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353 lines
8.5 KiB
353 lines
8.5 KiB
/* 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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retq |
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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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/* 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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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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jmp ftrace_epilogue |
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SYM_FUNC_END(ftrace_caller); |
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SYM_FUNC_START(ftrace_epilogue) |
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER |
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SYM_INNER_LABEL(ftrace_graph_call, SYM_L_GLOBAL) |
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jmp ftrace_stub |
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#endif |
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/* |
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* This is weak to keep gas from relaxing the jumps. |
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* It is also used to copy the retq for trampolines. |
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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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retq |
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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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/* 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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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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movq ORIG_RAX(%rsp), %rax |
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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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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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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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#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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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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SYM_INNER_LABEL(ftrace_stub, SYM_L_GLOBAL) |
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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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/* |
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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 fgraph_trace |
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SYM_FUNC_END(__fentry__) |
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EXPORT_SYMBOL(__fentry__) |
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#endif /* CONFIG_DYNAMIC_FTRACE */ |
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER |
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SYM_FUNC_START(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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leaq MCOUNT_REG_SIZE+8(%rsp), %rsi |
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movq $0, %rdx /* No framepointers needed */ |
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call prepare_ftrace_return |
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restore_mcount_regs |
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retq |
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SYM_FUNC_END(ftrace_graph_caller) |
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SYM_FUNC_START(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_NOSPEC rdi |
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SYM_FUNC_END(return_to_handler) |
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#endif
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