/*
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* The code up to this label is copied into trampolines so
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* think twice before adding any new code or changing the
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* layout here.
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*/
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SYM_INNER_LABEL(ftrace_caller_end, SYM_L_GLOBAL)
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ANNOTATE_NOENDBR
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jmp ftrace_epilogue
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SYM_FUNC_END(ftrace_caller);
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STACK_FRAME_NON_STANDARD_FP(ftrace_caller)
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SYM_FUNC_START(ftrace_epilogue)
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/*
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* This is weak to keep gas from relaxing the jumps.
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*/
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SYM_INNER_LABEL_ALIGN(ftrace_stub, SYM_L_WEAK)
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UNWIND_HINT_FUNC
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ENDBR
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RET
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SYM_FUNC_END(ftrace_epilogue)
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SYM_FUNC_START(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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SYM_INNER_LABEL(ftrace_regs_caller_op_ptr, SYM_L_GLOBAL)
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ANNOTATE_NOENDBR
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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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ENCODE_FRAME_POINTER
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/* regs go into 4th parameter */
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leaq (%rsp), %rcx
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SYM_INNER_LABEL(ftrace_regs_call, SYM_L_GLOBAL)
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ANNOTATE_NOENDBR
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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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movq ORIG_RAX(%rsp), %rax
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movq %rax, MCOUNT_REG_SIZE-8(%rsp)
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/*
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* If ORIG_RAX is anything but zero, make this a call to that.
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* See arch_ftrace_set_direct_caller().
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*/
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testq %rax, %rax
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SYM_INNER_LABEL(ftrace_regs_caller_jmp, SYM_L_GLOBAL)
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ANNOTATE_NOENDBR
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jnz 1f
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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_epilogue 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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SYM_INNER_LABEL(ftrace_regs_caller_end, SYM_L_GLOBAL)
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ANNOTATE_NOENDBR
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jmp ftrace_epilogue
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/* Swap the flags with orig_rax */
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1: movq MCOUNT_REG_SIZE(%rsp), %rdi
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movq %rdi, MCOUNT_REG_SIZE-8(%rsp)
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movq %rax, MCOUNT_REG_SIZE(%rsp)
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restore_mcount_regs 8
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/* Restore flags */
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popfq
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UNWIND_HINT_FUNC
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jmp ftrace_epilogue
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SYM_FUNC_END(ftrace_regs_caller)
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STACK_FRAME_NON_STANDARD_FP(ftrace_regs_caller)
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#else /* ! CONFIG_DYNAMIC_FTRACE */
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SYM_FUNC_START(__fentry__)
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cmpq $ftrace_stub, ftrace_trace_function
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jnz trace
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SYM_INNER_LABEL(ftrace_stub, SYM_L_GLOBAL)
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ENDBR
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RET
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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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/*
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* When DYNAMIC_FTRACE is not defined, ARCH_SUPPORTS_FTRACE_OPS is not
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* set (see include/asm/ftrace.h and include/linux/ftrace.h). Only the
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* ip and parent ip are used and the list function is called when
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* function tracing is enabled.
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*/
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movq ftrace_trace_function, %r8
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CALL_NOSPEC r8
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restore_mcount_regs
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jmp ftrace_stub
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SYM_FUNC_END(__fentry__)
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EXPORT_SYMBOL(__fentry__)
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STACK_FRAME_NON_STANDARD_FP(__fentry__)
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#endif /* CONFIG_DYNAMIC_FTRACE */
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER
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SYM_CODE_START(return_to_handler)
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UNWIND_HINT_EMPTY
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ANNOTATE_NOENDBR
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subq $16, %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 $16, %rsp
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/*
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* Jump back to the old return address. This cannot be JMP_NOSPEC rdi
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* since IBT would demand that contain ENDBR, which simply isn't so for
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* return addresses. Use a retpoline here to keep the RSB balanced.
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*/
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ANNOTATE_INTRA_FUNCTION_CALL
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call .Ldo_rop
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int3
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.Ldo_rop:
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mov %rdi, (%rsp)
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RET
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SYM_CODE_END(return_to_handler)
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#endif
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