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/*
* Copyright (C) 2017 Steven Rostedt, VMware Inc.
*/
#include <linux/linkage.h>
#include <asm/page_types.h>
#include <asm/segment.h>
#include <asm/export.h>
#include <asm/ftrace.h>
#ifdef CC_USING_FENTRY
# define function_hook __fentry__
EXPORT_SYMBOL(__fentry__)
#else
# define function_hook mcount
EXPORT_SYMBOL(mcount)
#endif
#ifdef CONFIG_DYNAMIC_FTRACE
/* mcount uses a frame pointer even if CONFIG_FRAME_POINTER is not set */
#if !defined(CC_USING_FENTRY) || defined(CONFIG_FRAME_POINTER)
# define USING_FRAME_POINTER
#endif
#ifdef USING_FRAME_POINTER
# define MCOUNT_FRAME 1 /* using frame = true */
#else
# define MCOUNT_FRAME 0 /* using frame = false */
#endif
ENTRY(function_hook)
ret
END(function_hook)
ENTRY(ftrace_caller)
#ifdef USING_FRAME_POINTER
# ifdef CC_USING_FENTRY
/*
* Frame pointers are of ip followed by bp.
* Since fentry is an immediate jump, we are left with
* parent-ip, function-ip. We need to add a frame with
* parent-ip followed by ebp.
*/
pushl 4(%esp) /* parent ip */
pushl %ebp
movl %esp, %ebp
pushl 2*4(%esp) /* function ip */
# endif
/* For mcount, the function ip is directly above */
pushl %ebp
movl %esp, %ebp
#endif
pushl %eax
pushl %ecx
pushl %edx
pushl $0 /* Pass NULL as regs pointer */
#ifdef USING_FRAME_POINTER
/* Load parent ebp into edx */
movl 4*4(%esp), %edx
#else
/* There's no frame pointer, load the appropriate stack addr instead */
lea 4*4(%esp), %edx
#endif
movl (MCOUNT_FRAME+4)*4(%esp), %eax /* load the rip */
/* Get the parent ip */
movl 4(%edx), %edx /* edx has ebp */
movl function_trace_op, %ecx
subl $MCOUNT_INSN_SIZE, %eax
.globl ftrace_call
ftrace_call:
call ftrace_stub
addl $4, %esp /* skip NULL pointer */
popl %edx
popl %ecx
popl %eax
#ifdef USING_FRAME_POINTER
popl %ebp
# ifdef CC_USING_FENTRY
addl $4,%esp /* skip function ip */
popl %ebp /* this is the orig bp */
addl $4, %esp /* skip parent ip */
# endif
#endif
.Lftrace_ret:
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
.globl ftrace_graph_call
ftrace_graph_call:
jmp ftrace_stub
#endif
/* This is weak to keep gas from relaxing the jumps */
WEAK(ftrace_stub)
ret
END(ftrace_caller)
ENTRY(ftrace_regs_caller)
/*
* i386 does not save SS and ESP when coming from kernel.
* Instead, to get sp, ®s->sp is used (see ptrace.h).
* Unfortunately, that means eflags must be at the same location
* as the current return ip is. We move the return ip into the
* regs->ip location, and move flags into the return ip location.
*/
pushl $__KERNEL_CS
pushl 4(%esp) /* Save the return ip */
pushl $0 /* Load 0 into orig_ax */
pushl %gs
pushl %fs
pushl %es
pushl %ds
pushl %eax
/* Get flags and place them into the return ip slot */
pushf
popl %eax
movl %eax, 8*4(%esp)
pushl %ebp
pushl %edi
pushl %esi
pushl %edx
pushl %ecx
pushl %ebx
#ifdef CC_USING_FENTRY
/* Load 4 off of the parent ip addr into ebp */
lea 14*4(%esp), %ebp
#endif
movl 12*4(%esp), %eax /* Load ip (1st parameter) */
subl $MCOUNT_INSN_SIZE, %eax /* Adjust ip */
movl 0x4(%ebp), %edx /* Load parent ip (2nd parameter) */
movl function_trace_op, %ecx /* Save ftrace_pos in 3rd parameter */
pushl %esp /* Save pt_regs as 4th parameter */
GLOBAL(ftrace_regs_call)
call ftrace_stub
addl $4, %esp /* Skip pt_regs */
/* restore flags */
push 14*4(%esp)
popf
/* Move return ip back to its original location */
movl 12*4(%esp), %eax
movl %eax, 14*4(%esp)
popl %ebx
popl %ecx
popl %edx
popl %esi
popl %edi
popl %ebp
popl %eax
popl %ds
popl %es
popl %fs
popl %gs
/* use lea to not affect flags */
lea 3*4(%esp), %esp /* Skip orig_ax, ip and cs */
jmp .Lftrace_ret
#else /* ! CONFIG_DYNAMIC_FTRACE */
ENTRY(function_hook)
cmpl $__PAGE_OFFSET, %esp
jb ftrace_stub /* Paging not enabled yet? */
cmpl $ftrace_stub, ftrace_trace_function
jnz .Ltrace
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
cmpl $ftrace_stub, ftrace_graph_return
jnz ftrace_graph_caller
cmpl $ftrace_graph_entry_stub, ftrace_graph_entry
jnz ftrace_graph_caller
#endif
.globl ftrace_stub
ftrace_stub:
ret
/* taken from glibc */
.Ltrace:
pushl %eax
pushl %ecx
pushl %edx
movl 0xc(%esp), %eax
movl 0x4(%ebp), %edx
subl $MCOUNT_INSN_SIZE, %eax
call *ftrace_trace_function
popl %edx
popl %ecx
popl %eax
jmp ftrace_stub
END(function_hook)
#endif /* CONFIG_DYNAMIC_FTRACE */
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
ENTRY(ftrace_graph_caller)
pushl %eax
pushl %ecx
pushl %edx
movl 3*4(%esp), %eax
/* Even with frame pointers, fentry doesn't have one here */
#ifdef CC_USING_FENTRY
lea 4*4(%esp), %edx
movl $0, %ecx
#else
lea 0x4(%ebp), %edx
movl (%ebp), %ecx
#endif
subl $MCOUNT_INSN_SIZE, %eax
call prepare_ftrace_return
popl %edx
popl %ecx
popl %eax
ret
END(ftrace_graph_caller)
.globl return_to_handler
return_to_handler:
pushl %eax
pushl %edx
#ifdef CC_USING_FENTRY
movl $0, %eax
#else
movl %ebp, %eax
#endif
call ftrace_return_to_handler
movl %eax, %ecx
popl %edx
popl %eax
jmp *%ecx
#endif
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